1
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van der Merwe NC, Buccimazza I, Rossouw B, Araujo M, Ntaita KS, Schoeman M, Vorster K, Napo K, Kotze MJ, Oosthuizen J. Clinical relevance of double heterozygosity revealed by next-generation sequencing of homologous recombination repair pathway genes in South African breast cancer patients. Breast Cancer Res Treat 2024; 207:331-342. [PMID: 38814507 PMCID: PMC11297091 DOI: 10.1007/s10549-024-07362-2] [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: 03/22/2024] [Accepted: 04/24/2024] [Indexed: 05/31/2024]
Abstract
PURPOSE Genetically predisposed breast cancer (BC) patients represent a minor but clinically meaningful subgroup of the disease, with 25% of all cases associated with actionable variants in BRCA1/2. Diagnostic implementation of next-generation sequencing (NGS) resulted in the rare identification of BC patients with double heterozygosity for deleterious variants in genes partaking in homologous recombination repair of DNA. As clinical heterogeneity poses challenges for genetic counseling, this study focused on the occurrence and clinical relevance of double heterozygous BC in South Africa. METHODS DNA samples were diagnostically screened using the NGS-based Oncomine™ BRCA Expanded Research Assay. Data was generated on the Ion GeneStudio S5 system and analyzed using the Torrent Suite™ and reporter software. The clinical significance of the variants detected was determined using international variant classification guidelines and treatment implications. RESULTS Six of 1600 BC patients (0.375%) tested were identified as being bi-allelic for two germline likely pathogenic or pathogenic variants. Most of the variants were present in BRCA1/2, including two founder-related small deletions in three cases, with family-specific variants detected in ATM, BARD1, FANCD2, NBN, and TP53. The scientific interpretation and clinical relevance were based on the clinical and tumor characteristics of each case. CONCLUSION This study increased current knowledge of the risk implications associated with the co-occurrence of more than one pathogenic variant in the BC susceptibility genes, confirmed to be a rare condition in South Africa. Further molecular pathology-based studies are warranted to determine whether clinical decision-making is affected by the detection of a second pathogenic variant in BRCA1/2 and TP53 carriers.
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Affiliation(s)
- Nerina C van der Merwe
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa.
- Division of Human Genetics, National Health Laboratory Service, Universitas Hospital, Bloemfontein, South Africa.
| | - Ines Buccimazza
- Genetics Unit, Inkosi Albert Luthuli General Hospital, Durban, South Africa
- Department of Surgery, Nelson R Mandela School of Medicine, Inkosi Albert Luthuli General Hospital, Durban, South Africa
| | - Bianca Rossouw
- Division of Human Genetics, National Health Laboratory Service, Braamfontein, Johannesburg, South Africa
- Division of Human Genetics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Monica Araujo
- Division of Human Genetics, National Health Laboratory Service, Braamfontein, Johannesburg, South Africa
- Division of Human Genetics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Kholiwe S Ntaita
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
- Division of Human Genetics, National Health Laboratory Service, Universitas Hospital, Bloemfontein, South Africa
| | - Mardelle Schoeman
- Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Karin Vorster
- Department of Oncology, Free State Department of Health, Universitas Annex Hospital, Bloemfontein, South Africa
- Department of Oncology, Faculty of Health Science, University of the Free State, Bloemfontein, South Africa
| | - Kgabo Napo
- Department of Oncology, Free State Department of Health, Universitas Annex Hospital, Bloemfontein, South Africa
- Department of Oncology, Faculty of Health Science, University of the Free State, Bloemfontein, South Africa
| | - Maritha J Kotze
- Division of Chemical Pathology, Department of Pathology, National Health Laboratory Service, Tygerberg Hospital, Cape Town, South Africa
- Division of Chemical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Jaco Oosthuizen
- Division of Human Genetics, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa
- Division of Human Genetics, National Health Laboratory Service, Universitas Hospital, Bloemfontein, South Africa
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2
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Ramirez-Otero MA, Costanzo V. "Bridging the DNA divide": Understanding the interplay between replication- gaps and homologous recombination proteins RAD51 and BRCA1/2. DNA Repair (Amst) 2024; 141:103738. [PMID: 39084178 DOI: 10.1016/j.dnarep.2024.103738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/24/2024] [Accepted: 07/25/2024] [Indexed: 08/02/2024]
