101
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Cai M, Zhang H, Hou L, Gao W, Song Y, Cui X, Li C, Guan R, Ma J, Wang X, Han Y, Lv Y, Chen F, Wang P, Meng X, Fu S. Inhibiting homologous recombination decreases extrachromosomal amplification but has no effect on intrachromosomal amplification in methotrexate-resistant colon cancer cells. Int J Cancer 2018; 144:1037-1048. [PMID: 30070702 PMCID: PMC6586039 DOI: 10.1002/ijc.31781] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 02/23/2018] [Accepted: 07/24/2018] [Indexed: 01/08/2023]
Abstract
Gene amplification, which involves the two major topographical structures double minutes (DMs) and homegeneously stained region (HSR), is a common mechanism of treatment resistance in cancer and is initiated by DNA double‐strand breaks. NHEJ, one of DSB repair pathways, is involved in gene amplification as we demonstrated previously. However, the involvement of homologous recombination, another DSB repair pathway, in gene amplification remains to be explored. To better understand the association between HR and gene amplification, we detected HR activity in DM‐ and HSR‐containing MTX‐resistant HT‐29 colon cancer cells. In DM‐containing MTX‐resistant cells, we found increased homologous recombination activity compared with that in MTX‐sensitive cells. Therefore, we suppressed HR activity by silencing BRCA1, the key player in the HR pathway. The attenuation of HR activity decreased the numbers of DMs and DM‐form amplified gene copies and increased the exclusion of micronuclei and nuclear buds that contained DM‐form amplification; these changes were accompanied by cell cycle acceleration and increased MTX sensitivity. In contrast, BRCA1 silencing did not influence the number of amplified genes and MTX sensitivity in HSR‐containing MTX‐resistant cells. In conclusion, our results suggest that the HR pathway plays different roles in extrachromosomal and intrachromosomal gene amplification and may be a new target to improve chemotherapeutic outcome by decreasing extrachromosomal amplification in cancer. What's new? Double‐strand DNA breaks (DSBs) initiate gene amplification, a phenomenon associated with therapeutic resistance in cancer that involves two topographical structures, double minutes (DMs) and homogeneously staining regions (HSRs). Whether DSB repair pathways, particularly homologous recombination (HR), also influence gene amplification is unknown. Here, in methotrexate‐resistant colon cancer cells, HR inhibition effectively reduced gene amplification, specifically the DM‐form, by blocking DM formation and promoting DM exclusion via micronuclei. HR inhibition had no influence on the HSR‐form of gene amplification. Loss of gene amplification by HR inhibition, through partial reversal of methotrexate resistance, may contribute to improved chemotherapeutic outcome.
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Affiliation(s)
- Mengdi Cai
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Huishu Zhang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Liqing Hou
- Department of Genetics, Inner Mongolia Maternal and Child Care Hospital, Hohhot, Inner Mongolia Autonomous Region, China
| | - Wei Gao
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Ying Song
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xiaobo Cui
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Chunxiang Li
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Rongwei Guan
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Jinfa Ma
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xu Wang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Yue Han
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Yafan Lv
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Feng Chen
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Ping Wang
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Xiangning Meng
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, 150081, China
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102
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Piffer A, Luporsi E, Mathelin C. [PALB2, a major susceptibility gene for breast cancer]. ACTA ACUST UNITED AC 2018; 46:701-705. [PMID: 30243941 DOI: 10.1016/j.gofs.2018.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Indexed: 01/01/2023]
Abstract
OBJECTIVES About 5% of breast cancers are linked to an inherited predisposition, the two most known susceptibility genes being BRCA1 and BRCA2. Recently, new susceptibility genes, including PALB2, have been identified. The risk of breast cancer associated with a deleterious mutation of PALB2, the age of onset of these cancers, their prognosis and associated cancers have so far been the subject of controversy. Our objective was to clarify these different questions from an updated review of the literature. METHODS The analyzed articles were taken from the PUBMED database between January 2008 and December 2015. The keywords used were "breast cancer" and "PALB2". RESULTS Women with PALB2 mutations have a higher risk than the general population of developing breast cancer. The relative risk is significant, varying according to the different studies between 3,4 (IC 95%: 2,4-5,9) and 9,47 (IC 95%: 5,72-14,39). The different mutations as well as environmental and geographical factors should be taking into account when interpreting these results. There is currently no proven link between a PALB2 mutation and the occurrence of ovarian or pancreas cancer. CONCLUSION PALB2 must be considered as a high-penetrance breast cancer predisposing gene. Women with a PALB2 mutation face an increased risk of triple negative breast cancer and higher risk of death from breast cancer.
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Affiliation(s)
- A Piffer
- Maternité régionale universitaire de Nancy, 10, avenue Dr Heydenreich, 54000 Nancy, France.
| | - E Luporsi
- Service d'oncologie de génétique, CHR Metz, 1, allée du Château, 57245 Ars-Laquenexy, France.
| | - C Mathelin
- Unité de sénologie, CHRU de Strasbourg, 1, avenue Molière, 67200 Strasbourg, France. carole.mathelin.@chru-strasbourg.fr
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103
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Caputo SM, Léone M, Damiola F, Ehlen A, Carreira A, Gaidrat P, Martins A, Brandão RD, Peixoto A, Vega A, Houdayer C, Delnatte C, Bronner M, Muller D, Castera L, Guillaud-Bataille M, Søkilde I, Uhrhammer N, Demontety S, Tubeuf H, Castelain G, Jensen UB, Petitalot A, Krieger S, Lefol C, Moncoutier V, Boutry-Kryza N, Nielsen HR, Sinilnikova O, Stoppa-Lyonnet D, Spurdle AB, Teixeira MR, Coulet F, Thomassen M, Rouleau E. Full in-frame exon 3 skipping of BRCA2 confers high risk of breast and/or ovarian cancer. Oncotarget 2018; 9:17334-17348. [PMID: 29707112 PMCID: PMC5915120 DOI: 10.18632/oncotarget.24671] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 02/24/2018] [Indexed: 12/18/2022] Open
Abstract
Germline pathogenic variants in the BRCA2 gene are associated with a cumulative high risk of breast/ovarian cancer. Several BRCA2 variants result in complete loss of the exon-3 at the transcript level. The pathogenicity of these variants and the functional impact of loss of exon 3 have yet to be established. As a collaboration of the COVAR clinical trial group (France), and the ENIGMA consortium for investigating breast cancer gene variants, this study evaluated 8 BRCA2 variants resulting in complete deletion of exon 3. Clinical information for 39 families was gathered from Portugal, France, Denmark and Sweden. Multifactorial likelihood analyses were conducted using information from 293 patients, for 7 out of the 8 variants (including 6 intronic). For all variants combined the likelihood ratio in favor of causality was 4.39*1025. These results provide convincing evidence for the pathogenicity of all examined variants that lead to a total exon 3 skipping, and suggest that other variants that result in complete loss of exon 3 at the molecular level could be associated with a high risk of cancer comparable to that associated with classical pathogenic variants in BRCA1 or BRCA2 gene. In addition, our functional study shows, for the first time, that deletion of exon 3 impairs the ability of cells to survive upon Mitomycin-C treatment, supporting lack of function for the altered BRCA2 protein in these cells. Finally, this study demonstrates that any variant leading to expression of only BRCA2 delta-exon 3 will be associated with an increased risk of breast and ovarian cancer.
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Affiliation(s)
| | - Mélanie Léone
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Asa Ehlen
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Aura Carreira
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France.,Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Pascaline Gaidrat
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Alexandra Martins
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Ana Peixoto
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Ana Vega
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal
| | - Claude Houdayer
- Institut Curie, Service de Génétique, Paris, France.,Université Paris Descartes, Paris, France
| | | | | | - Danièle Muller
- Laboratoire d'Oncogénétique, Centre Paul Strauss, Strasbourg, France
| | - Laurent Castera
- Laboratoire de biologie et de génétique du cancer, CLCC François Baclesse, INSERM 1079 Centre Normand de Génomique et de Médecine Personnalisée, Caen, France
| | | | - Inge Søkilde
- Section of Molecular Diagnostics, Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
| | - Nancy Uhrhammer
- Laboratoire de Biologie Médicale, CLCC Jean Perrin, Clermont-Ferrand, France
| | | | - Hélène Tubeuf
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France.,Interactive Biosoftware, Rouen, France
| | - Gaïa Castelain
- Inserm-U1245, UNIROUEN, Normandie University, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | | | - Uffe Birk Jensen
- Department of Clinical Genetics, Aarhus University Hospital, Aarhus, Denmark
| | | | - Sophie Krieger
- Laboratoire de biologie et de génétique du cancer, CLCC François Baclesse, INSERM 1079 Centre Normand de Génomique et de Médecine Personnalisée, Caen, France
| | | | | | - Nadia Boutry-Kryza
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Olga Sinilnikova
- Unité Mixte de Génétique Constitutionnelle des Cancers Fréquents, Hospices Civils de Lyon/Centre Léon Bérard, Lyon, France
| | | | - Amanda B Spurdle
- Genetics and Comp utational Biology Division, QIMR Berghofer Medical Research Institute, Herston, Brisbane, Australia
| | - Manuel R Teixeira
- Department of Genetics, Portuguese Oncology Institute, Porto, Portugal.,Institute of Biomedical Sciences, University of Porto, Porto, Portugal
| | - Florence Coulet
- Laboratoire d'Oncogénétique et d'Angiogénétique Moléculaire, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
| | - Mads Thomassen
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
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104
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Mylavarapu S, Das A, Roy M. Role of BRCA Mutations in the Modulation of Response to Platinum Therapy. Front Oncol 2018. [PMID: 29459887 DOI: 10.3389/fonc.2018.00016] [] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Recent years have seen cancer emerge as one of the leading cause of mortality worldwide with breast cancer being the second most common cause of death among women. Individuals harboring BRCA mutations are at a higher risk of developing breast and/or ovarian cancers. This risk is much greater in the presence of germline mutations. BRCA1 and BRCA2 play crucial role in the DNA damage response and repair pathway, a function that is critical in preserving the integrity of the genome. Mutations that interfere with normal cellular function of BRCA not only lead to onset and progression of cancer but also modulate therapy outcome of treatment with platinum drugs. In this review, we discuss the structural and functional impact of some of the prevalent BRCA mutations in breast and ovarian cancers and their role in platinum therapy response. Understanding the response of platinum drugs in the context of BRCA mutations may contribute toward developing better therapeutics that can improve survival and quality of life of patients.
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Affiliation(s)
- Sanghamitra Mylavarapu
- Invictus Oncology Pvt. Ltd., Delhi, India.,Department of Biotechnology, Delhi Technological University, Delhi, India
| | - Asmita Das
- Department of Biotechnology, Delhi Technological University, Delhi, India
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105
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Gene-Specific Genetic Complementation between Brca1 and Cobra1 During Mouse Mammary Gland Development. Sci Rep 2018; 8:2731. [PMID: 29426838 PMCID: PMC5807304 DOI: 10.1038/s41598-018-21044-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/29/2018] [Indexed: 12/22/2022] Open
Abstract
Germ-line mutations in breast cancer susceptibility gene, BRCA1, result in familial predisposition to breast and ovarian cancers. The BRCA1 protein has multiple functional domains that interact with a variety of proteins in multiple cellular processes. Understanding the biological consequences of BRCA1 interactions with its binding partners is important for elucidating its tissue-specific tumor suppression function. The Cofactor of BRCA1 (COBRA1) is a BRCA1-binding protein that, as a component of negative elongation factor (NELF), regulates RNA polymerase II pausing during transcription elongation. We recently identified a genetic interaction between mouse Brca1 and Cobra1 that antagonistically regulates mammary gland development. However, it remains unclear which of the myriad functions of Brca1 are required for its genetic interaction with Cobra1. Here, we show that, unlike deletion of Brca1 exon 11, separation-of-function mutations that abrogate either the E3 ligase activity of its RING domain or the phospho-recognition property of its BRCT domain are not sufficient to rescue the mammary developmental defects in Cobra1 knockout mice. Furthermore, deletion of mouse Palb2, another breast cancer susceptibility gene with functional similarities to BRCA1, does not rescue Cobra1 knockout-associated mammary defects. Thus, the Brca1/Cobra1 genetic interaction is both domain- and gene-specific in the context of mammary gland development.
