1
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Huang Y, Li W, Foo T, Ji JH, Wu B, Tomimatsu N, Fang Q, Gao B, Long M, Xu J, Maqbool R, Mukherjee B, Ni T, Alejo S, He Y, Burma S, Lan L, Xia B, Zhao W. DSS1 restrains BRCA2's engagement with dsDNA for homologous recombination, replication fork protection, and R-loop homeostasis. Nat Commun 2024; 15:7081. [PMID: 39152168 PMCID: PMC11329725 DOI: 10.1038/s41467-024-51557-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 08/09/2024] [Indexed: 08/19/2024] Open
Abstract
DSS1, essential for BRCA2-RAD51 dependent homologous recombination (HR), associates with the helical domain (HD) and OB fold 1 (OB1) of the BRCA2 DSS1/DNA-binding domain (DBD) which is frequently targeted by cancer-associated pathogenic variants. Herein, we reveal robust ss/dsDNA binding abilities in HD-OB1 subdomains and find that DSS1 shuts down HD-OB1's DNA binding to enable ssDNA targeting of the BRCA2-RAD51 complex. We show that C-terminal helix mutations of DSS1, including the cancer-associated R57Q mutation, disrupt this DSS1 regulation and permit dsDNA binding of HD-OB1/BRCA2-DBD. Importantly, these DSS1 mutations impair BRCA2/RAD51 ssDNA loading and focus formation and cause decreased HR efficiency, destabilization of stalled forks and R-loop accumulation, and hypersensitize cells to DNA-damaging agents. We propose that DSS1 restrains the intrinsic dsDNA binding of BRCA2-DBD to ensure BRCA2/RAD51 targeting to ssDNA, thereby promoting optimal execution of HR, and potentially replication fork protection and R-loop suppression.
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Affiliation(s)
- Yuxin Huang
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
| | - Wenjing Li
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
| | - Tzeh Foo
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, NJ, 08903, USA
| | - Jae-Hoon Ji
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Bo Wu
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
| | - Nozomi Tomimatsu
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Qingming Fang
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Boya Gao
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129, USA
| | - Melissa Long
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129, USA
| | - Jingfei Xu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Rouf Maqbool
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
| | - Bipasha Mukherjee
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, NJ, 08903, USA
| | - Tengyang Ni
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
| | - Salvador Alejo
- Department of Obstetrics & Gynecology, University of Texas Health Science Center, San Antonio, TX, 78229, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Sandeep Burma
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA
| | - Li Lan
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02129, USA
- Department of Molecular Genetics and Microbiology, School of Medicine, Duke University, Durham, NC, 27710, USA
| | - Bing Xia
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, NJ, 08903, USA
| | - Weixing Zhao
- Department of Biochemistry and Structural Biology, University of Texas Health and Science Center, San Antonio, TX, 78229, USA.
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA.
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2
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Alvaro-Aranda L, Petitalot A, Djeghmoum Y, Panigada D, Singh J, Ehlén Å, Vugic D, Martin C, Miron S, Contreras-Perez A, Nhiri N, Boucherit V, Lafitte P, Dumoulin I, Quiles F, Rouleau E, Jacquet E, Feliubadaló L, del Valle J, Sharan SK, Stoppa-Lyonnet D, Zinn-Justin S, Lázaro C, Caputo S, Carreira A. The BRCA2 R2645G variant increases DNA binding and induces hyper-recombination. Nucleic Acids Res 2024; 52:6964-6976. [PMID: 38142462 PMCID: PMC11229362 DOI: 10.1093/nar/gkad1222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/30/2023] [Accepted: 12/12/2023] [Indexed: 12/26/2023] Open
Abstract
BRCA2 tumor suppressor protein ensures genome integrity by mediating DNA repair via homologous recombination (HR). This function is executed in part by its canonical DNA binding domain located at the C-terminus (BRCA2CTD), the only folded domain of the protein. Most germline pathogenic missense variants are located in this highly conserved region which binds to single-stranded DNA (ssDNA) and to the acidic protein DSS1. These interactions are essential for the HR function of BRCA2. Here, we report that the variant R2645G, identified in breast cancer and located at the DSS1 interface, unexpectedly increases the ssDNA binding activity of BRCA2CTDin vitro. Human cells expressing this variant display a hyper-recombination phenotype, chromosomal instability in the form of chromatid gaps when exposed to DNA damage, and increased PARP inhibitor sensitivity. In mouse embryonic stem cells (mES), this variant alters viability and confers sensitivity to cisplatin and Mitomycin C. These results suggest that BRCA2 interaction with ssDNA needs to be tightly regulated to limit HR and prevent chromosomal instability and we propose that this control mechanism involves DSS1. Given that several missense variants located within this region have been identified in breast cancer patients, these findings might have clinical implications for carriers.
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Affiliation(s)
- Lucia Alvaro-Aranda
- Genome Instability and Cancer Predisposition Laboratory, Centro de Biologia Molecular Severo Ochoa (CBMSO), CSIC-UAM, Madrid 28049, Spain
| | - Ambre Petitalot
- Department of Genetics, Institut Curie, Paris 75005, France
- PSL Research University, Paris 75005, France
| | - Yasmina Djeghmoum
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Davide Panigada
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Jenny Kaur Singh
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Åsa Ehlén
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Domagoj Vugic
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Charlotte Martin
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Simona Miron
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, 91190 Gif-sur-Yvette, France
| | - Aida Contreras-Perez
- Genome Instability and Cancer Predisposition Laboratory, Centro de Biologia Molecular Severo Ochoa (CBMSO), CSIC-UAM, Madrid 28049, Spain
| | - Naima Nhiri
- Institut de Chimie des Substances Naturelles, Paris-Saclay University, CNRS, 91190 Gif-sur-Yvette, France
| | - Virginie Boucherit
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Philippe Lafitte
- Department of Genetics, Institut Curie, Paris 75005, France
- PSL Research University, Paris 75005, France
| | - Isaac Dumoulin
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Francisco Quiles
- Hereditary Cancer Program, Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain
- Ciber Oncología (CIBERONC), Instituto Salud Carlos III, Madrid, Spain
| | - Etienne Rouleau
- Department of Genetics, Institut Curie, Paris 75005, France
- PSL Research University, Paris 75005, France
| | - Eric Jacquet
- Institut de Chimie des Substances Naturelles, Paris-Saclay University, CNRS, 91190 Gif-sur-Yvette, France
| | - Lidia Feliubadaló
- Hereditary Cancer Program, Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain
- Ciber Oncología (CIBERONC), Instituto Salud Carlos III, Madrid, Spain
| | - Jesús del Valle
- Hereditary Cancer Program, Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain
- Ciber Oncología (CIBERONC), Instituto Salud Carlos III, Madrid, Spain
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Dominique Stoppa-Lyonnet
- Department of Genetics, Institut Curie, Paris 75005, France
- Paris-Cité University, Paris, France
- INSERM U830, Institut Curie, Paris 75005, France
| | - Sophie Zinn-Justin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Paris-Saclay University, 91190 Gif-sur-Yvette, France
| | - Conxi Lázaro
- Hereditary Cancer Program, Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), L’Hospitalet de Llobregat, Spain
- Ciber Oncología (CIBERONC), Instituto Salud Carlos III, Madrid, Spain
| | - Sandrine M Caputo
- Department of Genetics, Institut Curie, Paris 75005, France
- PSL Research University, Paris 75005, France
| | - Aura Carreira
- Genome Instability and Cancer Predisposition Laboratory, Centro de Biologia Molecular Severo Ochoa (CBMSO), CSIC-UAM, Madrid 28049, Spain
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France
- Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
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3
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Freire MV, Martin M, Segers K, Sepulchre E, Leroi N, Coupier J, Kalantari HR, Wolter P, Collignon J, Polus M, Plomteux O, Josse C, Bours V. Digenic Inheritance of Mutations in Homologous Recombination Genes in Cancer Patients. J Pers Med 2024; 14:584. [PMID: 38929805 PMCID: PMC11204488 DOI: 10.3390/jpm14060584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Revised: 05/21/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
BACKGROUND/OBJECTIVES BRCA1, BRCA2, ATM, and CHEK2 are known cancer predisposition genes (CPGs), but tumor risk in patients with simultaneous pathogenic variants (PVs) in CPGs remains largely unknown. In this study, we describe six patients from five families with multiple cancers who coinherited a combination of PVs in these genes. METHODS PVs were identified using NGS DNA sequencing and were confirmed by Sanger. RESULTS Families 1, 2, and 3 presented PVs in BRCA2 and ATM, family 4 in BRCA2 and BRCA1, and family 5 in BRCA2 and CHEK2. PVs were identified using NGS DNA sequencing and were confirmed by Sanger. The first family included patients with kidney, prostate, and breast cancer, in addition to pancreatic adenocarcinomas. In the second family, a female had breast cancer, while a male from the third family had prostate, gastric, and pancreatic cancer. The fourth family included a male with pancreatic cancer, and the fifth family a female with breast cancer. CONCLUSIONS The early age of diagnosis and the development of multiple cancers in the reported patients indicate a very high risk of cancer in double-heterozygous patients associated with PVs in HR-related CPGs. Therefore, in families with patients who differ from other family members in terms of phenotype, age of diagnosis, or type of cancer, the cascade testing needs to include the study of other CPGs.
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Affiliation(s)
- Maria Valeria Freire
- Department of Human Genetics, GIGA Research Center, University of Liège and CHU Liège, Av. Hippocrate 1/11, 4000 Liège, Belgium;
| | - Marie Martin
- Department of Human Genetics, CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (M.M.); (K.S.); (E.S.); (N.L.)
| | - Karin Segers
- Department of Human Genetics, CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (M.M.); (K.S.); (E.S.); (N.L.)
| | - Edith Sepulchre
- Department of Human Genetics, CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (M.M.); (K.S.); (E.S.); (N.L.)
| | - Natacha Leroi
- Department of Human Genetics, CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (M.M.); (K.S.); (E.S.); (N.L.)
| | - Jérôme Coupier
- Department of Human Genetics, CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (M.M.); (K.S.); (E.S.); (N.L.)
| | | | - Pascal Wolter
- Onco-Hematology Department, St Nikolaus Hospital, Hufengasse 4/8, 4700 Eupen, Belgium;
| | - Joëlle Collignon
- Department of Medical Oncology, GIGA Research Center, University of Liège and CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (J.C.); (C.J.)
| | - Marc Polus
- Department of Gastroenterology, CHU Liège, Av. Hippocrate 1/11, 4000 Liège, Belgium;
| | - Olivier Plomteux
- Gastro-Enterology Department, CHC, Boulevard Patience et Beaujonc 2, 4000 Liège, Belgium;
| | - Claire Josse
- Department of Medical Oncology, GIGA Research Center, University of Liège and CHU Liège, Domaine Universitaire, 4000 Liège, Belgium; (J.C.); (C.J.)
| | - Vincent Bours
- Department of Human Genetics, GIGA Research Center, University of Liège and CHU Liège, Av. Hippocrate 1/11, 4000 Liège, Belgium;
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4
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Grigore LG, Radoi VE, Serban A, Mihai AD, Stoica I. The Molecular Detection of Germline Mutations in the BRCA1 and BRCA2 Genes Associated with Breast and Ovarian Cancer in a Romanian Cohort of 616 Patients. Curr Issues Mol Biol 2024; 46:4630-4645. [PMID: 38785549 PMCID: PMC11119367 DOI: 10.3390/cimb46050281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024] Open
Abstract
The objective of this study was to identify and classify the spectrum of mutations found in the BRCA1 and BRCA2 genes associated with breast and ovarian cancer in female patients in Romania. Germline BRCA1 and BRCA2 mutations were investigated in a cohort of 616 female patients using NGS and/or MLPA methods followed by software-based data analysis and classification according to international guidelines. Out of the 616 female patients included in this study, we found that 482 patients (78.2%) did not have any mutation present in the two genes investigated; 69 patients (11.2%) had a BRCA1 mutation, 34 (5.5%) had a BRCA2 mutation, and 31 (5%) presented different type of mutations with uncertain clinical significance, moderate risk or a large mutation in the BRCA1 gene. Our investigation indicates the most common mutations in the BRCA1 and BRCA2 genes, associated with breast and ovarian cancer in the Romanian population. Our results also bring more data in support of the frequency of the c.5266 mutation in the BRCA1 gene, acknowledged in the literature as a founder mutation in Eastern Europe. We consider that the results of our study will provide necessary data regarding BRCA1 and BRCA2 mutations that would help to create a genetic database for the Romanian population.
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Affiliation(s)
- Liliana-Georgiana Grigore
- Doctoral School of Biology, Faculty of Biology, University of Bucharest, 030018 Bucharest, Romania
- Personal Genetics, 010987 Bucharest, Romania
| | - Viorica-Elena Radoi
- Department of Medical Genetics, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
- “Alessandrescu-Rusescu” National Institute for Maternal and Child Health, 20382 Bucharest, Romania
| | | | | | - Ileana Stoica
- Department of Genetics, Faculty of Biology, University of Bucharest, 030018 Bucharest, Romania
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5
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Syed RU, Afsar S, Aboshouk NAM, Salem Alanzi S, Abdalla RAH, Khalifa AAS, Enrera JA, Elafandy NM, Abdalla RAH, Ali OHH, Satheesh Kumar G, Alshammari MD. LncRNAs in necroptosis: Deciphering their role in cancer pathogenesis and therapy. Pathol Res Pract 2024; 256:155252. [PMID: 38479121 DOI: 10.1016/j.prp.2024.155252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 03/02/2024] [Accepted: 03/04/2024] [Indexed: 04/14/2024]
Abstract
Necroptosis, a controlled type of cell death that is different from apoptosis, has become a key figure in the aetiology of cancer and offers a possible target for treatment. A growing number of biological activities, including necroptosis, have been linked to long noncoding RNAs (lncRNAs), a varied family of RNA molecules with limited capacity to code for proteins. The complex interactions between LncRNAs and important molecular effectors of necroptosis, including mixed lineage kinase domain-like pseudokinase (MLKL) and receptor-interacting protein kinase 3 (RIPK3), will be investigated. We will explore the many methods that LncRNAs use to affect necroptosis, including protein-protein interactions, transcriptional control, and post-transcriptional modification. Additionally, the deregulation of certain LncRNAs in different forms of cancer will be discussed, highlighting their dual function in influencing necroptotic processes as tumour suppressors and oncogenes. The goal of this study is to thoroughly examine the complex role that LncRNAs play in controlling necroptotic pathways and how that regulation affects the onset and spread of cancer. In the necroptosis for cancer treatment, this review will also provide insight into the possible therapeutic uses of targeting LncRNAs. Techniques utilising LncRNA-based medicines show promise in controlling necroptotic pathways to prevent cancer from spreading and improve the effectiveness of treatment.