Abstract
A key but often neglected component of genomic instability is the emergence of single-stranded DNA (ssDNA) gaps during DNA replication in the absence of functional homologous recombination (HR) proteins, such as RAD51 and BRCA1/2. Research in prokaryotes has shed light on the dual role of RAD51's bacterial ortholog, RecA, in HR and the protection of replication forks, emphasizing its essential role in preventing the formation of ssDNA gaps, which is vital for cellular viability. This phenomenon was corroborated in eukaryotic cells deficient in HR, where the formation of ssDNA gaps within newly synthesized DNA and their subsequent processing by the MRE11 nuclease were observed. Without functional HR proteins, cells employ alternative ssDNA gap-filling mechanisms to ensure survival, though this compensatory response can compromise genomic stability. A notable example is the involvement of the translesion synthesis (TLS) polymerase POLζ, along with the repair protein POLθ, in the suppression of replicative ssDNA gaps. Persistent ssDNA gaps may result in replication fork collapse, chromosomal anomalies, and cell death, which contribute to cancer progression and resistance to therapy. Elucidating the processes that avert ssDNA gaps and safeguard replication forks is critical for enhancing cancer treatment approaches by exploiting the vulnerabilities of cancer cells in these pathways.
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Affiliation(s)
| | - Vincenzo Costanzo
- IFOM ETS - The AIRC Institute of Molecular Oncology, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
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3
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Benedict B, Kristensen SM, Duxin JP. What are the DNA lesions underlying formaldehyde toxicity? DNA Repair (Amst) 2024; 138:103667. [PMID: 38554505 DOI: 10.1016/j.dnarep.2024.103667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 02/22/2024] [Accepted: 03/01/2024] [Indexed: 04/01/2024]
Abstract
Formaldehyde is a highly reactive organic compound. Humans can be exposed to exogenous sources of formaldehyde, but formaldehyde is also produced endogenously as a byproduct of cellular metabolism. Because formaldehyde can react with DNA, it is considered a major endogenous source of DNA damage. However, the nature of the lesions underlying formaldehyde toxicity in cells remains vastly unknown. Here, we review the current knowledge of the different types of nucleic acid lesions that are induced by formaldehyde and describe the repair pathways known to counteract formaldehyde toxicity. Taking this knowledge together, we discuss and speculate on the predominant lesions generated by formaldehyde, which underly its natural toxicity.
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Affiliation(s)
- Bente Benedict
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Stella Munkholm Kristensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Julien P Duxin
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark.
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4
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Kong LR, Gupta K, Wu AJ, Perera D, Ivanyi-Nagy R, Ahmed SM, Tan TZ, Tan SLW, Fuddin A, Sundaramoorthy E, Goh GS, Wong RTX, Costa ASH, Oddy C, Wong H, Patro CPK, Kho YS, Huang XZ, Choo J, Shehata M, Lee SC, Goh BC, Frezza C, Pitt JJ, Venkitaraman AR. A glycolytic metabolite bypasses "two-hit" tumor suppression by BRCA2. Cell 2024; 187:2269-2287.e16. [PMID: 38608703 DOI: 10.1016/j.cell.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 02/01/2024] [Accepted: 03/07/2024] [Indexed: 04/14/2024]
Abstract
Knudson's "two-hit" paradigm posits that carcinogenesis requires inactivation of both copies of an autosomal tumor suppressor gene. Here, we report that the glycolytic metabolite methylglyoxal (MGO) transiently bypasses Knudson's paradigm by inactivating the breast cancer suppressor protein BRCA2 to elicit a cancer-associated, mutational single-base substitution (SBS) signature in nonmalignant mammary cells or patient-derived organoids. Germline monoallelic BRCA2 mutations predispose to these changes. An analogous SBS signature, again without biallelic BRCA2 inactivation, accompanies MGO accumulation and DNA damage in Kras-driven, Brca2-mutant murine pancreatic cancers and human breast cancers. MGO triggers BRCA2 proteolysis, temporarily disabling BRCA2's tumor suppressive functions in DNA repair and replication, causing functional haploinsufficiency. Intermittent MGO exposure incites episodic SBS mutations without permanent BRCA2 inactivation. Thus, a metabolic mechanism wherein MGO-induced BRCA2 haploinsufficiency transiently bypasses Knudson's two-hit requirement could link glycolysis activation by oncogenes, metabolic disorders, or dietary challenges to mutational signatures implicated in cancer evolution.