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106
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Mylavarapu S, Das A, Roy M. Role of BRCA Mutations in the Modulation of Response to Platinum Therapy. Front Oncol 2018; 8:16. [PMID: 29459887 PMCID: PMC5807680 DOI: 10.3389/fonc.2018.00016] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/17/2018] [Indexed: 12/11/2022] Open
Abstract
Recent years have seen cancer emerge as one of the leading cause of mortality worldwide with breast cancer being the second most common cause of death among women. Individuals harboring BRCA mutations are at a higher risk of developing breast and/or ovarian cancers. This risk is much greater in the presence of germline mutations. BRCA1 and BRCA2 play crucial role in the DNA damage response and repair pathway, a function that is critical in preserving the integrity of the genome. Mutations that interfere with normal cellular function of BRCA not only lead to onset and progression of cancer but also modulate therapy outcome of treatment with platinum drugs. In this review, we discuss the structural and functional impact of some of the prevalent BRCA mutations in breast and ovarian cancers and their role in platinum therapy response. Understanding the response of platinum drugs in the context of BRCA mutations may contribute toward developing better therapeutics that can improve survival and quality of life of patients.
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Affiliation(s)
- Sanghamitra Mylavarapu
- Invictus Oncology Pvt. Ltd., Delhi, India.,Department of Biotechnology, Delhi Technological University, Delhi, India
| | - Asmita Das
- Department of Biotechnology, Delhi Technological University, Delhi, India
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107
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Alavattam KG, Kato Y, Sin HS, Maezawa S, Kowalski IJ, Zhang F, Pang Q, Andreassen PR, Namekawa SH. Elucidation of the Fanconi Anemia Protein Network in Meiosis and Its Function in the Regulation of Histone Modifications. Cell Rep 2017; 17:1141-1157. [PMID: 27760317 PMCID: PMC5095620 DOI: 10.1016/j.celrep.2016.09.073] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 08/17/2016] [Accepted: 09/21/2016] [Indexed: 01/14/2023] Open
Abstract
Precise epigenetic regulation of the sex chromosomes is vital for the male germline. Here, we analyze meiosis in eight mouse models deficient for various DNA damage response (DDR) factors, including Fanconi anemia (FA) proteins. We reveal a network of FA and DDR proteins in which FA core factors FANCA, FANCB, and FANCC are essential for FANCD2 foci formation, whereas BRCA1 (FANCS), MDC1, and RNF8 are required for BRCA2 (FANCD1) and SLX4 (FANCP) accumulation on the sex chromosomes during meiosis. In addition, FA proteins modulate distinct histone marks on the sex chromosomes: FA core proteins and FANCD2 regulate H3K9 methylation, while FANCD2 and RNF8 function together to regulate H3K4 methylation independently of FA core proteins. Our data suggest that RNF8 integrates the FA-BRCA pathway. Taken together, our study reveals distinct functions for FA proteins and illuminates the male sex chromosomes as a model to dissect the function of the FA-BRCA pathway.
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Affiliation(s)
- Kris G Alavattam
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Yasuko Kato
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Ho-Su Sin
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - So Maezawa
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Ian J Kowalski
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Fan Zhang
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Qishen Pang
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA
| | - Satoshi H Namekawa
- Division of Reproductive Sciences and Division of Developmental Biology, Perinatal Institute, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 49229, USA.
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108
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Bleuyard JY, Butler RM, Esashi F. Perturbation of PALB2 function by the T413S mutation found in small cell lung cancer. Wellcome Open Res 2017; 2:110. [PMID: 29387807 PMCID: PMC5721578 DOI: 10.12688/wellcomeopenres.13113.2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2017] [Indexed: 12/22/2022] Open
Abstract
Background: Germline mutations in the
PALB2 gene are associated with the genetic disorder Fanconi anaemia and increased predisposition to cancer. Disease-associated variants are mainly protein-truncating mutations, whereas a few missense substitutions are reported to perturb its interaction with breast cancer susceptibility proteins BRCA1 and BRCA2, which play essential roles in homology-directed repair (HDR). More recently, PALB2 was shown to associate with active genes independently of BRCA1, and through this mechanism, safeguards these regions from DNA replicative stresses. However, it is unknown whether PALB2 tumour suppressor function requires its chromatin association. Methods: Mining the public database of cancer mutations, we identified four potentially deleterious cancer-associated missense mutations within the PALB2 chromatin association motif (ChAM). To assess the impact of these mutations on PALB2 function, we generated cell lines expressing PALB2 variants harbouring corresponding ChAM mutations, and evaluated PALB2 chromatin association properties and the cellular resistance to camptothecin (CPT). Additionally, we examined the accumulation of γH2A.X and the RAD51 recombinase as readouts of DNA damage signalling and HDR, respectively. Results: We demonstrate that a small-cell lung cancer (SCLC)-associated T413S mutation in PALB2 impairs its chromatin association and confers reduced resistance to CPT, the only FDA-approved drug for relapsed SCLC. Unexpectedly, we found a less efficient γH2A.X nuclear foci formation in PALB2 T413S expressing cells, whereas a near-normal level of RAD51 nuclear foci was visible. Conclusions: These findings support the importance of PALB2 chromatin association in the suppression of tumours, including SCLC, an unusually aggressive type of cancer with poor prognosis. PALB2 T413S has little impact on RAD51 recruitment, likely due to its intact interaction with BRCA1 and BRCA2. However, this mutant shows inefficient DNA stress signalling. This finding sheds new light on the function of PALB2, playing a role in efficient DNA stress signalling through constitutive chromatin association.
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Affiliation(s)
- Jean-Yves Bleuyard
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Rosie M Butler
- St John's Institute of Dermatology, Division of Genetics and Molecular Medicine, Faculty of Life Sciences & Medicine, King's College London, London, SE1 9RT, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
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109
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Bleuyard JY, Butler RM, Esashi F. Perturbation of PALB2 function by the T413S mutation found in small cell lung cancer. Wellcome Open Res 2017. [PMID: 29387807 DOI: 10.12688/wellcomeopenres.13113.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Background: Germline mutations in the PALB2 gene are associated with the genetic disorder Fanconi anaemia and increased predisposition to cancer. Disease-associated variants are mainly protein-truncating mutations, whereas a few missense substitutions are reported to perturb its interaction with breast cancer susceptibility proteins BRCA1 and BRCA2, which play essential roles in homology-directed repair (HDR). More recently, PALB2 was shown to associate with active genes independently of BRCA1, and through this mechanism, safeguards these regions from DNA replicative stresses. However, it is unknown whether PALB2 tumour suppressor function requires its chromatin association. Methods: Mining the public database of cancer mutations, we identified four potentially deleterious cancer-associated missense mutations within the PALB2 chromatin association motif (ChAM). To assess the impact of these mutations on PALB2 function, we generated cell lines expressing PALB2 variants harbouring corresponding ChAM mutations, and evaluated PALB2 chromatin association properties and the cellular resistance to camptothecin (CPT). Additionally, we examined the accumulation of γH2A.X and the RAD51 recombinase as readouts of DNA damage signalling and HDR, respectively. Results: We demonstrate that a small-cell lung cancer (SCLC)-associated T413S mutation in PALB2 impairs its chromatin association and confers reduced resistance to CPT, the only FDA-approved drug for relapsed SCLC. Unexpectedly, we found a less efficient γH2A.X nuclear foci formation in PALB2 T413S expressing cells, whereas a near-normal level of RAD51 nuclear foci was visible. Conclusions: These findings support the importance of PALB2 chromatin association in the suppression of tumours, including SCLC, an unusually aggressive type of cancer with poor prognosis. PALB2 T413S has little impact on RAD51 recruitment, likely due to its intact interaction with BRCA1 and BRCA2. However, this mutant shows inefficient DNA stress signalling. This finding sheds new light on the function of PALB2, playing a role in efficient DNA stress signalling through constitutive chromatin association.
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Affiliation(s)
- Jean-Yves Bleuyard
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Rosie M Butler
- St John's Institute of Dermatology, Division of Genetics and Molecular Medicine, Faculty of Life Sciences & Medicine, King's College London, London, SE1 9RT, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
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110
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Bhangoo MS, Costantini C, Clifford BT, Chung JH, Schrock AB, Ali SM, Klempner SJ. Biallelic Deletion of PALB2 Occurs Across Multiple Tumor Types and Suggests Responsiveness to Poly (ADP-ribose) Polymerase Inhibition. JCO Precis Oncol 2017; 1:1-7. [DOI: 10.1200/po.17.00043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Munveer S. Bhangoo
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Carrie Costantini
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Brian T. Clifford
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Jon H. Chung
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Alexa B. Schrock
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Siraj M. Ali
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
| | - Samuel J. Klempner
- Munveer S. Bhangoo, Carrie Costantini, and Brian T. Clifford, Scripps Clinic, La Jolla; Samuel J. Klempner, The Angeles Clinic and Research Institute; and Cedars-Sinai Medical Center, Los Angeles, CA; Jon H. Chung, Alexa B. Schrock, and Siraj M. Ali, Foundation Medicine, Cambridge, MA
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111
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Jara L, Morales S, de Mayo T, Gonzalez-Hormazabal P, Carrasco V, Godoy R. Mutations in BRCA1, BRCA2 and other breast and ovarian cancer susceptibility genes in Central and South American populations. Biol Res 2017; 50:35. [PMID: 28985766 PMCID: PMC6389095 DOI: 10.1186/s40659-017-0139-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 09/20/2017] [Indexed: 12/11/2022] Open
Abstract
Breast cancer (BC) is the most common malignancy among women worldwide. A major advance in the understanding of the genetic etiology of BC was the discovery of BRCA1 and BRCA2 (BRCA1/2) genes, which are considered high-penetrance BC genes. In non-carriers of BRCA1/2 mutations, disease susceptibility may be explained of a small number of mutations in BRCA1/2 and a much higher proportion of mutations in ethnicity-specific moderate- and/or low-penetrance genes. In Central and South American populations, studied have focused on analyzing the distribution and prevalence of BRCA1/2 mutations and other susceptibility genes that are scarce in Latin America as compared to North America, Europe, Australia, and Israel. Thus, the aim of this review is to present the current state of knowledge regarding pathogenic BRCA variants and other BC susceptibility genes. We conducted a comprehensive review of 47 studies from 12 countries in Central and South America published between 2002 and 2017 reporting the prevalence and/or spectrum of mutations and pathogenic variants in BRCA1/2 and other BC susceptibility genes. The studies on BRCA1/2 mutations screened a total of 5956 individuals, and studies on susceptibility genes analyzed a combined sample size of 11,578 individuals. To date, a total of 190 different BRCA1/2 pathogenic mutations in Central and South American populations have been reported in the literature. Pathogenic mutations or variants that increase BC risk have been reported in the following genes or genomic regions: ATM, BARD1, CHECK2, FGFR2, GSTM1, MAP3K1, MTHFR, PALB2, RAD51, TOX3, TP53, XRCC1, and 2q35.
