1
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Nesic K, Krais JJ, Vandenberg CJ, Wang Y, Patel P, Cai KQ, Kwan T, Lieschke E, Ho GY, Barker HE, Bedo J, Casadei S, Farrell A, Radke M, Shield-Artin K, Penington JS, Geissler F, Kyran E, Zhang F, Dobrovic A, Olesen I, Kristeleit R, Oza A, Ratnayake G, Traficante N, DeFazio A, Bowtell DDL, Harding TC, Lin K, Swisher EM, Kondrashova O, Scott CL, Johnson N, Wakefield MJ. BRCA1 secondary splice-site mutations drive exon-skipping and PARP inhibitor resistance. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.03.20.23287465. [PMID: 36993400 PMCID: PMC10055590 DOI: 10.1101/2023.03.20.23287465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
BRCA1 splice isoforms Δ11 and Δ11q can contribute to PARP inhibitor (PARPi) resistance by splicing-out the mutation-containing exon, producing truncated, partially-functional proteins. However, the clinical impact and underlying drivers of BRCA1 exon skipping remain undetermined. We analyzed nine ovarian and breast cancer patient derived xenografts (PDX) with BRCA1 exon 11 frameshift mutations for exon skipping and therapy response, including a matched PDX pair derived from a patient pre- and post-chemotherapy/PARPi. BRCA1 exon 11 skipping was elevated in PARPi resistant PDX tumors. Two independent PDX models acquired secondary BRCA1 splice site mutations (SSMs), predicted in silico to drive exon skipping. Predictions were confirmed using qRT-PCR, RNA sequencing, western blots and BRCA1 minigene modelling. SSMs were also enriched in post-PARPi ovarian cancer patient cohorts from the ARIEL2 and ARIEL4 clinical trials. We demonstrate that SSMs drive BRCA1 exon 11 skipping and PARPi resistance, and should be clinically monitored, along with frame-restoring secondary mutations.
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Affiliation(s)
- Ksenija Nesic
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | - Cassandra J. Vandenberg
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | | | | | - Tanya Kwan
- Clovis Oncology Inc., San Francisco, CA, USA
| | - Elizabeth Lieschke
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Gwo-Yaw Ho
- School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
| | - Holly E. Barker
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Justin Bedo
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | | | - Andrew Farrell
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Marc Radke
- University of Washington, Seattle, WA, USA
| | - Kristy Shield-Artin
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Jocelyn S. Penington
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Franziska Geissler
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Elizabeth Kyran
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Fan Zhang
- University of Melbourne Department of Surgery, Austin Health, Heidelberg, Victoria, Australia
| | - Alexander Dobrovic
- University of Melbourne Department of Surgery, Austin Health, Heidelberg, Victoria, Australia
| | - Inger Olesen
- The Andrew Love Cancer Centre, Barwon Health, Geelong, Victoria, Australia
| | - Rebecca Kristeleit
- Department of Oncology, Guys and St Thomas’ NHS Foundation Trust, London, UK
- National Institute for Health Research, University College London Hospitals Clinical Research Facility, London, UK
| | - Amit Oza
- Princess Margaret Cancer Center, Toronto, ON, Canada
| | | | - Nadia Traficante
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
| | | | - Anna DeFazio
- The Daffodil Centre, The University of Sydney, a joint venture with Cancer Council New South Wales, Sydney, New South Wales, Australia
- The Westmead Institute for Medical Research, Sydney, New South Wales, Australia
- Department of Gynecological Oncology, Westmead Hospital, Western Sydney Local Health District, New South Wales, Australia
| | - David D. L. Bowtell
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
| | | | - Kevin Lin
- Clovis Oncology Inc., San Francisco, CA, USA
| | | | - Olga Kondrashova
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Clare L. Scott
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
- Royal Women’s Hospital, Parkville, VIC, Australia
- Sir Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, VIC, Australia
- Department of Obstetrics and Gynecology, University of Melbourne, Parkville, VIC, Australia
| | | | - Matthew J. Wakefield
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
- Department of Obstetrics and Gynecology, University of Melbourne, Parkville, VIC, Australia
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2
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Kaissarian NM, Meyer D, Kimchi-Sarfaty C. Synonymous Variants: Necessary Nuance in our Understanding of Cancer Drivers and Treatment Outcomes. J Natl Cancer Inst 2022; 114:1072-1094. [PMID: 35477782 PMCID: PMC9360466 DOI: 10.1093/jnci/djac090] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/24/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Once called "silent mutations" and assumed to have no effect on protein structure and function, synonymous variants are now recognized to be drivers for some cancers. There have been significant advances in our understanding of the numerous mechanisms by which synonymous single nucleotide variants (sSNVs) can affect protein structure and function by affecting pre-mRNA splicing, mRNA expression, stability, folding, miRNA binding, translation kinetics, and co-translational folding. This review highlights the need for considering sSNVs in cancer biology to gain a better understanding of the genetic determinants of human cancers and to improve their diagnosis and treatment. We surveyed the literature for reports of sSNVs in cancer and found numerous studies on the consequences of sSNVs on gene function with supporting in vitro evidence. We also found reports of sSNVs that have statistically significant associations with specific cancer types but for which in vitro studies are lacking to support the reported associations. Additionally, we found reports of germline and somatic sSNVs that were observed in numerous clinical studies and for which in silico analysis predicts possible effects on gene function. We provide a review of these investigations and discuss necessary future studies to elucidate the mechanisms by which sSNVs disrupt protein function and are play a role in tumorigeneses, cancer progression, and treatment efficacy. As splicing dysregulation is one of the most well recognized mechanisms by which sSNVs impact protein function, we also include our own in silico analysis for predicting which sSNVs may disrupt pre-mRNA splicing.
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Affiliation(s)
- Nayiri M Kaissarian
- Hemostasis Branch, Division of Plasma Protein Therapeutics, Office of Tissues and Advanced Therapies, Center for Biologics Evaluation & Research, US Food and Drug Administration, Silver Spring, MD, USA
| | - Douglas Meyer
- Hemostasis Branch, Division of Plasma Protein Therapeutics, Office of Tissues and Advanced Therapies, Center for Biologics Evaluation & Research, US Food and Drug Administration, Silver Spring, MD, USA
| | - Chava Kimchi-Sarfaty
- Hemostasis Branch, Division of Plasma Protein Therapeutics, Office of Tissues and Advanced Therapies, Center for Biologics Evaluation & Research, US Food and Drug Administration, Silver Spring, MD, USA
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3
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Zeng Z, Bromberg Y. Inferring Potential Cancer Driving Synonymous Variants. Genes (Basel) 2022; 13:778. [PMID: 35627162 PMCID: PMC9140830 DOI: 10.3390/genes13050778] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/25/2022] [Accepted: 04/26/2022] [Indexed: 02/01/2023] Open
Abstract
Synonymous single nucleotide variants (sSNVs) are often considered functionally silent, but a few cases of cancer-causing sSNVs have been reported. From available databases, we collected four categories of sSNVs: germline, somatic in normal tissues, somatic in cancerous tissues, and putative cancer drivers. We found that screening sSNVs for recurrence among patients, conservation of the affected genomic position, and synVep prediction (synVep is a machine learning-based sSNV effect predictor) recovers cancer driver variants (termed proposed drivers) and previously unknown putative cancer genes. Of the 2.9 million somatic sSNVs found in the COSMIC database, we identified 2111 proposed cancer driver sSNVs. Of these, 326 sSNVs could be further tagged for possible RNA splicing effects, RNA structural changes, and affected RBP motifs. This list of proposed cancer driver sSNVs provides computational guidance in prioritizing the experimental evaluation of synonymous mutations found in cancers. Furthermore, our list of novel potential cancer genes, galvanized by synonymous mutations, may highlight yet unexplored cancer mechanisms.