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Affiliation(s)
- Li Ren Kong
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Department of Pharmacology, National University of Singapore, Singapore 117600, Singapore
| | - Komal Gupta
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK
| | - Andy Jialun Wu
- Cancer Science Institute of Singapore, Singapore 117599, Singapore
| | - David Perera
- MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK
| | | | - Syed Moiz Ahmed
- Cancer Science Institute of Singapore, Singapore 117599, Singapore
| | - Tuan Zea Tan
- Cancer Science Institute of Singapore, Singapore 117599, Singapore
| | - Shawn Lu-Wen Tan
- MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Institute of Molecular and Cell Biology (IMCB), A(∗)STAR, Singapore 138673, Singapore
| | | | | | | | | | - Ana S H Costa
- MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK
| | - Callum Oddy
- Department of Oncology, University of Cambridge, Cambridge CB2 0XZ, UK
| | - Hannan Wong
- Cancer Science Institute of Singapore, Singapore 117599, Singapore
| | - C Pawan K Patro
- Cancer Science Institute of Singapore, Singapore 117599, Singapore
| | - Yun Suen Kho
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore
| | - Xiao Zi Huang
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore
| | - Joan Choo
- Department of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Mona Shehata
- MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Department of Oncology, University of Cambridge, Cambridge CB2 0XZ, UK
| | - Soo Chin Lee
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore; Department of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Boon Cher Goh
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore; Department of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Christian Frezza
- MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; University of Cologne, 50923 Köln, Germany
| | - Jason J Pitt
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore; Genome Institute of Singapore, A(∗)STAR, Singapore 138673, Singapore
| | - Ashok R Venkitaraman
- Cancer Science Institute of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research (N2CR), National University of Singapore, Singapore 117599, Singapore; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Institute of Molecular and Cell Biology (IMCB), A(∗)STAR, Singapore 138673, Singapore; Department of Oncology, University of Cambridge, Cambridge CB2 0XZ, UK; Department of Medicine, National University of Singapore, Singapore 119228, Singapore.
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5
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Jaiswal RK, Lei KH, Chastain M, Wang Y, Shiva O, Li S, You Z, Chi P, Chai W. CaMKK2 and CHK1 phosphorylate human STN1 in response to replication stress to protect stalled forks from aberrant resection. Nat Commun 2023; 14:7882. [PMID: 38036565 PMCID: PMC10689503 DOI: 10.1038/s41467-023-43685-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 11/16/2023] [Indexed: 12/02/2023] Open
Abstract
Keeping replication fork stable is essential for safeguarding genome integrity; hence, its protection is highly regulated. The CTC1-STN1-TEN1 (CST) complex protects stalled forks from aberrant MRE11-mediated nascent strand DNA degradation (NSD). However, the activation mechanism for CST at forks is unknown. Here, we report that STN1 is phosphorylated in its intrinsic disordered region. Loss of STN1 phosphorylation reduces the replication stress-induced STN1 localization to stalled forks, elevates NSD, increases MRE11 access to stalled forks, and decreases RAD51 localization at forks, leading to increased genome instability under perturbed DNA replication condition. STN1 is phosphorylated by both the ATR-CHK1 and the calcium-sensing kinase CaMKK2 in response to hydroxyurea/aphidicolin treatment or elevated cytosolic calcium concentration. Cancer-associated STN1 variants impair STN1 phosphorylation, conferring inability of fork protection. Collectively, our study uncovers that CaMKK2 and ATR-CHK1 target STN1 to enable its fork protective function, and suggests an important role of STN1 phosphorylation in cancer development.
