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Palathingal Bava E, Sanfrancesco JM, Alkashash A, Favazza L, Aldilami A, Williamson SR, Cheng L, Idrees MT, Al-Obaidy KI. Acquired cystic disease associated renal cell carcinoma: A clinicopathologic and molecular study of 31 tumors. Hum Pathol 2024; 149:48-54. [PMID: 38862094 DOI: 10.1016/j.humpath.2024.06.002] [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: 04/02/2024] [Revised: 05/31/2024] [Accepted: 06/08/2024] [Indexed: 06/13/2024]
Abstract
Acquired cystic disease associated renal cell carcinomas (ACD-RCC) are rare and their molecular and histopathological characteristics are still being explored. We therefore investigated the clinicopathologic and molecular characteristics of 31 tumors. The patients were predominantly male (n = 30), with tumors mainly left-sided (n = 17), unifocal (n = 19), and unilateral (n = 29) and a mean tumor size of 25 mm (range, 3-65 mm). Microscopically, several histologic patterns were present, including pure classic sieve-like (n = 4), and varied proportions of mixed classic sieve-like with papillary (n = 23), tubulocystic (n = 9), compact tubular (n = 4) and solid (n = 1) patterns. Calcium-oxalate crystals were seen in all tumors. Molecular analysis of 9 tumors using next generation sequencing showed alterations in SMARCB1 in 3 tumors (1 with frameshift deletion and 2 with copy number loss in chromosome 22 involving SMARCB1 region), however, INI1 stain was retained in all. Nonrecurrent genetic alterations in SETD2, NF1, NOTCH4, BRCA2 and CANT1 genes were also seen. Additionally, MTOR p.Pro351Ser was identified in one tumor. Copy number analysis showed gains in chromosome 16 (n = 5), 17 (n = 2) and 8 (n = 2) as well as loss in chromosome 22 (n = 2). In summary, ACD-RCC is a recognized subtype of kidney tumors, with several histological architectural patterns. Our molecular data identifies genetic alterations in chromatin modifying genes (SMARCB1 and SETD2), which may suggest a role of such genes in ACD-RCC development.
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Affiliation(s)
- Ejas Palathingal Bava
- Department of Pathology and Laboratory Medicine, Henry Ford Health, Detroit, MI, USA.
| | | | - Ahmed Alkashash
- Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN, USA.
| | - Laura Favazza
- Department of Pathology and Laboratory Medicine, Henry Ford Health, Detroit, MI, USA.
| | - Akram Aldilami
- Department of Neurology, Henry Ford Health, Detroit, MI, USA.
| | - Sean R Williamson
- Pathology and Laboratory Medicine Institute, The Cleveland Clinic, Cleveland, OH, USA.
| | - Liang Cheng
- Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, USA.
| | - Mohammed T Idrees
- Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN, USA.
| | - Khaleel I Al-Obaidy
- Department of Pathology and Laboratory Medicine, Henry Ford Health, Detroit, MI, USA; Department of Medicine, College of Human Medicine, Michigan State University, East Lansing, MI, USA.
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2
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Panagiotou E, Vathiotis IA, Makrythanasis P, Hirsch F, Sen T, Syrigos K. Biological and therapeutic implications of the cancer-related germline mutation landscape in lung cancer. THE LANCET. RESPIRATORY MEDICINE 2024:S2213-2600(24)00124-3. [PMID: 38885686 DOI: 10.1016/s2213-2600(24)00124-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 06/20/2024]
Abstract
Although smoking is the primary cause of lung cancer, only about 15% of lifelong smokers develop the disease. Moreover, a substantial proportion of lung cancer cases occur in never-smokers, highlighting the potential role of inherited genetic factors in the cause of lung cancer. Lung cancer is significantly more common among those with a positive family history, especially for early-onset disease. Therefore, the presence of pathogenic germline variants might act synergistically with environmental factors. The incorporation of next-generation sequencing in routine clinical practice has led to the identification of cancer-predisposing mutations in an increasing proportion of patients with lung cancer. This Review summarises the landscape of germline susceptibility in lung cancer and highlights the importance of germline testing in patients diagnosed with the disease, which has the potential to identify individuals at risk, with implications for tailored therapeutic approaches and successful prevention through genetic counselling and screening.
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Affiliation(s)
- Emmanouil Panagiotou
- Third Department of Internal Medicine, Sotiria General Hospital for Chest Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Ioannis A Vathiotis
- Third Department of Internal Medicine, Sotiria General Hospital for Chest Diseases, National and Kapodistrian University of Athens, Athens, Greece.
| | - Periklis Makrythanasis
- Laboratory of Medical Genetics, Medical School, National and Kapodistrian University of Athens, Athens, Greece; Department of Genetic Medicine and Development, Medical School, University of Geneva, Geneva, Switzerland; Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Fred Hirsch
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Triparna Sen
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Konstantinos Syrigos
- Third Department of Internal Medicine, Sotiria General Hospital for Chest Diseases, National and Kapodistrian University of Athens, Athens, Greece
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3
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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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Rein HL, Bernstein KA. Finding significance: New perspectives in variant classification of the RAD51 regulators, BRCA2 and beyond. DNA Repair (Amst) 2023; 130:103563. [PMID: 37651978 PMCID: PMC10529980 DOI: 10.1016/j.dnarep.2023.103563] [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: 04/25/2023] [Revised: 08/11/2023] [Accepted: 08/15/2023] [Indexed: 09/02/2023]
Abstract
For many individuals harboring a variant of uncertain functional significance (VUS) in a homologous recombination (HR) gene, their risk of developing breast and ovarian cancer is unknown. Integral to the process of HR are BRCA1 and regulators of the central HR protein, RAD51, including BRCA2, PALB2, RAD51C and RAD51D. Due to advancements in sequencing technology and the continued expansion of cancer screening panels, the number of VUS identified in these genes has risen significantly. Standard practices for variant classification utilize different types of predictive, population, phenotypic, allelic and functional evidence. While variant analysis is improving, there remains a struggle to keep up with demand. Understanding the effects of an HR variant can aid in preventative care and is critical for developing an effective cancer treatment plan. In this review, we discuss current perspectives in the classification of variants in the breast and ovarian cancer genes BRCA1, BRCA2, PALB2, RAD51C and RAD51D.
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Affiliation(s)
- Hayley L Rein
- University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, USA
| | - Kara A Bernstein
- University of Pennsylvania School of Medicine, Department of Biochemistry and Biophysics, 421 Curie Boulevard, Philadelphia, PA, USA.
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5
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Mutational spectrum in clinically aggressive low-grade serous carcinoma/serous borderline tumors of the ovary-Clinical significance of BRCA2 gene variants in genomically stable tumors. Gynecol Oncol 2021; 161:762-768. [PMID: 33773808 DOI: 10.1016/j.ygyno.2021.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/15/2021] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The mutational spectra of low-grade serous carcinomas (LGSCs) and serous borderline tumors (SBTs) of the ovary are poorly characterized. We present 17 cases of advanced or recurrent LGSC/SBT patients who underwent molecular profiling. METHODS Thirteen LGSCs and four SBTs underwent targeted gene panel testing by massively parallel sequencing. Microsatellite stability and tumor mutation burdens (TMBs) were determined based on panel sequencing data. RESULTS The mean TMB was 5.2 mutations/megabase (range 3-10) in 14 cases. Twelve of twelve (12/12) cases were microsatellite stable. Clear driver mutations were identified in 11 cases, namely KRAS (5/17), BRAF (2/17), NRAS (2/17) and ERBB2 (2/17). Five cases harbored BRCA2 alterations (allele fractions: 44-51%), including two classified as likely benign/benign variants, and three classified as variants of uncertain significance (VUSs), with two variants being confirmed to be germline. The three BRCA2 VUSs were missense variants that were assessed to be of unlikely clinical significance, based on family cancer history and expected impact on protein function. Two patients received PARP inhibitors during their disease course, with neither of the patients demonstrating appreciable response. CONCLUSIONS The mutational spectra in 17 clinically aggressive SBT/LGSC cases demonstrate genomically stable tumors, frequently driven by the RTK/RAS/MAPK pathway. While BRCA2 variants were identified, our data demonstrate BRCA2 gene variants are at most VUSs and of dubious clinical significance, in contrast to disease-associated BRCA1/2 variants that may be identified in high-grade serous carcinoma. Germline testing and PARP inhibitors are thus expected to provide limited benefit to patients with LGSC/SBTs.