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Affiliation(s)
- Rahamat Unissa Syed
- Department of Pharmaceutics, College of Pharmacy, University of Ha'il, Hail 81442, Saudi Arabia.
| | - S Afsar
- Department of Virology, Sri Venkateswara University, Tirupathi, Andhra Pradesh 517502, India.
| | - Nayla Ahmed Mohammed Aboshouk
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | | | | | - Amna Abakar Suleiman Khalifa
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | - Jerlyn Apatan Enrera
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | - Nancy Mohammad Elafandy
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | - Randa Abdeen Husien Abdalla
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | - Omar Hafiz Haj Ali
- Department of Clinical laboratory Sciences, College of Applied Medical Sciences, University of Hail, Hail 81442, Saudi Arabia
| | - G Satheesh Kumar
- Department of Pharmaceutical Chemistry, College of Pharmacy, Seven Hills College of Pharmacy, Venkataramapuram, Tirupati, India
| | - Maali D Alshammari
- Department of Pharmaceutical Chemistry, College of Pharmacy, University of Hail, Hail 81442, Saudi Arabia
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6
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Hu C, Huang H, Na J, Lumby C, Abozaid M, Holdren MA, Rao TJ, Karam R, Pesaran T, Weyandt JD, Csuy CM, Seelaus CA, Young CC, Fulk K, Heidari Z, Morais Lyra PC, Couch RE, Persons B, Polley EC, Gnanaolivu RD, Boddicker NJ, Monteiro ANA, Yadav S, Domchek SM, Richardson ME, Couch FJ. Functional analysis and clinical classification of 462 germline BRCA2 missense variants affecting the DNA binding domain. Am J Hum Genet 2024; 111:584-593. [PMID: 38417439 PMCID: PMC10940015 DOI: 10.1016/j.ajhg.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 02/01/2024] [Accepted: 02/01/2024] [Indexed: 03/01/2024] Open
Abstract
Variants of uncertain significance (VUSs) in BRCA2 are a common result of hereditary cancer genetic testing. While more than 4,000 unique VUSs, comprised of missense or intronic variants, have been identified in BRCA2, the few missense variants now classified clinically as pathogenic or likely pathogenic are predominantly located in the region encoding the C-terminal DNA binding domain (DBD). We report on functional evaluation of the influence of 462 BRCA2 missense variants affecting the DBD on DNA repair activity of BRCA2 using a homology-directed DNA double-strand break repair assay. Of these, 137 were functionally abnormal, 313 were functionally normal, and 12 demonstrated intermediate function. Comparisons with other functional studies of BRCA2 missense variants yielded strong correlations. Sequence-based in silico prediction models had high sensitivity, but limited specificity, relative to the homology-directed repair assay. Combining the functional results with clinical and genetic data in an American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP)-like variant classification framework from a clinical testing laboratory, after excluding known splicing variants and functionally intermediate variants, classified 431 of 442 (97.5%) missense variants (129 as pathogenic/likely pathogenic and 302 as benign/likely benign). Functionally abnormal variants classified as pathogenic by ACMG/AMP rules were associated with a slightly lower risk of breast cancer (odds ratio [OR] 5.15, 95% confidence interval [CI] 3.43-7.83) than BRCA2 DBD protein truncating variants (OR 8.56, 95% CI 6.03-12.36). Overall, functional studies of BRCA2 variants using validated assays substantially improved the variant classification yield from ACMG/AMP models and are expected to improve clinical management of many individuals found to harbor germline BRCA2 missense VUS.
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Affiliation(s)
- Chunling Hu
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Huaizhi Huang
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Jie Na
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | - Carolyn Lumby
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Mohamed Abozaid
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Megan A Holdren
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Tara J Rao
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | | | | | | | | | | | | | - Kelly Fulk
- Ambry Genetics, Aliso Viejo, CA 92656, USA
| | | | | | - Ronan E Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Benjamin Persons
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA
| | - Eric C Polley
- Department of Public Health Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Rohan D Gnanaolivu
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | - Nicholas J Boddicker
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA
| | | | - Siddhartha Yadav
- Department of Medical Oncology, Mayo Clinic, Rochester, MN 55902, USA
| | - Susan M Domchek
- Division of Hematology Oncology, Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Fergus J Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55902, USA; Department of Quantitative Health Sciences, Mayo Clinic, Rochester, MN 55902, USA.
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7
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Minello A, Carreira A. BRCA1/2 Haploinsufficiency: Exploring the Impact of Losing one Allele. J Mol Biol 2024; 436:168277. [PMID: 37714298 DOI: 10.1016/j.jmb.2023.168277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/17/2023]
Abstract
Since their discovery in the late 20th century, significant progress has been made in elucidating the functions of the tumor suppressor proteins BRCA1 and BRCA2. These proteins play vital roles in maintaining genome integrity, including DNA repair, replication fork protection, and chromosome maintenance. It is well-established that germline mutations in BRCA1 and BRCA2 increase the risk of breast and ovarian cancer; however, the precise mechanism underlying tumor formation in this context is not fully understood. Contrary to the long-standing belief that the loss of the second wild-type allele is necessary for tumor development, a growing body of evidence suggests that tumorigenesis can occur despite the presence of a single functional allele. This entails that heterozygosity in BRCA1/2 confers haploinsufficiency, where a single copy of the gene is not sufficient to fully suppress tumor formation. Here we provide an overview of the findings and the ongoing debate regarding BRCA haploinsufficiency. We further put out the challenges in studying this topic and discuss its potential relevance in the prevention and treatment of BRCA-related cancers.
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Affiliation(s)
- Anna Minello
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France; Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France
| | - Aura Carreira
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405 Orsay, France; Paris-Saclay University CNRS, UMR3348, F-91405 Orsay, France; Genome Instability and Cancer Predisposition Lab, Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa (CBMSO, CSIC-UAM), Madrid 28049, Spain.
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8
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Militello AM, Orsi G, Cavaliere A, Niger M, Avallone A, Salvatore L, Tortora G, Rapposelli IG, Giordano G, Noventa S, Giommoni E, Bozzarelli S, Macchini M, Peretti U, Procaccio L, Puccini A, Cascinu S, Montagna C, Milella M, Reni M. Clinical outcomes and response to chemotherapy in a cohort of pancreatic cancer patients with germline variants of unknown significance (VUS) in BRCA1 and BRCA2 genes. Cancer Chemother Pharmacol 2023; 92:501-510. [PMID: 37725113 DOI: 10.1007/s00280-023-04585-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 08/22/2023] [Indexed: 09/21/2023]
Abstract
PURPOSE The clinical outcome and the efficacy of chemotherapy in pancreatic cancer patients with BRCA1/2 Variants of Unknown Significance (VUS) is unknown. We explored the effects of chemotherapy with or without Platinum in non metastatic and metastatic pancreatic cancer patients with BRCA1/2 VUS. METHODS A retrospective analysis of non-metastatic or metastatic pancreatic cancer patients with gBRCA1/2 VUS treated in 13 Italian centers between November 2015 and December 2020 was performed. All patients were assessed for toxicity and RECIST 1.1 response. Metastatic patients were evaluated for survival outcome. RESULTS 30 pancreatic cancer patients with gBRCA1/2 VUS were considered: 20 were M+ and 10 were non-M+. Pl-CT was recommended to 16 patients: 10 M+ (6 FOLFIRINOX and 4 PAXG) and 6 non-M+ (3 FOLFIRINOX and 3 PAXG); 11 patients received Nabpaclitaxel-Gemcitabine (AG; 8 M+) and 3 patients (2 M+) were treated with Gemcitabine (G). The RECIST 1.1 response rate was 27% for AG and 44% for Pl-CT (22% for (m) FOLFIRINOX and 71% PAXG). 1 year Progression-Free Survival was 37.5% for patients treated with AG and 33% in the Pl-CT subgroup. Median Overall Survival (OS) was 23.5 months for patients treated with AG and 14 months for the Pl-CT subgroup. 1 Year and 2 Year OS were numerically better for AG (1 Year OS: 75% vs 60% and 2 Year OS: 50% and 20% in AG and Pl-CT subgroups, respectively) as well. CONCLUSIONS Pl-CT does not seem to be associated with a better outcome compared to AG chemotherapy in PDAC patients with BRCA 1/2 VUS.
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Affiliation(s)
- Anna Maria Militello
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy
| | - Giulia Orsi
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy
| | - Alessandro Cavaliere
- Department of Oncology, University of Torino, Candiolo, Italy
- Candiolo Cancer Institute, FPO - IRCCS Candiolo, Candiolo, Italy
| | - Monica Niger
- Medical Oncology Department, Fondazione IRCCS Istituto Nazionale Dei Tumori Di Milano, Milan, Italy
| | - Antonio Avallone
- Biologia Cellulare e Bioterapie, Istituto Nazionale per lo Studio e la Cura dei Tumori ''Fondazione Giovanni Pascale'' - IRCCS, Naples, Italy
| | - Lisa Salvatore
- Unit of Medical Oncology, Comprehensive Cancer Center, Fondazione Policlinico Universitario, Agostino Gemelli IRCCS, Rome, Italy
- Università Cattolica del Sacro Cuore, Rome, Italy
| | - Giampaolo Tortora
- Unit of Medical Oncology, Comprehensive Cancer Center, Fondazione Policlinico Universitario, Agostino Gemelli IRCCS, Rome, Italy
- Università Cattolica del Sacro Cuore, Rome, Italy
| | - Ilario Giovanni Rapposelli
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) ''Dino Amadori'', Meldola, Italy
| | - Guido Giordano
- Unit of Medical Oncology and Biomolecular Therapy, Policlinico Riuniti, Foggia, Italy
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
| | - Silvia Noventa
- Department of Medical Oncology, Fondazione Poliambulanza Istituto Ospedaliero, Brescia, Italy
| | - Elisa Giommoni
- Medical Oncology Division, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
| | - Silvia Bozzarelli
- Department of Medical Oncology and Hematology, Humanitas Cancer Center, IRCCS Humanitas Research Hospital, Milan, Italy
| | - Marina Macchini
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy
| | - Umberto Peretti
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy
| | - Letizia Procaccio
- Medical Oncology 1 Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
- Department of Surgery, Oncology and Gastroenterology, University of Padova, Padua, Italy
| | - Alberto Puccini
- University of Genoa, Ospedale Policlinico San Martino IRCCS, Genoa, Italy
| | - Stefano Cascinu
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy
| | - Cristina Montagna
- Department of Radiation Oncology and Genomic Instability and Cancer Genetics, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
| | - Michele Milella
- Section of Oncology, Department of Medicine, University of Verona School of Medicine and Verona University Hospital Trust, Verona, Italy
| | - Michele Reni
- Department of Medical Oncology, IRCCS San Raffaele Scientific Institute, Vita-Salute University, Via Olgettina 60, 20123, Milan, Italy.
- Pancreas Translational & Clinical Research Center, San Raffaele Scientific Institute, Milan, Italy.
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9
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Mishra AP, Hartford S, Chittela RK, Sahu S, Kharat SS, Alvaro-Aranda L, Contreras-Perez A, Sullivan T, Martin BK, Albaugh M, Southon E, Burkett S, Karim B, Carreira A, Tessarollo L, Sharan SK. Characterization of BRCA2 R3052Q variant in mice supports its functional impact as a low-risk variant. Cell Death Dis 2023; 14:753. [PMID: 37980415 PMCID: PMC10657400 DOI: 10.1038/s41419-023-06289-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/29/2023] [Accepted: 11/07/2023] [Indexed: 11/20/2023]
Abstract
Pathogenic variants in BRCA2 are known to significantly increase the lifetime risk of developing breast and ovarian cancers. Sequencing-based genetic testing has resulted in the identification of thousands of BRCA2 variants that are considered to be variants of uncertain significance (VUS) because the disease risk associated with them is unknown. One such variant is p.Arg3052Gln, which has conflicting interpretations of pathogenicity in the ClinVar variant database. Arginine at position 3052 in BRCA2 plays an important role in stabilizing its C-terminal DNA binding domain. We have generated a knock-in mouse model expressing this variant to examine its role on growth and survival in vivo. Homozygous as well as hemizygous mutant mice are viable, fertile and exhibit no overt phenotype. While we did not observe any hematopoietic defects in adults, we did observe a marked reduction in the in vitro proliferative ability of fetal liver cells that were also hypersensitive to PARP inhibitor, olaparib. In vitro studies performed on embryonic and adult fibroblasts derived from the mutant mice showed significant reduction in radiation induced RAD51 foci formation as well as increased genomic instability after mitomycin C treatment. We observed mis-localization of a fraction of R3052Q BRCA2 protein to the cytoplasm which may explain the observed in vitro phenotypes. Our findings suggest that BRCA2 R3052Q should be considered as a hypomorphic variant.
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Affiliation(s)
- Arun Prakash Mishra
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Suzanne Hartford
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY, USA
| | - Rajani Kant Chittela
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Applied Genomics Section, Bhabha Atomic Research Center, Trombay, Mumbai, 400085, India
| | - Sounak Sahu
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Suhas S Kharat
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
| | - Lucia Alvaro-Aranda
- Genome Instability and Cancer Predisposition Lab, Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa (CBMSO, CSIC-UAM), Madrid, Spain
| | - Aida Contreras-Perez
- Genome Instability and Cancer Predisposition Lab, Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa (CBMSO, CSIC-UAM), Madrid, Spain
| | - Teresa Sullivan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Betty K Martin
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Mary Albaugh
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Eileen Southon
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Laboratory Animal Sciences Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Sandra Burkett
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Baktiar Karim
- Molecular Histotechnology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Aura Carreira
- Genome Instability and Cancer Predisposition Lab, Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa (CBMSO, CSIC-UAM), Madrid, Spain
| | - Lino Tessarollo
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA.