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Affiliation(s)
- Rishi Kumar Jaiswal
- Department of Cancer Biology, Cardinal Bernardin Cancer Center, Loyola University Chicago Stritch School of Medicine, Maywood, IL, USA
| | - Kai-Hang Lei
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Megan Chastain
- Office of Research, Washington State University, Spokane, WA, USA
| | - Yuan Wang
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, USA
| | - Olga Shiva
- Office of Research, Washington State University, Spokane, WA, USA
| | - Shan Li
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Peter Chi
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Weihang Chai
- Department of Cancer Biology, Cardinal Bernardin Cancer Center, Loyola University Chicago Stritch School of Medicine, Maywood, IL, USA.
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6
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Appleby R, Joudeh L, Cobbett K, Pellegrini L. Structural basis for stabilisation of the RAD51 nucleoprotein filament by BRCA2. Nat Commun 2023; 14:7003. [PMID: 37919288 PMCID: PMC10622577 DOI: 10.1038/s41467-023-42830-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/23/2023] [Indexed: 11/04/2023] Open
Abstract
The BRCA2 tumour suppressor protein preserves genomic integrity via interactions with the DNA-strand exchange RAD51 protein in homology-directed repair. The RAD51-binding TR2 motif at the BRCA2 C-terminus is essential for protection and restart of stalled replication forks. Biochemical evidence shows that TR2 recognises filamentous RAD51, but existing models of TR2 binding to RAD51 lack a structural basis. Here we used cryo-electron microscopy and structure-guided mutagenesis to elucidate the mechanism of TR2 binding to nucleoprotein filaments of human RAD51. We find that TR2 binds across the protomer interface in the filament, acting as a brace for adjacent RAD51 molecules. TR2 targets an acidic-patch motif on human RAD51 that serves as a recruitment hub in fission yeast Rad51 for recombination mediators Rad52 and Rad55-Rad57. Our findings provide a structural rationale for RAD51 filament stabilisation by BRCA2 and reveal a common recruitment mechanism of recombination mediators to the RAD51 filament.
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Affiliation(s)
- Robert Appleby
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Luay Joudeh
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Katie Cobbett
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - Luca Pellegrini
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK.
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7
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Najafabadi MG, Gray GK, Kong LR, Gupta K, Perera D, Naylor H, Brugge JS, Venkitaraman AR, Shehata M. A transcriptional response to replication stress selectively expands a subset of Brca2-mutant mammary epithelial cells. Nat Commun 2023; 14:5206. [PMID: 37626143 PMCID: PMC10457340 DOI: 10.1038/s41467-023-40956-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Germline BRCA2 mutation carriers frequently develop luminal-like breast cancers, but it remains unclear how BRCA2 mutations affect mammary epithelial subpopulations. Here, we report that monoallelic Brca2mut/WT mammary organoids subjected to replication stress activate a transcriptional response that selectively expands Brca2mut/WT luminal cells lacking hormone receptor expression (HR-). While CyTOF analyses reveal comparable epithelial compositions among wildtype and Brca2mut/WT mammary glands, Brca2mut/WT HR- luminal cells exhibit greater organoid formation and preferentially survive and expand under replication stress. ScRNA-seq analysis corroborates the expansion of HR- luminal cells which express elevated transcript levels of Tetraspanin-8 (Tspan8) and Thrsp, plus pathways implicated in replication stress survival including Type I interferon responses. Notably, CRISPR/Cas9-mediated deletion of Tspan8 or Thrsp prevents Brca2mut/WT HR- luminal cell expansion. Our findings indicate that Brca2mut/WT cells activate a transcriptional response after replication stress that preferentially favours outgrowth of HR- luminal cells through the expression of interferon-responsive and mammary alveolar genes.