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Affiliation(s)
- Zishuo Zeng
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08873, USA
| | - Yana Bromberg
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08873, USA
- Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA
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4
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Ruiz de Garibay G, Fernandez-Garcia I, Mazoyer S, Leme de Calais F, Ameri P, Vijayakumar S, Martinez-Ruiz H, Damiola F, Barjhoux L, Thomassen M, Andersen LVB, Herranz C, Mateo F, Palomero L, Espín R, Gómez A, García N, Jimenez D, Bonifaci N, Extremera AI, Castaño J, Raya A, Eyras E, Puente XS, Brunet J, Lázaro C, Radice P, Barnes DR, Antoniou AC, Spurdle AB, de la Hoya M, Baralle D, Barcellos-Hoff MH, Pujana MA. Altered regulation of BRCA1 exon 11 splicing is associated with breast cancer risk in carriers of BRCA1 pathogenic variants. Hum Mutat 2021; 42:1488-1502. [PMID: 34420246 DOI: 10.1002/humu.24276] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/11/2021] [Accepted: 08/18/2021] [Indexed: 11/12/2022]
Abstract
Germline pathogenic variants in BRCA1 confer a high risk of developing breast and ovarian cancer. The BRCA1 exon 11 (formally exon 10) is one of the largest exons and codes for the nuclear localization signals of the corresponding gene product. This exon can be partially or entirely skipped during pre-mRNA splicing, leading to three major in-frame isoforms that are detectable in most cell types and tissue, and in normal and cancer settings. However, it is unclear whether the splicing imbalance of this exon is associated with cancer risk. Here we identify a common genetic variant in intron 10, rs5820483 (NC_000017.11:g.43095106_43095108dup), which is associated with exon 11 isoform expression and alternative splicing, and with the risk of breast cancer, but not ovarian cancer, in BRCA1 pathogenic variant carriers. The identification of this genetic effect was confirmed by analogous observations in mouse cells and tissue in which a loxP sequence was inserted in the syntenic intronic region. The prediction that the rs5820483 minor allele variant would create a binding site for the splicing silencer hnRNP A1 was confirmed by pull-down assays. Our data suggest that perturbation of BRCA1 exon 11 splicing modifies the breast cancer risk conferred by pathogenic variants of this gene.
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Affiliation(s)
- Gorka Ruiz de Garibay
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Ignacio Fernandez-Garcia
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA
| | - Sylvie Mazoyer
- Equipe GENDEV, INSERM U1028, CNRS UMR5292, Centre de Recherche en Neurosciences de Lyon, Université Lyon 1, Université St Etienne, Lyon, France
| | - Flavia Leme de Calais
- School of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Pietro Ameri
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA
| | - Sangeetha Vijayakumar
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA
| | - Haydeliz Martinez-Ruiz
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA
| | - Francesca Damiola
- Department of Biopathology, Pathology Research Platform, Centre Léon Bérard, Lyon, France
| | - Laure Barjhoux
- Department of Biopathology, Pathology Research Platform, Centre Léon Bérard, Lyon, France
| | - Mads Thomassen
- Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark
| | - Lars V B Andersen
- Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark
| | - Carmen Herranz
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Francesca Mateo
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Luis Palomero
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Roderic Espín
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Antonio Gómez
- Gene Regulation, Stem Cells and Cancer, Center for Genomic Regulation (CRG), Barcelona, Catalonia, Spain
| | - Nadia García
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Daniel Jimenez
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Núria Bonifaci
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Ana I Extremera
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
| | - Julio Castaño
- Regenerative Medicine Program, Bellvitge Institute for Biomedical Research (IDIBELL) and Program for Clinical Translation of Regenerative Medicine in Catalonia (P-CMRC), L'Hospitalet del Llobregat, Barcelona, Spain
| | - Angel Raya
- Regenerative Medicine Program, Bellvitge Institute for Biomedical Research (IDIBELL) and Program for Clinical Translation of Regenerative Medicine in Catalonia (P-CMRC), L'Hospitalet del Llobregat, Barcelona, Spain.,Centre for Networked Biomedical Research on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain.,Catalan Institution for Research and Advanced Studies, Barcelona, Spain
| | - Eduardo Eyras
- Catalan Institution for Research and Advanced Studies, Barcelona, Spain.,Department of Genome Sciences, The John Curtin School of Medical Research, EMBL Australia Partner Laboratory Network, Australian National University, Canberra, Australia
| | - Xose S Puente
- Department of Biochemistry and Molecular Biology, University Institute of Oncology, University of Oviedo, Oviedo, Spain.,Biomedical Research Centre in Cancer (CIBERONC), Instituto Salud Carlos III, Madrid, Spain
| | - Joan Brunet
- Hereditary Cancer Program, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, and Girona Biomedical Research Institute (IDIBGI), Girona, Catalonia, Spain
| | - Conxi Lázaro
- Biomedical Research Centre in Cancer (CIBERONC), Instituto Salud Carlos III, Madrid, Spain.,Hereditary Cancer Program, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, and Girona Biomedical Research Institute (IDIBGI), Girona, Catalonia, Spain
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- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
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- Department of Public Health and Primary Care, Centre for Cancer Genetic Epidemiology, University of Cambridge, Cambridge, UK
| | - Paolo Radice
- Unit of Molecular Bases of Genetic Risk and Genetic Testing, Research Department, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Daniel R Barnes
- Department of Public Health and Primary Care, Centre for Cancer Genetic Epidemiology, University of Cambridge, Cambridge, UK
| | - Antonis C Antoniou
- Department of Public Health and Primary Care, Centre for Cancer Genetic Epidemiology, University of Cambridge, Cambridge, UK
| | - Amanda B Spurdle
- Genetics and Computational Division, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Miguel de la Hoya
- Biomedical Research Centre in Cancer (CIBERONC), Instituto Salud Carlos III, Madrid, Spain.,Molecular Oncology Laboratory, Hospital Clínico San Carlos, Health Research Institute of the Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Diana Baralle
- School of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK.,Wessex Clinical Genetics Service, Southampton University Hospital NHS Trust, Southampton, UK
| | - Mary Helen Barcellos-Hoff
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA.,Department of Radiation Oncology, School of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Miquel A Pujana
- ProCURE, Oncobell, Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Barcelona, Catalonia, Spain
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5
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The BRCA1 c.788G > T (NM_007294.4) variant in a high grade serous ovarian cancer (HGSOC) patient: foods for thought. Mol Biol Rep 2021; 48:2985-2992. [PMID: 33656647 DOI: 10.1007/s11033-021-06243-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/18/2021] [Indexed: 12/20/2022]
Abstract
In this report we described the case of a BRCA1/2 (BRCA) molecular testing performed on tumor sample in a High Grade Serous Ovarian Cancer (HGSOC) patient with two different Next Generation Tumor Sequencing (NGTS) pipelines. The two clinical reports leaded to apparently different BRCA status, providing important foods for thought. After NGTS, the gene sequencing information (i.e., reads) are aligned to the reference gene sequences obtained from public databases, in order to provide an uniform nomenclature for unambiguous variant designation. However, the criteria adopted for variant reporting in tissue test are not always univocal. Particularly, this is the case of rare and unclassified BRCA variants for which the molecular evaluation may be a relevant challenge. Here we described a BRCA1 unclassified variant that may be re-evaluated in the context of alternative BRCA1 transcripts due to its different biological effect. We underlined that an in-depth knowledge of BRCA testing is mandatory for its appropriate use.