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6
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Meulemans L, Mesman RLS, Caputo SM, Krieger S, Guillaud-Bataille M, Caux-Moncoutier V, Léone M, Boutry-Kryza N, Sokolowska J, Révillion F, Delnatte C, Tubeuf H, Soukarieh O, Bonnet-Dorion F, Guibert V, Bronner M, Bourdon V, Lizard S, Vilquin P, Privat M, Drouet A, Grout C, Calléja FMGR, Golmard L, Vrieling H, Stoppa-Lyonnet D, Houdayer C, Frebourg T, Vreeswijk MPG, Martins A, Gaildrat P. Skipping Nonsense to Maintain Function: The Paradigm of BRCA2 Exon 12. Cancer Res 2020; 80:1374-1386. [PMID: 32046981 DOI: 10.1158/0008-5472.can-19-2491] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/18/2019] [Accepted: 02/06/2020] [Indexed: 11/16/2022]
Abstract
Germline nonsense and canonical splice site variants identified in disease-causing genes are generally considered as loss-of-function (LoF) alleles and classified as pathogenic. However, a fraction of such variants could maintain function through their impact on RNA splicing. To test this hypothesis, we used the alternatively spliced BRCA2 exon 12 (E12) as a model system because its in-frame skipping leads to a potentially functional protein. All E12 variants corresponding to putative LoF variants or predicted to alter splicing (n = 40) were selected from human variation databases and characterized for their impact on splicing in minigene assays and, when available, in patient lymphoblastoid cell lines. Moreover, a selection of variants was analyzed in a mouse embryonic stem cell-based functional assay. Using these complementary approaches, we demonstrate that a subset of variants, including nonsense variants, induced in-frame E12 skipping through the modification of splice sites or regulatory elements and, consequently, led to an internally deleted but partially functional protein. These data provide evidence, for the first time in a cancer-predisposition gene, that certain presumed null variants can retain function due to their impact on splicing. Further studies are required to estimate cancer risk associated with these hypomorphic variants. More generally, our findings highlight the need to exercise caution in the interpretation of putative LoF variants susceptible to induce in-frame splicing modifications. SIGNIFICANCE: This study presents evidence that certain presumed loss-of-function variants in a cancer predisposition gene can retain function due to their direct impact on RNA splicing.
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Affiliation(s)
- Laëtitia Meulemans
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Romy L S Mesman
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Sandrine M Caputo
- Department of Genetics, Institut Curie, Paris, France.,PSL Research University, Paris, France
| | - Sophie Krieger
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Laboratory of Cancer Biology and Genetics, Centre François Baclesse, Caen, France.,Normandie University, UNICAEN, Caen, France
| | | | | | | | | | | | | | | | - Hélène Tubeuf
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Interactive Biosoftware, Rouen, France
| | - Omar Soukarieh
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Virginie Guibert
- Department of Genetics, Nantes University Hospital, Nantes, France
| | - Myriam Bronner
- Department of Genetics, Nancy University Hospital, Nancy, France
| | - Violaine Bourdon
- Department of Genetics, Institut Paoli-Calmettes, Marseille, France
| | - Sarab Lizard
- Department of Genetics, Nancy University Hospital, Nancy, France
| | - Paul Vilquin
- Department of Pathology and Oncobiology, Montpellier University Hospital, Montpellier, France
| | - Maud Privat
- University of Clermont Auvergne, Inserm U1240, Clermont Ferrand, France.,Department of Oncogenetics, Centre Jean Perrin, Clermont Ferrand, France
| | - Aurélie Drouet
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Charlotte Grout
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Lisa Golmard
- Department of Genetics, Institut Curie, Paris, France.,PSL Research University, Paris, France
| | - Harry Vrieling
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Dominique Stoppa-Lyonnet
- Department of Genetics, Institut Curie, Paris, France.,Inserm U830, University Paris Descartes, Paris, France
| | - Claude Houdayer
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Department of Genetics, Institut Curie, Paris, France.,Department of Genetics, Rouen University Hospital, Rouen, France
| | - Thierry Frebourg
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Department of Genetics, Rouen University Hospital, Rouen, France
| | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Alexandra Martins
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Pascaline Gaildrat
- Normandie Univ, UNIROUEN, Inserm U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.
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7
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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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8
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Zhao W, Wiese C, Kwon Y, Hromas R, Sung P. The BRCA Tumor Suppressor Network in Chromosome Damage Repair by Homologous Recombination. Annu Rev Biochem 2019; 88:221-245. [PMID: 30917004 DOI: 10.1146/annurev-biochem-013118-111058] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations in the BRCA1 and BRCA2 genes predispose afflicted individuals to breast, ovarian, and other cancers. The BRCA-encoded products form complexes with other tumor suppressor proteins and with the recombinase enzyme RAD51 to mediate chromosome damage repair by homologous recombination and also to protect stressed DNA replication forks against spurious nucleolytic attrition. Understanding how the BRCA tumor suppressor network executes its biological functions would provide the foundation for developing targeted cancer therapeutics, but progress in this area has been greatly hampered by the challenge of obtaining purified BRCA complexes for mechanistic studies. In this article, we review how recent effort begins to overcome this technical challenge, leading to functional and structural insights into the biochemical attributes of these complexes and the multifaceted roles that they fulfill in genome maintenance. We also highlight the major mechanistic questions that remain.
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Affiliation(s)
- Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Claudia Wiese
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Robert Hromas
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
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9
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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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10
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Brandão RD, Mensaert K, López‐Perolio I, Tserpelis D, Xenakis M, Lattimore V, Walker LC, Kvist A, Vega A, Gutiérrez‐Enríquez S, Díez O, de la Hoya M, Spurdle AB, De Meyer T, Blok MJ. Targeted RNA-seq successfully identifies normal and pathogenic splicing events in breast/ovarian cancer susceptibility and Lynch syndrome genes. Int J Cancer 2019; 145:401-414. [PMID: 30623411 PMCID: PMC6635756 DOI: 10.1002/ijc.32114] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 11/27/2018] [Accepted: 12/12/2018] [Indexed: 12/21/2022]
Abstract
A subset of genetic variants found through screening of patients with hereditary breast and ovarian cancer syndrome (HBOC) and Lynch syndrome impact RNA splicing. Through target enrichment of the transcriptome, it is possible to perform deep-sequencing and to identify the different and even rare mRNA isoforms. A targeted RNA-seq approach was used to analyse the naturally-occurring splicing events for a panel of 8 breast and/or ovarian cancer susceptibility genes (BRCA1, BRCA2, RAD51C, RAD51D, PTEN, STK11, CDH1, TP53), 3 Lynch syndrome genes (MLH1, MSH2, MSH6) and the fanconi anaemia SLX4 gene, in which monoallelic mutations were found in non-BRCA families. For BRCA1, BRCA2, RAD51C and RAD51D the results were validated by capillary electrophoresis and were compared to a non-targeted RNA-seq approach. We also compared splicing events from lymphoblastoid cell-lines with those from breast and ovarian fimbriae tissues. The potential of targeted RNA-seq to detect pathogenic changes in RNA-splicing was validated by the inclusion of samples with previously well characterized BRCA1/2 genetic variants. In our study, we update the catalogue of normal splicing events for BRCA1/2, provide an extensive catalogue of normal RAD51C and RAD51D alternative splicing, and list splicing events found for eight other genes. Additionally, we show that our approach allowed the identification of aberrant splicing events due to the presence of BRCA1/2 genetic variants and distinguished between complete and partial splicing events. In conclusion, targeted-RNA-seq can be very useful to classify variants based on their putative pathogenic impact on splicing.