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10
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Khan MA, Varma AK. In silico and structure-based assessment to classify VUS identified in the α-helical domain of BRCA2. J Biomol Struct Dyn 2023; 41:9879-9889. [PMID: 36404616 DOI: 10.1080/07391102.2022.2148127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/10/2022] [Indexed: 11/22/2022]
Abstract
Breast cancer type 2 susceptibility (BRCA2) protein plays a crucial role in DNA double-strand breaks repair mechanism by homologous recombination. Pathogenic mutations in the BRCA2 gene confer an increased risk of hereditary breast and ovarian cancer (HBOC). Different missense mutations are identified from a larger cohort of patient populations in the BRCA2. However, most missense mutations are classified as 'Variants of Uncertain Significance' (VUS) due to a lack of data from structural, functional, and clinical assessments. Therefore, this study focused on assessing VUS identified in the α-helical domain of h-BRCA2 using different in silico tools and structure-based molecular dynamics simulation. A total of 286 identified VUS were evaluated using Align-GVGD, PROVEAN and PANTHER servers and 18 variants were predicted to be pathogenic. Further, out of 18 variants analyzed using the ConSurf server, 16 variants were found to be evolutionary conserved. These 16 conserved variants were submitted to PremPS and Dynamut server to assess the effect of the mutation at the protein structure level; 12 mutations were predicted to have a destabilizing effect on the native protein structure. Finally, molecular dynamics simulations revealed 5 variants BRCA2 Cys2646Tyr, Asp2665Val, Trp2619Arg, Trp2619Ser and Tyr2660Cys can alter the folding pattern and need further validation using in vitro, structural and in vivo studies to classify as pathogenic.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mudassar Ali Khan
- Tata Memorial Centre, Advanced Centre for Treatment, Research and Education in Cancer, Navi Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Mumbai, Maharashtra, India
| | - Ashok K Varma
- Tata Memorial Centre, Advanced Centre for Treatment, Research and Education in Cancer, Navi Mumbai, Maharashtra, India
- Homi Bhabha National Institute, Mumbai, Maharashtra, India
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11
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Nguyen TT, Hamdan D, Angeli E, Feugeas JP, Le QV, Pamoukdjian F, Bousquet G. Genomics of Breast Cancer Brain Metastases: A Meta-Analysis and Therapeutic Implications. Cancers (Basel) 2023; 15:cancers15061728. [PMID: 36980614 PMCID: PMC10046845 DOI: 10.3390/cancers15061728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/05/2023] [Accepted: 03/05/2023] [Indexed: 03/14/2023] Open
Abstract
Breast cancer brain metastases are a challenging daily practice, and the biological link between gene mutations and metastatic spread to the brain remains to be determined. Here, we performed a meta-analysis on genomic data obtained from primary tumors, extracerebral metastases and brain metastases, to identify gene alterations associated with metastatic processes in the brain. Articles with relevant findings were selected using Medline via PubMed, from January 1999 up to February 2022. A critical review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement (PRISMA). Fifty-seven publications were selected for this meta-analysis, including 37,218 patients in all, 11,906 primary tumor samples, 5541 extracerebral metastasis samples, and 1485 brain metastasis samples. We report the overall and sub-group prevalence of gene mutations, including comparisons between primary tumors, extracerebral metastases and brain metastases. In particular, we identified six genes with a higher mutation prevalence in brain metastases than in extracerebral metastases, with a potential role in metastatic processes in the brain: ESR1, ERBB2, EGFR, PTEN, BRCA2 and NOTCH1. We discuss here the therapeutic implications. Our results underline the added value of obtaining biopsies from brain metastases to fully explore their biology, in order to develop personalized treatments.
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Affiliation(s)
- Thuy Thi Nguyen
- National Cancer Hospital, Ha Noi 100000, Vietnam
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
- Department of Pediatrics, Hanoi Medical University, Ha Noi 100000, Vietnam
- Institut Galilée, Université Sorbonne Paris Nord, 93439 Villetaneuse, France
| | - Diaddin Hamdan
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
- Hôpital La Porte Verte, 78000 Versailles, France
| | - Eurydice Angeli
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
- Institut Galilée, Université Sorbonne Paris Nord, 93439 Villetaneuse, France
- Service d’Oncologie Médicale, Hôpital Avicenne, Assistance Publique Hôpitaux de Paris, 93000 Bobigny, France
| | - Jean-Paul Feugeas
- INSERM U1098, 25030 Besançon, France
- Laboratoire de Biochimie Hôpital Jean Minjoz, Université de Franche-Comté, 25000 Besançon, France
- Correspondence: (J.-P.F.); (G.B.)
| | - Quang Van Le
- National Cancer Hospital, Ha Noi 100000, Vietnam
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
| | - Frédéric Pamoukdjian
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
- Institut Galilée, Université Sorbonne Paris Nord, 93439 Villetaneuse, France
- Service de Médecine Gériatrique, Hôpital Avicenne, Assistance Publique Hôpitaux de Paris, 93000 Bobigny, France
| | - Guilhem Bousquet
- Institut National de la Santé Et de la Recherche Médicale (INSERM), Université Paris Cité, UMR_S942 MASCOT, 75006 Paris, France (F.P.)
- Institut Galilée, Université Sorbonne Paris Nord, 93439 Villetaneuse, France
- Service d’Oncologie Médicale, Hôpital Avicenne, Assistance Publique Hôpitaux de Paris, 93000 Bobigny, France
- Correspondence: (J.-P.F.); (G.B.)
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12
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Dong Z, Wang Y, Zhang J, Zhu F, Liu Z, Kang Y, Lin M, Shi H. Analyzing the effects of BRCA1/2 variants on mRNA splicing by minigene assay. J Hum Genet 2023; 68:65-71. [PMID: 36446827 DOI: 10.1038/s10038-022-01077-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/15/2022] [Accepted: 08/23/2022] [Indexed: 11/30/2022]
Abstract
As BRCA1/2 gene sequencing become more extensive, a large number VUS (variants of uncertain significance) emerge rapidly. Verifying the splicing effect is an effective means for VUS reclassification. The Minigene Assay platform was established and its reliability was verified in this article. 47 BRCA1 or BRCA2 variants were selected and performed to validate their effect on mRNA splicing. The results showed that, a total of 16 variants were experimentally proved to have effects on mRNA splicing, among which 14 variants were shown to cause truncated proteins by Sanger sequencing. While the other two variants, BRCA2 c.7976 + 3 A > G and BRCA1 c.5152 + 3_5152 + 4insT was analyzed to cause 57 bp and 26 bp base in-frame deletion, respectively. The remaining 31 variants were not shown to cause mRNA splicing abnormity, including several sites at the edge of exons, which were predicted to affect splicing of mRNA by multiple bioinformatic software. Based on our experimental results, 37 variants were reclassified by ACMG rules. Our study showed that experimental splicing analysis was effectual for variants classification, and multiple functional assay or clinical data were also necessary for comprehensive judgment of variants.
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Affiliation(s)
- Zhouhuan Dong
- The First Medical Center, Chinese PLA General Hospital & PLA Medical School, Beijing, 100853, PR China
| | - Yun Wang
- The First Medical Center, Chinese PLA General Hospital & PLA Medical School, Beijing, 100853, PR China
| | - Jing Zhang
- The First Medical Center, Chinese PLA General Hospital & PLA Medical School, Beijing, 100853, PR China
| | - Fengwei Zhu
- The First Medical Center, Chinese PLA General Hospital & PLA Medical School, Beijing, 100853, PR China
| | - Zhiyuan Liu
- Amoy Diagnostics Co., Ltd., Xiamen, 361027, PR China
| | - Yajun Kang
- Amoy Diagnostics Co., Ltd., Xiamen, 361027, PR China
| | - Mingyuan Lin
- Amoy Diagnostics Co., Ltd., Xiamen, 361027, PR China
| | - Huaiyin Shi
- The First Medical Center, Chinese PLA General Hospital & PLA Medical School, Beijing, 100853, PR China.
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13
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Replication gap suppression depends on the double-strand DNA binding activity of BRCA2. Nat Commun 2023; 14:446. [PMID: 36707518 PMCID: PMC9883520 DOI: 10.1038/s41467-023-36149-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 01/17/2023] [Indexed: 01/28/2023] Open
Abstract
Replication stress (RS) is a major source of genomic instability and is intrinsic to cancer cells. RS is also the consequence of chemotherapeutic drugs for treating cancer. However, adaptation to RS is also a mechanism of resistance to chemotherapy. BRCA2 deficiency results in replication stress in human cells. BRCA2 protein's main functions include DNA repair by homologous recombination (HR) both at induced DNA double-strand breaks (DSB) and spontaneous replicative lesions. At stalled replication forks, BRCA2 protects the DNA from aberrant nucleolytic degradation and is thought to limit the appearance of ssDNA gaps by arresting replication and via post-replicative HR. However, whether and how BRCA2 acts to limit the formation of ssDNA gaps or mediate their repair, remains ill-defined. Here, we use breast cancer variants affecting different domains of BRCA2 to shed light on this function. We demonstrate that the N-terminal DNA binding domain (NTD), and specifically, its dsDNA binding activity, is required to prevent and repair/fill-in ssDNA gaps upon nucleotide depletion but not to limit PARPi-induced ssDNA gaps. Thus, these findings suggest that nucleotide depletion and PARPi trigger gaps via distinct mechanisms and that the NTD of BRCA2 prevents nucleotide depletion-induced ssDNA gaps.
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14
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Jimenez-Sainz J, Mathew J, Moore G, Lahiri S, Garbarino J, Eder JP, Rothenberg E, Jensen RB. BRCA2 BRC missense variants disrupt RAD51-dependent DNA repair. eLife 2022; 11:e79183. [PMID: 36098506 PMCID: PMC9545528 DOI: 10.7554/elife.79183] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 09/12/2022] [Indexed: 11/24/2022] Open
Abstract
Pathogenic mutations in the BRCA2 tumor suppressor gene predispose to breast, ovarian, pancreatic, prostate, and other cancers. BRCA2 maintains genome stability through homology-directed repair (HDR) of DNA double-strand breaks (DSBs) and replication fork protection. Nonsense or frameshift mutations leading to truncation of the BRCA2 protein are typically considered pathogenic; however, missense mutations resulting in single amino acid substitutions can be challenging to functionally interpret. The majority of missense mutations in BRCA2 have been classified as Variants of Uncertain Significance (VUS) with unknown functional consequences. In this study, we identified three BRCA2 VUS located within the BRC repeat region to determine their impact on canonical HDR and fork protection functions. We provide evidence that S1221P and T1980I, which map to conserved residues in the BRC2 and BRC7 repeats, compromise the cellular response to chemotherapeutics and ionizing radiation, and display deficits in fork protection. We further demonstrate biochemically that S1221P and T1980I disrupt RAD51 binding and diminish the ability of BRCA2 to stabilize RAD51-ssDNA complexes. The third variant, T1346I, located within the spacer region between BRC2 and BRC3 repeats, is fully functional. We conclude that T1346I is a benign allele, whereas S1221P and T1980I are hypomorphic disrupting the ability of BRCA2 to fully engage and stabilize RAD51 nucleoprotein filaments. Our results underscore the importance of correctly classifying BRCA2 VUS as pathogenic variants can impact both future cancer risk and guide therapy selection during cancer treatment.
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Affiliation(s)
| | - Joshua Mathew
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Gemma Moore
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Sudipta Lahiri
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Jennifer Garbarino
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
| | - Joseph P Eder
- Department of Medical Oncology, Yale University School of Medicine, Yale Cancer CenterNew HavenUnited States
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York UniversityNew YorkUnited States
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale UniversityNew HavenUnited States
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15
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Hu C, Susswein LR, Roberts ME, Yang H, Marshall ML, Hiraki S, Berkofsky-Fessler W, Gupta S, Shen W, Dunn CA, Huang H, Na J, Domchek SM, Yadav S, Monteiro AN, Polley EC, Hart SN, Hruska KS, Couch FJ. Classification of BRCA2 Variants of Uncertain Significance (VUS) Using an ACMG/AMP Model Incorporating a Homology-Directed Repair (HDR) Functional Assay. Clin Cancer Res 2022; 28:3742-3751. [PMID: 35736817 PMCID: PMC9433957 DOI: 10.1158/1078-0432.ccr-22-0203] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/03/2022] [Accepted: 06/20/2022] [Indexed: 01/09/2023]
Abstract
PURPOSE The identification of variants of uncertain significance (VUS) in the BRCA1 and BRCA2 genes by hereditary cancer testing poses great challenges for the clinical management of variant carriers. The ACMG/AMP (American College of Medical Genetics and Genomics/Association for Molecular Pathology) variant classification framework, which incorporates multiple sources of evidence, has the potential to establish the clinical relevance of many VUS. We sought to classify the clinical relevance of 133 single-nucleotide substitution variants encoding missense variants in the DNA-binding domain (DBD) of BRCA2 by incorporating results from a validated functional assay into an ACMG/AMP-variant classification model from a hereditary cancer-testing laboratory. EXPERIMENTAL DESIGN The 133 selected VUS were evaluated using a validated homology-directed double-strand DNA break repair (HDR) functional assay. Results were combined with clinical and genetic data from variant carriers in a rules-based variant classification model for BRCA2. RESULTS Of 133 missense variants, 44 were designated as non-functional and 89 were designated as functional in the HDR assay. When combined with genetic and clinical information from a single diagnostic laboratory in an ACMG/AMP-variant classification framework, 66 variants previously classified by the diagnostic laboratory were correctly classified, and 62 of 67 VUS (92.5%) were reclassified as likely pathogenic (n = 22) or likely benign (n = 40). In total, 44 variants were classified as pathogenic/likely pathogenic, 84 as benign/likely benign, and 5 remained as VUS. CONCLUSIONS Incorporation of HDR functional analysis into an ACMG/AMP framework model substantially improves BRCA2 VUS re-classification and provides an important tool for determining the clinical relevance of individual BRCA2 VUS.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Wei Shen
- Mayo Clinic, Rochester, Minnesota
| | | | | | - Jie Na
- Mayo Clinic, Rochester, Minnesota
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16
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Shinde S, Satpute DP, Behera SK, Kumar D. Computational Biology of BRCA2 in Male Breast Cancer, through Prediction of Probable nsSNPs, and Hit Identification. ACS OMEGA 2022; 7:30447-30461. [PMID: 36061650 PMCID: PMC9434626 DOI: 10.1021/acsomega.2c03851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Male breast cancer (MBC) is a relatively rare disease, but emerging data recommend the development of novel therapeutics considering its alarming threats. Compared to female breast cancer (FBC), MBC is reportedly associated with inferior outcomes (poor survival) owing to their late diagnosis and lack of adequate treatment. Treatment typically correlates with FBC, involving surgical removal of the breast tissue along with chemo/hormonal/radiation therapy, the tamoxifen being a standard adjuvant. Considering the distinct immunophenotypic (implying different pathogenesis and progression) differences from FBC, the identification of diagnostics, prognostics, and therapeutics for MBC is highly desirable. In this context, we have analyzed the most deleterious nsSNPs of BRCA2, a human tumor suppressor gene constituting the potential biomarker for tumors including MBC, to predict the structural changes associated with the mutants hampering the normal protein-protein and protein-ligand interactions, resulting in MBC progression. Among 27 nsSNPs confined to 21 rsIDs pertaining to MBC, the 19 nsSNPs constituting 14 rsIDs have been predicted as highly deleterious. We believe that these nsSNPs could serve as potential biomarkers for diagnostic and prognostic purposes and could be the pivotal target for MBC drug discovery. Subsequently, the study highlights the exploration of the key nsSNPs (of BRCA2 associated with the MBC) and its applications toward the identification of therapeutic hit TIP006136 following the homology modeling, virtual screening of 5284 phytochemicals retrieved from the TIPdb (a database of phytochemicals from indigenous plants in Taiwan) database, molecular docking (against native and mutant BRCA2), dynamic simulations (against native and mutant BRCA2), density functional theory (DFT), and molecular electrostatic potential. To the best of our knowledge, this is the first report to use diverse computational modules to investigate the important nsSNPs of BRCA2 related to MBC, implying that TIP006136 could be a potential hit and must be studied further (in vitro and in vivo) to establish its anticancer property and efficacy against MBC.