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Affiliation(s)
- Lilian Jara
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile. .,Laboratorio de Genética Molecular Humana, Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM), Programa de Genética, Universidad de Chile, Independencia 1027, Santiago, Chile.
| | - Sebastian Morales
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile
| | - Tomas de Mayo
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile.,Center for Genetics and Genomics Faculty of Medicine, Clinica Alemana Universidad del desarrollo, Avenida Las Condes, 12438 Lo Barnechea, Santiago, Chile.,Laboratorio de Genética Molecular Humana, Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM), Programa de Genética, Universidad de Chile, Independencia 1027, Santiago, Chile
| | - Patricio Gonzalez-Hormazabal
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile
| | - Valentina Carrasco
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile
| | - Raul Godoy
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Santiago, Chile
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112
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Sato K, Koyasu M, Nomura S, Sato Y, Kita M, Ashihara Y, Adachi Y, Ohno S, Iwase T, Kitagawa D, Nakashima E, Yoshida R, Miki Y, Arai M. Mutation status of RAD51C, PALB2 and BRIP1 in 100 Japanese familial breast cancer cases without BRCA1 and BRCA2 mutations. Cancer Sci 2017; 108:2287-2294. [PMID: 28796317 PMCID: PMC5666035 DOI: 10.1111/cas.13350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/24/2017] [Accepted: 08/05/2017] [Indexed: 12/31/2022] Open
Abstract
In addition to BRCA1 and BRCA2, RAD51C,PALB2 and BRIP1 are known as breast cancer susceptibility genes. However, the mutation status of these genes in Japanese familial breast cancer cases has not yet been evaluated. To this end, we analyzed the exon sequence and genomic rearrangement of RAD51C,PALB2 and BRIP1 in 100 Japanese patients diagnosed with familial breast and ovarian cancer and without BRCA1 and BRCA2 mutations. We detected a large deletion from exons 6 to 9 in RAD51C, 4 novel BRIP1 missense variants containing 3 novel non‐synonymous variants, c.89A>C, c.736A>G and c.2131A>G, and a splice donor site variant c.918+2T>C. No deleterious variant of PALB2 was detected. The results of pedigree analysis showed that the proband with a large deletion on RAD51C had a family history of both breast and ovarian cancer, and the families of probands with novel BRIP1 missense variants included a male patient with breast cancer or many patients with breast cancer within the second‐degree relatives. We showed that the mutation frequency of RAD51C in Japanese familial breast cancer cases was similar to that in Western countries and that the prevalence of deleterious mutation of PALB2 was possibly lower. Furthermore, our results suggested that BRIP1 mutation frequency in Japan might differ from that in Western countries.
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Affiliation(s)
- Katsutoshi Sato
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Mio Koyasu
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Sachio Nomura
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan.,Translational Research Support, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Yuri Sato
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Mizuho Kita
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Yuumi Ashihara
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Yasue Adachi
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Shinji Ohno
- Department of Surgical Oncology, Breast Oncology Center, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Takuji Iwase
- Department of Surgical Oncology, Breast Oncology Center, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Dai Kitagawa
- Department of Surgical Oncology, Breast Oncology Center, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Eri Nakashima
- Department of Surgical Oncology, Breast Oncology Center, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Reiko Yoshida
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
| | - Yoshio Miki
- Division of Medical Genomics, Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masami Arai
- Clinical Genetic Oncology, Cancer Institute Hospital, Japanese Foundation of Cancer Research, Tokyo, Japan
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113
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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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114
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Nepomuceno TC, De Gregoriis G, de Oliveira FMB, Suarez-Kurtz G, Monteiro AN, Carvalho MA. The Role of PALB2 in the DNA Damage Response and Cancer Predisposition. Int J Mol Sci 2017; 18:ijms18091886. [PMID: 28858227 PMCID: PMC5618535 DOI: 10.3390/ijms18091886] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/21/2017] [Accepted: 08/26/2017] [Indexed: 01/01/2023] Open
Abstract
The deoxyribonucleic acid (DNA) damage response (DDR) is a major feature in the maintenance of genome integrity and in the suppression of tumorigenesis. PALB2 (Partner and Localizer of Breast Cancer 2 (BRCA2)) plays an important role in maintaining genome integrity through its role in the Fanconi anemia (FA) and homologous recombination (HR) DNA repair pathways. Since its identification as a BRCA2 interacting partner, PALB2 has emerged as a pivotal tumor suppressor protein associated to hereditary cancer susceptibility to breast and pancreatic cancers. In this review, we discuss how other DDR proteins (such as the kinases Ataxia Telangiectasia Mutated (ATM) and ATM- and Rad3-Related (ATR), mediators BRCA1 (Breast Cancer 1)/BRCA2 and effectors RAD51/DNA Polymerase η (Polη) interact with PALB2 to orchestrate DNA repair. We also examine the involvement of PALB2 mutations in the predisposition to cancer and the role of PALB2 in stimulating error-free DNA repair through the FA/HR pathway.
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Affiliation(s)
- Thales C Nepomuceno
- Programa de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro 20231-050, Brazil.
| | - Giuliana De Gregoriis
- Programa de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro 20231-050, Brazil.
| | | | - Guilherme Suarez-Kurtz
- Programa de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro 20231-050, Brazil.
| | - Alvaro N Monteiro
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL 33612, USA.
| | - Marcelo A Carvalho
- Programa de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro 20231-050, Brazil.
- Instituto Federal do Rio de Janeiro-IFRJ, Rio de Janeiro 20270-021, Brazil.
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115
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Bleuyard JY, Fournier M, Nakato R, Couturier AM, Katou Y, Ralf C, Hester SS, Dominguez D, Rhodes D, Humphrey TC, Shirahige K, Esashi F. MRG15-mediated tethering of PALB2 to unperturbed chromatin protects active genes from genotoxic stress. Proc Natl Acad Sci U S A 2017; 114:7671-7676. [PMID: 28673974 PMCID: PMC5530651 DOI: 10.1073/pnas.1620208114] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The partner and localiser of BRCA2 (PALB2) plays important roles in the maintenance of genome integrity and protection against cancer. Although PALB2 is commonly described as a repair factor recruited to sites of DNA breaks, recent studies provide evidence that PALB2 also associates with unperturbed chromatin. Here, we investigated the previously poorly described role of chromatin-associated PALB2 in undamaged cells. We found that PALB2 associates with active genes through its major binding partner, MRG15, which recognizes histone H3 trimethylated at lysine 36 (H3K36me3) by the SETD2 methyltransferase. Missense mutations that ablate PALB2 binding to MRG15 confer elevated sensitivity to the topoisomerase inhibitor camptothecin (CPT) and increased levels of aberrant metaphase chromosomes and DNA stress in gene bodies, which were suppressed by preventing DNA replication. Remarkably, the level of PALB2 at genic regions was frequently decreased, rather than increased, upon CPT treatment. We propose that the steady-state presence of PALB2 at active genes, mediated through the SETD2/H3K36me3/MRG15 axis, ensures an immediate response to DNA stress and therefore effective protection of these regions during DNA replication. This study provides a conceptual advance in demonstrating that the constitutive chromatin association of repair factors plays a key role in the maintenance of genome stability and furthers our understanding of why PALB2 defects lead to human genome instability syndromes.
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Affiliation(s)
- Jean-Yves Bleuyard
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Marjorie Fournier
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Ryuichiro Nakato
- Research Center for Epigenetic Disease, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Anthony M Couturier
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Yuki Katou
- Research Center for Epigenetic Disease, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Christine Ralf
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom
| | - Svenja S Hester
- Advanced Proteomics Facility, Department of Biochemisty, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Daniel Dominguez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139-4307
| | - Daniela Rhodes
- NTU Institute of Structural Biology, Nanyang Technological University, 636921 Singapore
| | - Timothy C Humphrey
- Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, United Kingdom
| | - Katsuhiko Shirahige
- Research Center for Epigenetic Disease, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, United Kingdom;
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116
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Chatterjee N, Walker GC. Mechanisms of DNA damage, repair, and mutagenesis. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2017; 58:235-263. [PMID: 28485537 PMCID: PMC5474181 DOI: 10.1002/em.22087] [Citation(s) in RCA: 975] [Impact Index Per Article: 139.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 03/16/2017] [Indexed: 05/08/2023]
Abstract
Living organisms are continuously exposed to a myriad of DNA damaging agents that can impact health and modulate disease-states. However, robust DNA repair and damage-bypass mechanisms faithfully protect the DNA by either removing or tolerating the damage to ensure an overall survival. Deviations in this fine-tuning are known to destabilize cellular metabolic homeostasis, as exemplified in diverse cancers where disruption or deregulation of DNA repair pathways results in genome instability. Because routinely used biological, physical and chemical agents impact human health, testing their genotoxicity and regulating their use have become important. In this introductory review, we will delineate mechanisms of DNA damage and the counteracting repair/tolerance pathways to provide insights into the molecular basis of genotoxicity in cells that lays the foundation for subsequent articles in this issue. Environ. Mol. Mutagen. 58:235-263, 2017. © 2017 Wiley Periodicals, Inc.
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117
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Anantha RW, Simhadri S, Foo TK, Miao S, Liu J, Shen Z, Ganesan S, Xia B. Functional and mutational landscapes of BRCA1 for homology-directed repair and therapy resistance. eLife 2017; 6. [PMID: 28398198 PMCID: PMC5432210 DOI: 10.7554/elife.21350] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 04/10/2017] [Indexed: 12/20/2022] Open
Abstract
BRCA1 plays a critical role in homology-directed repair (HDR) of DNA double strand breaks, and the repair defect of BRCA1-mutant cancer cells is being targeted with platinum drugs and poly (ADP-ribose) polymerase (PARP) inhibitors. We have employed relatively simple and sensitive assays to determine the function of BRCA1 variants or mutants in two HDR mechanisms, homologous recombination (HR) and single strand annealing (SSA), and in conferring resistance to cisplatin and olaparib in human cancer cells. Our results define the functionality of the top 22 patient-derived BRCA1 missense variants and the contribution of different domains of BRCA1 and its E3 ubiquitin ligase activity to HDR and drug resistance. Importantly, our results also demonstrate that the BRCA1-PALB2 interaction dictates the choice between HR and SSA. These studies establish functional and mutational landscapes of BRCA1 for HDR and therapy resistance, while revealing novel insights into BRCA1 regulatory mechanisms and HDR pathway choice. DOI:http://dx.doi.org/10.7554/eLife.21350.001 Genes are the instruction manuals of life and contain the information needed to build the proteins that keep cells alive. Over time, genes can accumulate errors or mutations and eventually become faulty, which can lead to diseases like cancer. Sometimes mutations can be passed on through generations and increase the chances of getting cancer. The BRCA1 gene, for example, provides instructions for making a protein that helps to repair or remove damaged DNA and stops cells from growing uncontrollably. When the BRCA1 gene becomes faulty, cells could continue to grow with damaged DNA. This makes it more likely for cancer to develop, especially breast cancer and ovarian cancer. However, not all changes in BRCA1 gene cause the protein to become faulty or lead to cancer. In fact, about 30% of BRCA1 gene changes identified by genetic tests are referred to as ‘variants of uncertain clinical significance’, meaning that it is not clear if these variants are indeed mutations that could affect the clinical outcome of the people that carry them. Software predictions based largely on patient data have categorized many of these variants as not cancer-causing, but the majority still need to be experimentally tested and confirmed. Many studies have tried to determine the effect of selected variants on the BRCA1 protein, but a complete picture remains lacking. Now, Anantha et al. have tested the top 22 common variants in the BRCA1 gene, some of which had known effects and some did not. The study tested how these variants affect the ability of the protein to repair damaged DNA and the efficacy of chemotherapies targeting cancer cells with a DNA repair defect. The experiments revealed that three specific parts of the protein must remain intact in order for the protein to carry out this activity, i.e. mutations that affect these three areas are likely to cause cancer and also make cancer cells vulnerable to these chemotherapies. Anantha et al. also generated a series of 10 artificially shortened BRCA1 proteins, each missing a specific part, to determine the possible effects of other variants in those missing parts. Together the findings reveal previously unknown effects of certain variants that are commonly seen in cancer patients as well new insights into how the BRCA1 protein repairs DNA. The next step will be to assess rarer variants where little data is available. A better understanding of how these variants affect DNA repair and drug response will help to improve the genetic counseling and treatment of patients with breast cancer and ovarian cancer. DOI:http://dx.doi.org/10.7554/eLife.21350.002
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Affiliation(s)
- Rachel W Anantha
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Srilatha Simhadri
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Medicine, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Tzeh Keong Foo
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Susanna Miao
- Department of Genetics, School of Arts and Sciences, Rutgers, The State University of New Jersey, Piscataway, United States
| | - Jingmei Liu
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Zhiyuan Shen
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Shridar Ganesan
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Radiation Oncology, Rutgers, The State University of New Jersey, New Brunswick, United States.,Department of Medicine, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, United States
| | - Bing Xia
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, United States
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118
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Foo TK, Tischkowitz M, Simhadri S, Boshari T, Zayed N, Burke KA, Berman SH, Blecua P, Riaz N, Huo Y, Ding YC, Neuhausen SL, Weigelt B, Reis-Filho JS, Foulkes WD, Xia B. Compromised BRCA1-PALB2 interaction is associated with breast cancer risk. Oncogene 2017; 36:4161-4170. [PMID: 28319063 PMCID: PMC5519427 DOI: 10.1038/onc.2017.46] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 12/14/2022]
Abstract
The major breast cancer suppressor proteins BRCA1 and BRCA2 play essential roles in homologous recombination (HR)-mediated DNA repair, which is thought to be critical for tumor suppression. The two BRCA proteins are linked by a third tumor suppressor, PALB2, in the HR pathway. While truncating mutations in these genes are generally pathogenic, interpretations of missense variants remains a challenge. To date, patient-derived missense variants that disrupt PALB2 binding have been identified in BRCA1 and BRCA2; however, there has not been sufficient evidence to prove their pathogenicity in humans, and no variants in PALB2 that disrupt either its BRCA1 or BRCA2 binding have been reported. Here, we report on the identification of a novel PALB2 variant, c.104T>C [p.L35P], that segregated in a family with a strong history of breast cancer. Functional analyses showed that L35P abrogates the PALB2-BRCA1 interaction and completely disables its abilities to promote HR and confer resistance to platinum salts and PARP inhibitors. Whole-exome sequencing of a breast cancer from a c.104T>C carrier revealed a second, somatic, truncating mutation affecting PALB2, and the tumor displays hallmark genomic features of tumors with BRCA mutations and HR defects, cementing the pathogenicity of L35P. Parallel analyses of other germline variants in the PALB2 N-terminal BRCA1-binding domain identified multiple variants that affect HR function to varying degrees, suggesting their possible contribution to cancer development. Our findings establish L35P as the first pathogenic missense mutation in PALB2 and directly demonstrate the requirement of the PALB2-BRCA1 interaction for breast cancer suppression.
