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Winship AL, Alesi LR, Stringer JM, Cao Y, Lewis YM, Tu L, Swindells EOK, Giridharan S, Cai X, Griffiths MJ, Zerafa N, Gilham L, Hickey M, Hutt KJ. Conditional loss of Brca1 in oocytes causes reduced litter size, ovarian reserve depletion and impaired oocyte in vitro maturation with advanced reproductive age in mice. EBioMedicine 2024; 106:105262. [PMID: 39084071 DOI: 10.1016/j.ebiom.2024.105262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 07/14/2024] [Accepted: 07/16/2024] [Indexed: 08/02/2024] Open
Abstract
BACKGROUND An estimated 1 in 350 women carry germline BRCA1/2 mutations, which confer an increased risk of developing breast and ovarian cancer, and may also contribute to subfertility. All mature, sex steroid-producing ovarian follicles are drawn from the pool of non-renewable primordial follicles, termed the 'ovarian reserve'. The clinical implications of early ovarian reserve exhaustion extend beyond infertility, to include the long-term adverse health consequences of loss of endocrine function and premature menopause. We aimed to determine whether conditional loss of Brca1 in oocytes impacts ovarian follicle numbers, oocyte quality and fertility in mice with advancing maternal age. We also aimed to determine the utility of AMH as a marker of ovarian function, by assessing circulating AMH levels in mice and women with BRCA1/2 mutations, and correlating this with ovarian follicle counts. METHODS In this study, we addressed a longstanding question in the field regarding the functional consequences of BRCA1 inactivation in oocytes. To recapitulate loss of BRCA1 protein function in oocytes, we generated mice with conditional gene deletion of Brca1 in oocytes using Gdf9-Cre recombinase (WT: Brca1fl/flGdf9+/+; cKO: Brca1fl/flGdf9cre/+). FINDINGS While the length of the fertile lifespan was not altered between groups after a comprehensive breeding trial, conditional loss of Brca1 in oocytes led to reduced litter size in female mice. Brca1 cKO animals had a reduced ovarian reserve and oocyte maturation was impaired with advanced maternal age at postnatal day (PN)300, compared to WT animals. Serum anti-Müllerian hormone (AMH) concentrations (the gold-standard indirect marker of the ovarian reserve used in clinical practice) were not predictive of reduced primordial follicle number in Brca1 cKO mice versus WT. Furthermore, we found no correlation between follicle number or density and serum AMH concentrations in matched samples from a small cohort of premenopausal women with BRCA1/2 mutations. INTERPRETATION Together, our data demonstrate that BRCA1 is a key regulator of oocyte number and quality in females and suggest that caution should be used in relying on AMH as a reliable marker of the ovarian reserve in this context. FUNDING This work was made possible through Victorian State Government Operational Infrastructure Support and Australian Government NHMRC IRIISS. This work was supported by funding from the Australian Research Council (ALW - DE21010037 and KJH - FT190100265), as well as the National Breast Cancer Foundation (IIRS-22-092) awarded to ALW and KJH. LRA, YML, LT, EOKS and MG were supported by Australian Government Research Training Program Scholarships. LRA, YML and LT were also supported by a Monash Graduate Excellence Scholarship. YC, SG and XC were supported by Monash Biomedicine Discovery Institute PhD Scholarships. LRA was also supported by a Monash University ECPF24-6809920940 Fellowship. JMS was supported by NHMRC funding (2011299). MH was supported by an NHMRC Investigator Grant (1193838).
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Affiliation(s)
- Amy L Winship
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia.
| | - Lauren R Alesi
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Jessica M Stringer
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Yujie Cao
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Yasmin M Lewis
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Lisa Tu
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Elyse O K Swindells
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Saranya Giridharan
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Xuebi Cai
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Meaghan J Griffiths
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia; University of Edinburgh, MRC Centre for Reproductive Health, Queens Medical Research Institute, Edinburgh, UK
| | - Nadeen Zerafa
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia
| | - Leslie Gilham
- Breast Cancer Network Australia and Breast Cancer Trials Australia, Camberwell, VIC, Australia
| | - Martha Hickey
- Gynaecology Research Centre, Royal Women's Hospital, Parkville, VIC, Australia; Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, Australia
| | - Karla J Hutt
- Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Development and Stem Cells Program, Monash University, Clayton, VIC, Australia.