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Affiliation(s)
- Sangita
Dattatray Shinde
- Department
of Medicinal Chemistry, National Institute
of Pharmaceutical Education and Research (NIPER) − Ahmadabad, Palaj, Gandhinagar 382355, Gujarat, India
| | - Dinesh Parshuram Satpute
- Department
of Medicinal Chemistry, National Institute
of Pharmaceutical Education and Research (NIPER) − Ahmadabad, Palaj, Gandhinagar 382355, Gujarat, India
| | - Santosh Kumar Behera
- Department
of Biotechnology, National Institute of
Pharmaceutical Education and Research (NIPER) − Ahmadabad, Palaj, Gandhinagar 382355, Gujarat, India
| | - Dinesh Kumar
- Department
of Medicinal Chemistry, National Institute
of Pharmaceutical Education and Research (NIPER) − Ahmadabad, Palaj, Gandhinagar 382355, Gujarat, India
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17
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Jimenez-Sainz J, Krysztofiak A, Garbarino J, Rogers F, Jensen RB. The Pathogenic R3052W BRCA2 Variant Disrupts Homology-Directed Repair by Failing to Localize to the Nucleus. Front Genet 2022; 13:884210. [PMID: 35711920 PMCID: PMC9197106 DOI: 10.3389/fgene.2022.884210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/22/2022] [Indexed: 12/04/2022] Open
Abstract
The BRCA2 germline missense variant, R3052W, resides in the DNA binding domain and has been previously classified as a pathogenic allele. In this study, we sought to determine how R3052W alters the cellular functions of BRCA2 in the DNA damage response. The BRCA2 R3052W mutated protein exacerbates genome instability, is unable to rescue homology-directed repair, and fails to complement cell survival following exposure to PARP inhibitors and crosslinking drugs. Surprisingly, despite anticipated defects in DNA binding or RAD51-mediated DNA strand exchange, the BRCA2 R3052W protein mislocalizes to the cytoplasm precluding its ability to perform any DNA repair functions. Rather than acting as a simple loss-of-function mutation, R3052W behaves as a dominant negative allele, likely by sequestering RAD51 in the cytoplasm.
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Affiliation(s)
| | | | | | | | - Ryan B. Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, United States
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18
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Khan MA, Siddiqui MQ, Kuligina E, Varma AK. Evaluation of conformational transitions of h-BRCA2 functional domain and unclassified variant Arg2502Cys using multimodal approach. Int J Biol Macromol 2022; 209:716-724. [PMID: 35413318 DOI: 10.1016/j.ijbiomac.2022.04.049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 04/02/2022] [Accepted: 04/06/2022] [Indexed: 11/26/2022]
Abstract
Breast cancer type 2 susceptibility (BRCA2) protein plays an essential role in the repair mechanism of DNA double-strand breaks and interstrand cross-links by Homologous recombination. Germline mutations identified in the BRCA2 gene confer an increased risk of hereditary breast and ovarian cancer. Missense mutations are identified all over the gene, including the DNA binding region of BRCA2 that interacts with FANCD2. However, the majority of these missense mutations are classified as 'Variants of Uncertain Significance' due to a lack of structural, functional and clinical correlations. Therefore, multi-disciplinary in-silico, in-vitro and biophysical approaches have been explored to characterize an unclassified missense mutation, BRCA2 Arg2502Cys, identified from a case-control study. Circular-dichroism and Fluorescence spectroscopy show that the Arg2502Cys mutation in hBRCA2 (residues 2350-2545) decreases the α-helical/β-sheet propensity of the wild-type protein and perturb the tertiary structure conformation. Molecular dynamics simulations revealed alteration in the intramolecular H-bonds, overall compactness and stability of the hydrophobic core were observed in the mutant protein. Principle component analysis indicated that Arg2502Cys mutant exhibited comparatively large conformational transitions and periodic fluctuation. Therefore, to our conclusion, BRCA2 Arg2502Cys mutant perturbed the structural integrity and conformational dynamics of BRCA2.
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Affiliation(s)
- Mudassar Ali Khan
- Advanced Centre for Treatment, Research and Education in Cancer, Kharghar, Navi Mumbai, Maharashtra 410210, India; Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India
| | - M Quadir Siddiqui
- Advanced Centre for Treatment, Research and Education in Cancer, Kharghar, Navi Mumbai, Maharashtra 410210, India; Present address: Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Ekaterina Kuligina
- N.N. Petrov Institute of Oncology, Laboratory of Molecular Oncology, RU-197758, Pesochny-2, St.-Petersburg, Russia
| | - Ashok K Varma
- Advanced Centre for Treatment, Research and Education in Cancer, Kharghar, Navi Mumbai, Maharashtra 410210, India; Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India.
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19
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CDK5RAP3, a New BRCA2 Partner That Regulates DNA Repair, Is Associated with Breast Cancer Survival. Cancers (Basel) 2022; 14:cancers14020353. [PMID: 35053516 PMCID: PMC8773632 DOI: 10.3390/cancers14020353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/27/2021] [Accepted: 10/30/2021] [Indexed: 02/01/2023] Open
Abstract
BRCA2 is essential for homologous recombination DNA repair. BRCA2 mutations lead to genome instability and increased risk of breast and ovarian cancer. Similarly, mutations in BRCA2-interacting proteins are also known to modulate sensitivity to DNA damage agents and are established cancer risk factors. Here we identify the tumor suppressor CDK5RAP3 as a novel BRCA2 helical domain-interacting protein. CDK5RAP3 depletion induced DNA damage resistance, homologous recombination and single-strand annealing upregulation, and reduced spontaneous and DNA damage-induced genomic instability, suggesting that CDK5RAP3 negatively regulates double-strand break repair in the S-phase. Consistent with this cellular phenotype, analysis of transcriptomic data revealed an association between low CDK5RAP3 tumor expression and poor survival of breast cancer patients. Finally, we identified common genetic variations in the CDK5RAP3 locus as potentially associated with breast and ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. Our results uncover CDK5RAP3 as a critical player in DNA repair and breast cancer outcomes.
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20
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Lee M, Shorthouse D, Mahen R, Hall BA, Venkitaraman AR. Cancer-causing BRCA2 missense mutations disrupt an intracellular protein assembly mechanism to disable genome maintenance. Nucleic Acids Res 2021; 49:5588-5604. [PMID: 33978741 PMCID: PMC8191791 DOI: 10.1093/nar/gkab308] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/11/2021] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Cancer-causing missense mutations in the 3418 amino acid BRCA2 breast and ovarian cancer suppressor protein frequently affect a short (∼340 residue) segment in its carboxyl-terminal domain (DBD). Here, we identify a shared molecular mechanism underlying their pathogenicity. Pathogenic BRCA2 missense mutations cluster in the DBD’s helical domain (HD) and OB1-fold motifs, which engage the partner protein DSS1. Pathogenic - but not benign – DBD mutations weaken or abolish DSS1-BRCA2 assembly, provoking mutant BRCA2 oligomers that are excluded from the cell nucleus, and disable DNA repair by homologous DNA recombination (HDR). DSS1 inhibits the intracellular oligomerization of wildtype, but not mutant, forms of BRCA2. Remarkably, DSS1 expression corrects defective HDR in cells bearing pathogenic BRCA2 missense mutants with weakened, but not absent, DSS1 binding. Our findings identify a DSS1-mediated intracellular protein assembly mechanism that is disrupted by cancer-causing BRCA2 missense mutations, and suggest an approach for its therapeutic correction.
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Affiliation(s)
- Miyoung Lee
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - David Shorthouse
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Robert Mahen
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Benjamin A Hall
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK.,The Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599 & Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove 138648, Singapore
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21
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Andreassen PR, Seo J, Wiek C, Hanenberg H. Understanding BRCA2 Function as a Tumor Suppressor Based on Domain-Specific Activities in DNA Damage Responses. Genes (Basel) 2021; 12:genes12071034. [PMID: 34356050 PMCID: PMC8307705 DOI: 10.3390/genes12071034] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/23/2021] [Accepted: 06/29/2021] [Indexed: 01/14/2023] Open
Abstract
BRCA2 is an essential genome stability gene that has various functions in cells, including roles in homologous recombination, G2 checkpoint control, protection of stalled replication forks, and promotion of cellular resistance to numerous types of DNA damage. Heterozygous mutation of BRCA2 is associated with an increased risk of developing cancers of the breast, ovaries, pancreas, and other sites, thus BRCA2 acts as a classic tumor suppressor gene. However, understanding BRCA2 function as a tumor suppressor is severely limited by the fact that ~70% of the encoded protein has not been tested or assigned a function in the cellular DNA damage response. Remarkably, even the specific role(s) of many known domains in BRCA2 are not well characterized, predominantly because stable expression of the very large BRCA2 protein in cells, for experimental purposes, is challenging. Here, we review what is known about these domains and the assay systems that are available to study the cellular roles of BRCA2 domains in DNA damage responses. We also list criteria for better testing systems because, ultimately, functional assays for assessing the impact of germline and acquired mutations identified in genetic screens are important for guiding cancer prevention measures and for tailored cancer treatments.
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Affiliation(s)
- Paul R. Andreassen
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
- Correspondence: ; Tel.: +1-(513)-636-0499
| | - Joonbae Seo
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
| | - Helmut Hanenberg
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
- Department of Pediatrics III, Children’s Hospital, University of Duisburg-Essen, 45122 Essen, Germany
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22
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Brnich SE, Arteaga EC, Wang Y, Tan X, Berg JS. A Validated Functional Analysis of Partner and Localizer of BRCA2 Missense Variants for Use in Clinical Variant Interpretation. J Mol Diagn 2021; 23:847-864. [PMID: 33964450 PMCID: PMC8491091 DOI: 10.1016/j.jmoldx.2021.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/06/2021] [Indexed: 12/29/2022] Open
Abstract
Clinical genetic testing readily detects germline genetic variants. Yet, the rarity of individual variants limits the evidence available for variant classification, leading to many variants of uncertain significance (VUS). VUS cannot guide clinical decisions, complicating counseling and management. In hereditary breast cancer gene PALB2, approximately 50% of clinically identified germline variants are VUS and approximately 90% of VUS are missense. Truncating PALB2 variants have homologous recombination (HR) defects and rely on error-prone nonhomologous end-joining for DNA damage repair (DDR). Recent reports show that some missense PALB2 variants may also be damaging, but most functional studies have lacked benchmarking controls required for sufficient predictive power for clinical use. Here, variant-level DDR capacity in hereditary breast cancer genes was assessed using the Traffic Light Reporter (TLR) to quantify cellular HR/nonhomologous end-joining with fluorescent markers. First, using BRCA2 missense variants of known significance as benchmarks, the TLR distinguished between normal/abnormal HR function. The TLR was then validated for PALB2 and used to test 37 PALB2 variants. Based on the TLR's ability to correctly classify PALB2 validation controls, these functional data where applied in subsequent germline variant interpretations at a moderate level of evidence toward a pathogenic interpretation (PS3_moderate) for 8 variants with abnormal DDR, or a supporting level of evidence toward a benign interpretation (BS3_supporting) for 13 variants with normal DDR.
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Affiliation(s)
- Sarah E Brnich
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Eyla Cristina Arteaga
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Yueting Wang
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Xianming Tan
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jonathan S Berg
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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23
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Jimenez-Sainz J, Jensen RB. Imprecise Medicine: BRCA2 Variants of Uncertain Significance (VUS), the Challenges and Benefits to Integrate a Functional Assay Workflow with Clinical Decision Rules. Genes (Basel) 2021; 12:genes12050780. [PMID: 34065235 PMCID: PMC8161351 DOI: 10.3390/genes12050780] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 12/20/2022] Open
Abstract
Pathological mutations in homology-directed repair (HDR) genes impact both future cancer risk and therapeutic options for patients. HDR is a high-fidelity DNA repair pathway for resolving DNA double-strand breaks throughout the genome. BRCA2 is an essential protein that mediates the loading of RAD51 onto resected DNA breaks, a key step in HDR. Germline mutations in BRCA2 are associated with an increased risk for breast, ovarian, prostate, and pancreatic cancer. Clinical findings of germline or somatic BRCA2 mutations in tumors suggest treatment with platinum agents or PARP inhibitors. However, when genetic analysis reveals a variant of uncertain significance (VUS) in the BRCA2 gene, precision medicine-based decisions become complex. VUS are genetic changes with unknown pathological impact. Current statistics indicate that between 10–20% of BRCA sequencing results are VUS, and of these, more than 50% are missense mutations. Functional assays to determine the pathological outcome of VUS are urgently needed to provide clinical guidance regarding cancer risk and treatment options. In this review, we provide a brief overview of BRCA2 functions in HDR, describe how BRCA2 VUS are currently assessed in the clinic, and how genetic and biochemical functional assays could be integrated into the clinical decision process. We suggest a multi-step workflow composed of robust and accurate functional assays to correctly evaluate the potential pathogenic or benign nature of BRCA2 VUS. Success in this precision medicine endeavor will offer actionable information to patients and their physicians.
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Affiliation(s)
- Judit Jimenez-Sainz
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
| | - Ryan B. Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
- Correspondence: (J.J.-S.); (R.B.J.); Tel.:+1-203-737-6456 (R.B.J.)