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Affiliation(s)
- T K Foo
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
| | - M Tischkowitz
- Department of Medical Genetics, University of Cambridge, Cambridge, UK
| | - S Simhadri
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
| | - T Boshari
- Department of Medical Genetics and Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - N Zayed
- Department of Medical Genetics and Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - K A Burke
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - S H Berman
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - P Blecua
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - N Riaz
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Y Huo
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
| | - Y C Ding
- Department of Population Sciences, Beckman Research Institute at the City of Hope, Duarte, CA, USA
| | - S L Neuhausen
- Department of Population Sciences, Beckman Research Institute at the City of Hope, Duarte, CA, USA
| | - B Weigelt
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - J S Reis-Filho
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - W D Foulkes
- Department of Medical Genetics and Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - B Xia
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
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119
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Pauty J, Couturier AM, Rodrigue A, Caron MC, Coulombe Y, Dellaire G, Masson JY. Cancer-causing mutations in the tumor suppressor PALB2 reveal a novel cancer mechanism using a hidden nuclear export signal in the WD40 repeat motif. Nucleic Acids Res 2017; 45:2644-2657. [PMID: 28158555 PMCID: PMC5389658 DOI: 10.1093/nar/gkx011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 12/31/2016] [Accepted: 01/24/2017] [Indexed: 12/22/2022] Open
Abstract
One typical mechanism to promote genomic instability, a hallmark of cancer, is to inactivate tumor suppressors, such as PALB2. It has recently been reported that mutations in PALB2 increase the risk of breast cancer by 8-9-fold by age 40 and the life time risk is ∼3-4-fold. To date, predicting the functional consequences of PALB2 mutations has been challenging as they lead to different cancer risks. Here, we performed a structure-function analysis of PALB2, using PALB2 truncated mutants (R170fs, L531fs, Q775X and W1038X), and uncovered a new mechanism by which cancer cells could drive genomic instability. Remarkably, the PALB2 W1038X mutant, harboring a mutation in its C-terminal domain, is still proficient in stimulating RAD51-mediated recombination in vitro, although it is unusually localized to the cytoplasm. After further investigation, we identified a hidden NES within the WD40 domain of PALB2 and found that the W1038X truncation leads to the exposure of this NES to CRM1, an export protein. This concept was also confirmed with another WD40-containing protein, RBBP4. Consequently, our studies reveal an unreported mechanism linking the nucleocytoplasmic translocation of PALB2 mutants to cancer formation.
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Affiliation(s)
- Joris Pauty
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
| | - Anthony M. Couturier
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
| | - Amélie Rodrigue
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
| | - Marie-Christine Caron
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
| | - Yan Coulombe
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
| | - Graham Dellaire
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, 9 McMahon, Québec City, QC G1R 2J6, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology; Laval University Cancer Research Center, Laval University, Québec City, QC G1V 0A6, Canada
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120
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Densham RM, Morris JR. The BRCA1 Ubiquitin ligase function sets a new trend for remodelling in DNA repair. Nucleus 2017; 8:116-125. [PMID: 28032817 PMCID: PMC5403137 DOI: 10.1080/19491034.2016.1267092] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 11/24/2016] [Indexed: 02/05/2023] Open
Abstract
The protein product of the breast and ovarian cancer gene, BRCA1, is part of an obligate heterodimer with BARD1. Together these RING bearing proteins act as an E3 ubiquitin ligase. Several functions have been attributed to BRCA1 that contribute to genome integrity but which of these, if any, require this enzymatic function was unclear. Here we review recent studies clarifying the role of BRCA1 E3 ubiquitin ligase in DNA repair. Perhaps the most surprising finding is the narrow range of BRCA1 functions this activity relates to. Remarkably ligase activity promotes chromatin remodelling and 53BP1 positioning through the remodeller SMARCAD1, but the activity is dispensable for the cellular survival in response to cisplatin or replication stressing agents. Implications for therapy response and tumor susceptibility are discussed.
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Affiliation(s)
- Ruth M. Densham
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, Medical and Dental School, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Joanna R. Morris
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, Medical and Dental School, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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121
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Luijsterburg MS, Typas D, Caron MC, Wiegant WW, van den Heuvel D, Boonen RA, Couturier AM, Mullenders LH, Masson JY, van Attikum H. A PALB2-interacting domain in RNF168 couples homologous recombination to DNA break-induced chromatin ubiquitylation. eLife 2017; 6. [PMID: 28240985 PMCID: PMC5328590 DOI: 10.7554/elife.20922] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 02/06/2017] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSB) elicit a ubiquitylation cascade that controls DNA repair pathway choice. This cascade involves the ubiquitylation of histone H2A by the RNF168 ligase and the subsequent recruitment of RIF1, which suppresses homologous recombination (HR) in G1 cells. The RIF1-dependent suppression is relieved in S/G2 cells, allowing PALB2-driven HR to occur. With the inhibitory impact of RIF1 relieved, it remains unclear how RNF168-induced ubiquitylation influences HR. Here, we uncover that RNF168 links the HR machinery to H2A ubiquitylation in S/G2 cells. We show that PALB2 indirectly recognizes histone ubiquitylation by physically associating with ubiquitin-bound RNF168. This direct interaction is mediated by the newly identified PALB2-interacting domain (PID) in RNF168 and the WD40 domain in PALB2, and drives DNA repair by facilitating the assembly of PALB2-containing HR complexes at DSBs. Our findings demonstrate that RNF168 couples PALB2-dependent HR to H2A ubiquitylation to promote DNA repair and preserve genome integrity. DOI:http://dx.doi.org/10.7554/eLife.20922.001
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Affiliation(s)
| | - Dimitris Typas
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marie-Christine Caron
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, McMahon, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Wouter W Wiegant
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Diana van den Heuvel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Rick A Boonen
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Anthony M Couturier
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, McMahon, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Leon H Mullenders
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Jean-Yves Masson
- Genome Stability Laboratory, CHU de Québec Research Center, HDQ Pavilion, Oncology Axis, McMahon, Québec City, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, Canada
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
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122
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Goodfellow E, Senhaji Mouhri Z, Williams C, Jean-Claude BJ. Design, synthesis and biological activity of novel molecules designed to target PARP and DNA. Bioorg Med Chem Lett 2017; 27:688-694. [DOI: 10.1016/j.bmcl.2016.09.054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 10/21/2022]
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123
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Vriend LEM, Krawczyk PM. Nick-initiated homologous recombination: Protecting the genome, one strand at a time. DNA Repair (Amst) 2016; 50:1-13. [PMID: 28087249 DOI: 10.1016/j.dnarep.2016.12.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 12/17/2016] [Indexed: 01/13/2023]
Abstract
Homologous recombination (HR) is an essential, widely conserved mechanism that utilizes a template for accurate repair of DNA breaks. Some early HR models, developed over five decades ago, anticipated single-strand breaks (nicks) as initiating lesions. Subsequent studies favored a more double-strand break (DSB)-centered view of HR initiation and at present this pathway is primarily considered to be associated with DSB repair. However, mounting evidence suggests that nicks can indeed initiate HR directly, without first being converted to DSBs. Moreover, recent studies reported on novel branches of nick-initiated HR (nickHR) that rely on single-, rather than double-stranded repair templates and that are characterized by mechanistically and genetically unique properties. The physiological significance of nickHR is not well documented, but its high-fidelity nature and low mutagenic potential are relevant in recently developed, precise gene editing approaches. Here, we review the evidence for stimulation of HR by nicks, as well as the data on the interactions of nickHR with other DNA repair pathways and on its mechanistic properties. We conclude that nickHR is a bona-fide pathway for nick repair, sharing the molecular machinery with the canonical HR but nevertheless characterized by unique properties that secure its inclusion in DNA repair models and warrant future investigations.
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Affiliation(s)
- Lianne E M Vriend
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
| | - Przemek M Krawczyk
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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124
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p97 Promotes a Conserved Mechanism of Helicase Unloading during DNA Cross-Link Repair. Mol Cell Biol 2016; 36:2983-2994. [PMID: 27644328 DOI: 10.1128/mcb.00434-16] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/16/2016] [Indexed: 01/07/2023] Open
Abstract
Interstrand cross-links (ICLs) are extremely toxic DNA lesions that create an impassable roadblock to DNA replication. When a replication fork collides with an ICL, it triggers a damage response that promotes multiple DNA processing events required to excise the cross-link from chromatin and resolve the stalled replication fork. One of the first steps in this process involves displacement of the CMG replicative helicase (comprised of Cdc45, MCM2-7, and GINS), which obstructs the underlying cross-link. Here we report that the p97/Cdc48/VCP segregase plays a critical role in ICL repair by unloading the CMG complex from chromatin. Eviction of the stalled helicase involves K48-linked polyubiquitylation of MCM7, p97-mediated extraction of CMG, and a largely degradation-independent mechanism of MCM7 deubiquitylation. Our results show that ICL repair and replication termination both utilize a similar mechanism to displace the CMG complex from chromatin. However, unlike termination, repair-mediated helicase unloading involves the tumor suppressor protein BRCA1, which acts upstream of MCM7 ubiquitylation and p97 recruitment. Together, these findings indicate that p97 plays a conserved role in dismantling the CMG helicase complex during different cellular events, but that distinct regulatory signals ultimately control when and where unloading takes place.