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6
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Sylvester B, Brindopke F, Suzuki A, Giron M, Auslander A, Maas RL, Tsai B, Gao H, Magee W, Cox TC, Sanchez-Lara PA. A Synonymous Exonic Splice Silencer Variant in IRF6 as a Novel and Cryptic Cause of Non-Syndromic Cleft Lip and Palate. Genes (Basel) 2020; 11:genes11080903. [PMID: 32784565 PMCID: PMC7465030 DOI: 10.3390/genes11080903] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/28/2020] [Accepted: 08/04/2020] [Indexed: 12/31/2022] Open
Abstract
Missense, nonsense, splice site and regulatory region variants in interferon regulatory factor 6 (IRF6) have been shown to contribute to both syndromic and non-syndromic forms of cleft lip and/or palate (CL/P). We report the diagnostic evaluation of a complex multigeneration family of Honduran ancestry with a pedigree structure consistent with autosomal-dominant inheritance with both incomplete penetrance and variable expressivity. The proband's grandmother bore children with two partners and CL/P segregates on both sides of each lineage. Through whole-exome sequencing of five members of the family, we identified a single shared synonymous variant, located in the middle of exon 7 of IRF6 (p.Ser307Ser; g.209963979 G>A; c.921C>T). The variant was shown to segregate in the seven affected individuals and through three unaffected obligate carriers, spanning both sides of this pedigree. This variant is very rare, only being found in three (all of Latino ancestry) of 251,352 alleles in the gnomAD database. While the variant did not create a splice acceptor/donor site, in silico analysis predicted it to impact an exonic splice silencer element and the binding of major splice regulatory factors. In vitro splice assays supported this by revealing multiple abnormal splicing events, estimated to impact >60% of allelic transcripts. Sequencing of the alternate splice products demonstrated the unmasking of a cryptic splice site six nucleotides 5' of the variant, as well as variable utilization of cryptic splice sites in intron 6. The ectopic expression of different splice regulatory proteins altered the proportion of abnormal splicing events seen in the splice assay, although the alteration was dependent on the splice factor. Importantly, each alternatively spliced mRNA is predicted to result in a frame shift and prematurely truncated IRF6 protein. This is the first study to identify a synonymous variant as a likely cause of NS-CL/P and highlights the care that should be taken by laboratories when considering and interpreting variants.
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Affiliation(s)
- Beau Sylvester
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
| | | | - Akiko Suzuki
- Department of Oral & Craniofacial Sciences, University of Missouri-Kansas City School of Dentistry, Kansas City, MO 64108, USA; (A.S.); (T.C.C.)
| | - Melissa Giron
- Operación Sonrisa Honduras, Tegucigalpa 11101, Honduras;
| | - Allyn Auslander
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
- Department of Preventive Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033, USA
| | - Richard L. Maas
- Division of Genetics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
| | - Becky Tsai
- Fulgent Genetics, Temple City, CA 91780, USA; (B.T.); (H.G.)
| | - Hanlin Gao
- Fulgent Genetics, Temple City, CA 91780, USA; (B.T.); (H.G.)
| | - William Magee
- Division of Plastic and Maxillofacial Surgery, Children’s Hospital Los Angeles, Los Angeles, CA 90027, USA; (B.S.); (A.A.); (W.M.III)
| | - Timothy C. Cox
- Department of Oral & Craniofacial Sciences, University of Missouri-Kansas City School of Dentistry, Kansas City, MO 64108, USA; (A.S.); (T.C.C.)
- Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108, USA
| | - Pedro A. Sanchez-Lara
- Department of Pediatrics, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90048, USA
- Correspondence: ; Tel.: +1-(310)-423-4461
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7
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Abstract
Synonymous mutations have been viewed as silent mutations, since they only affect the DNA and mRNA, but not the amino acid sequence of the resulting protein. Nonetheless, recent studies suggest their significant impact on splicing, RNA stability, RNA folding, translation or co-translational protein folding. Hence, we compile 659194 synonymous mutations found in human cancer and characterize their properties. We provide the user-friendly, comprehensive resource for synonymous mutations in cancer, SynMICdb (http://SynMICdb.dkfz.de), which also contains orthogonal information about gene annotation, recurrence, mutation loads, cancer association, conservation, alternative events, impact on mRNA structure and a SynMICdb score. Notably, synonymous and missense mutations are depleted at the 5'-end of the coding sequence as well as at the ends of internal exons independent of mutational signatures. For patient-derived synonymous mutations in the oncogene KRAS, we indicate that single point mutations can have a relevant impact on expression as well as on mRNA secondary structure. Synonymous mutations do not alter amino acid sequence but may exert oncogenic effects in other ways. Here, the authors present a catalogue of synonymous mutations in cancer and characterise their properties.
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8
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Li D, Harlan-Williams LM, Kumaraswamy E, Jensen RA. BRCA1-No Matter How You Splice It. Cancer Res 2019; 79:2091-2098. [PMID: 30992324 PMCID: PMC6497576 DOI: 10.1158/0008-5472.can-18-3190] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/09/2019] [Accepted: 03/05/2019] [Indexed: 02/07/2023]
Abstract
BRCA1 (breast cancer 1, early onset), a well-known breast cancer susceptibility gene, is a highly alternatively spliced gene. BRCA1 alternative splicing may serve as an alternative regulatory mechanism for the inactivation of the BRCA1 gene in both hereditary and sporadic breast cancers, and other BRCA1-associated cancers. The alternative transcripts of BRCA1 can mimic known functions, possess unique functions compared with the full-length BRCA1 transcript, and in some cases, appear to function in opposition to full-length BRCA1 In this review, we will summarize the functional "naturally occurring" alternative splicing transcripts of BRCA1 and then discuss the latest next-generation sequencing-based detection methods and techniques to detect alternative BRCA1 splicing patterns and their potential use in cancer diagnosis, prognosis, and therapy.
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Affiliation(s)
- Dan Li
- The University of Kansas Cancer Center, Kansas City, Kansas
| | - Lisa M Harlan-Williams
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Easwari Kumaraswamy
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Roy A Jensen
- The University of Kansas Cancer Center, Kansas City, Kansas.