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24
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Lattanzi W, Ripoli C, Greco V, Barba M, Iavarone F, Minucci A, Urbani A, Grassi C, Parolini O. Basic and Preclinical Research for Personalized Medicine. J Pers Med 2021; 11:jpm11050354. [PMID: 33946634 PMCID: PMC8146055 DOI: 10.3390/jpm11050354] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/19/2021] [Accepted: 04/26/2021] [Indexed: 12/18/2022] Open
Abstract
Basic and preclinical research founded the progress of personalized medicine by providing a prodigious amount of integrated profiling data and by enabling the development of biomedical applications to be implemented in patient-centered care and cures. If the rapid development of genomics research boosted the birth of personalized medicine, further development in omics technologies has more recently improved our understanding of the functional genome and its relevance in profiling patients’ phenotypes and disorders. Concurrently, the rapid biotechnological advancement in diverse research areas enabled uncovering disease mechanisms and prompted the design of innovative biological treatments tailored to individual patient genotypes and phenotypes. Research in stem cells enabled clarifying their role in tissue degeneration and disease pathogenesis while providing novel tools toward the development of personalized regenerative medicine strategies. Meanwhile, the evolving field of integrated omics technologies ensured translating structural genomics information into actionable knowledge to trace detailed patients’ molecular signatures. Finally, neuroscience research provided invaluable models to identify preclinical stages of brain diseases. This review aims at discussing relevant milestones in the scientific progress of basic and preclinical research areas that have considerably contributed to the personalized medicine revolution by bridging the bench-to-bed gap, focusing on stem cells, omics technologies, and neuroscience fields as paradigms.
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Affiliation(s)
- Wanda Lattanzi
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Cristian Ripoli
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Viviana Greco
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Marta Barba
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Federica Iavarone
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Angelo Minucci
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
| | - Andrea Urbani
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Claudio Grassi
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento di Neuroscienze, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Ornella Parolini
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (W.L.); (C.R.); (V.G.); (M.B.); (F.I.); (A.M.); (A.U.); (C.G.)
- Dipartimento Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
- Correspondence:
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25
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Huang C, Li G, Wu J, Liang J, Wang X. Identification of pathogenic variants in cancer genes using base editing screens with editing efficiency correction. Genome Biol 2021; 22:80. [PMID: 33691754 PMCID: PMC7945310 DOI: 10.1186/s13059-021-02305-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 02/24/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Millions of nucleotide variants are identified through cancer genome sequencing and it is clinically important to identify the pathogenic variants among them. By introducing base substitutions at guide RNA target regions in the genome, CRISPR-Cas9-based base editors provide the possibility for evaluating a large number of variants in their genomic context. However, the variability in editing efficiency and the complexity of outcome mapping are two existing problems for assigning guide RNA effects to variants in base editing screens. RESULTS To improve the identification of pathogenic variants, we develop a framework to combine base editing screens with sgRNA efficiency and outcome mapping. We apply the method to evaluate more than 9000 variants across all the exons of BRCA1 and BRCA2 genes. Our efficiency-corrected scoring model identifies 910 loss-of-function variants for BRCA1/2, including 151 variants in the noncoding part of the genes such as the 5' untranslated regions. Many of them are identified in cancer patients and are reported as "benign/likely benign" or "variants of uncertain significance" by clinicians. Our data suggest a need to re-evaluate their clinical significance, which may be helpful for risk assessment and treatment of breast and ovarian cancer. CONCLUSIONS Our results suggest that base editing screens with efficiency correction is a powerful strategy to identify pathogenic variants in a high-throughput manner. Applying this strategy to assess variants in both coding and noncoding regions of the genome could have a direct impact on the interpretation of cancer variants.
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Affiliation(s)
- Changcai Huang
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Guangyu Li
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Jiayu Wu
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Junbo Liang
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China.
| | - Xiaoyue Wang
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China.
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26
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Richardson ME, Hu C, Lee KY, LaDuca H, Fulk K, Durda KM, Deckman AM, Goldgar DE, Monteiro AN, Gnanaolivu R, Hart SN, Polley EC, Chao E, Pesaran T, Couch FJ. Strong functional data for pathogenicity or neutrality classify BRCA2 DNA-binding-domain variants of uncertain significance. Am J Hum Genet 2021; 108:458-468. [PMID: 33609447 PMCID: PMC8008494 DOI: 10.1016/j.ajhg.2021.02.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/02/2021] [Indexed: 12/14/2022] Open
Abstract
Determination of the clinical relevance of rare germline variants of uncertain significance (VUSs) in the BRCA2 cancer predisposition gene remains a challenge as a result of limited availability of data for use in classification models. However, laboratory-based functional data derived from validated functional assays of known sensitivity and specificity may influence the interpretation of VUSs. We evaluated 252 missense VUSs from the BRCA2 DNA-binding domain by using a homology-directed DNA repair (HDR) assay and identified 90 as non-functional and 162 as functional. The functional assay results were integrated with other available data sources into an ACMG/AMP rules-based classification framework used by a hereditary cancer testing laboratory. Of the 186 missense variants observed by the testing laboratory, 154 were classified as VUSs without functional data. However, after applying protein functional data, 86% (132/154) of the VUSs were reclassified as either likely pathogenic/pathogenic (39/132) or likely benign/benign (93/132), which impacted testing results for 1,900 individuals. These results indicate that validated functional assay data can have a substantial impact on VUS classification and associated clinical management for many individuals with inherited alterations in BRCA2.
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27
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Sessa G, Gómez-González B, Silva S, Pérez-Calero C, Beaurepere R, Barroso S, Martineau S, Martin C, Ehlén Å, Martínez JS, Lombard B, Loew D, Vagner S, Aguilera A, Carreira A. BRCA2 promotes DNA-RNA hybrid resolution by DDX5 helicase at DNA breaks to facilitate their repair‡. EMBO J 2021; 40:e106018. [PMID: 33634895 DOI: 10.15252/embj.2020106018] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/22/2021] [Accepted: 01/25/2021] [Indexed: 12/19/2022] Open
Abstract
The BRCA2 tumor suppressor is a DNA double-strand break (DSB) repair factor essential for maintaining genome integrity. BRCA2-deficient cells spontaneously accumulate DNA-RNA hybrids, a known source of genome instability. However, the specific role of BRCA2 on these structures remains poorly understood. Here we identified the DEAD-box RNA helicase DDX5 as a BRCA2-interacting protein. DDX5 associates with DNA-RNA hybrids that form in the vicinity of DSBs, and this association is enhanced by BRCA2. Notably, BRCA2 stimulates the DNA-RNA hybrid-unwinding activity of DDX5 helicase. An impaired BRCA2-DDX5 interaction, as observed in cells expressing the breast cancer variant BRCA2-T207A, reduces the association of DDX5 with DNA-RNA hybrids, decreases the number of RPA foci, and alters the kinetics of appearance of RAD51 foci upon irradiation. Our findings are consistent with DNA-RNA hybrids constituting an impediment for the repair of DSBs by homologous recombination and reveal BRCA2 and DDX5 as active players in their removal.
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Affiliation(s)
- Gaetana Sessa
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Belén Gómez-González
- Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER, University of Seville-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, University of Seville, Seville, Spain
| | - Sonia Silva
- Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER, University of Seville-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, University of Seville, Seville, Spain
| | - Carmen Pérez-Calero
- Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER, University of Seville-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, University of Seville, Seville, Spain
| | - Romane Beaurepere
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Sonia Barroso
- Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER, University of Seville-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, University of Seville, Seville, Spain
| | - Sylvain Martineau
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Charlotte Martin
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Åsa Ehlén
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Juan S Martínez
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Bérangère Lombard
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Damarys Loew
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, PSL Research University, Paris, France
| | - Stephan Vagner
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Andrés Aguilera
- Andalusian Molecular Biology and Regenerative Medicine Centre-CABIMER, University of Seville-CSIC, Seville, Spain.,Departamento de Genética, Facultad de Biología, University of Seville, Seville, Spain
| | - Aura Carreira
- Institut Curie, Université PSL, CNRS UMR3348, Orsay, France.,Université Paris-Saclay, CNRS UMR3348, Orsay, France
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28
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Yoshida R, Hagio T, Kaneyasu T, Gotoh O, Osako T, Tanaka N, Amino S, Yaguchi N, Nakashima E, Kitagawa D, Ueno T, Ohno S, Nakajima T, Nakamura S, Miki Y, Hirota T, Takahashi S, Matsuura M, Noda T, Mori S. Pathogenicity assessment of variants for breast cancer susceptibility genes based on BRCAness of tumor sample. Cancer Sci 2021; 112:1310-1319. [PMID: 33421217 PMCID: PMC7935793 DOI: 10.1111/cas.14803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/03/2020] [Accepted: 01/05/2021] [Indexed: 12/26/2022] Open
Abstract
Genes involved in the homologous recombination repair pathway—as exemplified by BRCA1, BRCA2, PALB2, ATM, and CHEK2—are frequently associated with hereditary breast and ovarian cancer syndrome. Germline mutations in the loci of these genes with loss of heterozygosity or additional somatic truncation at the WT allele lead to the development of breast cancers with characteristic clinicopathological features and prominent genomic features of homologous recombination deficiency, otherwise referred to as “BRCAness.” Although clinical genetic testing for these and other genes has increased the chances of identifying pathogenic variants, there has also been an increase in the prevalence of variants of uncertain significance, which poses a challenge to patient care because of the difficulties associated with making further clinical decisions. To overcome this challenge, we sought to develop a methodology to reclassify the pathogenicity of these unknown variants using statistical modeling of BRCAness. The model was developed with Lasso logistic regression by comparing 116 genomic attributes derived from 37 BRCA1/2 biallelic mutant and 32 homologous recombination‐quiescent breast cancer exomes. The model showed 95.8% and 86.7% accuracies in the training cohort and The Cancer Genome Atlas validation cohort, respectively. Through application of the model for variant reclassification of homologous recombination‐associated hereditary breast and ovarian cancer causal genes and further assessment with clinicopathological features, we finally identified one likely pathogenic and five likely benign variants. As such, the BRCAness model developed from the tumor exome was robust and provided a reasonable basis for variant reclassification.
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Affiliation(s)
- Reiko Yoshida
- Department of Oncotherapeutic Medicine, Graduate School of Medicine, Tohoku University, Sendai, Japan.,Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Department of Clinical Genetic Oncology, Cancer Institute Hospital (CIH), JFCR, Tokyo, Japan
| | - Taichi Hagio
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | - Tomoko Kaneyasu
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | - Osamu Gotoh
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | - Tomo Osako
- Division of Pathology, Cancer Institute, JFCR, Tokyo, Japan
| | - Norio Tanaka
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | - Sayuri Amino
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Genomics-based Cancer Medicine, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | - Noriko Yaguchi
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
| | | | - Dai Kitagawa
- Breast Oncology Center, CIH, JFCR, Tokyo, Japan.,Department of Breast Surgical Oncology, Center Hospital of the National Center for Global Health and Medicine, Tokyo, Japan
| | | | - Shinji Ohno
- Breast Oncology Center, CIH, JFCR, Tokyo, Japan
| | - Takeshi Nakajima
- Department of Clinical Genetic Oncology, Cancer Institute Hospital (CIH), JFCR, Tokyo, Japan
| | - Seigo Nakamura
- Division of Breast Surgical Oncology, Showa University School of Medicine, Tokyo, Japan
| | - Yoshio Miki
- Division of Genetic Diagnosis, Cancer Institute, JFCR, Tokyo, Japan
| | - Toru Hirota
- Department of Cellular and Molecular Imaging of Cancer, Graduate School of Medicine, Tohoku University, Sendai, Japan.,Division of Experimental Pathology, Cancer Institute, JFCR, Tokyo, Japan
| | - Shunji Takahashi
- Department of Oncotherapeutic Medicine, Graduate School of Medicine, Tohoku University, Sendai, Japan.,Department of Medical Oncology, CIH, JFCR, Tokyo, Japan
| | - Masaaki Matsuura
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan
| | - Tetsuo Noda
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Genomics-based Cancer Medicine, Cancer Precision Medicine Center, JFCR, Tokyo, Japan.,Cancer, Institute, JFCR, Tokyo, Japan
| | - Seiichi Mori
- Division of Cancer Genomics, Cancer Institute, Japanese Foundation for Cancer Research (JFCR), Tokyo, Japan.,Project for Development of Innovative Research on Cancer Therapeutics, Cancer Precision Medicine Center, JFCR, Tokyo, Japan
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29
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Abstract
DNA double-strand breaks (DSBs) are among the most toxic lesions. This type of DNA damage is repaired by two major pathways, homologous recombination (HR), operating only in S/G2 cell-cycle phases and nonhomologous end joining (NHEJ) which is operative throughout the cell cycle. Because HR is a template-directed repair, it is generally less prone to errors and/or translocations than NHEJ.The HR pathway involves several effector proteins and regulators that modulate the efficiency of repair and limit the repair outside S/G2 phase. Some of the genes coding for these proteins are frequently mutated in human diseases such as cancer, and pathogenic mutations or variants identified in patients often alter the HR proficiency of the cells.This chapter describes a cell-based gene-targeting reporter assay in human cells to evaluate the repair of a site-specific DSB by HR . In it, a promoter-less fluorescent protein is encoded in a plasmid flanked by two homology arms directed to a safe-harbour locus in the genome. The expression of the fluorescent protein is driven by the promoter of the endogenous locus enabling to quantify the efficiency of HR by flow cytometry. This approach can be used to determine the requirement of certain proteins, protein domains, or protein modifications for HR . It can also be used to functionally evaluate variants of the genes encoding these proteins such as BRCA1, BRCA2, RAD51C, and PALB2; which may help assess their pathogenicity. Here, we use the homologous recombination mediator BRCA2 to illustrate the assay.
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Affiliation(s)
- Domagoj Vugic
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Åsa Ehlén
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Aura Carreira
- Institut Curie, PSL Research University, CNRS, UMR3348, F-91405, Orsay, France.
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France.
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30
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Biswas K, Lipton GB, Stauffer S, Sullivan T, Cleveland L, Southon E, Reid S, Magidson V, Iversen ES, Sharan SK. A computational model for classification of BRCA2 variants using mouse embryonic stem cell-based functional assays. NPJ Genom Med 2020; 5:52. [PMID: 33293522 PMCID: PMC7722754 DOI: 10.1038/s41525-020-00158-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 10/29/2020] [Indexed: 12/12/2022] Open
Abstract
Sequencing-based genetic tests to identify individuals at increased risk of hereditary breast and ovarian cancers have resulted in the identification of more than 40,000 sequence variants of BRCA1 and BRCA2. A majority of these variants are considered to be variants of uncertain significance (VUS) because their impact on disease risk remains unknown, largely due to lack of sufficient familial linkage and epidemiological data. Several assays have been developed to examine the effect of VUS on protein function, which can be used to assess their impact on cancer susceptibility. In this study, we report the functional characterization of 88 BRCA2 variants, including several previously uncharacterized variants, using a well-established mouse embryonic stem cell (mESC)-based assay. We have examined their ability to rescue the lethality of Brca2 null mESC as well as sensitivity to six DNA damaging agents including ionizing radiation and a PARP inhibitor. We have also examined the impact of BRCA2 variants on splicing. In addition, we have developed a computational model to determine the probability of impact on function of the variants that can be used for risk assessment. In contrast to the previous VarCall models that are based on a single functional assay, we have developed a new platform to analyze the data from multiple functional assays separately and in combination. We have validated our VarCall models using 12 known pathogenic and 10 neutral variants and demonstrated their usefulness in determining the pathogenicity of BRCA2 variants that are listed as VUS or as variants with conflicting functional interpretation.