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125
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Park JY, Virts EL, Jankowska A, Wiek C, Othman M, Chakraborty SC, Vance GH, Alkuraya FS, Hanenberg H, Andreassen PR. Complementation of hypersensitivity to DNA interstrand crosslinking agents demonstrates that XRCC2 is a Fanconi anaemia gene. J Med Genet 2016; 53:672-680. [PMID: 27208205 PMCID: PMC5035190 DOI: 10.1136/jmedgenet-2016-103847] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/19/2016] [Indexed: 01/31/2023]
Abstract
BACKGROUND Fanconi anaemia (FA) is a heterogeneous inherited disorder clinically characterised by progressive bone marrow failure, congenital anomalies and a predisposition to malignancies. OBJECTIVE Determine, based on correction of cellular phenotypes, whether XRCC2 is a FA gene. METHODS Cells (900677A) from a previously identified patient with biallelic mutation of XRCC2, among other mutations, were genetically complemented with wild-type XRCC2. RESULTS Wild-type XRCC2 corrects each of three phenotypes characteristic of FA cells, all related to the repair of DNA interstrand crosslinks, including increased sensitivity to mitomycin C (MMC), chromosome breakage and G2-M accumulation in the cell cycle. Further, the p.R215X mutant of XRCC2, which is harboured by the patient, is unstable. This provides an explanation for the pathogenesis of this mutant, as does the fact that 900677A cells have reduced levels of other proteins in the XRCC2-RAD51B-C-D complex. Also, FANCD2 monoubiquitination and foci formation, but not assembly of RAD51 foci, are normal in 900677A cells. Thus, XRCC2 acts late in the FA-BRCA pathway as also suggested by hypersensitivity of 900677A cells to ionising radiation. These cells also share milder sensitivities towards olaparib and formaldehyde with certain other FA cells. CONCLUSIONS XRCC2/FANCU is a FA gene, as is another RAD51 paralog gene, RAD51C/FANCO. Notably, similar to a subset of FA genes that act downstream of FANCD2, biallelic mutation of XRCC2/FANCU has not been associated with bone marrow failure. Taken together, our results yield important insights into phenotypes related to FA and its genetic origins.
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Affiliation(s)
- Jung-Young Park
- Division of Experimental Hematology & Cancer Biology, Cincinnati Children’s Research Foundation, Cincinnati, OH 45229
| | - Elizabeth L. Virts
- Wells Center for Pediatric Research, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Anna Jankowska
- Wells Center for Pediatric Research, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Constanze Wiek
- Department of Otorhinolaryngology & Head/Neck Surgery, Heinrich Heine University 40225 Duesseldorf, Germany
| | - Mohamed Othman
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, 11211, Saudi Arabia
| | - Sujata C. Chakraborty
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Gail H. Vance
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Fowzan S. Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, 11211, Saudi Arabia
- Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Helmut Hanenberg
- Wells Center for Pediatric Research, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, IN 46202
- Department of Otorhinolaryngology & Head/Neck Surgery, Heinrich Heine University 40225 Duesseldorf, Germany
- Division of Pediatrics III, University Children’s Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
| | - Paul R. Andreassen
- Division of Experimental Hematology & Cancer Biology, Cincinnati Children’s Research Foundation, Cincinnati, OH 45229
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229
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126
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Fradet-Turcotte A, Sitz J, Grapton D, Orthwein A. BRCA2 functions: from DNA repair to replication fork stabilization. Endocr Relat Cancer 2016; 23:T1-T17. [PMID: 27530658 DOI: 10.1530/erc-16-0297] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 08/16/2016] [Indexed: 12/12/2022]
Abstract
Maintaining genomic integrity is essential to preserve normal cellular physiology and to prevent the emergence of several human pathologies including cancer. The breast cancer susceptibility gene 2 (BRCA2, also known as the Fanconi anemia (FA) complementation group D1 (FANCD1)) is a potent tumor suppressor that has been extensively studied in DNA double-stranded break (DSB) repair by homologous recombination (HR). However, BRCA2 participates in numerous other processes central to maintaining genome stability, including DNA replication, telomere homeostasis and cell cycle progression. Consequently, inherited mutations in BRCA2 are associated with an increased risk of breast, ovarian and pancreatic cancers. Furthermore, bi-allelic mutations in BRCA2 are linked to FA, a rare chromosome instability syndrome characterized by aplastic anemia in children as well as susceptibility to leukemia and cancer. Here, we discuss the recent developments underlying the functions of BRCA2 in the maintenance of genomic integrity. The current model places BRCA2 as a central regulator of genome stability by repairing DSBs and limiting replication stress. These findings have direct implications for the development of novel anticancer therapeutic approaches.
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Affiliation(s)
- Amélie Fradet-Turcotte
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Justine Sitz
- Laval University Cancer Research CenterCHU de Québec Research Center - Université Laval, Hôtel-Dieu de Québec, Oncology Axis, Quebec City, Canada
| | - Damien Grapton
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada
| | - Alexandre Orthwein
- Lady Davis Institute for Medical ResearchSegal Cancer Centre, Jewish General Hospital, Montreal, Canada Department of OncologyMcGill University, Montreal, Canada
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127
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Dhillon KK, Bajrami I, Taniguchi T, Lord CJ. Synthetic lethality: the road to novel therapies for breast cancer. Endocr Relat Cancer 2016; 23:T39-55. [PMID: 27528623 DOI: 10.1530/erc-16-0228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 08/15/2016] [Indexed: 12/12/2022]
Abstract
When the BRCA1 and BRCA2 tumour suppressor genes were identified in the early 1990s, the immediate implications of mapping, cloning and delineating the sequence of these genes were that individuals in families with a BRCA gene mutation could be tested for the presence of a mutation and their risk of developing cancer could be predicted. Over time though, the discovery of BRCA1 and BRCA2 has had a much greater influence than many might have imagined. In this review, we discuss how the discovery of BRCA1 and BRCA2 has not only provided an understanding of the molecular processes that drive tumourigenesis but also reignited an interest in therapeutically exploiting loss-of-function alterations in tumour suppressor genes.
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Affiliation(s)
| | - Ilirjana Bajrami
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research CentreThe Institute of Cancer Research, London, UK
| | | | - Christopher J Lord
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research CentreThe Institute of Cancer Research, London, UK
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128
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Bick G, Zhang F, Meetei AR, Andreassen PR. Coordination of the recruitment of the FANCD2 and PALB2 Fanconi anemia proteins by an ubiquitin signaling network. Chromosoma 2016; 126:417-430. [PMID: 27277787 DOI: 10.1007/s00412-016-0602-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/11/2016] [Accepted: 05/13/2016] [Indexed: 12/26/2022]
Abstract
Fanconi anemia (FA) is a chromosome instability syndrome and the 20 identified FA proteins are organized into two main arms which are thought to function at distinct steps in the repair of DNA interstrand crosslinks (ICLs). These two arms include the upstream FA pathway, which culminates in the monoubiquitination of FANCD2 and FANCI, and downstream breast cancer (BRCA)-associated proteins that interact in protein complexes. How, and whether, these two groups of FA proteins are integrated is unclear. Here, we show that FANCD2 and PALB2, as indicators of the upstream and downstream arms, respectively, colocalize independently of each other in response to DNA damage induced by mitomycin C (MMC). We also show that ubiquitin chains are induced by MMC and colocalize with both FANCD2 and PALB2. Our finding that the RNF8 E3 ligase has a role in recruiting FANCD2 and PALB2 also provides support for the hypothesis that the two branches of the FA-BRCA pathway are coordinated by ubiquitin signaling. Interestingly, we find that the RNF8 partner, MDC1, as well as the ubiquitin-binding protein, RAP80, specifically recruit PALB2, while a different ubiquitin-binding protein, FAAP20, functions only in the recruitment of FANCD2. Thus, FANCD2 and PALB2 are not recruited in a single linear pathway, rather we define how their localization is coordinated and integrated by a network of ubiquitin-related proteins. We propose that such regulation may enable upstream and downstream FA proteins to act at distinct steps in the repair of ICLs.
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Affiliation(s)
- Gregory Bick
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Fan Zhang
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - A Ruhikanta Meetei
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA. .,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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129
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Fenoy IM, Bogado SS, Contreras SM, Gottifredi V, Angel SO. The Knowns Unknowns: Exploring the Homologous Recombination Repair Pathway in Toxoplasma gondii. Front Microbiol 2016; 7:627. [PMID: 27199954 PMCID: PMC4853372 DOI: 10.3389/fmicb.2016.00627] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/18/2016] [Indexed: 12/17/2022] Open
Abstract
Toxoplasma gondii is an apicomplexan parasite of medical and veterinary importance which causes toxoplasmosis in humans. Great effort is currently being devoted toward the identification of novel drugs capable of targeting such illness. In this context, we believe that the thorough understanding of the life cycle of this model parasite will facilitate the identification of new druggable targets in T. gondii. It is important to exploit the available knowledge of pathways which could modulate the sensitivity of the parasite to DNA damaging agents. The homologous recombination repair (HRR) pathway may be of particular interest in this regard as its inactivation sensitizes other cellular models such as human cancer to targeted therapy. Herein we discuss the information available on T. gondii's HRR pathway from the perspective of its conservation with respect to yeast and humans. Special attention was devoted to BRCT domain-containing and end-resection associated proteins in T. gondii as in other experimental models such proteins have crucial roles in early/late steps or HRR and in the pathway choice for double strand break resolution. We conclude that T. gondii HRR pathway is a source of several lines of investigation that allow to to comprehend the extent of diversification of HRR in T. gondii. Such an effort will serve to determine if HRR could represent a potential targer for the treatment of toxoplasmosis.
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Affiliation(s)
- Ignacio M Fenoy
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Silvina S Bogado
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Susana M Contreras
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Vanesa Gottifredi
- Cell Cycle Genomic Instability Laboratory, Fundación Instituto Leloir, IIBBA-CONICET Chascomús, Argentina
| | - Sergio O Angel
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
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130
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Borecka M, Zemankova P, Vocka M, Soucek P, Soukupova J, Kleiblova P, Sevcik J, Kleibl Z, Janatova M. Mutation analysis of the PALB2 gene in unselected pancreatic cancer patients in the Czech Republic. Cancer Genet 2016; 209:199-204. [DOI: 10.1016/j.cancergen.2016.03.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 03/10/2016] [Accepted: 03/21/2016] [Indexed: 12/19/2022]
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131
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Ahlskog JK, Larsen BD, Achanta K, Sørensen CS. ATM/ATR-mediated phosphorylation of PALB2 promotes RAD51 function. EMBO Rep 2016; 17:671-81. [PMID: 27113759 PMCID: PMC5341514 DOI: 10.15252/embr.201541455] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 11/09/2022] Open
Abstract
DNA damage activates the ATM and ATR kinases that coordinate checkpoint and DNA repair pathways. An essential step in homology-directed repair (HDR) of DNA breaks is the formation of RAD51 nucleofilaments mediated by PALB2-BRCA2; however, roles of ATM and ATR in this critical step of HDR are poorly understood. Here, we show that PALB2 is markedly phosphorylated in response to genotoxic stresses such as ionizing radiation and hydroxyurea. This response is mediated by the ATM and ATR kinases through three N-terminal S/Q-sites in PALB2, the consensus target sites for ATM and ATR Importantly, a phospho-deficient PALB2 mutant is unable to support proper RAD51 foci formation, a key PALB2 regulated repair event, whereas a phospho-mimicking PALB2 version supports RAD51 foci formation. Moreover, phospho-deficient PALB2 is less potent in HDR than wild-type PALB2. Further, this mutation reveals a separation in PALB2 function, as the PALB2-dependent checkpoint response is normal in cells expressing the phospho-deficient PALB2 mutant. Collectively, our findings highlight a critical importance of PALB2 phosphorylation as a novel regulatory step in genome maintenance after genotoxic stress.