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Affiliation(s)
- Rita D. Brandão
- Department of Clinical GeneticsMaastricht University Medical Centre+, GROW‐ School for Oncology and Developmental BiologyMaastrichtThe Netherlands
| | - Klaas Mensaert
- Department of Data Analysis and Mathematical Modelling and Bioinformatics Institute Ghent N2NGhent UniversityGhentBelgium
| | - Irene López‐Perolio
- Molecular Oncology Laboratory CIBERONCHospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Demis Tserpelis
- Department of Clinical GeneticsMaastricht University Medical Centre+, GROW‐ School for Oncology and Developmental BiologyMaastrichtThe Netherlands
| | - Markos Xenakis
- Department of Clinical GeneticsMaastricht University Medical Centre+, GROW‐ School for Oncology and Developmental BiologyMaastrichtThe Netherlands
- Department of Data Science and Knowledge EngineeringMaastricht UniversityMaastrichtThe Netherlands
| | - Vanessa Lattimore
- Department of Pathology and Biomedical ScienceUniversity of OtagoChristchurchNew Zealand
| | - Logan C. Walker
- Department of Pathology and Biomedical ScienceUniversity of OtagoChristchurchNew Zealand
| | - Anders Kvist
- Division of Oncology and Pathology, Department of Clinical SciencesLund UniversityLundSweden
| | - Ana Vega
- Fundación Pública Galega de Medicina Xenómica‐Servicio Galgo de SaúdeGrupo de Medicina Xenómica‐USC, CIBERER, IDISSantiago de CompostelaSpain
| | | | - Orland Díez
- Oncogenetics GroupVall d'Hebron Institute of Oncology (VHIO)BarcelonaSpain
- Area of Clinical and Molecular GeneticsUniversity Hospital of Vall d'HebronBarcelonaSpain
| | | | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONCHospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos)MadridSpain
| | - Amanda B. Spurdle
- Department of Genetics and Computational BiologyQIMR Berghofer Medical Research InstituteBrisbaneQLDAustralia
| | - Tim De Meyer
- Department of Data Analysis and Mathematical Modelling and Bioinformatics Institute Ghent N2NGhent UniversityGhentBelgium
- CRIG (Cancer Research Institute Ghent)Ghent UniversityGhentBelgium
| | - Marinus J. Blok
- Department of Clinical GeneticsMaastricht University Medical Centre+, GROW‐ School for Oncology and Developmental BiologyMaastrichtThe Netherlands
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11
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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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12
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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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13
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Germline and Somatic Defects in DNA Repair Pathways in Prostate Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1210:279-300. [PMID: 31900913 DOI: 10.1007/978-3-030-32656-2_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent studies have provided a better understanding of the molecular underpinnings of prostate cancer. Alterations in genes encoding for proteins involved in the different pathways in charge of preserving genomic integrity and repairing DNA damage are common in prostate cancer, particularly in late-stage disease. Generally, these alterations would confer a survival advantage for tumors, resulting in a more aggressive phenotype. However, DNA repair defects can also represent a vulnerability for tumors that can be exploited therapeutically, offering the possibility of precision medicine strategies. Moreover, many of these mutations are linked to hereditary risk for cancers; hence, identification of DNA repair mutations could also be relevant for cancer prevention and screening in healthy individuals, including relatives of prostate cancer patients. In this chapter, we summarize current knowledge about the prevalence of different DNA repair gene alterations across different stages of prostate cancer and review the clinical relevance of such events in terms of prognosis and treatment stratification.
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14
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Pathania S, Garber JE. Mixing Mutation Location With Carcinogen Exposure: A Recipe for Tissue Specificity in BRCA2-Associated Cancers? J Natl Cancer Inst 2018; 110:925-926. [PMID: 29767746 DOI: 10.1093/jnci/djy047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/02/2018] [Indexed: 11/15/2022] Open
Affiliation(s)
- Shailja Pathania
- Center for Personalized Cancer Therapy, Department of Biology, University of Massachusetts Boston, Boston, MA
| | - Judy E Garber
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA
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15
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Montalban G, Fraile-Bethencourt E, López-Perolio I, Pérez-Segura P, Infante M, Durán M, Alonso-Cerezo MC, López-Fernández A, Diez O, de la Hoya M, Velasco EA, Gutiérrez-Enríquez S. Characterization of spliceogenic variants located in regions linked to high levels of alternative splicing: BRCA2 c.7976+5G > T as a case study. Hum Mutat 2018; 39:1155-1160. [PMID: 29969168 DOI: 10.1002/humu.23583] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 06/04/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022]
Abstract
Many BRCA1 and BRCA2 (BRCA1/2) genetic variants have been studied at mRNA level and linked to hereditary breast and ovarian cancer due to splicing alteration. In silico tools are reliable when assessing variants located in consensus splice sites, but we may identify variants in complex genomic contexts for which bioinformatics is not precise enough. In this study, we characterize BRCA2 c.7976 + 5G > T variant located in intron 17 which has an atypical donor site (GC). This variant was identified in three unrelated Spanish families and we have detected exon 17 skipping as the predominant transcript occurring in carriers. We have also detected several isoforms (Δ16-18, Δ17,18, Δ18, and ▼17q224 ) at different expression levels among carriers and controls. This study remarks the challenge of interpreting genetic variants when multiple alternative isoforms are present, and that caution must be taken when using in silico tools to identify potential spliceogenic variants located in GC-AG introns.
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Affiliation(s)
- Gemma Montalban
- Oncogenetics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Eugenia Fraile-Bethencourt
- Splicing and genetic susceptibility to cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Irene López-Perolio
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Pedro Pérez-Segura
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Mar Infante
- Cancer Genetics, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - Mercedes Durán
- Cancer Genetics, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
| | - María Concepción Alonso-Cerezo
- Genética Clínica. Servicio Análisis Clínicos. Hospital Universitario de la Princesa, Instituto de Investigación Sanitaria Hospital Universitario de la Princesa, Madrid, Spain
| | - Adrià López-Fernández
- High Risk and Cancer Prevention Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Orland Diez
- 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
| | - Miguel de la Hoya
- Molecular Oncology Laboratory CIBERONC, Hospital Clinico San Carlos, IdISSC (Instituto de Investigación Sanitaria del Hospital Clínico San Carlos), Madrid, Spain
| | - Eladio A Velasco
- Splicing and genetic susceptibility to cancer, Instituto de Biología y Genética Molecular (CSIC-UVa), Valladolid, Spain
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16
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El Shamieh S, Saleh F, Moussa S, Kattan J, Farhat F. RICTOR gene amplification is correlated with metastasis and therapeutic resistance in triple-negative breast cancer. Pharmacogenomics 2018; 19:757-760. [PMID: 29790419 DOI: 10.2217/pgs-2018-0019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Triple-negative breast cancer (TNBC) is characterized by its aggressive behavior, metastasis and lack of targeted therapies. Herein, we discuss the clinical, histopathological and genetic profile of a woman diagnosed with TNBC. Since the patient had no durable response to chemotherapy, a genetic profiling was carried out. Next-generation sequencing analysis of 592 genes showed a missense mutation, p.E545A in PIK3CA, thus the patient was started on the mTOR inhibitor everolimus, in combination with exemestane, which controlled her pain; however, the disease progressed aggressively. More importantly, next-generation sequencing analysis showed a RICTOR gene amplification (eight copies) suggesting that RICTOR promotes the genesis of TNBC. We conclude that determining regulators of RICTOR and furthermore, their inhibitors might decrease cancer cells proliferation rate in patients with TNBC.