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Affiliation(s)
- Kajal Biswas
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Gary B Lipton
- Department of Statistical Science, Duke University, Durham, NC, 27708, USA
| | - Stacey Stauffer
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Teresa Sullivan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Linda Cleveland
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Eileen Southon
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
- Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Susan Reid
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Valentin Magidson
- Optical Microscopy and Analysis Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Edwin S Iversen
- Department of Statistical Science, Duke University, Durham, NC, 27708, USA.
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
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31
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Agata S, Tognazzo S, Alducci E, Matricardi L, Moserle L, Barana D, Montagna M. Segregation analysis of the BRCA2 c.9227G>T variant in multiple families suggests a pathogenic role in breast and ovarian cancer predisposition. Sci Rep 2020; 10:13987. [PMID: 32814805 PMCID: PMC7438490 DOI: 10.1038/s41598-020-70729-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/20/2020] [Indexed: 11/09/2022] Open
Abstract
Classification of variants in the BRCA1 and BRCA2 genes has a major impact on the clinical management of subjects at high risk for breast and ovarian cancer. The identification of a pathogenic variant allows for early detection/prevention strategies in healthy carriers as well as targeted treatments in patients affected by BRCA-associated tumors. The BRCA2 c.9227G>T p.(Gly3076Val) variant recurs in families from Northeast Italy and is rarely reported in international databases. This variant substitutes the evolutionary invariant glycine 3076 with a valine in the DNA binding domain of the BRCA2 protein, thus suggesting a high probability of pathogenicity. We analysed clinical and genealogic data of carriers from 15 breast/ovarian cancer families in whom no other pathogenic variants were detected. The variant was shown to co-segregate with breast and ovarian cancer in the most informative families. Combined segregation data led to a likelihood ratio of 81,527:1 of pathogenicity vs. neutrality. We conclude that c.9227G>T is a BRCA2 pathogenic variant that recurs in Northeast Italy. It can now be safely used for the predictive testing of healthy family members to guide preventive surgery and/or early tumor detection strategies, as well as for PARP inhibitors treatments in patients with BRCA2-associated tumors.
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Affiliation(s)
- Simona Agata
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Silvia Tognazzo
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Elisa Alducci
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Laura Matricardi
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Lidia Moserle
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy
| | - Daniela Barana
- Oncology Unit, Local Health and Social Care Unit ULSS8 Berica, Montecchio Maggiore, Italy
| | - Marco Montagna
- Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy.
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32
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Le Page C, Amuzu S, Rahimi K, Gotlieb W, Ragoussis J, Tonin PN. Lessons learned from understanding chemotherapy resistance in epithelial tubo-ovarian carcinoma from BRCA1and BRCA2mutation carriers. Semin Cancer Biol 2020; 77:110-126. [PMID: 32827632 DOI: 10.1016/j.semcancer.2020.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/20/2020] [Accepted: 08/12/2020] [Indexed: 02/07/2023]
Abstract
BRCA1 and BRCA2 are multi-functional proteins and key factors for maintaining genomic stability through their roles in DNA double strand break repair by homologous recombination, rescuing stalled or damaged DNA replication forks, and regulation of cell cycle DNA damage checkpoints. Impairment of any of these critical roles results in genomic instability, a phenotypic hallmark of many cancers including breast and epithelial ovarian carcinomas (EOC). Damaging, usually loss of function germline and somatic variants in BRCA1 and BRCA2, are important drivers of the development, progression, and management of high-grade serous tubo-ovarian carcinoma (HGSOC). However, mutations in these genes render patients particularly sensitive to platinum-based chemotherapy, and to the more innovative targeted therapies with poly-(ADP-ribose) polymerase inhibitors (PARPis) that are targeted to BRCA1/BRCA2 mutation carriers. Here, we reviewed the literature on the responsiveness of BRCA1/2-associated HGSOC to platinum-based chemotherapy and PARPis, and propose mechanisms underlying the frequent development of resistance to these therapeutic agents.
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Affiliation(s)
- Cécile Le Page
- McGill Research Institute of the McGill University Health Center, Montreal, QC, Canada.
| | - Setor Amuzu
- McGill Genome Centre, and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Kurosh Rahimi
- Department of Pathology du Centre hospitalier de l'Université de Montréal, Montreal, QC, Canada
| | - Walter Gotlieb
- Laboratory of Gynecologic Oncology, Lady Davis Research Institute, Jewish General Hospital, Montreal, QC, Canada
| | - Jiannis Ragoussis
- McGill Genome Centre, and Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Patricia N Tonin
- Departments of Medicine and Human Genetics, McGill University, Cancer Research Program, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada.
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33
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Bouwman P, van der Heijden I, van der Gulden H, de Bruijn R, Braspenning ME, Moghadasi S, Wessels LFA, Vreeswijk MPG, Jonkers J. Functional Categorization of BRCA1 Variants of Uncertain Clinical Significance in Homologous Recombination Repair Complementation Assays. Clin Cancer Res 2020; 26:4559-4568. [PMID: 32546644 DOI: 10.1158/1078-0432.ccr-20-0255] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/29/2020] [Accepted: 06/12/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE Because BRCA1 is a high-risk breast/ovarian cancer susceptibility gene, BRCA1 sequence variants of uncertain clinical significance (VUS) complicate genetic counseling. As most VUS are rare, reliable classification based on clinical and genetic data is often impossible. However, all pathogenic BRCA1 variants analyzed result in defective homologous recombination DNA repair (HRR). Thus, BRCA1 VUS may be categorized based on their functional impact on this pathway. EXPERIMENTAL DESIGN Two hundred thirty-eight BRCA1 VUS-comprising most BRCA1 VUS known in the Netherlands and Belgium-were tested for their ability to complement Brca1-deficient mouse embryonic stem cells in HRR, using cisplatin and olaparib sensitivity assays and a direct repeat GFP (DR-GFP) HRR assay. Assays were validated using 25 known benign and 25 known pathogenic BRCA1 variants. For assessment of pathogenicity by a multifactorial likelihood analysis method, we collected clinical and genetic data for functionally deleterious VUS and VUS occurring in three or more families. RESULTS All three assays showed 100% sensitivity and specificity (95% confidence interval, 83%-100%). Out of 238 VUS, 45 showed functional defects, 26 of which were deleterious in all three assays. For 13 of these 26 variants, we could calculate the probability of pathogenicity using clinical and genetic data, resulting in the identification of 7 (likely) pathogenic variants. CONCLUSIONS We have functionally categorized 238 BRCA1 VUS using three different HRR-related assays. Classification based on clinical and genetic data alone for a subset of these variants confirmed the high sensitivity and specificity of our functional assays.
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Affiliation(s)
- Peter Bouwman
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
| | - Ingrid van der Heijden
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Hanneke van der Gulden
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Roebi de Bruijn
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.,Oncode Institute and Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Merel E Braspenning
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Setareh Moghadasi
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Lodewyk F A Wessels
- Oncode Institute and Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, the Netherlands
| | | | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Jos Jonkers
- Oncode Institute and Division of Molecular Pathology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
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34
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Rickman KA, Noonan RJ, Lach FP, Sridhar S, Wang AT, Abhyankar A, Huang A, Kelly M, Auerbach AD, Smogorzewska A. Distinct roles of BRCA2 in replication fork protection in response to hydroxyurea and DNA interstrand cross-links. Genes Dev 2020; 34:832-846. [PMID: 32354836 PMCID: PMC7263144 DOI: 10.1101/gad.336446.120] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/01/2020] [Indexed: 02/07/2023]
Abstract
DNA interstrand cross-links (ICLs) are a form of DNA damage that requires the interplay of a number of repair proteins including those of the Fanconi anemia (FA) and the homologous recombination (HR) pathways. Pathogenic variants in the essential gene BRCA2/FANCD1, when monoallelic, predispose to breast and ovarian cancer, and when biallelic, result in a severe subtype of Fanconi anemia. BRCA2 function in the FA pathway is attributed to its role as a mediator of the RAD51 recombinase in HR repair of programmed DNA double-strand breaks (DSB). BRCA2 and RAD51 functions are also required to protect stalled replication forks from nucleolytic degradation during response to hydroxyurea (HU). While RAD51 has been shown to be necessary in the early steps of ICL repair to prevent aberrant nuclease resection, the role of BRCA2 in this process has not been described. Here, based on the analysis of BRCA2 DNA-binding domain (DBD) mutants (c.8488-1G>A and c.8524C>T) discovered in FA patients presenting with atypical FA-like phenotypes, we establish that BRCA2 is necessary for the protection of DNA at ICLs. Cells carrying BRCA2 DBD mutations are sensitive to ICL-inducing agents but resistant to HU treatment consistent with relatively high HR repair in these cells. BRCA2 function at an ICL protects against DNA2-WRN nuclease-helicase complex and not the MRE11 nuclease that is implicated in the resection of HU-induced stalled replication forks. Our results also indicate that unlike the processing at HU-induced stalled forks, the function of the SNF2 translocases (SMARCAL1, ZRANB3, or HLTF), implicated in fork reversal, are not an integral component of the ICL repair, pointing to a different mechanism of fork protection at different DNA lesions.
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Affiliation(s)
- Kimberly A Rickman
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | - Raymond J Noonan
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | - Francis P Lach
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | - Sunandini Sridhar
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | - Anderson T Wang
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | | | - Athena Huang
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
| | - Michael Kelly
- Tufts Medical Center, Boston, Massachusetts 02111, USA
| | - Arleen D Auerbach
- Human Genetics and Hematology, The Rockefeller University, New York, New York 10065, USA
| | - Agata Smogorzewska
- Laboratory of Genome Maintenance, The Rockefeller University, New York, New York 10065, USA
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35
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Caburet S, Heddar A, Dardillac E, Creux H, Lambert M, Messiaen S, Tourpin S, Livera G, Lopez BS, Misrahi M. Homozygous hypomorphic BRCA2 variant in primary ovarian insufficiency without cancer or Fanconi anaemia trait. J Med Genet 2020; 58:jmedgenet-2019-106672. [PMID: 32482800 DOI: 10.1136/jmedgenet-2019-106672] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 04/08/2020] [Accepted: 04/12/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND Primary ovarian insufficiency (POI) affects 1% of women under 40 years and is a public health problem. The genetic causes of POI are highly heterogeneous with isolated or syndromic forms. Recently, variants in genes involved in DNA repair have been shown to cause POI. Notably, syndromic POI with Fanconi anaemia (FA) traits related to biallelic BRCA2 truncated variants has been reported. Here, we report a novel phenotype of isolated POI with a BRCA2 variant in a consanguineous Turkish family. METHODS Exome sequencing (ES) was performed in the patient. We also performed functional studies, including a homologous recombination (HR) test, cell proliferation, radiation-induced RAD51 foci formation assays and chromosome breakage studies in primary and lymphoblastoid immortalised cells. The expression of BRCA2 in human foetal ovaries was studied. RESULTS ES identified a homozygous missense c.8524C>T/p.R2842C-BRCA2 variant. BRCA2 defects induce cancer predisposition and FA. Remarkably, neither the patient nor her family exhibited somatic pathologies. The patient's cells showed intermediate levels of chromosomal breaks, cell proliferation and radiation-induced RAD51 foci formation compared with controls and FA cells. R2842C-BRCA2 only partially complemented HR efficiency compared with wild type-BRCA2. BRCA2 is expressed in human foetal ovaries in pachytene stage oocytes, when meiotic HR occurs. CONCLUSION We describe the functional assessment of a homozygous hypomorphic BRCA2 variant in a patient with POI without cancer or FA trait. Our findings extend the phenotype of BRCA2 biallelic alterations to fully isolated POI. This study has a major impact on the management and genetic counselling of patients with POI.
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Affiliation(s)
- Sandrine Caburet
- Institut Jacques Monod, Université de Paris, Paris, Île-de-France, France
| | - Abdelkader Heddar
- Faculte de Medecine, Universite Paris Saclay, Hopital Bicêtre APHP, Le Kremlin-Bicetre, France
| | - Elodie Dardillac
- Institut Cochin, INSERM U1016, UMR 8104 CNRS, Université de Paris, Paris, Île-de-France, France
| | - Héléne Creux
- Service de Gynécologie et Médecine de la Reproduction, CHU de Bordeaux, Bordeaux, Aquitaine, France
| | - Marie Lambert
- Service de Gynécologie et Médecine de la Reproduction, CHU de Bordeaux, Bordeaux, Aquitaine, France
| | - Sébastien Messiaen
- UMR Stabilité Génétique, Cellules Souches et Radiations, Université Paris-Saclay, Fontenay aux Roses, Île-de-France, France
| | - Sophie Tourpin
- UMR Stabilité Génétique, Cellules Souches et Radiations, Université Paris-Saclay, Fontenay aux Roses, Île-de-France, France
| | - Gabriel Livera
- UMR Stabilité Génétique, Cellules Souches et Radiations, Université Paris-Saclay, Fontenay aux Roses, Île-de-France, France
| | - Bernard S Lopez
- Institut Cochin, INSERM U1016, UMR 8104 CNRS, Université de Paris, Paris, Île-de-France, France
| | - Micheline Misrahi
- Faculte de Medecine, Universite Paris Saclay, Hopital Bicêtre APHP, Le Kremlin-Bicetre, France
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High-throughput functional evaluation of BRCA2 variants of unknown significance. Nat Commun 2020; 11:2573. [PMID: 32444794 PMCID: PMC7244490 DOI: 10.1038/s41467-020-16141-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 04/17/2020] [Indexed: 12/14/2022] Open
Abstract
Numerous nontruncating missense variants of the BRCA2 gene have been identified, but there is a lack of convincing evidence, such as familial data, demonstrating their clinical relevance and they thus remain unactionable. To assess the pathogenicity of variants of unknown significance (VUSs) within BRCA2, here we develop a method, the MANO-B method, for high-throughput functional evaluation utilizing BRCA2-deficient cells and poly (ADP-ribose) polymerase (PARP) inhibitors. The estimated sensitivity and specificity of this assay compared to those of the International Agency for Research on Cancer classification system is 95% and 95% (95% confidence intervals: 77–100% and 82–99%), respectively. We classify the functional impact of 186 BRCA2 VUSs with our computational pipeline, resulting in the classification of 126 variants as normal/likely normal, 23 as intermediate, and 37 as abnormal/likely abnormal. We further describe a simplified, on-demand annotation system that could be used as a companion diagnostic for PARP inhibitors in patients with unknown BRCA2 VUSs. Many germline variants are found in the BRCA2 gene, some of which pre-dispose women to breast and ovarian cancer. Here, the authors develop a method to determine the functional significance of BRCA2 variants and show that it is comparable to the IARC system of classifying variants.