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Affiliation(s)
- Johanna K Ahlskog
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Brian D Larsen
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Kavya Achanta
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
| | - Claus S Sørensen
- Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark
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132
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Byrd PJ, Stewart GS, Smith A, Eaton C, Taylor AJ, Guy C, Eringyte I, Fooks P, Last JI, Horsley R, Oliver AW, Janic D, Dokmanovic L, Stankovic T, Taylor AMR. A Hypomorphic PALB2 Allele Gives Rise to an Unusual Form of FA-N Associated with Lymphoid Tumour Development. PLoS Genet 2016; 12:e1005945. [PMID: 26990772 PMCID: PMC4798644 DOI: 10.1371/journal.pgen.1005945] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/26/2016] [Indexed: 12/26/2022] Open
Abstract
Patients with biallelic truncating mutations in PALB2 have a severe form of Fanconi anaemia (FA-N), with a predisposition for developing embryonal-type tumours in infancy. Here we describe two unusual patients from a single family, carrying biallelic PALB2 mutations, one truncating, c.1676_1677delAAinsG;(p.Gln559ArgfsTer2), and the second, c.2586+1G>A; p.Thr839_Lys862del resulting in an in frame skip of exon 6 (24 amino acids). Strikingly, the affected individuals did not exhibit the severe developmental defects typical of FA-N patients and initially presented with B cell non-Hodgkin lymphoma. The expressed p.Thr839_Lys862del mutant PALB2 protein retained the ability to interact with BRCA2, previously unreported in FA-N patients. There was also a large increased chromosomal radiosensitivity following irradiation in G2 and increased sensitivity to mitomycin C. Although patient cells were unable to form Rad51 foci following exposure to either DNA damaging agent, U2OS cells, in which the mutant PALB2 with in frame skip of exon 6 was induced, did show recruitment of Rad51 to foci following damage. We conclude that a very mild form of FA-N exists arising from a hypomorphic PALB2 allele.
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Affiliation(s)
- Philip J. Byrd
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Grant. S. Stewart
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Anna Smith
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Charlotte Eaton
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Alexander J. Taylor
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Chloe Guy
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ieva Eringyte
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Peggy Fooks
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - James I. Last
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Robert Horsley
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Antony W. Oliver
- Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom
| | - Dragana Janic
- University Children’s Hospital, School of Medicine University of Belgrade, Belgrade, Serbia
| | - Lidija Dokmanovic
- University Children’s Hospital, School of Medicine University of Belgrade, Belgrade, Serbia
| | - Tatjana Stankovic
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - A. Malcolm R. Taylor
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
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133
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Abstract
Replication stress, defined as the slowing or stalling of cellular DNA replication forks, represents a serious threat to genome stability. Numerous cellular pathways protect against replication stress and maintain genomic integrity. Among these, the Fanconi Anemia/homologous recombination pathways are critical for recognizing and repairing stalled replication forks. Members of these pathways play a vital role in protecting damaged forks from uncontrolled attack from cellular nucleases, which would otherwise render these irreparable. Recent studies have begun to shed light on the protective factors necessary to suppress nucleolytic over-processing of nascent DNA, and on the different cellular nucleases involved. Here, we review our recent identification of a novel fork protection factor, BOD1L, and discuss its role in preventing the processing of stalled replication forks within the context of current knowledge of the replication fork 'protectosome'.
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Affiliation(s)
- Martin R Higgs
- a Institute of Cancer and Genomic Studies , University of Birmingham , Birmingham , UK
| | - Grant S Stewart
- a Institute of Cancer and Genomic Studies , University of Birmingham , Birmingham , UK
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134
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Investigation on the formation, conversion and bioactivity of a G-quadruplex structure in the PALB2 gene. Int J Biol Macromol 2016; 83:242-8. [DOI: 10.1016/j.ijbiomac.2015.11.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 11/23/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
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135
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Kan C, Zhang J. BRCA1 Mutation: A Predictive Marker for Radiation Therapy? Int J Radiat Oncol Biol Phys 2015; 93:281-93. [PMID: 26383678 DOI: 10.1016/j.ijrobp.2015.05.037] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/08/2015] [Accepted: 05/21/2015] [Indexed: 02/01/2023]
Abstract
DNA repair, in particular, DNA double-strand break (DSB) repair, is essential for the survival of both normal and cancer cells. An elaborate repair mechanism has been developed in cells to efficiently repair the damaged DNA. The pathways predominately involved in DSB repair are homologous recombination and classic nonhomologous end-joining, although the alternative NHEJ pathway, a third DSB repair pathway, could also be important in certain contexts. The protein of BRCA1 encoded by the tumor suppressor gene BRCA1 regulates all DSB repair pathways. Given that DSBs represent the most biologically significant lesions induced by ionizing radiation and that impaired DSB repair leads to radiation sensitivity, it has been expected that cancer patients with BRCA1 mutations should benefit from radiation therapy. However, the clinical data have been conflicting and inconclusive. We provide an overview about the current status of the data regarding BRCA1 deficiency and radiation therapy sensitivity in both experimental models and clinical investigations. In addition, we discuss a strategy to potentiate the effects of radiation therapy by poly(ADP-ribose) polymerase inhibitors, the pharmacologic drugs being investigated as monotherapy for the treatment of patients with BRCA1/2 mutations.
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Affiliation(s)
- Charlene Kan
- Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Junran Zhang
- Department of Radiation Oncology, Case Western Reserve University School of Medicine, Cleveland, Ohio.
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136
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Abstract
Both proteolytic and nonproteolytic functions of ubiquitination are essential regulatory mechanisms for promoting DNA repair and the DNA damage response in mammalian cells. Deubiquitinating enzymes (DUBs) have emerged as key players in the maintenance of genome stability. In this minireview, we discuss the recent findings on human DUBs that participate in genome maintenance, with a focus on the role of DUBs in the modulation of DNA repair and DNA damage signaling.
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137
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Obermeier K, Sachsenweger J, Friedl TWP, Pospiech H, Winqvist R, Wiesmüller L. Heterozygous PALB2 c.1592delT mutation channels DNA double-strand break repair into error-prone pathways in breast cancer patients. Oncogene 2015; 35:3796-806. [PMID: 26640152 PMCID: PMC4962030 DOI: 10.1038/onc.2015.448] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 09/29/2015] [Accepted: 10/15/2015] [Indexed: 12/14/2022]
Abstract
Hereditary heterozygous mutations in a variety of DNA double-strand break (DSB) repair genes have been associated with increased breast cancer risk. In the Finnish population, PALB2 (partner and localizer of BRCA2) represents a major susceptibility gene for female breast cancer, and so far, only one mutation has been described, c.1592delT, which leads to a sixfold increased disease risk. PALB2 is thought to participate in homologous recombination (HR). However, the effect of the Finnish founder mutation on DSB repair has not been investigated. In the current study, we used a panel of lymphoblastoid cell lines (LCLs) derived from seven heterozygous female PALB2 c.1592delT mutation carriers with variable health status and six wild-type matched controls. The results of our DSB repair analysis showed that the PALB2 mutation causes specific changes in pathway usage, namely increases in error-prone single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) compared with wild-type LCLs. These data indicated haploinsufficiency regarding the suppression of error-prone DSB repair in PALB2 mutation carriers. To the contrary, neither reduced HR activities, nor impaired RAD51 filament assembly, nor sensitization to PARP inhibition were consistently observed. Expression of truncated mutant versus wild-type PALB2 verified a causal role of PALB2 c.1592delT in the shift to error-prone repair. Discrimination between healthy and malignancy-presenting PALB2 mutation carriers revealed a pathway shift particularly in the breast cancer patients, suggesting interaction of PALB2 c.1592delT with additional genomic lesions. Interestingly, the studied PALB2 mutation was associated with 53BP1 accumulation in the healthy mutation carriers but not the patients, and 53BP1 was limiting for error-prone MMEJ in patients but not in healthy carriers. Our study identified a rise in error-prone DSB repair as a potential threat to genomic integrity in heterozygous PALB2 mutation carriers. The used phenotypic marker system has the capacity to capture dysfunction caused by polygenic mechanisms and therefore offers new strategies of cancer risk prediction.
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Affiliation(s)
- K Obermeier
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - J Sachsenweger
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - T W P Friedl
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
| | - H Pospiech
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.,Research Group Biochemistry, Leibniz Institute for Age Research-Fritz Lipmann Institute, Jena, Germany
| | - R Winqvist
- Laboratory of Cancer Genetics and Tumor Biology, Cancer and Translational Medical Research Unit and Biocenter Oulu, University of Oulu, Oulu, Finland.,Northern Finland Laboratory Centre NordLab, Oulu, Finland
| | - L Wiesmüller
- Department of Obstetrics and Gynecology, Ulm University, Ulm, Germany
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138
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Francies FZ, Wainstein T, De Leeneer K, Cairns A, Murdoch M, Nietz S, Cubasch H, Poppe B, Van Maerken T, Crombez B, Coene I, Kerr R, Slabbert JP, Vral A, Krause A, Baeyens A, Claes KBM. BRCA1, BRCA2 and PALB2 mutations and CHEK2 c.1100delC in different South African ethnic groups diagnosed with premenopausal and/or triple negative breast cancer. BMC Cancer 2015; 15:912. [PMID: 26577449 PMCID: PMC4647511 DOI: 10.1186/s12885-015-1913-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 11/05/2015] [Indexed: 12/20/2022] Open
Abstract
Background Current knowledge of the aetiology of hereditary breast cancer in the four main South African population groups (black, coloured, Indian and white) is limited. Risk assessments in the black, coloured and Indian population groups are challenging because of restricted information regarding the underlying genetic contributions to inherited breast cancer in these populations. We focused this study on premenopausal patients (diagnosed with breast cancer before the age of 50; n = 78) and triple negative breast cancer (TNBC) patients (n = 30) from the four South African ethnic groups. The aim of this study was to determine the frequency and spectrum of germline mutations in BRCA1, BRCA2 and PALB2 and to evaluate the presence of the CHEK2 c.1100delC allele in these patients. Methods In total, 108 South African breast cancer patients underwent mutation screening using a Next-Generation Sequencing (NGS) approach in combination with Multiplex Ligation-dependent Probe Amplification (MLPA) to detect large rearrangements in BRCA1 and BRCA2. Results In 13 (12 %) patients a deleterious mutation in BRCA1/2 was detected, three of which were novel mutations in black patients. None of the study participants was found to have an unequivocal pathogenic mutation in PALB2. Two (white) patients tested positive for the CHEK2 c.1100delC mutation, however, one of these also carried a deleterious BRCA2 mutation. Additionally, six variants of unknown clinical significance were identified (4 in BRCA2, 2 in PALB2), all in black patients. Within the group of TNBC patients, a higher mutation frequency was obtained (23.3 %; 7/30) than in the group of patients diagnosed before the age of 50 (7.7 %; 6/78). Conclusion This study highlights the importance of evaluating germline mutations in major breast cancer genes in all of the South African population groups. This NGS study shows that mutation analysis is warranted in South African patients with triple negative and/or in premenopausal breast cancer. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1913-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- F Z Francies
- iThemba LABS-National Research Foundation, Somerset West, South Africa. .,Department of Radiation Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - T Wainstein
- Division of Human Genetics, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
| | - K De Leeneer
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - A Cairns
- Department of Surgery, Charlotte Maxeke Johannesburg Academic Hospital and Donald Gordon Medical Centre, Johannesburg, South Africa.