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
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9
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Zuntini R, Ferrari S, Bonora E, Buscherini F, Bertonazzi B, Grippa M, Godino L, Miccoli S, Turchetti D. Dealing With BRCA1/2 Unclassified Variants in a Cancer Genetics Clinic: Does Cosegregation Analysis Help? Front Genet 2018; 9:378. [PMID: 30254663 PMCID: PMC6141711 DOI: 10.3389/fgene.2018.00378] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/24/2018] [Indexed: 12/11/2022] Open
Abstract
Background: Detection of variants of uncertain significance (VUSs) in BRCA1 and BRCA2 genes poses relevant challenges for counseling and managing patients. VUS carriers should be managed similarly to probands with no BRCA1/2 variants detected, and predictive genetic testing in relatives is discouraged. However, miscomprehension of VUSs is common and can lead to inaccurate risk perception and biased decisions about prophylactic surgery. Therefore, efforts are needed to improve VUS evaluation and communication at an individual level. Aims: We aimed at investigating whether cosegregation analysis, integrated with a careful review of available functional data and in silico predictions, may improve VUSs interpretation and counseling in individual families. Methods: Patients with Breast Cancer (BC) and/or Ovarian Cancer (OC) fulfilling established criteria were offered genetic counseling and BRCA1/2 testing; VUSs identified in index cases were checked in other relatives affected by BC/OC whenever possible. As an alternative, if BC/OC clustered only in one branch of the family, the parental origin of the VUS was investigated. Public prediction tools and databases were used to collect additional information on the variants analyzed. Results: Out of 1045 patients undergoing BRCA1/2 testing in the period October 2011–April 2018, 66 (6.3%) carried class 3 VUSs. Cosegregation analysis was performed for 13 VUSs in 11 kindreds. Seven VUSs (53.8%) did not cosegregate with breast/ovarian cancer in the family, which provided evidence against their role in cancer clustering in those families. Among the 6 cosegregating VUSs, for two (BRCA1 c.5152+2T>G and BRCA2 c.7975A>G) additional evidence exists from databases and in silico tools supporting their pathogenicity, which reinforces the hypothesis they may have had a predisposing effect in respective families. For the remaining four VUSs (31%), cosegregation analysis failed to provide relevant information. Conclusion: Our findings suggest that cosegregation analysis in a clinical context may be helpful to improve test result interpretation in the specific family and, therefore, should be offered whenever possible. Besides, obtaining and sharing cosegregation data helps gathering evidence that may eventually contribute to VUS classification.
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Affiliation(s)
- Roberta Zuntini
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Simona Ferrari
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Elena Bonora
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Francesco Buscherini
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Benedetta Bertonazzi
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Mina Grippa
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Lea Godino
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Sara Miccoli
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
| | - Daniela Turchetti
- UO Genetica Medica, Azienda Ospedaliero-Universitaria di Bologna Policlinico S.Orsola-Malpighi and Centro di Ricerca sui Tumori Ereditari, Dipartimento di Scienze Mediche e Chirurgiche, Universitá di Bologna, Bologna, Italy
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10
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Kamps R, Brandão RD, Bosch BJVD, Paulussen ADC, Xanthoulea S, Blok MJ, Romano A. Next-Generation Sequencing in Oncology: Genetic Diagnosis, Risk Prediction and Cancer Classification. Int J Mol Sci 2017; 18:ijms18020308. [PMID: 28146134 PMCID: PMC5343844 DOI: 10.3390/ijms18020308] [Citation(s) in RCA: 284] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/19/2017] [Indexed: 12/17/2022] Open
Abstract
Next-generation sequencing (NGS) technology has expanded in the last decades with significant improvements in the reliability, sequencing chemistry, pipeline analyses, data interpretation and costs. Such advances make the use of NGS feasible in clinical practice today. This review describes the recent technological developments in NGS applied to the field of oncology. A number of clinical applications are reviewed, i.e., mutation detection in inherited cancer syndromes based on DNA-sequencing, detection of spliceogenic variants based on RNA-sequencing, DNA-sequencing to identify risk modifiers and application for pre-implantation genetic diagnosis, cancer somatic mutation analysis, pharmacogenetics and liquid biopsy. Conclusive remarks, clinical limitations, implications and ethical considerations that relate to the different applications are provided.
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Affiliation(s)
- Rick Kamps
- Department of Clinical Genetics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Rita D Brandão
- Department of Clinical Genetics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Bianca J van den Bosch
- Department of Clinical Genetics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Aimee D C Paulussen
- Department of Clinical Genetics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Sofia Xanthoulea
- Department of Gynaecology and Obstetrics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Marinus J Blok
- Department of Clinical Genetics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
| | - Andrea Romano
- Department of Gynaecology and Obstetrics: GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, 6229HX Maastricht, The Netherlands.
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11
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Diederichs S, Bartsch L, Berkmann JC, Fröse K, Heitmann J, Hoppe C, Iggena D, Jazmati D, Karschnia P, Linsenmeier M, Maulhardt T, Möhrmann L, Morstein J, Paffenholz SV, Röpenack P, Rückert T, Sandig L, Schell M, Steinmann A, Voss G, Wasmuth J, Weinberger ME, Wullenkord R. The dark matter of the cancer genome: aberrations in regulatory elements, untranslated regions, splice sites, non-coding RNA and synonymous mutations. EMBO Mol Med 2016; 8:442-57. [PMID: 26992833 PMCID: PMC5126213 DOI: 10.15252/emmm.201506055] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cancer is a disease of the genome caused by oncogene activation and tumor suppressor gene inhibition. Deep sequencing studies including large consortia such as TCGA and ICGC identified numerous tumor‐specific mutations not only in protein‐coding sequences but also in non‐coding sequences. Although 98% of the genome is not translated into proteins, most studies have neglected the information hidden in this “dark matter” of the genome. Malignancy‐driving mutations can occur in all genetic elements outside the coding region, namely in enhancer, silencer, insulator, and promoter as well as in 5′‐UTR and 3′‐UTR. Intron or splice site mutations can alter the splicing pattern. Moreover, cancer genomes contain mutations within non‐coding RNA, such as microRNA, lncRNA, and lincRNA. A synonymous mutation changes the coding region in the DNA and RNA but not the protein sequence. Importantly, oncogenes such as TERT or miR‐21 as well as tumor suppressor genes such as TP53/p53,APC,BRCA1, or RB1 can be affected by these alterations. In summary, coding‐independent mutations can affect gene regulation from transcription, splicing, mRNA stability to translation, and hence, this largely neglected area needs functional studies to elucidate the mechanisms underlying tumorigenesis. This review will focus on the important role and novel mechanisms of these non‐coding or allegedly silent mutations in tumorigenesis.
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Affiliation(s)
- Sven Diederichs
- Division of Cancer Research, Department of Thoracic Surgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany Division of RNA Biology & Cancer (B150), German Cancer Research Center (DKFZ), Heidelberg, Germany German Cancer Consortium (DKTK), Freiburg, Germany
| | - Lorenz Bartsch
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Julia C Berkmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Karin Fröse
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Jana Heitmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Caroline Hoppe
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Deetje Iggena
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Danny Jazmati
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Philipp Karschnia
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Miriam Linsenmeier
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Thomas Maulhardt
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Lino Möhrmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Johannes Morstein
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Stella V Paffenholz
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Paula Röpenack
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Timo Rückert
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Ludger Sandig
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Maximilian Schell
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Anna Steinmann
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Gjendine Voss
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Jacqueline Wasmuth
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Maria E Weinberger
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
| | - Ramona Wullenkord
- German Academic Scholarship Foundation - Studienstiftung des deutschen Volkes, Bonn, Germany
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12
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Vallée MP, Di Sera TL, Nix DA, Paquette AM, Parsons MT, Bell R, Hoffman A, Hogervorst FBL, Goldgar DE, Spurdle AB, Tavtigian SV. Adding In Silico Assessment of Potential Splice Aberration to the Integrated Evaluation of BRCA Gene Unclassified Variants. Hum Mutat 2016; 37:627-39. [PMID: 26913838 PMCID: PMC4907813 DOI: 10.1002/humu.22973] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 01/29/2016] [Indexed: 01/05/2023]
Abstract
Clinical mutation screening of the cancer susceptibility genes BRCA1 and BRCA2 generates many unclassified variants (UVs). Most of these UVs are either rare missense substitutions or nucleotide substitutions near the splice junctions of the protein coding exons. Previously, we developed a quantitative method for evaluation of BRCA gene UVs—the “integrated evaluation”—that combines a sequence analysis‐based prior probability of pathogenicity with patient and/or tumor observational data to arrive at a posterior probability of pathogenicity. One limitation of the sequence analysis‐based prior has been that it evaluates UVs from the perspective of missense substitution severity but not probability to disrupt normal mRNA splicing. Here, we calibrated output from the splice‐site fitness program MaxEntScan to generate spliceogenicity‐based prior probabilities of pathogenicity for BRCA gene variants; these range from 0.97 for variants with high probability to damage a donor or acceptor to 0.02 for exonic variants that do not impact a splice junction and are unlikely to create a de novo donor. We created a database http://priors.hci.utah.edu/PRIORS/ that provides the combined missense substitution severity and spliceogenicity‐based probability of pathogenicity for BRCA gene single‐nucleotide substitutions. We also updated the BRCA gene Ex‐UV LOVD, available at http://hci‐exlovd.hci.utah.edu, with 77 re‐evaluable variants.