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Monteiro AN, Bouwman P, Kousholt AN, Eccles DM, Millot GA, Masson JY, Schmidt MK, Sharan SK, Scully R, Wiesmüller L, Couch F, Vreeswijk MPG. Variants of uncertain clinical significance in hereditary breast and ovarian cancer genes: best practices in functional analysis for clinical annotation. J Med Genet 2020; 57:509-518. [PMID: 32152249 DOI: 10.1136/jmedgenet-2019-106368] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/28/2019] [Accepted: 12/01/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Alvaro N Monteiro
- Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
| | - Peter Bouwman
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Arne N Kousholt
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Diana M Eccles
- Cancer Sciences, University of Southampton Faculty of Medicine, Southampton, UK
| | - Gael A Millot
- Hub-DBC, Institut Pasteur, USR 3756 CNRS, Paris, France
| | - Jean-Yves Masson
- CHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec, Canada
| | - Marjanka K Schmidt
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Shyam K Sharan
- National Cancer Institute at Frederick, Frederick, Maryland, USA
| | - Ralph Scully
- Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
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Variants of uncertain significance in the era of high-throughput genome sequencing: a lesson from breast and ovary cancers. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2020; 39:46. [PMID: 32127026 PMCID: PMC7055088 DOI: 10.1186/s13046-020-01554-6] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023]
Abstract
The promising expectations about personalized medicine have opened the path to routine large-scale sequencing and increased the importance of genetic counseling for hereditary cancers, among which hereditary breast and ovary cancers (HBOC) have a major impact. High-throughput sequencing, or Next-Generation Sequencing (NGS), has improved cancer patient management, ameliorating diagnosis and treatment decisions. In addition to its undeniable clinical utility, NGS is also unveiling a large number of variants that we are still not able to clearly define and classify, the variants of uncertain significance (VUS), which account for about 40% of total variants. At present, VUS use in the clinical context is challenging. Medical reports may omit this kind of data and, even when included, they limit the clinical utility of genetic information. This has prompted the scientific community to seek easily applicable tests to accurately classify VUS and increase the amount of usable information from NGS data. In this review, we will focus on NGS and classification systems for VUS investigation, with particular attention on HBOC-related genes and in vitro functional tests developed for ameliorating and accelerating variant classification in cancer.
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Systematic misclassification of missense variants in BRCA1 and BRCA2 "coldspots". Genet Med 2020; 22:825-830. [PMID: 31911673 PMCID: PMC7200594 DOI: 10.1038/s41436-019-0740-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/19/2019] [Indexed: 12/15/2022] Open
Abstract
Purpose Guidelines for variant interpretation incorporate variant hotspots in critical functional domains as evidence for pathogenicity (e.g., PM1 and PP2), but do not use “coldspots,” that is, regions without essential functions that tolerate variation, as evidence a variant is benign. To improve variant classification we evaluated BRCA1 and BRCA2 missense variants reported in ClinVar to identify regions where pathogenic missenses are extremely infrequent, defined as coldspots. Methods We used Bayesian approaches to model variant classification in these regions. Results BRCA1 exon 11 (~60% of the coding sequence), and BRCA2 exons 10 and 11 (~65% of the coding sequence), are coldspots. Of 89 pathogenic (P) or likely pathogenic (LP) missense variants in BRCA1, none are in exon 11 (odds <0.01, 95% confidence interval [CI] 0.0–0.01). Of 34 P or LP missense variants in BRCA2, none are in exons 10–11 (odds <0.01, 95% CI 0.0–0.01). More than half of reported missense variants of uncertain significance (VUS) in BRCA1 and BRCA2 are in coldspots (3115/5301 = 58.8%). Reclassifying these 3115 VUS as likely benign would substantially improve variant classification. Conclusion In BRCA1 and BRCA2 coldspots, missense variants are very unlikely to be pathogenic. Classification schemes that incorporate coldspots can reduce the number of VUS and mitigate risks from reporting benign variation as VUS.
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Impact of proactive high-throughput functional assay data on BRCA1 variant interpretation in 3684 patients with breast or ovarian cancer. J Hum Genet 2020; 65:209-220. [PMID: 31907386 DOI: 10.1038/s10038-019-0713-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/12/2019] [Accepted: 12/16/2019] [Indexed: 11/08/2022]
Abstract
The clinical utility of BRCA1/2 genotyping was recently extended from the selection of subjects at high risk for hereditary breast and ovary cancer to the identification of candidates for poly (ADP-ribose) polymerase (PARP) inhibitor treatment. This underscores the importance of accurate interpretation of BRCA1/2 genetic variants and of reducing the number of variants of uncertain significance (VUSs). Two recent studies by Findlay et al. and Starita et al. introduced high-throughput functional assays, and proactively analyzed variants in specific regions regardless of whether they had been previously observed. We retrospectively reviewed all BRCA1 and BRCA2 germline genetic test reports from patients with breast or ovarian cancer examined at Asan Medical Center (Seoul, Korea) between September 2011 and December 2018. Variants were assigned pathogenic or benign strong evidence codes according to the functional classification and were reclassified according to the ACMG/AMP 2015 guidelines. Among 3684 patients with available BRCA1 and BRCA2 germline genetic test reports, 429 unique variants (181 from BRCA1) were identified. Of 34 BRCA1 variants intersecting with the data reported by Findlay et al., three missense single-nucleotide variants from four patients (0.11%, 4/3684) were reclassified from VUSs to likely pathogenic variants. Four variants scored as functional were reclassified into benign or likely benign variants. Three variants that overlapped with the data reported by Starita et al. could not be reclassified. In conclusion, proactive high-throughput functional study data are useful for the reclassification of clinically observed VUSs. Integrating additional evidence, including functional assay results, may help reduce the number of VUSs.
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Esposito MV, Minopoli G, Esposito L, D'Argenio V, Di Maggio F, Sasso E, D'Aiuto M, Zambrano N, Salvatore F. A Functional Analysis of the Unclassified Pro2767Ser BRCA2 Variant Reveals Its Potential Pathogenicity that Acts by Hampering DNA Binding and Homology-Mediated DNA Repair. Cancers (Basel) 2019; 11:E1454. [PMID: 31569370 PMCID: PMC6826418 DOI: 10.3390/cancers11101454] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/16/2019] [Accepted: 09/25/2019] [Indexed: 12/12/2022] Open
Abstract
BRCA1 and BRCA2 are the genes most frequently associated with hereditary breast and ovarian cancer (HBOC). They are crucial for the maintenance of genome stability, particularly in the homologous recombination-mediated repair pathway of DNA double-strand breaks (HR-DSBR). Widespread BRCA1/2 next-generation sequencing (NGS) screening has revealed numerous variants of uncertain significance. Assessing the clinical significance of these variants is challenging, particularly regarding the clinical management of patients. Here, we report the functional characterization of the unclassified BRCA2 c.8299C > T variant, identified in a young breast cancer patient during BRCA1/2 NGS screening. This variant causes the change of Proline 2767 to Serine in the DNA binding domain (DBD) of the BRCA2 protein, necessary for the loading of RAD51 on ssDNA during the HR-DSBR. Our in silico analysis and 3D-structure modeling predicted that the p.Pro2767Ser substitution is likely to alter the BRCA2 DBD structure and function. Therefore, to evaluate the functional impact of the p.Pro2767Ser variant, we used a minigene encoding a truncated protein that contains the BRCA2 DBD and the nearby nuclear localization sequence. We found that the ectopically expressed truncated protein carrying the normal DBD, which retains the DNA binding function and lacks the central RAD51 binding domain, interferes with endogenous wild-type BRCA2 mediator functions in the HR-DSBR. We also demonstrated that the BRCA2 Pro2767Ser DBD is unable to compete with endogenous BRCA2 DNA binding, thereby suggesting that the p.Pro2767Ser substitution in the full-length protein causes the functional loss of BRCA2. Consequently, our data suggest that the p.Pro2767Ser variant should be considered pathogenic, thus supporting a revision of the ClinVar interpretation. Moreover, our experimental strategy could be a valid method with which to preliminarily evaluate the pathogenicity of the unclassified BRCA2 germline variants in the DBD and their risk of predisposing to HBOC.
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Affiliation(s)
- Maria Valeria Esposito
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Giuseppina Minopoli
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Luciana Esposito
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, I-80134 Naples, Italy.
| | - Valeria D'Argenio
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Federica Di Maggio
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Emanuele Sasso
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Massimiliano D'Aiuto
- Department of Senology, Istituto Nazionale Tumori-IRCCS Fondazione Pascale, 80131 Naples, Italy.
| | - Nicola Zambrano
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
| | - Francesco Salvatore
- CEINGE-Biotecnologie Avanzate, 8014 Naples, Italy.
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, 80131 Naples, Italy.
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Padilla N, Moles-Fernández A, Riera C, Montalban G, Özkan S, Ootes L, Bonache S, Díez O, Gutiérrez-Enríquez S, de la Cruz X. BRCA1- and BRCA2-specific in silico tools for variant interpretation in the CAGI 5 ENIGMA challenge. Hum Mutat 2019; 40:1593-1611. [PMID: 31112341 DOI: 10.1002/humu.23802] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/15/2019] [Accepted: 05/17/2019] [Indexed: 11/09/2022]
Abstract
BRCA1 and BRCA2 (BRCA1/2) germline variants disrupting the DNA protective role of these genes increase the risk of hereditary breast and ovarian cancers. Correct identification of these variants then becomes clinically relevant, because it may increase the survival rates of the carriers. Unfortunately, we are still unable to systematically predict the impact of BRCA1/2 variants. In this article, we present a family of in silico predictors that address this problem, using a gene-specific approach. For each protein, we have developed two tools, aimed at predicting the impact of a variant at two different levels: Functional and clinical. Testing their performance in different datasets shows that specific information compensates the small number of predictive features and the reduced training sets employed to develop our models. When applied to the variants of the BRCA1/2 (ENIGMA) challenge in the fifth Critical Assessment of Genome Interpretation (CAGI 5) we find that these methods, particularly those predicting the functional impact of variants, have a good performance, identifying the large compositional bias towards neutral variants in the CAGI sample. This performance is further improved when incorporating to our prediction protocol estimates of the impact on splicing of the target variant.
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Affiliation(s)
- Natàlia Padilla
- Research Unit in Clinical and Translational Bioinformatics, Vall d'Hebron Institute of Research (VHIR). Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | - Casandra Riera
- Research Unit in Clinical and Translational Bioinformatics, Vall d'Hebron Institute of Research (VHIR). Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Gemma Montalban
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Selen Özkan
- Research Unit in Clinical and Translational Bioinformatics, Vall d'Hebron Institute of Research (VHIR). Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Lars Ootes
- Research Unit in Clinical and Translational Bioinformatics, Vall d'Hebron Institute of Research (VHIR). Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Sandra Bonache
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Orland Díez
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain.,Area of Clinical and Molecular Genetics, University Hospital of Vall d'Hebron, Barcelona, Spain
| | | | - Xavier de la Cruz
- Research Unit in Clinical and Translational Bioinformatics, Vall d'Hebron Institute of Research (VHIR). Universitat Autònoma de Barcelona, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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Samadder NJ, Giridhar KV, Baffy N, Riegert-Johnson D, Couch FJ. Hereditary Cancer Syndromes-A Primer on Diagnosis and Management: Part 1: Breast-Ovarian Cancer Syndromes. Mayo Clin Proc 2019; 94:1084-1098. [PMID: 31171119 DOI: 10.1016/j.mayocp.2019.02.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 02/05/2019] [Accepted: 02/14/2019] [Indexed: 12/12/2022]
Abstract
Cancer is the second leading cause of death in both men and women in the United States, with colorectal cancer and breast cancer being two of the most frequent cancer types. Hereditary causes occurring due to pathogenic sequence variants and defects in certain genes makes up roughly 5% of all colorectal cancers and breast-ovarian cancers. High-risk hereditary predisposition syndromes have been associated with a substantially increased lifetime risk for the development of colorectal cancers and breast-ovarian cancers depending on the genetic syndrome, and many people also carry an increased risk of several other cancers compared with the general population. The aim of this review was to provide comprehensive literature on the most commonly encountered hereditary predisposition syndromes, including Lynch syndrome, familial adenomatous polyposis, MUTYH-associated polyposis, hamartomatous polyposis, and breast-ovarian cancer conditions. This will be presented as a 2-part series: the first part will cover the breast-ovarian cancer syndromes, and the second will focus on the inherited colorectal cancer and polyposis conditions.
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Affiliation(s)
- N Jewel Samadder
- Division of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ; Department of Clinical Genomics, Mayo Clinic, Scottsdale, AZ; Department of Clinical Genomics, Mayo Clinic, Jacksonville, FL.
| | | | - Noemi Baffy
- Division of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ
| | - Douglas Riegert-Johnson
- Department of Clinical Genomics, Mayo Clinic, Scottsdale, AZ; Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL; Department of Clinical Genomics, Mayo Clinic, Jacksonville, FL
| | - Fergus J Couch
- Department of Laboratory Medicine, Mayo Clinic, Rochester, MN
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Deveryshetty J, Peterlini T, Ryzhikov M, Brahiti N, Dellaire G, Masson JY, Korolev S. Novel RNA and DNA strand exchange activity of the PALB2 DNA binding domain and its critical role for DNA repair in cells. eLife 2019; 8:44063. [PMID: 31017574 PMCID: PMC6533086 DOI: 10.7554/elife.44063] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 04/23/2019] [Indexed: 12/14/2022] Open
Abstract
BReast Cancer Associated proteins 1 and 2 (BRCA1, -2) and Partner and Localizer of BRCA2 (PALB2) protein are tumour suppressors linked to a spectrum of malignancies, including breast cancer and Fanconi anemia. PALB2 coordinates functions of BRCA1 and BRCA2 during homology-directed repair (HDR) and interacts with several chromatin proteins. In addition to protein scaffold function, PALB2 binds DNA. The functional role of this interaction is poorly understood. We identified a major DNA-binding site of PALB2, mutations in which reduce RAD51 foci formation and the overall HDR efficiency in cells by 50%. PALB2 N-terminal DNA-binding domain (N-DBD) stimulates the function of RAD51 recombinase. Surprisingly, it possesses the strand exchange activity without RAD51. Moreover, N-DBD stimulates the inverse strand exchange and can use DNA and RNA substrates. Our data reveal a versatile DNA interaction property of PALB2 and demonstrate a critical role of PALB2 DNA binding for chromosome repair in cells.