| | - M Murdoch
- Department of Surgery, Charlotte Maxeke Johannesburg Academic Hospital and Donald Gordon Medical Centre, Johannesburg, South Africa.
| | - S Nietz
- Department of Surgery, Charlotte Maxeke Johannesburg Academic Hospital and Donald Gordon Medical Centre, Johannesburg, South Africa.
| | - H Cubasch
- Batho Pele Breast Unit, Chris Hani Baragwanath Academic Hospital, Johannesburg, South Africa.
| | - B Poppe
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - T Van Maerken
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - B Crombez
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - I Coene
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
| | - R Kerr
- Division of Human Genetics, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
| | - J P Slabbert
- iThemba LABS-National Research Foundation, Somerset West, South Africa.
| | - A Vral
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium.
| | - A Krause
- Division of Human Genetics, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa. .,Division of Human Genetics, National Health Laboratory Services, Johannesburg, South Africa.
| | - A Baeyens
- iThemba LABS-National Research Foundation, Somerset West, South Africa. .,Department of Radiation Sciences, University of the Witwatersrand, Johannesburg, South Africa. .,Department of Basic Medical Sciences, Ghent University, Ghent, Belgium.
| | - K B M Claes
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
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139
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Guo Y, Feng W, Sy SMH, Huen MSY. ATM-dependent Phosphorylation of the Fanconi Anemia Protein PALB2 Promotes the DNA Damage Response. J Biol Chem 2015; 290:27545-56. [PMID: 26420486 PMCID: PMC4646007 DOI: 10.1074/jbc.m115.672626] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/27/2015] [Indexed: 11/06/2022] Open
Abstract
The Fanconi anemia protein PALB2, also known as FANCN, protects genome integrity by regulating DNA repair and cell cycle checkpoints. Exactly how PALB2 functions may be temporally coupled with detection and signaling of DNA damage is not known. Intriguingly, we found that PALB2 is transformed into a hyperphosphorylated state in response to ionizing radiation (IR). IR treatment specifically triggered PALB2 phosphorylation at Ser-157 and Ser-376 in manners that required the master DNA damage response kinase Ataxia telangiectasia mutated, revealing potential mechanistic links between PALB2 and the Ataxia telangiectasia mutated-dependent DNA damage responses. Consistently, dysregulated PALB2 phosphorylation resulted in sustained activation of DDRs. Full-blown PALB2 phosphorylation also required the breast and ovarian susceptible gene product BRCA1, highlighting important roles of the BRCA1-PALB2 interaction in orchestrating cellular responses to genotoxic stress. In summary, our phosphorylation analysis of tumor suppressor protein PALB2 uncovers new layers of regulatory mechanisms in the maintenance of genome stability and tumor suppression.
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Affiliation(s)
| | | | - Shirley M H Sy
- From the School of Biomedical Sciences, Centre for Cancer Research, LKS Faculty of Medicine,
| | - Michael S Y Huen
- From the School of Biomedical Sciences, Centre for Cancer Research, LKS Faculty of Medicine, State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong
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140
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Therapeutic Implications for Overcoming Radiation Resistance in Cancer Therapy. Int J Mol Sci 2015; 16:26880-913. [PMID: 26569225 PMCID: PMC4661850 DOI: 10.3390/ijms161125991] [Citation(s) in RCA: 151] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 09/29/2015] [Accepted: 10/29/2015] [Indexed: 12/17/2022] Open
Abstract
Ionizing radiation (IR), such as X-rays and gamma (γ)-rays, mediates various forms of cancer cell death such as apoptosis, necrosis, autophagy, mitotic catastrophe, and senescence. Among them, apoptosis and mitotic catastrophe are the main mechanisms of IR action. DNA damage and genomic instability contribute to IR-induced cancer cell death. Although IR therapy may be curative in a number of cancer types, the resistance of cancer cells to radiation remains a major therapeutic problem. In this review, we describe the morphological and molecular aspects of various IR-induced types of cell death. We also discuss cytogenetic variations representative of IR-induced DNA damage and genomic instability. Most importantly, we focus on several pathways and their associated marker proteins responsible for cancer resistance and its therapeutic implications in terms of cancer cell death of various types and characteristics. Finally, we propose radiation-sensitization strategies, such as the modification of fractionation, inflammation, and hypoxia and the combined treatment, that can counteract the resistance of tumors to IR.
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141
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Kowalczykowski SC. An Overview of the Molecular Mechanisms of Recombinational DNA Repair. Cold Spring Harb Perspect Biol 2015; 7:a016410. [PMID: 26525148 PMCID: PMC4632670 DOI: 10.1101/cshperspect.a016410] [Citation(s) in RCA: 302] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Recombinational DNA repair is a universal aspect of DNA metabolism and is essential for genomic integrity. It is a template-directed process that uses a second chromosomal copy (sister, daughter, or homolog) to ensure proper repair of broken chromosomes. The key steps of recombination are conserved from phage through human, and an overview of those steps is provided in this review. The first step is resection by helicases and nucleases to produce single-stranded DNA (ssDNA) that defines the homologous locus. The ssDNA is a scaffold for assembly of the RecA/RAD51 filament, which promotes the homology search. On finding homology, the nucleoprotein filament catalyzes exchange of DNA strands to form a joint molecule. Recombination is controlled by regulating the fate of both RecA/RAD51 filaments and DNA pairing intermediates. Finally, intermediates that mature into Holliday structures are disjoined by either nucleolytic resolution or topological dissolution.
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Affiliation(s)
- Stephen C Kowalczykowski
- Department of Microbiology & Molecular Genetics and Department of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616
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142
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Higgs MR, Reynolds JJ, Winczura A, Blackford AN, Borel V, Miller ES, Zlatanou A, Nieminuszczy J, Ryan EL, Davies NJ, Stankovic T, Boulton SJ, Niedzwiedz W, Stewart GS. BOD1L Is Required to Suppress Deleterious Resection of Stressed Replication Forks. Mol Cell 2015; 59:462-77. [PMID: 26166705 DOI: 10.1016/j.molcel.2015.06.007] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 05/15/2015] [Accepted: 06/04/2015] [Indexed: 10/23/2022]
Abstract
Recognition and repair of damaged replication forks are essential to maintain genome stability and are coordinated by the combined action of the Fanconi anemia and homologous recombination pathways. These pathways are vital to protect stalled replication forks from uncontrolled nucleolytic activity, which otherwise causes irreparable genomic damage. Here, we identify BOD1L as a component of this fork protection pathway, which safeguards genome stability after replication stress. Loss of BOD1L confers exquisite cellular sensitivity to replication stress and uncontrolled resection of damaged replication forks, due to a failure to stabilize RAD51 at these forks. Blocking DNA2-dependent resection, or downregulation of the helicases BLM and FBH1, suppresses both catastrophic fork processing and the accumulation of chromosomal damage in BOD1L-deficient cells. Thus, our work implicates BOD1L as a critical regulator of genome integrity that restrains nucleolytic degradation of damaged replication forks.
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Affiliation(s)
- Martin R Higgs
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - John J Reynolds
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Alicja Winczura
- The Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Andrew N Blackford
- The Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Valérie Borel
- The Francis Crick Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
| | - Edward S Miller
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Anastasia Zlatanou
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Jadwiga Nieminuszczy
- The Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Ellis L Ryan
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Nicholas J Davies
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Tatjana Stankovic
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Simon J Boulton
- The Francis Crick Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
| | - Wojciech Niedzwiedz
- The Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Grant S Stewart
- School of Cancer Sciences, University of Birmingham, Birmingham B15 2TT, UK.
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143
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Typas D, Luijsterburg MS, Wiegant WW, Diakatou M, Helfricht A, Thijssen PE, van den Broek B, Mullenders LH, van Attikum H. The de-ubiquitylating enzymes USP26 and USP37 regulate homologous recombination by counteracting RAP80. Nucleic Acids Res 2015; 43:6919-33. [PMID: 26101254 PMCID: PMC4538816 DOI: 10.1093/nar/gkv613] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 06/01/2015] [Indexed: 12/20/2022] Open
Abstract
The faithful repair of DNA double-strand breaks (DSBs) is essential to safeguard genome stability. DSBs elicit a signaling cascade involving the E3 ubiquitin ligases RNF8/RNF168 and the ubiquitin-dependent assembly of the BRCA1-Abraxas-RAP80-MERIT40 complex. The association of BRCA1 with ubiquitin conjugates through RAP80 is known to be inhibitory to DSB repair by homologous recombination (HR). However, the precise regulation of this mechanism remains poorly understood. Through genetic screens we identified USP26 and USP37 as key de-ubiquitylating enzymes (DUBs) that limit the repressive impact of RNF8/RNF168 on HR. Both DUBs are recruited to DSBs where they actively remove RNF168-induced ubiquitin conjugates. Depletion of USP26 or USP37 disrupts the execution of HR and this effect is alleviated by the simultaneous depletion of RAP80. We demonstrate that USP26 and USP37 prevent excessive spreading of RAP80-BRCA1 from DSBs. On the other hand, we also found that USP26 and USP37 promote the efficient association of BRCA1 with PALB2. This suggests that these DUBs limit the ubiquitin-dependent sequestration of BRCA1 via the BRCA1-Abraxas-RAP80-MERIT40 complex, while promoting complex formation and cooperation of BRCA1 with PALB2-BRCA2-RAD51 during HR. These findings reveal a novel ubiquitin-dependent mechanism that regulates distinct BRCA1-containing complexes for efficient repair of DSBs by HR.
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Affiliation(s)
- Dimitris Typas
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Martijn S Luijsterburg
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Wouter W Wiegant
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Michaela Diakatou
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Angela Helfricht
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Peter E Thijssen
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Bram van den Broek
- Biophysics of Cell Signaling, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Leon H Mullenders
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
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144
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Torgovnick A, Schumacher B. DNA repair mechanisms in cancer development and therapy. Front Genet 2015; 6:157. [PMID: 25954303 PMCID: PMC4407582 DOI: 10.3389/fgene.2015.00157] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 04/07/2015] [Indexed: 01/18/2023] Open
Abstract
DNA damage has been long recognized as causal factor for cancer development. When erroneous DNA repair leads to mutations or chromosomal aberrations affecting oncogenes and tumor suppressor genes, cells undergo malignant transformation resulting in cancerous growth. Genetic defects can predispose to cancer: mutations in distinct DNA repair systems elevate the susceptibility to various cancer types. However, DNA damage not only comprises a root cause for cancer development but also continues to provide an important avenue for chemo- and radiotherapy. Since the beginning of cancer therapy, genotoxic agents that trigger DNA damage checkpoints have been applied to halt the growth and trigger the apoptotic demise of cancer cells. We provide an overview about the involvement of DNA repair systems in cancer prevention and the classes of genotoxins that are commonly used for the treatment of cancer. A better understanding of the roles and interactions of the highly complex DNA repair machineries will lead to important improvements in cancer therapy.
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Affiliation(s)
- Alessandro Torgovnick
- Institute for Genome Stability in Ageing and Disease, Medical Faculty, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases Research Center, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Björn Schumacher
- Institute for Genome Stability in Ageing and Disease, Medical Faculty, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases Research Center, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
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145
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Prakash R, Zhang Y, Feng W, Jasin M. Homologous recombination and human health: the roles of BRCA1, BRCA2, and associated proteins. Cold Spring Harb Perspect Biol 2015; 7:a016600. [PMID: 25833843 DOI: 10.1101/cshperspect.a016600] [Citation(s) in RCA: 549] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Homologous recombination (HR) is a major pathway for the repair of DNA double-strand breaks in mammalian cells, the defining step of which is homologous strand exchange directed by the RAD51 protein. The physiological importance of HR is underscored by the observation of genomic instability in HR-deficient cells and, importantly, the association of cancer predisposition and developmental defects with mutations in HR genes. The tumor suppressors BRCA1 and BRCA2, key players at different stages of HR, are frequently mutated in familial breast and ovarian cancers. Other HR proteins, including PALB2 and RAD51 paralogs, have also been identified as tumor suppressors. This review summarizes recent findings on BRCA1, BRCA2, and associated proteins involved in human disease with an emphasis on their molecular roles and interactions.