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Affiliation(s)
- Said El Shamieh
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Fatima Saleh
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Salim Moussa
- Department of Medical Laboratory Sciences, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
| | - Joseph Kattan
- Department of Hematology-Oncology, Saint Joseph Faculty of Medicine, Beirut, Lebanon
| | - Fadi Farhat
- Department of Hematology-Oncology, Saint Joseph Faculty of Medicine, Beirut, Lebanon.,Department of Hematology & Oncology, Hammoud Hospital UMC, Saida, Lebanon
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17
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Guidugli L, Shimelis H, Masica DL, Pankratz VS, Lipton GB, Singh N, Hu C, Monteiro ANA, Lindor NM, Goldgar DE, Karchin R, Iversen ES, Couch FJ. Assessment of the Clinical Relevance of BRCA2 Missense Variants by Functional and Computational Approaches. Am J Hum Genet 2018; 102:233-248. [PMID: 29394989 DOI: 10.1016/j.ajhg.2017.12.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/18/2017] [Indexed: 11/30/2022] Open
Abstract
Many variants of uncertain significance (VUS) have been identified in BRCA2 through clinical genetic testing. VUS pose a significant clinical challenge because the contribution of these variants to cancer risk has not been determined. We conducted a comprehensive assessment of VUS in the BRCA2 C-terminal DNA binding domain (DBD) by using a validated functional assay of BRCA2 homologous recombination (HR) DNA-repair activity and defined a classifier of variant pathogenicity. Among 139 variants evaluated, 54 had ?99% probability of pathogenicity, and 73 had ?95% probability of neutrality. Functional assay results were compared with predictions of variant pathogenicity from the Align-GVGD protein-sequence-based prediction algorithm, which has been used for variant classification. Relative to the HR assay, Align-GVGD significantly (p < 0.05) over-predicted pathogenic variants. We subsequently combined functional and Align-GVGD prediction results in a Bayesian hierarchical model (VarCall) to estimate the overall probability of pathogenicity for each VUS. In addition, to predict the effects of all other BRCA2 DBD variants and to prioritize variants for functional studies, we used the endoPhenotype-Optimized Sequence Ensemble (ePOSE) algorithm to train classifiers for BRCA2 variants by using data from the HR functional assay. Together, the results show that systematic functional assays in combination with in silico predictors of pathogenicity provide robust tools for clinical annotation of BRCA2 VUS.
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Affiliation(s)
- Lucia Guidugli
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - Hermela Shimelis
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - David L Masica
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Vernon S Pankratz
- Division of Nephrology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Gary B Lipton
- Department of Statistical Science, Duke University, Durham, NC 27708, USA
| | - Namit Singh
- Department of Structural Biology, University of California, San Diego, San Diego, CA 92093, USA
| | - Chunling Hu
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - Alvaro N A Monteiro
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
| | - Noralane M Lindor
- Department of Health Sciences Research, Mayo Clinic, Scottsdale, AZ 85259, USA
| | - David E Goldgar
- Huntsman Cancer Institute and Department of Dermatology, University of Utah, Salt Lake City, UT 84132, USA
| | - Rachel Karchin
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21218, USA
| | - Edwin S Iversen
- Department of Statistical Science, Duke University, Durham, NC 27708, USA
| | - Fergus J Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
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18
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Double Heterozygosity for BRCA1 Pathogenic Variant and BRCA2 Polymorphic Stop Codon K3326X: A Case Report in a Southern Italian Family. Int J Mol Sci 2018; 19:ijms19010285. [PMID: 29346284 PMCID: PMC5796231 DOI: 10.3390/ijms19010285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 11/17/2022] Open
Abstract
Here, we describe a patient with bilateral breast cancer and melanoma, and with a concomitant double variant, namely p.Gln563Ter in BRCA1 and p.Lys3326Ter in BRCA2. The BRCA2 p.Lys3326Ter (K3326X) (rs11571833) mutation identified in our patient is a debated substitution of thymidine for adenine which is currently regarded as benign polymorphism in main gene databases. Recent studies, however, describe this variant as associated with breast and ovarian tumors. Based on the observation of the cancer’s earliest age of onset in this subject, our purpose was to reevaluate this variant according to recent papers indicating a role of powerful modifier of the genetic penetrance. Genetic testing was performed in all consenting patient’s relatives, and in the collection of the clinical data particular attention was paid to the age of onset of the neoplasia. Following our observation that the our patient with double heterozygosis had an early age of onset for cancer similar to a few rare cases of double mutation for BRCA1 and BRCA2, we also performed an extensive review of the literature relative to patients carrying a double heterozygosity for both genes. In line with previous studies relative to the rare double heterozygosity in both BRCA1/2 genes, we found the earlier onset of breast cancer in our patient with both BRCA1/2 mutations with respect to other relatives carrying the single BRCA1 mutation. The presence of the second K3326X variant in our case induces a phenotype characterized by early onset of the neoplasia in a manner similar to the other cases of double heterozygosity previously described. Therefore, we suggest that during the genetic counseling, it should be recommendable to evaluate the presence of the K3326X variant in association with other pathogenic mutations.
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19
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Lev A, Deihimi S, Shagisultanova E, Xiu J, Lulla AR, Dicker DT, El-Deiry WS. Preclinical rationale for combination of crizotinib with mitomycin C for the treatment of advanced colorectal cancer. Cancer Biol Ther 2017; 18:694-704. [PMID: 28886275 DOI: 10.1080/15384047.2017.1364323] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Colorectal cancer (CRC) is a leading cause of cancer-related deaths in the United States. We analyzed 26 MSI-High and 558 non-MSI-High CRC tumors. BRCA2 mutations were highly enriched (50%) in MSI-High CRC. Immunohistochemistry showed that BRCA2-mutated MSI-High CRC had high c-MET (64%) expression compared with BRCA-WT (17%). We hypothesized a mechanistic link between BRCA2-deficiency and c-MET overexpression and synergistic interaction between drugs that treat BRCA-deficient tumors (mitomycin C (MMC) or PARP inhibitors) and c-MET inhibitors (crizotinib). We tested CRC cell lines for sensitivity to MMC plus crizotinib or other drug combinations including PARP-inhibitors. Combined treatment of tumor cells with crizotinib and MMC led to increased apoptosis as compared with each drug alone. Additionally, combination treatment with increasing concentrations of both drugs demonstrated a synergistic anti-cancer effect (CI = 0.006-0.74). However, we found no evidence for c-MET upregulation upon effective BRCA2 knockdown in tumor cells -/+DNA damage. Although we found no mechanistic link between BRCA2 deficiency and c-MET overexpression, c-MET is frequently overexpressed in CRC and BRCA2 is mutated especially in MSI-H CRC. The combination of crizotinib with MMC appeared synergistic regardless of MSI or BRCA2 status. Using an in-vivo CRC xenograft model we found reduced tumor growth with combined crizotinib and MMC therapy (p = 0.0088). Our preclinical results support clinical testing of the combination of MMC and crizotinib in advanced CRC. Targeting cell survival mediated by c-MET in combination with targeting DNA repair may be a reasonable strategy for therapy development in CRC or other cancers.