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Affiliation(s)
- Jaigeeth Deveryshetty
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
| | - Thibaut Peterlini
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | - Mikhail Ryzhikov
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
| | - Nadine Brahiti
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | | | - Jean-Yves Masson
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | - Sergey Korolev
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
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Genetic Testing to Guide Risk-Stratified Screens for Breast Cancer. J Pers Med 2019; 9:jpm9010015. [PMID: 30832243 PMCID: PMC6462925 DOI: 10.3390/jpm9010015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/18/2019] [Accepted: 02/22/2019] [Indexed: 12/14/2022] Open
Abstract
Breast cancer screening modalities and guidelines continue to evolve and are increasingly based on risk factors, including genetic risk and a personal or family history of cancer. Here, we review genetic testing of high-penetrance hereditary breast and ovarian cancer genes, including BRCA1 and BRCA2, for the purpose of identifying high-risk individuals who would benefit from earlier screening and more sensitive methods such as magnetic resonance imaging. We also consider risk-based screening in the general population, including whether every woman should be genetically tested for high-risk genes and the potential use of polygenic risk scores. In addition to enabling early detection, the results of genetic screens of breast cancer susceptibility genes can be utilized to guide decision-making about when to elect prophylactic surgeries that reduce cancer risk and the choice of therapeutic options. Variants of uncertain significance, especially missense variants, are being identified during panel testing for hereditary breast and ovarian cancer. A finding of a variant of uncertain significance does not provide a basis for increased cancer surveillance or prophylactic procedures. Given that variant classification is often challenging, we also consider the role of multifactorial statistical analyses by large consortia and functional tests for this purpose.
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46
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Reinterpretation of BRCA1 and BRCA2 variants of uncertain significance in patients with hereditary breast/ovarian cancer using the ACMG/AMP 2015 guidelines. Breast Cancer 2019; 26:510-519. [PMID: 30725392 DOI: 10.1007/s12282-019-00951-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/25/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND Although BRCA1 or BRCA2 (BRCA1/2) genetic testing plays an important role in determining treatment modalities in patients with hereditary breast and ovarian cancer, sequence variants with unknown clinical significance or variant of uncertain significance (VUS) have limited use in medical decision-making. With vast quantities of gene-related data being updated, the clinical significance of VUS may change over time. We reinterpreted the sequence variant previously reported as BRCA1/2 VUS results in patients with breast or ovarian cancer and assessed whether the clinical significance of VUS was changed. METHODS We retrospectively reviewed medical records of 423 breast or ovarian cancer patients who underwent BRCA1/2 genetic testing from 2010 to 2017. The VUSs in BRCA1/2 were reanalyzed using the 2015 American College of Medical Genetics and Genomics and the Association for Molecular Pathology standards and guidelines (ACMG/AMP 2015 guidelines) and the VUS was reclassified into five categories: "pathogenic", "likely pathogenic", "VUS", "likely benign", and "benign". RESULTS A total of 75 patients (48 sequence types of VUS) were identified as carrying either one or more VUS in BRCA1/2. Among the 75 patients, two patients (2.7%) were reclassified as "likely pathogenic", 30 patients (40.0%) were reclassified as either "benign" or "likely benign", and the remaining 43 patients (57.3%) were still classified as VUS category. CONCLUSIONS Since the clinical significance of VUS in BRCA1/2 may vary from time to time, reinterpretation of the VUS results could contribute to clinical decision-making.
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47
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Caleca L, Colombo M, van Overeem Hansen T, Lázaro C, Manoukian S, Parsons MT, Spurdle AB, Radice P. GFP-Fragment Reassembly Screens for the Functional Characterization of Variants of Uncertain Significance in Protein Interaction Domains of the BRCA1 and BRCA2 Genes. Cancers (Basel) 2019; 11:E151. [PMID: 30696104 PMCID: PMC6406614 DOI: 10.3390/cancers11020151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 01/22/2019] [Indexed: 01/14/2023] Open
Abstract
Genetic testing for BRCA1 and BRCA2 genes has led to the identification of many unique variants of uncertain significance (VUS). Multifactorial likelihood models that predict the odds ratio for VUS in favor or against cancer causality, have been developed, but their use is conditioned by the amount of necessary data, which are difficult to obtain if a variant is rare. As an alternative, variants mapping to the coding regions can be examined using in vitro functional assays. BRCA1 and BRCA2 proteins promote genome protection by interacting with different proteins. In this study, we assessed the functional effect of two sets of variants in BRCA genes by exploiting the green fluorescent protein (GFP)-reassembly in vitro assay, which was set-up to test the BRCA1/BARD1, BRCA1/UbcH5a, and BRCA2/DSS1 interactions. Based on the findings observed for the validation panels of previously classified variants, BRCA1/UbcH5a and BRCA2/DSS1 binding assays showed 100% sensitivity and specificity in identifying pathogenic and non-pathogenic variants. While the actual efficiency of these assays in assessing the clinical significance of BRCA VUS has to be verified using larger validation panels, our results suggest that the GFP-reassembly assay is a robust method to identify variants affecting normal protein functioning and contributes to the classification of VUS.
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Affiliation(s)
- Laura Caleca
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy.
| | - Mara Colombo
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy.
| | - Thomas van Overeem Hansen
- Center for Genomic Medicine, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark.
| | - Conxi Lázaro
- Hereditary Cancer Program, Catalan Institute of Oncology. Program in Molecular Mechanisms and Experimental Therapy in Oncology (Oncobell), IDIBELL, Hospitalet de Llobregat, 08900 Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), 28029 Madrid, Spain.
| | - Siranoush Manoukian
- Unit of Medical Genetics, Department of Medical Oncology and Hematology, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy.
| | - Michael T Parsons
- Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane 4029, Australia.
| | - Amanda B Spurdle
- Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane 4029, Australia.
| | - Paolo Radice
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of Research, Fondazione IRCCS Istituto Nazionale dei Tumori, 20133 Milan, Italy.
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Heczkova M, Machackova E, Macinga P, Gallmeier E, Cahova M, Spicak J, Jirsa M, Foretova L, Hucl T. Functional evaluation of variants of unknown significance in the BRCA2 gene identified in genetic testing. Cancer Biol Ther 2019; 20:633-641. [PMID: 30638113 DOI: 10.1080/15384047.2018.1550566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Heterozygous germline BRCA2 mutations predispose to breast, ovarian, pancreatic and other types of cancer. The presence of a pathogenic mutation in patients or their family members warrants close surveillance or prophylactic surgery. Besides clearly pathogenic mutations, variants leading only to a single amino acid substitution are often identified. The influence of such variants on cancer risk is often unknown, making their presence a major clinical problem. When genetic methods are insufficient to classify these variants, functional assays with various cellular models are performed. We developed and applied a new syngeneic model of human cancer cells to test all variants of unknown significance in exon 18 identified by genetic testing of high-risk cancer patients in the Czech Republic, via introduction of constructs containing each of these variants into the wild-type allele of BRCA2-heterozygous DLD1 cells (BRCA2wt/Δex11). We found unaffected DNA repair function of BRCA2 in cell lines BRCA27997G>C/Δex11, BRCA28111C>T/Δex11, BRCA28149G>T/Δex11, BRCA28182G>A/Δex11, and BRCA28182G>T/Δex11, whereas the cell line BRCA28168A>G/Δex11 and the nonsense mutation carrying line BRCA28305G>T/Δex11 did affect protein function. Targeting the BRCA2 wild-type allele with a construct carrying the variant c.7988A> G resulted in incorporation exclusively into the already defective allele in all viable clones, strongly suggesting a detrimental phenotype. Our model thus offers a valuable tool for the functional evaluation of unclassified variants in the BRCA2 gene and provides a stable and distributable cellular resource for further research.
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Affiliation(s)
- Marie Heczkova
- a Center for Experimental Medicine , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
| | - Eva Machackova
- b Department of Cancer Epidemiology and Genetics , Masaryk Memorial Cancer Institute , Brno , Czech Republic
| | - Peter Macinga
- c Department of Gastroenterology and Hepatology , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
| | - Eike Gallmeier
- d Department of Internal Medicine , Philipps University of Marburg , Marburg , Germany
| | - Monika Cahova
- a Center for Experimental Medicine , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
| | - Julius Spicak
- c Department of Gastroenterology and Hepatology , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
| | - Milan Jirsa
- a Center for Experimental Medicine , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
| | - Lenka Foretova
- b Department of Cancer Epidemiology and Genetics , Masaryk Memorial Cancer Institute , Brno , Czech Republic
| | - Tomas Hucl
- a Center for Experimental Medicine , Institute of Clinical and Experimental Medicine , Prague , Czech Republic.,c Department of Gastroenterology and Hepatology , Institute of Clinical and Experimental Medicine , Prague , Czech Republic
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Fernández-Lopez JC, Romero-Córdoba S, Rebollar-Vega R, Alfaro-Ruiz LA, Jiménez-Morales S, Beltrán-Anaya F, Arellano-Llamas R, Cedro-Tanda A, Rios-Romero M, Ramirez-Florencio M, Bautista-Piña V, Dominguez-Reyes C, Villegas-Carlos F, Tenorio-Torres A, Hidalgo-Miranda A. Population and breast cancer patients' analysis reveals the diversity of genomic variation of the BRCA genes in the Mexican population. Hum Genomics 2019; 13:3. [PMID: 30630528 PMCID: PMC6327376 DOI: 10.1186/s40246-018-0188-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 12/18/2018] [Indexed: 01/08/2023] Open
Abstract
Interpretation of variants of unknown significance (VUS) in genetic tests is complicated in ethnically diverse populations, given the lack of information regarding the common spectrum of genetic variation in clinically relevant genes. Public availability of data obtained from high-throughput genotyping and/or exome massive parallel sequencing (MPS)-based projects from several thousands of outbred samples might become useful tools to evaluate the pathogenicity of a VUS, based on its frequency in different populations. In the case of the Mexican and other Latino populations, several thousands of samples have been genotyped or sequenced during the last few years as part of different efforts to identify common variants associated to common diseases. In this report, we analyzed Mexican population data from a sample of 3985 outbred individuals, and additional 66 hereditary breast cancer patients were analyzed in order to better define the spectrum of common genomic variation of the BRCA1 and BRCA2 genes. Our analyses identified the most common genetic variants in these clinically relevant genes as well as the presence and frequency of specific pathogenic mutations present in the Mexican population. Analysis of the 3985 population samples by MPS identified three pathogenic mutations in BRCA1, only one population sample showed a BRCA1 exon 16-17 deletion by MLPA. This resulted in a basal prevalence of deleterious mutations of 0.10% (1:996) for BRCA1 and 11 pathogenic mutations in BRCA2, resulting in a basal prevalence of deleterious mutations of 0.276% (1:362) for BRCA2, combined of 0.376% (1:265). Separate analysis of the breast cancer patients identified the presence of pathogenic mutations in 18% (12 pathogenic mutations in 66 patients) of the samples by MPS and 13 additional alterations by MLPA. These results will support a better interpretation of clinical studies focused on the detection of BRCA mutations in Mexican and Latino populations and will help to define the general prevalence of deleterious mutations within these populations.
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Affiliation(s)
- J C Fernández-Lopez
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - S Romero-Córdoba
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - R Rebollar-Vega
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - L A Alfaro-Ruiz
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - S Jiménez-Morales
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - F Beltrán-Anaya
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - R Arellano-Llamas
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - A Cedro-Tanda
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - M Rios-Romero
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - M Ramirez-Florencio
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico
| | - V Bautista-Piña
- Instituto de Enfermedades la Mama FUCAM, Avenida El Bordo 100, Santa Ursula Coapa, 04980, Mexico City, CP, Mexico
| | - C Dominguez-Reyes
- Instituto de Enfermedades la Mama FUCAM, Avenida El Bordo 100, Santa Ursula Coapa, 04980, Mexico City, CP, Mexico
| | - F Villegas-Carlos
- Instituto de Enfermedades la Mama FUCAM, Avenida El Bordo 100, Santa Ursula Coapa, 04980, Mexico City, CP, Mexico
| | - A Tenorio-Torres
- Instituto de Enfermedades la Mama FUCAM, Avenida El Bordo 100, Santa Ursula Coapa, 04980, Mexico City, CP, Mexico
| | - A Hidalgo-Miranda
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Perfiérico Sur, 4809, Arenal Tepepan, 14610, Mexico City, CP, Mexico.
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50
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Starita LM, Islam MM, Banerjee T, Adamovich AI, Gullingsrud J, Fields S, Shendure J, Parvin JD. A Multiplex Homology-Directed DNA Repair Assay Reveals the Impact of More Than 1,000 BRCA1 Missense Substitution Variants on Protein Function. Am J Hum Genet 2018; 103:498-508. [PMID: 30219179 DOI: 10.1016/j.ajhg.2018.07.016] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 07/19/2018] [Indexed: 10/28/2022] Open
Abstract
Loss-of-function pathogenic variants in BRCA1 confer a predisposition to breast and ovarian cancer. Genetic testing for sequence changes in BRCA1 frequently reveals a missense variant for which the impact on cancer risk and on the molecular function of BRCA1 is unknown. Functional BRCA1 is required for the homology-directed repair (HDR) of double-strand DNA breaks, a critical activity for maintaining genome integrity and tumor suppression. Here, we describe a multiplex HDR reporter assay for concurrently measuring the effects of hundreds of variants of BRCA1 for their role in DNA repair. Using this assay, we characterized the effects of 1,056 amino acid substitutions in the first 192 residues of BRCA1. Benchmarking these results against variants with known effects on DNA repair function or on cancer predisposition, we demonstrate accurate discrimination of loss-of-function versus benign missense variants. We anticipate that this assay can be used to functionally characterize BRCA1 missense variants at scale, even before the variants are observed in results from genetic testing.
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