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Affiliation(s)
- Maxime P Vallée
- Department of Molecular Medicine, CHUQ Research Center, Quebec City, Canada
| | - Tonya L Di Sera
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah
| | - David A Nix
- ARUP Laboratories, University of Utah School of Medicine, Salt Lake City, Utah
| | - Andrew M Paquette
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah
| | | | - Russel Bell
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah
| | - Andrea Hoffman
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | - David E Goldgar
- Department of Dermatology, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah
| | | | - Sean V Tavtigian
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, Utah
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13
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Caminsky NG, Mucaki EJ, Rogan PK. Interpretation of mRNA splicing mutations in genetic disease: review of the literature and guidelines for information-theoretical analysis. F1000Res 2015. [DOI: 10.12688/f1000research.5654.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The interpretation of genomic variants has become one of the paramount challenges in the post-genome sequencing era. In this review we summarize nearly 20 years of research on the applications of information theory (IT) to interpret coding and non-coding mutations that alter mRNA splicing in rare and common diseases. We compile and summarize the spectrum of published variants analyzed by IT, to provide a broad perspective of the distribution of deleterious natural and cryptic splice site variants detected, as well as those affecting splicing regulatory sequences. Results for natural splice site mutations can be interrogated dynamically with Splicing Mutation Calculator, a companion software program that computes changes in information content for any splice site substitution, linked to corresponding publications containing these mutations. The accuracy of IT-based analysis was assessed in the context of experimentally validated mutations. Because splice site information quantifies binding affinity, IT-based analyses can discern the differences between variants that account for the observed reduced (leaky) versus abolished mRNA splicing. We extend this principle by comparing predicted mutations in natural, cryptic, and regulatory splice sites with observed deleterious phenotypic and benign effects. Our analysis of 1727 variants revealed a number of general principles useful for ensuring portability of these analyses and accurate input and interpretation of mutations. We offer guidelines for optimal use of IT software for interpretation of mRNA splicing mutations.
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14
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Caminsky N, Mucaki EJ, Rogan PK. Interpretation of mRNA splicing mutations in genetic disease: review of the literature and guidelines for information-theoretical analysis. F1000Res 2014; 3:282. [PMID: 25717368 PMCID: PMC4329672 DOI: 10.12688/f1000research.5654.1] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/10/2014] [Indexed: 12/14/2022] Open
Abstract
The interpretation of genomic variants has become one of the paramount challenges in the post-genome sequencing era. In this review we summarize nearly 20 years of research on the applications of information theory (IT) to interpret coding and non-coding mutations that alter mRNA splicing in rare and common diseases. We compile and summarize the spectrum of published variants analyzed by IT, to provide a broad perspective of the distribution of deleterious natural and cryptic splice site variants detected, as well as those affecting splicing regulatory sequences. Results for natural splice site mutations can be interrogated dynamically with Splicing Mutation Calculator, a companion software program that computes changes in information content for any splice site substitution, linked to corresponding publications containing these mutations. The accuracy of IT-based analysis was assessed in the context of experimentally validated mutations. Because splice site information quantifies binding affinity, IT-based analyses can discern the differences between variants that account for the observed reduced (leaky) versus abolished mRNA splicing. We extend this principle by comparing predicted mutations in natural, cryptic, and regulatory splice sites with observed deleterious phenotypic and benign effects. Our analysis of 1727 variants revealed a number of general principles useful for ensuring portability of these analyses and accurate input and interpretation of mutations. We offer guidelines for optimal use of IT software for interpretation of mRNA splicing mutations.
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Affiliation(s)
- Natasha Caminsky
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada
| | - Eliseos J Mucaki
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, N6A 2C1, Canada
| | - Peter K Rogan
- Departments of Biochemistry and Computer Science, Western University, London, ON, N6A 2C1, Canada
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15
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Santos C, Peixoto A, Rocha P, Pinto P, Bizarro S, Pinheiro M, Pinto C, Henrique R, Teixeira MR. Pathogenicity evaluation of BRCA1 and BRCA2 unclassified variants identified in Portuguese breast/ovarian cancer families. J Mol Diagn 2014; 16:324-34. [PMID: 24607278 DOI: 10.1016/j.jmoldx.2014.01.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 01/18/2023] Open
Abstract
Hereditary breast/ovarian cancer syndrome is caused by germline deleterious mutations in BRCA1 and BRCA2. A major problem of genetic testing and counseling is the finding of variants of uncertain significance (VUS). We sought to ascertain the pathogenicity of 25 BRCA1 and BRCA2 VUS identified in Portuguese families during genetic testing. We performed cosegregation analysis of VUS with cancer in families, evaluated their frequency in unaffected controls, and looked for loss of heterozygosity in tumors. In addition, three different bioinformatic algorithms were used (Interactive Biosoftware, ESEfinder, and PolyPhen). Finally, six VUS located in exon-intron boundaries were analyzed by RT-PCR. We found that seven variants segregated with the disease, six variants co-occurred with a pathogenic mutation in the same gene, and four variants co-occurred with a deleterious mutation in the other BRCA gene. By RT-PCR, we observed that four variants (BRCA1 c.4484G>T, BRCA2 c.682-2A>C, BRCA2 c.8488-1G>A, and BRCA2 c.8954-5A>G) disrupted splicing. After the combined analysis, we were able to classify 4 splicing variants as pathogenic mutations, 16 variants as neutral, and 3 variants as polymorphisms; only 2 variants remained classified as VUS. This work highlights the contribution of DNA, RNA, and in silico data to assess the pathogenicity of BRCA1/2 VUS, which, in turn, allows more accurate genetic counseling and clinical management of the families carrying them.
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Affiliation(s)
- Catarina Santos
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Ana Peixoto
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Patrícia Rocha
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Pedro Pinto
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Susana Bizarro
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Manuela Pinheiro
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Carla Pinto
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Rui Henrique
- Department of Pathology, Portuguese Oncology Institute, Porto, Portugal; Biomedical Sciences Institute (ICBAS), University of Porto, Porto, Portugal
| | - Manuel R Teixeira
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal; Biomedical Sciences Institute (ICBAS), University of Porto, Porto, Portugal.