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Affiliation(s)
- Avital Lev
- a Laboratory of Translational Oncology and Experimental Cancer Therapeutics , Molecular Therapeutics Program, Fox Chase Cancer Center , Philadelphia , PA , USA
| | - Safoora Deihimi
- a Laboratory of Translational Oncology and Experimental Cancer Therapeutics , Molecular Therapeutics Program, Fox Chase Cancer Center , Philadelphia , PA , USA
| | - Elena Shagisultanova
- b Department of Medical Oncology , University of Colorado Denver Cancer Center , Denver , CO , USA
| | - Joanne Xiu
- c Caris life science , Phoenix , AZ , USA
| | - Amriti R Lulla
- a Laboratory of Translational Oncology and Experimental Cancer Therapeutics , Molecular Therapeutics Program, Fox Chase Cancer Center , Philadelphia , PA , USA
| | - David T Dicker
- a Laboratory of Translational Oncology and Experimental Cancer Therapeutics , Molecular Therapeutics Program, Fox Chase Cancer Center , Philadelphia , PA , USA
| | - Wafik S El-Deiry
- a Laboratory of Translational Oncology and Experimental Cancer Therapeutics , Molecular Therapeutics Program, Fox Chase Cancer Center , Philadelphia , PA , USA
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20
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Toland AE, Andreassen PR. DNA repair-related functional assays for the classification of BRCA1 and BRCA2 variants: a critical review and needs assessment. J Med Genet 2017; 54:721-731. [PMID: 28866612 DOI: 10.1136/jmedgenet-2017-104707] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/04/2017] [Accepted: 06/27/2017] [Indexed: 01/02/2023]
Abstract
Mutation of BRCA1 and BRCA2 is the most common cause of inherited breast and ovarian cancer. Genetic screens to detect carriers of variants can aid in cancer prevention by identifying individuals with a greater cancer risk and can potentially be used to predict the responsiveness of tumours to therapy. Frequently, classification cannot be performed based on traditional approaches such as segregation analyses, including for many missense variants, which are therefore referred to as variants of uncertain significance (VUS). Functional assays provide an important alternative for classification of BRCA1 and BRCA2 VUS. As reviewed here, both of these tumour suppressors promote the maintenance of genome stability via homologous recombination. Thus, related assays may be particularly relevant to cancer risk. Progress in implementing functional assays to assess missense variants of BRCA1 and BRCA2 is considered here, along with current limitations and the path to more impactful assay systems. While functional assays have been developed to independently evaluate BRCA1 and BRCA2 VUS, high-throughput assays with sufficient sensitivity to characterise the large number of identified variants are lacking. Additionally, because of relatively low conservation of certain domains of BRCA1, and of BRCA2, between humans and rodents, heterologous expression in rodent cells may have limited reliability or capacity to assess variants present throughout either protein. Moving forward, it will be important to perform assays in human cell lines with relevance to particular tumour types, and to strengthen risk predictions based on multifactorial statistical analyses that also include available data on cosegregation and tumour pathology.
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Affiliation(s)
- Amanda Ewart Toland
- Department of Cancer Biology & Genetics and Division of Human Genetics, Department of Internal Medicine, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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21
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Stafford JL, Dyson G, Levin NK, Chaudhry S, Rosati R, Kalpage H, Wernette C, Petrucelli N, Simon MS, Tainsky MA. Reanalysis of BRCA1/2 negative high risk ovarian cancer patients reveals novel germline risk loci and insights into missing heritability. PLoS One 2017; 12:e0178450. [PMID: 28591191 PMCID: PMC5462348 DOI: 10.1371/journal.pone.0178450] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 05/12/2017] [Indexed: 12/30/2022] Open
Abstract
While up to 25% of ovarian cancer (OVCA) cases are thought to be due to inherited factors, the majority of genetic risk remains unexplained. To address this gap, we sought to identify previously undescribed OVCA risk variants through the whole exome sequencing (WES) and candidate gene analysis of 48 women with ovarian cancer and selected for high risk of genetic inheritance, yet negative for any known pathogenic variants in either BRCA1 or BRCA2. In silico SNP analysis was employed to identify suspect variants followed by validation using Sanger DNA sequencing. We identified five pathogenic variants in our sample, four of which are in two genes featured on current multi-gene panels; (RAD51D, ATM). In addition, we found a pathogenic FANCM variant (R1931*) which has been recently implicated in familial breast cancer risk. Numerous rare and predicted to be damaging variants of unknown significance were detected in genes on current commercial testing panels, most prominently in ATM (n = 6) and PALB2 (n = 5). The BRCA2 variant p.K3326*, resulting in a 93 amino acid truncation, was overrepresented in our sample (odds ratio = 4.95, p = 0.01) and coexisted in the germline of these women with other deleterious variants, suggesting a possible role as a modifier of genetic penetrance. Furthermore, we detected loss of function variants in non-panel genes involved in OVCA relevant pathways; DNA repair and cell cycle control, including CHEK1, TP53I3, REC8, HMMR, RAD52, RAD1, POLK, POLQ, and MCM4. In summary, our study implicates novel risk loci as well as highlights the clinical utility for retesting BRCA1/2 negative OVCA patients by genomic sequencing and analysis of genes in relevant pathways.
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Affiliation(s)
- Jaime L. Stafford
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Gregory Dyson
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Nancy K. Levin
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Sophia Chaudhry
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Rita Rosati
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Hasini Kalpage
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Courtney Wernette
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Nancie Petrucelli
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Michael S. Simon
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
| | - Michael A. Tainsky
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, United States of America
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States of America
- Molecular Therapeutics Program, Karmanos Cancer Institute at Wayne State University School of Medicine, Detroit, MI, United States of America
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22
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Shimelis H, Mesman RLS, Von Nicolai C, Ehlen A, Guidugli L, Martin C, Calléja FMGR, Meeks H, Hallberg E, Hinton J, Lilyquist J, Hu C, Aalfs CM, Aittomäki K, Andrulis I, Anton-Culver H, Arndt V, Beckmann MW, Benitez J, Bogdanova NV, Bojesen SE, Bolla MK, Borresen-Dale AL, Brauch H, Brennan P, Brenner H, Broeks A, Brouwers B, Brüning T, Burwinkel B, Chang-Claude J, Chenevix-Trench G, Cheng CY, Choi JY, Collée JM, Cox A, Cross SS, Czene K, Darabi H, Dennis J, Dörk T, Dos-Santos-Silva I, Dunning AM, Fasching PA, Figueroa J, Flyger H, García-Closas M, Giles GG, Glendon G, Guénel P, Haiman CA, Hall P, Hamann U, Hartman M, Hogervorst FB, Hollestelle A, Hopper JL, Ito H, Jakubowska A, Kang D, Kosma VM, Kristensen V, Lai KN, Lambrechts D, Marchand LL, Li J, Lindblom A, Lophatananon A, Lubinski J, Machackova E, Mannermaa A, Margolin S, Marme F, Matsuo K, Miao H, Michailidou K, Milne RL, Muir K, Neuhausen SL, Nevanlinna H, Olson JE, Olswold C, Oosterwijk JJC, Osorio A, Peterlongo P, Peto J, Pharoah PDP, Pylkäs K, Radice P, Rashid MU, Rhenius V, Rudolph A, Sangrajrang S, Sawyer EJ, Schmidt MK, Schoemaker MJ, Seynaeve C, Shah M, Shen CY, Shrubsole M, Shu XO, Slager S, Southey MC, Stram DO, Swerdlow A, Teo SH, Tomlinson I, Torres D, Truong T, van Asperen CJ, van der Kolk LE, Wang Q, Winqvist R, Wu AH, Yu JC, Zheng W, Zheng Y, Leary J, Walker L, Foretova L, Fostira F, Claes KBM, Varesco L, Moghadasi S, Easton DF, Spurdle A, Devilee P, Vrieling H, Monteiro ANA, Goldgar DE, Carreira A, Vreeswijk MPG, Couch FJ. BRCA2 Hypomorphic Missense Variants Confer Moderate Risks of Breast Cancer. Cancer Res 2017; 77:2789-2799. [PMID: 28283652 PMCID: PMC5508554 DOI: 10.1158/0008-5472.can-16-2568] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/14/2016] [Accepted: 03/03/2017] [Indexed: 12/20/2022]
Abstract
Breast cancer risks conferred by many germline missense variants in the BRCA1 and BRCA2 genes, often referred to as variants of uncertain significance (VUS), have not been established. In this study, associations between 19 BRCA1 and 33 BRCA2 missense substitution variants and breast cancer risk were investigated through a breast cancer case-control study using genotyping data from 38 studies of predominantly European ancestry (41,890 cases and 41,607 controls) and nine studies of Asian ancestry (6,269 cases and 6,624 controls). The BRCA2 c.9104A>C, p.Tyr3035Ser (OR = 2.52; P = 0.04), and BRCA1 c.5096G>A, p.Arg1699Gln (OR = 4.29; P = 0.009) variant were associated with moderately increased risks of breast cancer among Europeans, whereas BRCA2 c.7522G>A, p.Gly2508Ser (OR = 2.68; P = 0.004), and c.8187G>T, p.Lys2729Asn (OR = 1.4; P = 0.004) were associated with moderate and low risks of breast cancer among Asians. Functional characterization of the BRCA2 variants using four quantitative assays showed reduced BRCA2 activity for p.Tyr3035Ser compared with wild-type. Overall, our results show how BRCA2 missense variants that influence protein function can confer clinically relevant, moderately increased risks of breast cancer, with potential implications for risk management guidelines in women with these specific variants. Cancer Res; 77(11); 2789-99. ©2017 AACR.