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2
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Yueh WT, Glass DJ, Johnson N. Brca1 Mouse Models: Functional Insights and Therapeutic Opportunities. J Mol Biol 2024; 436:168372. [PMID: 37979908 PMCID: PMC10882579 DOI: 10.1016/j.jmb.2023.168372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
Brca1 mouse models were first reported in the mid-1990's shortly after cloning the human gene. Since then, many mouse models with a range of mutations have been generated, some mimic patient mutations, others are designed to probe specific protein domains and functions. In this review, we discuss early and recent studies using engineered Brca1 mouse alleles, and their implications for understanding Brca1 protein function in the context of DNA repair, tumorigenesis, and anti-cancer therapeutics.
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Affiliation(s)
- Wei-Ting Yueh
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - David J Glass
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Neil Johnson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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3
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Diabate M, Islam MM, Nagy G, Banerjee T, Dhar S, Smith N, Adamovich AI, Starita LM, Parvin JD. DNA repair function scores for 2172 variants in the BRCA1 amino-terminus. PLoS Genet 2023; 19:e1010739. [PMID: 37578980 PMCID: PMC10449183 DOI: 10.1371/journal.pgen.1010739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 08/24/2023] [Accepted: 07/16/2023] [Indexed: 08/16/2023] Open
Abstract
Single nucleotide variants are the most frequent type of sequence changes detected in the genome and these are frequently variants of uncertain significance (VUS). VUS are changes in DNA for which disease risk association is unknown. Thus, methods that classify the functional impact of a VUS can be used as evidence for variant interpretation. In the case of the breast and ovarian cancer specific tumor suppressor protein, BRCA1, pathogenic missense variants frequently score as loss of function in an assay for homology-directed repair (HDR) of DNA double-strand breaks. We previously published functional results using a multiplexed assay for 1056 amino acid substitutions residues 2-192 in the amino terminus of BRCA1. In this study, we have re-assessed the data from this multiplexed assay using an improved analysis pipeline. These new analysis methods yield functional scores for more variants in the first 192 amino acids of BRCA1, plus we report new results for BRCA1 amino acid residues 193-302. We now present the functional classification of 2172 BRCA1 variants in BRCA1 residues 2-302 using the multiplexed HDR assay. Comparison of the functional determinations of the missense variants with clinically known benign or pathogenic variants indicated 93% sensitivity and 100% specificity for this assay. The results from BRCA1 variants tested in this assay are a resource for clinical geneticists for evidence to evaluate VUS in BRCA1.
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Affiliation(s)
- Mariame Diabate
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Muhtadi M. Islam
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Gregory Nagy
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Tapahsama Banerjee
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Shruti Dhar
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Nahum Smith
- The University of Washington, Department of Genome Sciences, Seattle, Washington, United States of America
- Brotman Baty Institute for Precision Medicine, Seattle, Washington, United States of America
| | - Aleksandra I. Adamovich
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Lea M. Starita
- The University of Washington, Department of Genome Sciences, Seattle, Washington, United States of America
- Brotman Baty Institute for Precision Medicine, Seattle, Washington, United States of America
| | - Jeffrey D. Parvin
- The Ohio State University, Department of Biomedical Informatics, Columbus, Ohio, United States of America
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
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4
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The Landscape and Therapeutic Targeting of BRCA1, BRCA2 and Other DNA Damage Response Genes in Pancreatic Cancer. Curr Issues Mol Biol 2023; 45:2105-2120. [PMID: 36975505 PMCID: PMC10047276 DOI: 10.3390/cimb45030135] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/18/2023] [Accepted: 02/28/2023] [Indexed: 03/08/2023] Open
Abstract
Genes participating in the cellular response to damaged DNA have an important function to protect genetic information from alterations due to extrinsic and intrinsic cellular insults. In cancer cells, alterations in these genes are a source of genetic instability, which is advantageous for cancer progression by providing background for adaptation to adverse environments and attack by the immune system. Mutations in BRCA1 and BRCA2 genes have been known for decades to predispose to familial breast and ovarian cancers, and, more recently, prostate and pancreatic cancers have been added to the constellation of cancers that show increased prevalence in these families. Cancers associated with these genetic syndromes are currently treated with PARP inhibitors based on the exquisite sensitivity of cells lacking BRCA1 or BRCA2 function to inhibition of the PARP enzyme. In contrast, the sensitivity of pancreatic cancers with somatic BRCA1 and BRCA2 mutations and with mutations in other homologous recombination (HR) repair genes to PARP inhibitors is less established and the subject of ongoing investigations. This paper reviews the prevalence of pancreatic cancers with HR gene defects and treatment of pancreatic cancer patients with defects in HR with PARP inhibitors and other drugs in development that target these molecular defects.