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16
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Peng M, Yang Z, Zhang H, Jaafar L, Wang G, Liu M, Flores-Rozas H, Xu J, Mivechi NF, Ko L. GT198 Splice Variants Display Dominant-Negative Activities and Are Induced by Inactivating Mutations. Genes Cancer 2013; 4:26-38. [PMID: 23946869 DOI: 10.1177/1947601913486345] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 03/16/2013] [Indexed: 11/16/2022] Open
Abstract
Alternative pre-mRNA splicing yields functionally distinct splice variants in regulating normal cell differentiation as well as cancer development. The putative tumor suppressor gene GT198 (PSMC3IP), encoding a protein also known as TBPIP and Hop2, has been shown to regulate steroid hormone receptor-mediated transcription and to stimulate homologous recombination in DNA repair. Here, we have identified 6 distinct GT198 splice variant transcripts generated by alternative promoter usage or alternative splicing. Various splice variant transcripts preserve a common open reading frame, which encodes the DNA binding domain of GT198. The splice variants act as dominant negatives to counteract wild-type GT198 activity in transcription and to abolish Rad51 foci formation during radiation-induced DNA damage. In fallopian tube cancer, we have identified 44 point mutations in GT198 clustered in 2 mutation hotspot sequences. The mutation hotspots coincide with the regulatory sequences responsible for alternative splicing, strongly supporting that imbalanced alternative splicing is a selected consequence in cancer. In addition, splice variant-associated cytoplasmic expression is found in tumors carrying germline or somatic GT198 mutations. An altered alternative splicing pattern with increased variants is also present in lymphoblastoid cells derived from familial breast cancer patients carrying GT198 germline mutations. Furthermore, GT198 and its variant are reciprocally expressed during mouse stem cell differentiation. The constitutive expression of the GT198 variant but not the wild type induces tumor growth in nude mice. Our results collectively suggest that mutations in the GT198 gene deregulate alternative splicing. Defective alternative splicing promotes antagonizing variants and in turn induces a loss of the wild type in tumorigenesis. The study highlights the role of alternative splicing in tumor suppressor gene inactivation.
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Affiliation(s)
- Min Peng
- Cancer Center, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Georgia Regents University, Augusta, GA, USA
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17
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Wappenschmidt B, Becker AA, Hauke J, Weber U, Engert S, Köhler J, Kast K, Arnold N, Rhiem K, Hahnen E, Meindl A, Schmutzler RK. Analysis of 30 putative BRCA1 splicing mutations in hereditary breast and ovarian cancer families identifies exonic splice site mutations that escape in silico prediction. PLoS One 2012; 7:e50800. [PMID: 23239986 PMCID: PMC3519833 DOI: 10.1371/journal.pone.0050800] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 10/25/2012] [Indexed: 12/12/2022] Open
Abstract
Screening for pathogenic mutations in breast and ovarian cancer genes such as BRCA1/2, CHEK2 and RAD51C is common practice for individuals from high-risk families. However, test results may be ambiguous due to the presence of unclassified variants (UCV) in the concurrent absence of clearly cancer-predisposing mutations. Especially the presence of intronic or exonic variants within these genes that possibly affect proper pre-mRNA processing poses a challenge as their functional implications are not immediately apparent. Therefore, it appears necessary to characterize potential splicing UCV and to develop appropriate classification tools. We investigated 30 distinct BRCA1 variants, both intronic and exonic, regarding their spliceogenic potential by commonly used in silico prediction algorithms (HSF, MaxEntScan) along with in vitro transcript analyses. A total of 25 variants were identified spliceogenic, either causing/enhancing exon skipping or activation of cryptic splice sites, or both. Except from a single intronic variant causing minor effects on BRCA1 pre-mRNA processing in our analyses, 23 out of 24 intronic variants were correctly predicted by MaxEntScan, while HSF was less accurate in this cohort. Among the 6 exonic variants analyzed, 4 severely impair correct pre-mRNA processing, while the remaining two have partial effects. In contrast to the intronic alterations investigated, only half of the spliceogenic exonic variants were correctly predicted by HSF and/or MaxEntScan. These data support the idea that exonic splicing mutations are commonly disease-causing and concurrently prone to escape in silico prediction, hence necessitating experimental in vitro splicing analysis.
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Affiliation(s)
- Barbara Wappenschmidt
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alexandra A. Becker
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Jan Hauke
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Institute of Human Genetics, University of Cologne, Cologne, Germany
| | - Ute Weber
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Stefanie Engert
- Department of Gynaecology and Obstetrics, Klinikum rechts der Isar at the Technical University, Munich, Germany
| | - Juliane Köhler
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Karin Kast
- Department of Gynecology and Obstetrics, Technical University of Dresden, Dresden, Germany
| | - Norbert Arnold
- Division of Oncology, Department of Gynaecology and Obstetrics, University Hospital Schleswig-Holstein, Christian-Albrechts-University, Kiel, Germany
| | - Kerstin Rhiem
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Eric Hahnen
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alfons Meindl
- Department of Gynaecology and Obstetrics, Klinikum rechts der Isar at the Technical University, Munich, Germany
| | - Rita K. Schmutzler
- Division of Molecular Gynaeco-Oncology, Department of Gynaecology and Obstetrics, University Hospital of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- * E-mail:
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18
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Houdayer C, Caux-Moncoutier V, Krieger S, Barrois M, Bonnet F, Bourdon V, Bronner M, Buisson M, Coulet F, Gaildrat P, Lefol C, Léone M, Mazoyer S, Muller D, Remenieras A, Révillion F, Rouleau E, Sokolowska J, Vert JP, Lidereau R, Soubrier F, Sobol H, Sevenet N, Bressac-de Paillerets B, Hardouin A, Tosi M, Sinilnikova OM, Stoppa-Lyonnet D. Guidelines for splicing analysis in molecular diagnosis derived from a set of 327 combined in silico/in vitro studies on BRCA1 and BRCA2 variants. Hum Mutat 2012; 33:1228-38. [DOI: 10.1002/humu.22101] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 03/15/2012] [Accepted: 03/30/2012] [Indexed: 01/05/2023]
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19
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Théry JC, Krieger S, Gaildrat P, Révillion F, Buisine MP, Killian A, Duponchel C, Rousselin A, Vaur D, Peyrat JP, Berthet P, Frébourg T, Martins A, Hardouin A, Tosi M. Contribution of bioinformatics predictions and functional splicing assays to the interpretation of unclassified variants of the BRCA genes. Eur J Hum Genet 2011; 19:1052-8. [PMID: 21673748 DOI: 10.1038/ejhg.2011.100] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A large fraction of sequence variants of unknown significance (VUS) of the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 may induce splicing defects. We analyzed 53 VUSs of BRCA1 or BRCA2, detected in consecutive molecular screenings, by using five splicing prediction programs, and we classified them into two groups according to the strength of the predictions. In parallel, we tested them by using functional splicing assays. A total of 10 VUSs were predicted by two or more programs to induce a significant reduction of splice site strength or activation of cryptic splice sites or generation of new splice sites. Minigene-based splicing assays confirmed four of these predictions. Five additional VUSs, all at internal exon positions, were not predicted to induce alterations of splice sites, but revealed variable levels of exon skipping, most likely induced by the modification of exonic splicing regulatory elements. We provide new data in favor of the pathogenic nature of the variants BRCA1 c.212+3A>G and BRCA1 c.5194-12G>A, which induced aberrant out-of-frame mRNA forms. Moreover, the novel variant BRCA2 c.7977-7C>G induced in frame inclusion of 6 nt from the 3' end of intron 17. The novel variants BRCA2 c.520C>T and BRCA2 c.7992T>A induced incomplete skipping of exons 7 and 18, respectively. This work highlights the contribution of splicing minigene assays to the assessment of pathogenicity, not only when patient RNA is not available, but also as a tool to improve the accuracy of bioinformatics predictions.