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Affiliation(s)
- Hermela Shimelis
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Romy L S Mesman
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Asa Ehlen
- Genotoxic Stress and Cancer, Institut Curie, Orsay, France
| | - Lucia Guidugli
- Department of Human Genetics, University of Chicago, Chicago, Illinois
| | | | | | - Huong Meeks
- Cancer Control and Population Sciences, University of Utah, Salt Lake City, Utah
| | - Emily Hallberg
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Jamie Hinton
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Jenna Lilyquist
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Chunling Hu
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Cora M Aalfs
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Kristiina Aittomäki
- Department of Clinical Genetics, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | - Irene Andrulis
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Hoda Anton-Culver
- Department of Epidemiology, University of California Irvine, Irvine, California
| | - Volker Arndt
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Matthias W Beckmann
- Department of Gynaecology and Obstetrics, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
| | - Javier Benitez
- Human Cancer Genetics Program, Spanish National Cancer Research Centre, Madrid, Spain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Natalia V Bogdanova
- Department of Radiation Oncology, Hannover Medical School, Hannover, Germany
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
| | - Stig E Bojesen
- Copenhagen General Population Study, Herlevand Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark
- Department of Clinical Biochemistry, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manjeet K Bolla
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Anne-Lise Borresen-Dale
- Department of Cancer Genetics, Institute for Cancer Research, Oslo University Hospital Radiumhospitalet, Oslo, Norway
- K.G. Jebsen Center for Breast Cancer Research, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Hiltrud Brauch
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart, Germany
- University of Tübingen, Tübingen, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Paul Brennan
- International Agency for Research on Cancer, Lyon, France
| | - Hermann Brenner
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany
- German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany
| | - Annegien Broeks
- Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands
| | - Barbara Brouwers
- Laboratory of Experimental Oncology, Department of Oncology, University Hospitals Leuven, Leuven, Belgium
- Department of General Medical Oncology, Leuven Cancer Institute, University Hospitals Leuven, Leuven, Belgium
| | - Thomas Brüning
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr University Bochum, Bochum, Germany
| | - Barbara Burwinkel
- Department of Obstetrics and Gynecology, University of Heidelberg, Heidelberg, Germany
- Molecular Epidemiology Group, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Jenny Chang-Claude
- Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- University Cancer Center Hamburg (UCCH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Ching-Yu Cheng
- Singapore Eye Research Institute, National University of Singapore, Singapore, Singapore
| | - Ji-Yeob Choi
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University, Seoul, Korea
| | - J Margriet Collée
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Angela Cox
- Sheffield Cancer Research, Department of Oncology and Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Simon S Cross
- Academic Unit of Pathology, Department of Neuroscience, University of Sheffield, Sheffield, United Kingdom
| | - Kamila Czene
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Hatef Darabi
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Joe Dennis
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Thilo Dörk
- Gynaecology Research Unit, Hannover Medical School, Hannover, Germany
| | - Isabel Dos-Santos-Silva
- Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Alison M Dunning
- Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Peter A Fasching
- Department of Gynaecology and Obstetrics, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuremberg, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany
- Department of Medicine, Division of Hematology and Oncology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California
| | - Jonine Figueroa
- Usher Institute of Population Health Sciences and Informatics, The University of Edinburgh Medical School, Edinburgh, United Kingdom
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland
| | - Henrik Flyger
- Department of Breast Surgery, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark
| | | | - Graham G Giles
- Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Gord Glendon
- Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital, Toronto, Canada
| | - Pascal Guénel
- Cancer & Environment Group, Center for Research in Epidemiology and Population Health (CESP), INSERM, University Paris-Sud, University Paris-Saclay, Villejuif, France
| | - Christopher A Haiman
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Per Hall
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Ute Hamann
- Molecular Genetics of Breast Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mikael Hartman
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
- Department of Surgery, National University Health System, Singapore, Singapore
| | - Frans B Hogervorst
- Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands
| | - Antoinette Hollestelle
- Department of Medical Oncology, Family Cancer Clinic, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - John L Hopper
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Hidemi Ito
- Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, Nagoya, Japan
- Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Anna Jakubowska
- Department of Genetics and Pathology, Pomeranian Medical University, Szczecin, Poland
| | - Daehee Kang
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University, Seoul, Korea
- Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Veli-Matti Kosma
- Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
- Institute of Clinical Medicine, Pathology and Forensic Medicine, University of Eastern Finland, Kuopio, Finland
- Imaging Center, Department of Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
| | | | - Kah-Nyin Lai
- Cancer Research Initiatives Foundation, Subang Jaya, Selangor, Malaysia
- Breast Cancer Research Unit, Cancer Research Institute, University Malaya Medical Centre, Kuala Lumpur, Malaysia
| | - Diether Lambrechts
- Vesalius Research Center, Leuven, Belgium
- Laboratory for Translational Genetics, Department of Oncology, University of Leuven, Leuven, Belgium
| | | | - Jingmei Li
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - Annika Lindblom
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Artitaya Lophatananon
- Division of Health Sciences, Warwick Medical School, Warwick University, Coventry, United Kingdom
| | - Jan Lubinski
- Department of Genetics and Pathology, Pomeranian Medical University, Szczecin, Poland
| | - Eva Machackova
- Department of Cancer Epidemiology and Genetics, Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Arto Mannermaa
- Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
- Institute of Clinical Medicine, Pathology and Forensic Medicine, University of Eastern Finland, Kuopio, Finland
- Imaging Center, Department of Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
| | - Sara Margolin
- Department of Oncology - Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Frederik Marme
- Department of Obstetrics and Gynecology, University of Heidelberg, Heidelberg, Germany
- National Center for Tumor Diseases, University of Heidelberg, Heidelberg, Germany
| | - Keitaro Matsuo
- Department of Epidemiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Hui Miao
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | - Kyriaki Michailidou
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
- Department of Electron Microscopy/Molecular Pathology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Roger L Milne
- Cancer Epidemiology Centre, Cancer Council Victoria, Melbourne, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Kenneth Muir
- Division of Health Sciences, Warwick Medical School, Warwick University, Coventry, United Kingdom
- Institute of Population Health, University of Manchester, Manchester, United Kingdom
| | - Susan L Neuhausen
- Department of Population Sciences, Beckman Research Institute of City of Hope, Duarte, California
| | - Heli Nevanlinna
- Department of Obstetrics and Gynecology, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
| | - Janet E Olson
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Curtis Olswold
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Jan J C Oosterwijk
- Department of Genetics, University of Groningen, Groningen, the Netherlands
| | - Ana Osorio
- Human Cancer Genetics Program, Spanish National Cancer Research Centre, Madrid, Spain
- Centro de Investigación en Red de Enfermedades Raras (CIBERER), Valencia, Spain
| | - Paolo Peterlongo
- IFOM, The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology, Milan, Italy
| | - Julian Peto
- Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Paul D P Pharoah
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
- Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Katri Pylkäs