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5
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Biswas K, Mohammed A, Sharan SK, Shoemaker RH. Genetically engineered mouse models for hereditary cancer syndromes. Cancer Sci 2023; 114:1800-1815. [PMID: 36715493 PMCID: PMC10154891 DOI: 10.1111/cas.15737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/21/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Advances in molecular diagnostics have led to improved diagnosis and molecular understanding of hereditary cancers in the clinic. Improving the management, treatment, and potential prevention of cancers in carriers of predisposing mutations requires preclinical experimental models that reflect the key pathogenic features of the specific syndrome associated with the mutations. Numerous genetically engineered mouse (GEM) models of hereditary cancer have been developed. In this review, we describe the models of Lynch syndrome and hereditary breast and ovarian cancer syndrome, the two most common hereditary cancer predisposition syndromes. We focus on Lynch syndrome models as illustrative of the potential for using mouse models to devise improved approaches to prevention of cancer in a high-risk population. GEM models are an invaluable tool for hereditary cancer models. Here, we review GEM models for some hereditary cancers and their potential use in cancer prevention studies.
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Affiliation(s)
- Kajal Biswas
- Chemopreventive Agent Development Research Group, Division of Cancer Prevention, National Cancer Institute, Rockville, Maryland, USA
| | - Altaf Mohammed
- Chemopreventive Agent Development Research Group, Division of Cancer Prevention, National Cancer Institute, Rockville, Maryland, USA
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland, USA
| | - Robert H Shoemaker
- Chemopreventive Agent Development Research Group, Division of Cancer Prevention, National Cancer Institute, Rockville, Maryland, USA
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6
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Foo TK, Xia B. BRCA1-Dependent and Independent Recruitment of PALB2-BRCA2-RAD51 in the DNA Damage Response and Cancer. Cancer Res 2022; 82:3191-3197. [PMID: 35819255 PMCID: PMC9481714 DOI: 10.1158/0008-5472.can-22-1535] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/22/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022]
Abstract
The BRCA1-PALB2-BRCA2 axis plays essential roles in the cellular response to DNA double-strand breaks (DSB), maintenance of genome integrity, and suppression of cancer development. Upon DNA damage, BRCA1 is recruited to DSBs, where it facilitates end resection and recruits PALB2 and its associated BRCA2 to load the central recombination enzyme RAD51 to initiate homologous recombination (HR) repair. In recent years, several BRCA1-independent mechanisms of PALB2 recruitment have also been reported. Collectively, these available data illustrate a series of hierarchical, context-dependent, and cooperating mechanisms of PALB2 recruitment that is critical for HR and therapy response either in the presence or absence of BRCA1. Here, we review these BRCA1-dependent and independent mechanisms and their importance in DSB repair, cancer development, and therapy. As BRCA1-mutant cancer cells regain HR function, for which PALB2 is generally required, and become resistant to targeted therapies, such as PARP inhibitors, targeting BRCA1-independent mechanisms of PALB2 recruitment represents a potential new avenue to improve treatment of BRCA1-mutant tumors.
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Affiliation(s)
- Tzeh Keong Foo
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
| | - Bing Xia
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
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7
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Park D, Gharghabi M, Reczek CR, Plow R, Yungvirt C, Aldaz CM, Huebner K. Wwox Binding to the Murine Brca1-BRCT Domain Regulates Timing of Brip1 and CtIP Phospho-Protein Interactions with This Domain at DNA Double-Strand Breaks, and Repair Pathway Choice. Int J Mol Sci 2022; 23:ijms23073729. [PMID: 35409089 PMCID: PMC8999063 DOI: 10.3390/ijms23073729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/21/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022] Open
Abstract
Wwox-deficient human cells show elevated homologous recombination, leading to resistance to killing by double-strand break-inducing agents. Human Wwox binds to the Brca1 981-PPLF-984 Wwox-binding motif, likely blocking the pChk2 phosphorylation site at Brca1-S988. This phosphorylation site is conserved across mammalian species; the PPLF motif is conserved in primates but not in rodents. We now show that murine Wwox does not bind Brca1 near the conserved mouse Brca1 phospho-S971 site, leaving it open for Chk2 phosphorylation and Brca1 activation. Instead, murine Wwox binds to Brca1 through its BRCT domain, where pAbraxas, pBrip1, and pCtIP, of the A, B, and C binding complexes, interact to regulate double-strand break repair pathway response. In Wwox-deficient mouse cells, the Brca1-BRCT domain is thus accessible for immediate binding of these phospho-proteins. We confirm elevated homologous recombination in Wwox-silenced murine cells, as in human cells. Wwox-deficient murine cells showed increased ionizing radiation-induced Abraxas, Brca1, and CtIP foci and long resected single-strand DNA, early after ionizing radiation. Wwox deletion increased the basal level of Brca1-CtIP interaction and the expression level of the MRN-CtIP protein complex, key players in end-resection, and facilitated Brca1 release from foci. Inhibition of phospho-Chk2 phosphorylation of Brca1-S971 delays the end-resection; the delay of premature end-resection by combining Chk2 inhibition with ionizing radiation or carboplatin treatment restored ionizing radiation and platinum sensitivity in Wwox-deficient murine cells, as in human cells, supporting the use of murine in vitro and in vivo models in preclinical cancer treatment research.