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Affiliation(s)
- Jean Christophe Théry
- Inserm U614, IFRMP, Faculty of Medicine and Department of Genetics, University Hospital, Institute for Biomedical Research and Innovation, Rouen, France
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20
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Characterisation of unclassified variants in the BRCA1/2 genes with a putative effect on splicing. Breast Cancer Res Treat 2011; 129:971-82. [PMID: 21638052 DOI: 10.1007/s10549-011-1599-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 05/14/2011] [Indexed: 10/18/2022]
Abstract
A subset of the unclassified variants (UVs) identified during genetic screening of BRCA1/2 genes may affect splicing. We assessed at RNA level the effect of four BRCA1 and ten BRCA2 UVs with a putative splice effect, as predicted in silico. The variants selected for this study were beyond the positions -1, -2 or +1, +2 from the exon, and were not previously described (n = 8) or their effect on splicing was not assessed previously (n = 6). Lymphocytes from UV carriers and healthy controls were cultured and treated with puromycin to prevent nonsense-mediated mRNA decay. The relative contribution of each allele to the various transcripts was assessed using combinations of allele-specific and transcript-specific primers. BRCA2 c.425G>T, c.7976+3_7976+4del and c.8754+3G>C give rise to aberrant transcripts BRCA2Δ4, BRCA2Δ17 and retention of 46nt of intron 21, respectively, and were considered pathogenic. BRCA1 c.4987-3C>G gives rise to BRCA1Δ17 that is likely pathogenic; however, residual expression of the full-length transcript from the variant allele could not be excluded. BRCA1 c.692C>T, c.693G>A and BRCA2 c.6935A>T, besides expressing the full-length transcript, increased expression of BRCA1Δ11 and BRCA2Δ12, respectively. As these are naturally occurring isoforms, also observed in controls, the clinical relevance is unclear. The seven remaining UVs did not affect splicing and three intronic variants were therefore classified as neutral. In conclusion, the RNA analysis results clarified the clinical relevance of 6 of the 14 studied UVs and thereby greatly improve the genetic counselling of high-risk breast/ovarian cancer patients carrying these classified variants.
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21
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Mucaki EJ, Ainsworth P, Rogan PK. Comprehensive prediction of mRNA splicing effects of BRCA1 and BRCA2 variants. Hum Mutat 2011; 32:735-42. [DOI: 10.1002/humu.21513] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 04/08/2011] [Indexed: 12/17/2022]
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22
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Guillaumot P, Luquain C, Malek M, Huber AL, Brugière S, Garin J, Grunwald D, Régnier D, Pétrilli V, Lefai E, Manié SN. Pdro, a protein associated with late endosomes and lysosomes and implicated in cellular cholesterol homeostasis. PLoS One 2010; 5:e10977. [PMID: 20544018 PMCID: PMC2882324 DOI: 10.1371/journal.pone.0010977] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 05/13/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Cellular cholesterol is a vital component of the cell membrane. Its concentration is tightly controlled by mechanisms that remain only partially characterized. In this study, we describe a late endosome/lysosomes-associated protein whose expression level affects cellular free cholesterol content. METHODOLOGY/PRINCIPAL FINDINGS Using a restricted proteomic analysis of detergent-resistant membranes (DRMs), we have identified a protein encoded by gene C11orf59. It is mainly localized to late endosome/lysosome (LE/LY) compartment through N-terminal myristoylation and palmitoylation. We named it Pdro for protein associated with DRMs and endosomes. Very recently, three studies have reported on the same protein under two other names: the human p27RF-Rho that regulates RhoA activation and actin dynamics, and its rodent orthologue p18 that controls both LE/LY dynamics through the MERK-ERK pathway and the lysosomal activation of mammalian target of rapamycin complex 1 by amino acids. We found that, consistent with the presence of sterol-responsive element consensus sequences in the promoter region of C11orf59, Pdro mRNA and protein expression levels are regulated positively by cellular cholesterol depletion and negatively by cellular cholesterol loading. Conversely, Pdro is involved in the regulation of cholesterol homeostasis, since its depletion by siRNA increases cellular free cholesterol content that is accompanied by an increased cholesterol efflux from cells. On the other hand, cells stably overexpressing Pdro display reduced cellular free cholesterol content. Pdro depletion-mediated excess cholesterol results, at least in part, from a stimulated low-density lipoprotein (LDL) uptake and an increased cholesterol egress from LE/LY. CONCLUSIONS/SIGNIFICANCE LDL-derived cholesterol release involves LE/LY motility that is linked to actin dynamics. Because Pdro regulates these two processes, we propose that modulation of Pdro expression in response to sterol levels regulates LDL-derived cholesterol through both LDL uptake and LE/LY dynamics, to ultimately control free cholesterol homeostasis.
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Affiliation(s)
- Patricia Guillaumot
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
| | - Céline Luquain
- Regulation Métabolique, Nutrition et Diabète, UMR 870 INSERM/Insa-Lyon, Villeurbanne, France
| | - Mouhannad Malek
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
| | - Anne-Laure Huber
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
| | - Sabine Brugière
- Laboratoire de Chimie des Protéines, ERM 201 INSERM/CEA/UJF, CEA/Grenoble, Grenoble, France
| | - Jérome Garin
- Laboratoire de Chimie des Protéines, ERM 201 INSERM/CEA/UJF, CEA/Grenoble, Grenoble, France
| | - Didier Grunwald
- Laboratoire Transduction de Signal, Unité 873, INSERM/CEA/DSV, Institut de Recherches en Technologies et Sciences pour le Vivant, Grenoble, France
| | - Daniel Régnier
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
| | - Virginie Pétrilli
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
| | | | - Serge N. Manié
- Génétique Moléculaire, Signalisation et Cancer, UMR 5201 CNRS, Centre Leon Berard, Lyon, France
- * E-mail:
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Whiley PJ, Pettigrew CA, Brewster BL, Walker LC, Spurdle AB, Brown MA. Effect of BRCA2 sequence variants predicted to disrupt exonic splice enhancers on BRCA2 transcripts. BMC MEDICAL GENETICS 2010; 11:80. [PMID: 20507642 PMCID: PMC2897790 DOI: 10.1186/1471-2350-11-80] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 05/28/2010] [Indexed: 12/02/2022]
Abstract
Background Genetic screening of breast cancer patients and their families have identified a number of variants of unknown clinical significance in the breast cancer susceptibility genes, BRCA1 and BRCA2. Evaluation of such unclassified variants may be assisted by web-based bioinformatic prediction tools, although accurate prediction of aberrant splicing by unclassified variants affecting exonic splice enhancers (ESEs) remains a challenge. Methods This study used a combination of RT-PCR analysis and splicing reporter minigene assays to assess five unclassified variants in the BRCA2 gene that we had previously predicted to disrupt an ESE using bioinformatic approaches. Results Analysis of BRCA2 c.8308 G > A (p.Ala2770Thr) by mRNA analysis, and BRCA2 c.8962A > G (p.Ser2988Gly), BRCA2 c.8972G > A (p.Arg2991His), BRCA2 c.9172A > G (p.Ser3058Gly), and BRCA2 c.9213G > T (p.Glu3071Asp) by a minigene assay, revealed no evidence for aberrant splicing. Conclusions These results illustrate the need for improved methods for predicting functional ESEs and the potential consequences of sequence variants contained therein.