- Laboratory of Cancer Genetics and Tumor Biology, Cancer and Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
- Laboratory of Cancer Genetics and Tumor Biology, Northern Finland Laboratory Centre Oulu, Oulu, Finland
| | - Paolo Radice
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Department of Preventive and Predictive Medicine, Fondazione IRCCS (Istituto Di Ricovero e Cura a Carattere Scientifico) Istituto Nazionale dei Tumori (INT), Milan, Italy
| | - Muhammad Usman Rashid
- Molecular Genetics of Breast Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Basic Sciences, Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan
| | - Valerie Rhenius
- Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Anja Rudolph
- Division of Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | | | - Elinor J Sawyer
- Research Oncology, Guy's Hospital, King's College London, London, United Kingdom
| | - Marjanka K Schmidt
- Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands
| | - Minouk J Schoemaker
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, United Kingdom
- Division of Breast Cancer Research, The Institute of Cancer Research, London, United Kingdom
| | - Caroline Seynaeve
- Department of Medical Oncology, Family Cancer Clinic, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
| | - Mitul Shah
- Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Chen-Yang Shen
- School of Public Health, China Medical University, Taichung, Taiwan
- Taiwan Biobank, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Martha Shrubsole
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Xiao-Ou Shu
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Susan Slager
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Melissa C Southey
- Department of Pathology, The University of Melbourne, Melbourne, Australia
| | - Daniel O Stram
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Anthony Swerdlow
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London, United Kingdom
- Division of Breast Cancer Research, The Institute of Cancer Research, London, United Kingdom
| | - Soo H Teo
- Cancer Research Initiatives Foundation, Subang Jaya, Selangor, Malaysia
- Breast Cancer Research Unit, Cancer Research Institute, University Malaya Medical Centre, Kuala Lumpur, Malaysia
| | - Ian Tomlinson
- Wellcome Trust Centre for Human Genetics and Oxford NIHR Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Diana Torres
- Molecular Genetics of Breast Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Institute of Human Genetics, Pontificia Universidad Javeriana, Bogota, Colombia
| | - Thérèse Truong
- Cancer & Environment Group, Center for Research in Epidemiology and Population Health (CESP), INSERM, University Paris-Sud, University Paris-Saclay, Villejuif, France
| | - Christi J van Asperen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Lizet E van der Kolk
- Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands
| | - Qin Wang
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
| | - Robert Winqvist
- Laboratory of Cancer Genetics and Tumor Biology, Cancer and Translational Medicine Research Unit, Biocenter Oulu, University of Oulu, Oulu, Finland
- Laboratory of Cancer Genetics and Tumor Biology, Northern Finland Laboratory Centre Oulu, Oulu, Finland
| | - Anna H Wu
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Jyh-Cherng Yu
- Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Wei Zheng
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ying Zheng
- Shanghai Municipal Center for Disease Control and Prevention, Shanghai, China
| | - Jennifer Leary
- Westmead Millenium Institute for Medical Research, University of Sydney, Sydney, Australia
| | - Logan Walker
- Department of Pathology, University of Otago, Christchurch, New Zealand
| | - Lenka Foretova
- Department of Cancer Epidemiology and Genetics, Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Florentia Fostira
- Molecular Diagnostics Laboratory, Institute of Radioisotopes and Radiodiagnostic Products (IRRP), Athens, Greece
| | | | - Liliana Varesco
- Unit of Hereditary Cancers, IRCCS AOU San Martino, Genova, Italy
| | - Setareh Moghadasi
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Douglas F Easton
- Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom
- Department of Oncology, University of Cambridge, Cambridge, United Kingdom
| | - Amanda Spurdle
- Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Peter Devilee
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Harry Vrieling
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Alvaro N A Monteiro
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
- Department of Oncologic Science, University of South Florida, Tampa, Florida
| | - David E Goldgar
- Huntsman Cancer Institute and Department of Dermatology, University of Utah, Salt Lake City, Utah
| | - Aura Carreira
- Genotoxic Stress and Cancer, Institut Curie, Orsay, France
| | - Maaike P G Vreeswijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Fergus J Couch
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
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23
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Functional classification of DNA variants by hybrid minigenes: Identification of 30 spliceogenic variants of BRCA2 exons 17 and 18. PLoS Genet 2017; 13:e1006691. [PMID: 28339459 PMCID: PMC5384790 DOI: 10.1371/journal.pgen.1006691] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 04/07/2017] [Accepted: 03/14/2017] [Indexed: 11/30/2022] Open
Abstract
Mutation screening of the breast cancer genes BRCA1 and BRCA2 identifies a large fraction of variants of uncertain clinical significance (VUS) whose functional and clinical interpretations pose a challenge for genomic medicine. Likewise, an increasing amount of evidence indicates that genetic variants can have deleterious effects on pre-mRNA splicing. Our goal was to investigate the impact on splicing of a set of reported variants of BRCA2 exons 17 and 18 to assess their role in hereditary breast cancer and to identify critical regulatory elements that may constitute hotspots for spliceogenic variants. A splicing reporter minigene with BRCA2 exons 14 to-20 (MGBR2_ex14-20) was constructed in the pSAD vector. Fifty-two candidate variants were selected with splicing prediction programs, introduced in MGBR2_ex14-20 by site-directed mutagenesis and assayed in triplicate in MCF-7 cells. Wild type MGBR2_ex14-20 produced a stable transcript of the expected size (1,806 nucleotides) and structure (V1-[BRCA2_exons_14–20]–V2). Functional mapping by microdeletions revealed essential sequences for exon recognition on the 3’ end of exon 17 (c.7944-7973) and the 5’ end of exon 18 (c.7979-7988, c.7999-8013). Thirty out of the 52 selected variants induced anomalous splicing in minigene assays with >16 different aberrant transcripts, where exon skipping was the most common event. A wide range of splicing motifs were affected including the canonical splice sites (15 variants), novel alternative sites (3 variants), the polypyrimidine tract (3 variants) and enhancers/silencers (9 variants). According to the guidelines of the American College of Medical Genetics and Genomics (ACMG), 20 variants could be classified as pathogenic (c.7806-2A>G, c.7806-1G>A, c.7806-1G>T, c.7806-1_7806-2dup, c.7976+1G>A, c.7977-3_7978del, c.7977-2A>T, c.7977-1G>T, c.7977-1G>C, c.8009C>A, c.8331+1G>T and c.8331+2T>C) or likely pathogenic (c.7806-9T>G, c.7976G>C, c.7976G>A, c.7977-7C>G, c.7985C>G, c.8023A>G, c.8035G>T and c.8331G>A), accounting for 30.8% of all pathogenic/likely pathogenic variants of exons 17–18 at the BRCA Share database. The remaining 8 variants (c.7975A>G, c.7977-6T>G, c.7988A>T, c.7992T>A, c.8007A>G, c.8009C>T, c.8009C>G, and c.8072C>T) induced partial splicing anomalies with important ratios of the full-length transcript (≥70%), so that they remained classified as VUS. Aberrant splicing is therefore especially prevalent in BRCA2 exons 17 and 18 due to the presence of active ESEs involved in exon recognition. Splicing functional assays with minigenes are a valuable strategy for the initial characterization of the splicing outcomes and the subsequent clinical interpretation of variants of any disease-gene, although these results should be checked, whenever possible, against patient RNA. A significant proportion of disease-causing mutations of inherited disorders impair splicing. Massive sequencing projects of genetic diseases generate thousands of sequence variations that require functional and clinical interpretations. We have shown that splicing reporter minigenes of the breast cancer genes BRCA1 and BRCA2 are useful tools to functionally test DNA variants. In this work, we have constructed a 7-exon BRCA2 minigene (exons 14 to 20) where we mapped critical splicing regulatory sequences and tested 52 selected variants of exons 17 and 18 detected in breast cancer patients. We finely located three DNA segments on both exons that presumably contain splicing enhancer sequences. We observed that a total of 30 variants of any type disrupted the splicing patterns and, given the severity of their outcomes, we classified 20 of them as pathogenic or likely pathogenic. We also showed that a wide range of splicing elements were affected including canonical and novel 5’ and 3’ splice sites, the polypyrimidine tract and enhancer and silencer sequences. We concluded that splicing aberrations are frequent in Hereditary Breast and Ovarian Cancer and that minigenes are valuable tools to functionally classify DNA variants of any human disease gene under the splicing viewpoint.