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Affiliation(s)
- Dongju Park
- Department of Cancer Biology and Genetics, The Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; (M.G.); (R.P.); (C.Y.)
- Correspondence: (D.P.); (K.H.); Tel.: +1-614-685-9124 (D.P.); +1-614-292-4850 (K.H.)
| | - Mehdi Gharghabi
- Department of Cancer Biology and Genetics, The Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; (M.G.); (R.P.); (C.Y.)
- Department of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA
| | - Colleen R. Reczek
- Department of Pathology & Cell Biology, Columbia University Irving Medical Center, Columbia University, New York, NY 10032, USA;
| | - Rebecca Plow
- Department of Cancer Biology and Genetics, The Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; (M.G.); (R.P.); (C.Y.)
| | - Charles Yungvirt
- Department of Cancer Biology and Genetics, The Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; (M.G.); (R.P.); (C.Y.)
| | - C. Marcelo Aldaz
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, 1881 East Road, Houston, TX 77054, USA;
| | - Kay Huebner
- Department of Cancer Biology and Genetics, The Comprehensive Cancer Center, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; (M.G.); (R.P.); (C.Y.)
- Correspondence: (D.P.); (K.H.); Tel.: +1-614-685-9124 (D.P.); +1-614-292-4850 (K.H.)
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8
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Mishra AP, Sahu S, Sharan SK. Coiled-Coil Domain: Uncoiling Tumor Suppression by BRCA1. Cancer Res 2021; 81:6080-6082. [PMID: 34911781 DOI: 10.1158/0008-5472.can-21-3480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022]
Abstract
The coiled-coil domain of BRCA1 is essential for its interaction with partner and localizer of BRCA2 (PALB2). In mice, loss of this interaction is known to result in Fanconi anemia-associated phenotypes. In a study published in this issue of Cancer Research, Pulver and colleagues from the Jonkers lab have generated a mouse model with a leucine to proline change in codon 1363 in the coiled-coil domain of BRCA1 (Brca1LP ), which disrupts its binding with PALB2. Unlike the previously reported viable coiled-coil defective mice, homozygous Brca1LP/LP mutant mice die during embryogenesis. The authors examined the role of the BRCA1/PALB2 interaction on mammary tumorigenesis and reported increased incidence of mammary tumors that are carcinosarcomas or sarcomatoids, unlike the adenocarcinomas that are characteristic mammary tumor types associated with loss of Brca1 and Trp53 in mice. The findings reveal the relevance of the coiled-coil domain in mammary tumor suppression by BRCA1.See related article by Pulver et al., p. 6171.
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Affiliation(s)
- Arun P Mishra
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, NIH, Frederick, Maryland
| | - Sounak Sahu
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, NIH, Frederick, Maryland
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, NIH, Frederick, Maryland.
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9
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Pulver EM, Mukherjee C, van de Kamp G, Roobol SJ, Rother MB, van der Gulden H, de Bruijn R, Lattanzio MV, van der Burg E, Drenth AP, Verkaik NS, Hahn K, Klarenbeek S, de Korte-Grimmerink R, van de Ven M, Pritchard CEJ, Huijbers IJ, Xia B, van Gent DC, Essers J, van Attikum H, Ray Chaudhuri A, Bouwman P, Jonkers J. A BRCA1 coiled-coil domain variant disrupting PALB2 interaction promotes the development of mammary tumors and confers a targetable defect in homologous recombination repair. Cancer Res 2021; 81:6171-6182. [PMID: 34548335 PMCID: PMC7612117 DOI: 10.1158/0008-5472.can-21-1415] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/21/2021] [Accepted: 09/20/2021] [Indexed: 11/16/2022]
Abstract
The BRCA1 tumor suppressor gene encodes a multi-domain protein for which several functions have been described. These include a key role in homologous recombination repair (HRR) of DNA double-strand breaks (DSB), which is shared with two other high-risk hereditary breast cancer suppressors, BRCA2 and PALB2. Although both BRCA1 and BRCA2 interact with PALB2, BRCA1 missense variants affecting its PALB2-interacting coiled-coil domain are considered variants of uncertain clinical significance (VUS). Using genetically engineered mice, we show here that a BRCA1 coiled-coil domain VUS, Brca1 p.L1363P, disrupts the interaction with PALB2 and leads to embryonic lethality. Brca1 p.L1363P led to a similar acceleration in the development of Trp53-deficient mammary tumors as Brca1 loss, but the tumors showed distinct histopathological features, with more stable DNA copy number profiles in Brca1 p.L1363P tumors. Nevertheless, Brca1 p.L1363P mammary tumors were HRR-incompetent and responsive to cisplatin and PARP inhibition. Overall, these results provide the first direct evidence that a BRCA1 missense variant outside of the RING and BRCT domains increases the risk of breast cancer.