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Affiliation(s)
- Phillip J Whiley
- School of Chemistry and Molecular Biosciences, The University of Queensland, Australia
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24
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Clinical relevance of rare germline sequence variants in cancer genes: evolution and application of classification models. Curr Opin Genet Dev 2010; 20:315-23. [PMID: 20456937 DOI: 10.1016/j.gde.2010.03.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 03/17/2010] [Accepted: 03/18/2010] [Indexed: 12/11/2022]
Abstract
Multifactorial models developed for BRCA1/2 variant classification have proved very useful for delineating BRCA1/2 variants associated with very high risk of cancer, or with little clinical significance. Recent linkage of this quantitative assessment of risk to clinical management guidelines has provided a basis to standardize variant reporting, variant classification and management of families with such variants, and can theoretically be applied to any disease gene. As proof of principle, the multifactorial approach already shows great promise for application to the evaluation of mismatch repair gene variants identified in families with suspected Lynch syndrome. However there is need to be cautious of the noted limitations and caveats of the current model, some of which may be exacerbated by differences in ascertainment and biological pathways to disease for different cancer syndromes.
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Dosil V, Tosar A, Cañadas C, Pérez-Segura P, Díaz-Rubio E, Caldés T, de la Hoya M. Alternative splicing and molecular characterization of splice site variants: BRCA1 c.591C>T as a case study. Clin Chem 2009; 56:53-61. [PMID: 19892845 DOI: 10.1373/clinchem.2009.132274] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Deleterious mutations in BRCA1 (breast cancer 1, early onset; MIM 113705) increase breast and ovarian cancer [B(O)C] risk; however, many variants cannot be readily classified as deleterious or neutral. Unclassified variants (UVs) pose serious problems in genetic counseling. RNA-splicing analysis is essential for the assessment of many UVs. METHODS Denaturing gradient gel electrophoresis was used to genotype the BRCA1 c.591C>T variant in 685 index cases of B(O)C families, 326 sporadic breast cancer cases, and 450 healthy controls from Spain. In silico tools were used to predict the effect of the c.591C>T variant on splicing. In vitro splicing analysis was performed in 7 c.591C>T carriers and 10 noncarriers. cDNAs were PCR-amplified with primers designed to detect BRCA1 alternative splicing isoforms. The products were analyzed by capillary electrophoresis. Peak areas were used to quantify the relative abundance of each isoform. Sequencing through exonic single-nucleotide polymorphisms (SNPs) enabled us to discriminate wild-type and variant transcripts. RESULTS c.591C>T was detected in B(O)C families (1.5%), breast cancer cases (0.3%), and controls (0.9%). c.591C>T induced BRCA1 exon 9 skipping and modified the relative expression of Delta(9,10), Delta(9,10,11B), Delta11B, and full-length isoforms. The mean ratio of Delta(9,10) to the full-length isoform increased from 0.25 in noncarriers to 1.5 in carriers. The mean Delta(9,10,11B)/Delta11B ratio increased from 0.2 to 4. Overall expression levels of c.591C>T and wild-type alleles were similar. CONCLUSIONS Our data support a nonpathogenic role for the BRCA1 c.591C>T variant. Naturally occurring alternative splicing isoforms need to be considered when assessing the role of BRCA1 UVs on splicing.
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Affiliation(s)
- Vanesa Dosil
- Laboratorio de Oncología Molecular, Hospital Clínico San Carlos, Madrid, Spain
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26
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Impact of BRCA1 and BRCA2 variants on splicing: clues from an allelic imbalance study. Eur J Hum Genet 2009; 17:1471-80. [PMID: 19471317 DOI: 10.1038/ejhg.2009.89] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Nearly one-half of BRCA1 and BRCA2 sequence variations are variants of uncertain significance (VUSs) and are candidates for splice alterations for example, by disrupting/creating splice sites. As out-of-frame splicing defects lead to a marked reduction of the level of the mutant mRNA cleared through nonsense-mediated mRNA decay, a cDNA-based test was developed to show the resulting allelic imbalance (AI). Fifty-four VUSs identified in 53 hereditary breast/ovarian cancer (HBOC) patients without BRCA1/2 mutation were included in the study. Two frequent exonic single-nucleotide polymorphisms on both BRCA1 and BRCA2 were investigated by using a semiquantitative single-nucleotide primer extension approach and the cDNA allelic ratios obtained were corrected using genomic DNA ratios from the same sample. A total of five samples showed AI. Subsequent transcript analyses ruled out the implication of VUS on AI and identified a deletion encompassing BRCA2 exons 12 and 13 in one sample. No sequence abnormality was found in the remaining four samples, suggesting implication of cis- or trans-acting factors in allelic expression regulation that might be disease causative in these HBOC patients. Overall, this study showed that AI screening is a simple way to detect deleterious splicing defects and that a major role for VUSs and deep intronic mutations in splicing anomalies is unlikely in BRCA1/2 genes. Methods to analyze gene expression and identify regulatory elements in BRCA1/2 are now needed to complement standard approaches to mutational analysis.
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27
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Desmet FO, Hamroun D, Lalande M, Collod-Béroud G, Claustres M, Béroud C. Human Splicing Finder: an online bioinformatics tool to predict splicing signals. Nucleic Acids Res 2009; 37:e67. [PMID: 19339519 PMCID: PMC2685110 DOI: 10.1093/nar/gkp215] [Citation(s) in RCA: 1992] [Impact Index Per Article: 132.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Thousands of mutations are identified yearly. Although many directly affect protein expression, an increasing proportion of mutations is now believed to influence mRNA splicing. They mostly affect existing splice sites, but synonymous, non-synonymous or nonsense mutations can also create or disrupt splice sites or auxiliary cis-splicing sequences. To facilitate the analysis of the different mutations, we designed Human Splicing Finder (HSF), a tool to predict the effects of mutations on splicing signals or to identify splicing motifs in any human sequence. It contains all available matrices for auxiliary sequence prediction as well as new ones for binding sites of the 9G8 and Tra2-β Serine-Arginine proteins and the hnRNP A1 ribonucleoprotein. We also developed new Position Weight Matrices to assess the strength of 5′ and 3′ splice sites and branch points. We evaluated HSF efficiency using a set of 83 intronic and 35 exonic mutations known to result in splicing defects. We showed that the mutation effect was correctly predicted in almost all cases. HSF could thus represent a valuable resource for research, diagnostic and therapeutic (e.g. therapeutic exon skipping) purposes as well as for global studies, such as the GEN2PHEN European Project or the Human Variome Project.
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28
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Spurdle AB, Couch FJ, Hogervorst FBL, Radice P, Sinilnikova OM. Prediction and assessment of splicing alterations: implications for clinical testing. Hum Mutat 2008; 29:1304-13. [PMID: 18951448 PMCID: PMC2832470 DOI: 10.1002/humu.20901] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Sequence variants that may result in splicing alterations are a particular class of inherited variants for which consequences can be more readily assessed, using a combination of bioinformatic prediction methods and in vitro assays. There is also a general agreement that a variant would invariably be considered pathogenic on the basis of convincing evidence that it results in transcript(s) carrying a premature stop codon or an in-frame deletion disrupting known functional domain(s). This commentary discusses current practices used to assess the clinical significance of this class of variants, provides suggestions to improve assessment, and highlights the issues involved in routine assessment of potential splicing aberrations. We conclude that classification of sequence variants that may alter splicing is greatly enhanced by supporting in vitro analysis. Additional studies that assess large numbers of variants for induction of splicing aberrations and exon skipping are needed to define the contribution of splicing/exon skipping to cancer and disease. These studies will also provide the impetus for development of algorithms that better predict splicing patterns. To facilitate variant classification and development of more specific bioinformatic tools, we call for the deposition of all laboratory data from splicing analyses into national and international databases.
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Affiliation(s)
- Amanda B Spurdle
- Genetics and Population Health Division, Queensland Institute of Medical Research, Brisbane, Australia.
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