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Affiliation(s)
- Rohit Prakash
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065
| | - Yu Zhang
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065
| | - Weiran Feng
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065 Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065 Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, New York 10065
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146
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β-HPV 5 and 8 E6 disrupt homology dependent double strand break repair by attenuating BRCA1 and BRCA2 expression and foci formation. PLoS Pathog 2015; 11:e1004687. [PMID: 25803638 PMCID: PMC4372404 DOI: 10.1371/journal.ppat.1004687] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 01/16/2015] [Indexed: 01/08/2023] Open
Abstract
Recent work has explored a putative role for the E6 protein from some β-human papillomavirus genus (β-HPVs) in the development of non-melanoma skin cancers, specifically β-HPV 5 and 8 E6. Because these viruses are not required for tumor maintenance, they are hypothesized to act as co-factors that enhance the mutagenic capacity of UV-exposure by disrupting the repair of the resulting DNA damage. Supporting this proposal, we have previously demonstrated that UV damage signaling is hindered by β-HPV 5 and 8 E6 resulting in an increase in both thymine dimers and UV-induced double strand breaks (DSBs). Here we show that β-HPV 5 and 8 E6 further disrupt the repair of these DSBs and provide a mechanism for this attenuation. By binding and destabilizing a histone acetyltransferase, p300, β-HPV 5 and 8 E6 reduce the enrichment of the transcription factor at the promoter of two genes critical to the homology dependent repair of DSBs (BRCA1 and BRCA2). The resulting diminished BRCA1/2 transcription not only leads to lower protein levels but also curtails the ability of these proteins to form repair foci at DSBs. Using a GFP-based reporter, we confirm that this reduced foci formation leads to significantly diminished homology dependent repair of DSBs. By deleting the p300 binding domain of β-HPV 8 E6, we demonstrate that the loss of robust repair is dependent on viral-mediated degradation of p300 and confirm this observation using a combination of p300 mutants that are β-HPV 8 E6 destabilization resistant and p300 knock-out cells. In conclusion, this work establishes an expanded ability of β-HPV 5 and 8 E6 to attenuate UV damage repair, thus adding further support to the hypothesis that β-HPV infections play a role in skin cancer development by increasing the oncogenic potential of UV exposure. Human Papillomaviruses are a family of viruses with over 100 different members that infect mucous membranes and skin. Infections with some of these viruses are linked to cancers of the cervix and oropharynx. In this work, we explore the question of whether other members of this virus family may also contribute to skin cancer by inhibiting the ability of cells to repair the damage caused from UV exposure. Here, we build on our previous work showing that the E6 protein from two of these viruses (β-HPV 5 and 8) reduces the cellular response to UV damage by decreasing the abundance of two cellular proteins (p300 and ATR) involved in repairing the UV-damaged DNA, leading to more double strand DNA breaks following UV exposure. Here we show that the loss of p300 has further deleterious consequences, specifically that it results in diminished expression of two proteins (BRCA1 and BRCA2) involved in the repair of double strand breaks. Our data shows that this results in fewer BRCA1 and BRCA2 repair foci forming at sites of damage and ultimately in attenuated repair of these lesions. Together, this work provides further support for a link between β-HPV infections and skin cancer.
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147
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Leyton Y, Gonzalez-Hormazabal P, Blanco R, Bravo T, Fernandez-Ramires R, Morales S, Landeros N, Reyes JM, Peralta O, Tapia JC, Gomez F, Waugh E, Ibañez G, Pakomio J, Grau G, Jara L. Association of PALB2 sequence variants with the risk of familial and early-onset breast cancer in a South-American population. BMC Cancer 2015; 15:30. [PMID: 25636233 PMCID: PMC4323211 DOI: 10.1186/s12885-015-1033-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/22/2015] [Indexed: 12/31/2022] Open
Abstract
Background Germline mutations in PALB2 have been identified in approximately 1% of familial breast cancer (BC) in several populations. Nevertheless its contribution in the South-American population is unknown. The goal of this study was to determine the prevalence of PALB2 mutations in the Chilean population. Methods 100 Chilean BRCA1/2-negatives familial BC cases were included for the PALB2 mutation analysis. We use conformational sensitive gel electrophoresis and direct sequencing. Using a case-control design, we studied the identified variants in 436 BC cases and 809 controls to evaluate their possible association with BC risk. Results No pathogenic mutations were detected. We identified three variants, the variant c.1861C > A not previously described was found in one of the 436 cases and none of the 809 controls. The bioinformatic analyses indicate that this variant probably is not pathogenic. PALB2 c.1676A > G (rs152451A/G) and c.2993C > T (rs45551636C/T) variants were significantly associated with increased BC risk only in cases with a strong family history of BC (OR = 1.9 [CI 95% 1.3-2.8] p < 0.01 and OR = 3.3 [CI 95% 1.4-7.3] p < 0.01, respectively). The rs152451A/G-rs45551636C/T composite genotype produce increase of the BC risk in cases with a strong family history of BC (OR = 3.6 [CI 95% 1.7-8.0] p = 0.003). The rs152451-G/rs45551636-C and rs152451-G/rs45551636-T haplotypes were associated with an increased BC risk only in cases with a strong family history of BC (OR = 1.6 [CI 95% 1.0-2.5] p = 0.05 and OR = 3.7 [CI 95% 1.8-7.5] p < 0.001, respectively). Conclusion Our results suggest that PALB2 c.1676A > G and c.2993C > T play roles in BC risk in women with a strong family history of BC. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1033-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yessica Leyton
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Patricio Gonzalez-Hormazabal
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Rafael Blanco
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Teresa Bravo
- National Cancer Society (Corporación Nacional del Cáncer -CONAC-), Santiago, Chile.
| | - Ricardo Fernandez-Ramires
- Research Institute in Dental Sciences, School of Odontology, University of Chile, Sergio Livingstone Pohlhammer 943, Santiago, Chile.
| | - Sebastian Morales
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Natalia Landeros
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | | | - Octavio Peralta
- Clínca Las Condes, Santiago, Chile. .,Department of Gyneacology and Obstetrics, School of Medicine, University of Chile, Av Santa Rosa 1234, Santiago, Chile.
| | - Julio C Tapia
- Cell Transformation Laboratory, Institute of Biomedical Sciences (ICBM), School of Medicine, Unversity of Chile, Av. Independencia 1027, Santiago, Chile.
| | | | | | - Gladys Ibañez
- Clínica Dávila, Av. Recoleta 464, Santiago, Chile. .,Hospital San José, San José 1196, Santiago, Chile.
| | - Janara Pakomio
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Gilberto Grau
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
| | - Lilian Jara
- Human Genetics Program, Institute of Biomedical Sciences (ICBM), School of Medicine, University of Chile, Av. Independencia 1027, Santiago, Chile.
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148
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Smith MA, Hampton OA, Reynolds CP, Kang MH, Maris JM, Gorlick R, Kolb EA, Lock R, Carol H, Keir ST, Wu J, Kurmasheva RT, Wheeler DA, Houghton PJ. Initial testing (stage 1) of the PARP inhibitor BMN 673 by the pediatric preclinical testing program: PALB2 mutation predicts exceptional in vivo response to BMN 673. Pediatr Blood Cancer 2015; 62:91-8. [PMID: 25263539 PMCID: PMC4456187 DOI: 10.1002/pbc.25201] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 07/07/2014] [Indexed: 12/31/2022]
Abstract
BACKGROUND BMN 673 is a potent inhibitor of poly-ADP ribose polymerase (PARP) that is in clinical testing with a primary focus on BRCA-mutated cancers. BMN 673 is active both through inhibiting PARP catalytic activity and by tightly trapping PARP to DNA at sites of single strand breaks. PROCEDURE BMN 673 was tested in vitro at concentrations ranging from 0.1 nM to 1 μM and in vivo at a daily dose of 0.33 mg/kg administered orally twice daily (Mon-Fri) and once daily on weekends (solid tumors) for 28 days. RESULTS The median relative IC50 (rIC50 ) concentration against the PPTP cell lines was 25.8 nM. The median rIC50 for the Ewing cell lines was lower than for the remaining cell lines (6.4 vs. 31.1 nM, respectively). In vivo BMN 673 induced statistically significant differences in EFS distribution in 17/43 (39.5%) xenograft models. Three objective regressions were observed: a complete response (CR) in a medulloblastoma line (BT-45), a maintained CR in a Wilms tumor line (KT-10), and a maintained CR in an ependymoma line (BT-41). BMN 673 maintained its high level of activity against KT-10 with a threefold reduction in dose. KT-10 possesses a truncating mutation in PALB2 analogous to PALB2 mutations associated with hereditary breast and ovarian cancer that abrogate homologous recombination (HR) repair. CONCLUSIONS The PPTP results suggest that single agent BMN 673 may have limited clinical activity against pediatric cancers. Single agent activity is more likely for patients whose tumors have defects in HR repair.
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Affiliation(s)
| | - Oliver A. Hampton
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | | | - Min H. Kang
- Texas Tech University Health Sciences Center, Lubbock, TX
| | - John M. Maris
- Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine and Abramson Family Cancer Research Institute, Philadelphia, PA
| | | | | | - Richard Lock
- Children's Cancer Institute Australia for Medical Research, Randwick, NSW, Australia
| | - Hernan Carol
- Children's Cancer Institute Australia for Medical Research, Randwick, NSW, Australia
| | | | - Jianrong Wu
- St. Jude Children's Research Hospital, Memphis, TN
| | | | - David A. Wheeler
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
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149
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Resistance to PARP Inhibitors Mediated by Secondary BRCA1/2 Mutations. CANCER DRUG DISCOVERY AND DEVELOPMENT 2015. [DOI: 10.1007/978-3-319-14151-0_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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150
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Suppression of BRCA1 sensitizes cells to proteasome inhibitors. Cell Death Dis 2014; 5:e1580. [PMID: 25522274 PMCID: PMC4649846 DOI: 10.1038/cddis.2014.537] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 02/08/2023]
Abstract
BRCA1 is a multifunctional protein best known for its role in DNA repair and association with breast and ovarian cancers. To uncover novel biologically significant molecular functions of BRCA1, we tested a panel of 198 approved and experimental drugs to inhibit growth of MDA-MB-231 breast cancer cells depleted for BRCA1 by siRNA. 26S proteasome inhibitors bortezomib and carfilzomib emerged as a new class of selective BRCA1-targeting agents. The effect was confirmed in HeLa and U2OS cancer cell lines using two independent siRNAs, and in mouse embryonic stem (ES) cells with inducible deletion of Brca1. Bortezomib treatment did not cause any increase in nuclear foci containing phosphorylated histone H2AX, and knockdown of BRCA2 did not entail sensitivity to bortezomib, suggesting that the DNA repair function of BRCA1 may not be directly involved. We found that a toxic effect of bortezomib on BRCA1-depleted cells is mostly due to deregulated cell cycle checkpoints mediated by RB1-E2F pathway and 53BP1. Similar to BRCA1, depletion of RB1 also conferred sensitivity to bortezomib, whereas suppression of E2F1 or 53BP1 together with BRCA1 reduced induction of apoptosis after bortezomib treatment. A gene expression microarray study identified additional genes activated by bortezomib treatment only in the context of inactivation of BRCA1 including a critical involvement of the ERN1-mediated unfolded protein response. Our data indicate that BRCA1 has a novel molecular function affecting cell cycle checkpoints in a manner dependent on the 26S proteasome activity.
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