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Affiliation(s)
- Emilia M Pulver
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute
| | | | | | - Stefan J Roobol
- Molecular Genetics, Radiology and Nuclear Medicine, Erasmus MC
| | | | - Hanneke van der Gulden
- Division of Molecular Pathology and Cancer Genomics Centre, The Netherlands Cancer Institute
| | - Roebi de Bruijn
- Division of Molecular Pathology, The Netherlands Cancer Institute
| | | | | | | | | | - Kerstin Hahn
- Molecular Pathology, Oncode Institute-Netherlands Cancer Institute
| | | | - Renske de Korte-Grimmerink
- Mouse Clinic for Cancer and Aging (MCCA) Preclinical Intervention Unit, The Netherlands Cancer Institute
| | - Marieke van de Ven
- Mouse Clinic for Cancer and Aging (MCCA) Preclinical Intervention Unit, The Netherlands Cancer Institute
| | | | - Ivo J Huijbers
- Transgenic core facility, Mouse Clinic for Cancer and Aging (MCCA), The Netherlands Cancer Institute
| | - Bing Xia
- Radiation Oncology, Rutgers Cancer Institute of New Jersey
| | - Dik C van Gent
- Molecular Genetics, Erasmus MC University Medical Center Rotterdam and Oncode Institute, The Netherlands
| | | | | | | | - Peter Bouwman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research
| | - Jos Jonkers
- Division of Molecular Pathology, Oncode Institute, The Netherlands Cancer Institute
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10
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Mouse Models for Deciphering the Impact of Homologous Recombination on Tumorigenesis. Cancers (Basel) 2021; 13:cancers13092083. [PMID: 33923105 PMCID: PMC8123484 DOI: 10.3390/cancers13092083] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022] Open
Abstract
Homologous recombination (HR) is a fundamental evolutionarily conserved process that plays prime role(s) in genome stability maintenance through DNA repair and through the protection and resumption of arrested replication forks. Many HR genes are deregulated in cancer cells. Notably, the breast cancer genes BRCA1 and BRCA2, two important HR players, are the most frequently mutated genes in familial breast and ovarian cancer. Transgenic mice constitute powerful tools to unravel the intricate mechanisms controlling tumorigenesis in vivo. However, the genes central to HR are essential in mammals, and their knockout leads to early embryonic lethality in mice. Elaborated strategies have been developed to overcome this difficulty, enabling one to analyze the consequences of HR disruption in vivo. In this review, we first briefly present the molecular mechanisms of HR in mammalian cells to introduce each factor in the HR process. Then, we present the different mouse models of HR invalidation and the consequences of HR inactivation on tumorigenesis. Finally, we discuss the use of mouse models for the development of targeted cancer therapies as well as perspectives on the future potential for understanding the mechanisms of HR inactivation-driven tumorigenesis in vivo.
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11
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Her J, Bunting SF. BRCA1 and PALB2 in a Messy Breakup. Cancer Res 2020; 80:4044-4045. [PMID: 33008804 DOI: 10.1158/0008-5472.can-20-2731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 08/11/2020] [Indexed: 11/16/2022]
Abstract
Mutations in the BRCA1 gene cause an extremely high lifetime risk of breast and ovarian cancer, but the exact mechanism by which the BRCA1 protein acts to prevent cancer onset remains unclear. In this edition of Cancer Research, Park and colleagues describe a new mouse model featuring a single amino acid substitution in the coiled-coil motif of BRCA1. This change prevents BRCA1 from interacting with PALB2 (partner and localizer of BRCA2), causing rapid cancer onset and a loss of blood cells similar to Fanconi anemia.See related article by Park et al., p. 4172.
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Affiliation(s)
- Joonyoung Her
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey
| | - Samuel F Bunting
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, New Jersey.
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