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24
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Guidugli L, Pankratz VS, Singh N, Thompson J, Erding CA, Engel C, Schmutzler R, Domchek S, Nathanson K, Radice P, Singer C, Tonin PN, Lindor NM, Goldgar DE, Couch FJ. A classification model for BRCA2 DNA binding domain missense variants based on homology-directed repair activity. Cancer Res 2012; 73:265-75. [PMID: 23108138 DOI: 10.1158/0008-5472.can-12-2081] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The relevance of many BRCA2 variants of uncertain significance (VUS) to breast cancer has not been determined due to limited genetic information from families carrying these alterations. Here, we classified six new variants as pathogenic or nonpathogenic by analysis of genetic information from families carrying 64 individual BRCA2 DNA binding domain (DBD) missense mutations using a multifactorial likelihood model of cancer causality. Next, we evaluated the use of a homology-directed DNA break repair (HDR) functional assay as a method for inferring the clinical relevance of VUS in the DBD of BRCA2 using 18 established nonpathogenic missense variants and all 13 established pathogenic missense mutations from the BRCA2 DBD. Compared with the known status of these variants based on the multifactorial likelihood model, the sensitivity of the HDR assay for pathogenic mutations was estimated at 100% [95% confidence interval (CI): 75.3%-100%] and specificity was estimated at 100% (95% CI: 81.5%-100%). A statistical classifier for predicting the probability of pathogenicity of BRCA2 DBD variants was developed using these functional results. When applied to 33 additional VUS, the classifier identified eight with 99% or more probability of nonpathogenicity and 18 with 99% or more probability of pathogenicity. Thus, in the absence of genetic evidence, a cell-based HDR assay can provide a probability of pathogenicity for all VUS in the BRCA2 DBD, suggesting that the assay can be used in combination with other information to determine the cancer relevance of BRCA2 VUS.
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Affiliation(s)
- Lucia Guidugli
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
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25
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Karchin R, Agarwal M, Sali A, Couch F, Beattie MS. Classifying Variants of Undetermined Significance in BRCA2 with protein likelihood ratios. Cancer Inform 2008; 6:203-16. [PMID: 19043619 PMCID: PMC2587343 DOI: 10.4137/cin.s618] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Missense (amino-acid changing) variants found in cancer predisposition genes often create difficulties when clinically interpreting genetic testing results. Although bioinformatics has developed approaches to predicting the impact of these variants, many of these approaches have not been readily applicable in the clinical setting. Bioinformatics approaches for predicting the impact of these variants have not yet found their footing in clinical practice because 1) interpreting the medical relevance of predictive scores is difficult; 2) the relationship between bioinformatics "predictors" (sequence conservation, protein structure) and cancer susceptibility is not understood. METHODOLOGY/PRINCIPAL FINDINGS We present a computational method that produces a probabilistic likelihood ratio predictive of whether a missense variant impairs protein function. We apply the method to a tumor suppressor gene, BRCA2, whose loss of function is important to cancer susceptibility. Protein likelihood ratios are computed for 229 unclassified variants found in individuals from high-risk breast/ovarian cancer families. We map the variants onto a protein structure model, and suggest that a cluster of predicted deleterious variants in the BRCA2 OB1 domain may destabilize BRCA2 and a protein binding partner, the small acidic protein DSS1. We compare our predictions with variant "re-classifications" provided by Myriad Genetics, a biotechnology company that holds the patent on BRCA2 genetic testing in the U.S., and with classifications made by an established medical genetics model [1]. Our approach uses bioinformatics data that is independent of these genetics-based classifications and yet shows significant agreement with them. Preliminary results indicate that our method is less likely to make false positive errors than other bioinformatics methods, which were designed to predict the impact of missense mutations in general. CONCLUSIONS/SIGNIFICANCE Missense mutations are the most common disease-producing genetic variants. We present a fast, scalable bioinformatics method that integrates information about protein sequence, conservation, and structure in a likelihood ratio that can be integrated with medical genetics likelihood ratios. The protein likelihood ratio, together with medical genetics likelihood ratios, can be used by clinicians and counselors to communicate the relevance of a VUS to the individual who has that VUS. The approach described here is generalizable to regions of any tumor suppressor gene that have been structurally determined by X-ray crystallography or for which a protein homology model can be built.
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Affiliation(s)
- Rachel Karchin
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21218, USA.
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Wiegant WW, Overmeer RM, Godthelp BC, van Buul PPW, Zdzienicka MZ. Chinese hamster cell mutant, V-C8, a model for analysis of Brca2 function. Mutat Res 2006; 600:79-88. [PMID: 16643964 DOI: 10.1016/j.mrfmmm.2006.03.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2006] [Revised: 03/01/2006] [Accepted: 03/03/2006] [Indexed: 05/08/2023]
Abstract
The previously described Chinese hamster cell mutant V-C8 that is defective in Brca2 shows a very complex phenotype, including increased sensitivity towards a wide variety of DNA damaging agents, chromosomal instability, abnormal centrosomes and impaired formation of Rad51 foci in response to DNA damage. Here, we demonstrate that V-C8 cells display biallelic nonsense mutations in Brca2, one in exon 15 and the other in exon 16, both resulting in truncated Brca2 proteins. We generated several independent mitomycin C (MMC)-resistant clones from V-C8 cells that had acquired an additional mutation leading to the restoration of the open reading frame of one of the Brca2 alleles. In two of these revertants, V-C8-Rev 1 and V-C8-Rev 6, the reversions lead to the wild-type Brca2 sequence. The V-C8 revertants did not gain the entire wild-type phenotype and still show a 2.5-fold increased sensitivity to mitomycin C (MMC), higher levels of spontaneous and MMC-induced chromosomal aberrations, as well as abnormal centrosomes when compared to wild-type cells. Our results suggest that Brca2 heterozygosity in hamster cells primarily gives rise to sensitivity to DNA cross-linking agents, especially chromosomal instability, a feature that might also be displayed in BRCA2 heterozygous mutation carriers.
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Affiliation(s)
- Wouter W Wiegant
- Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, Postzone S-6-P, P.O. Box 9600, 2300 RC Leiden, The Netherlands
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