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Affiliation(s)
| | - G Kenneth Gray
- Department of Cell Biology, Harvard Medical School (HMS), Boston, MA, USA
| | - Li Ren Kong
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- The Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- Department of Pharmacology, NUS School of Medicine, National University of Singapore, Singapore, Singapore
- NUS Centre for Cancer Research, National University of Singapore, Singapore, Singapore
| | - Komal Gupta
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
- The Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
- NUS Centre for Cancer Research, National University of Singapore, Singapore, Singapore
| | - David Perera
- MRC Cancer Unit, University of Cambridge, Cambridge, UK
| | - Huw Naylor
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Joan S Brugge
- Department of Cell Biology, Harvard Medical School (HMS), Boston, MA, USA
| | - Ashok R Venkitaraman
- MRC Cancer Unit, University of Cambridge, Cambridge, UK.
- The Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.
- Institute of Molecular & Cellular Biology Agency for Science, Technology and Research (A∗STAR), Singapore, Singapore.
| | - Mona Shehata
- Department of Oncology, University of Cambridge, Cambridge, UK.
- MRC Cancer Unit, University of Cambridge, Cambridge, UK.
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8
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Einig E, Jin C, Andrioletti V, Macek B, Popov N. RNAPII-dependent ATM signaling at collisions with replication forks. Nat Commun 2023; 14:5147. [PMID: 37620345 PMCID: PMC10449895 DOI: 10.1038/s41467-023-40924-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 08/16/2023] [Indexed: 08/26/2023] Open
Abstract
Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and are thought to underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII nucleates activation of the ATM kinase at TRCs to stimulate DNA repair. We show the ATPase WRNIP1 associates with RNAPII and limits ATM activation during unperturbed cell cycle. WRNIP1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase HUWE1. Mutation of HUWE1 induces TRCs, promotes WRNIP1 dissociation from RNAPII and binding to the replisome, stimulating ATM recruitment and activation at RNAPII. TRCs and translocation of WRNIP1 are rapidly induced in response to hydroxyurea treatment to activate ATM and facilitate subsequent DNA repair. We propose that TRCs can provide a controlled mechanism for stalling of replication forks and ATM activation, instrumental in cellular response to replicative stress.
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Affiliation(s)
- Elias Einig
- Department of Medical Oncology and Pulmonology, University Hospital Tübingen, Otfried-Mueller-Str 14, 72076, Tübingen, Germany
| | - Chao Jin
- Department of Medical Oncology and Pulmonology, University Hospital Tübingen, Otfried-Mueller-Str 14, 72076, Tübingen, Germany
| | - Valentina Andrioletti
- Department of Medical Oncology and Pulmonology, University Hospital Tübingen, Otfried-Mueller-Str 14, 72076, Tübingen, Germany
- enGenome S.R.L., Via Fratelli Cuzio 42, 27100, Pavia, Italy
| | - Boris Macek
- Interfaculty Institute of Cell Biology, Eberhard Karls University of Tübingen, Auf d. Morgenstelle 15, 72076, Tübingen, Germany
| | - Nikita Popov
- Department of Medical Oncology and Pulmonology, University Hospital Tübingen, Otfried-Mueller-Str 14, 72076, Tübingen, Germany.
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9
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Bhat D, Malacaria E, Biagi L, Razzaghi M, Honda M, Hobbs K, Hengel S, Pichierri P, Spies M, Spies M. Therapeutic disruption of RAD52-ssDNA complexation via novel drug-like inhibitors. NAR Cancer 2023; 5:zcad018. [PMID: 37139244 PMCID: PMC10150327 DOI: 10.1093/narcan/zcad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/09/2023] [Accepted: 04/14/2023] [Indexed: 05/05/2023] Open
Abstract
RAD52 protein is a coveted target for anticancer drug discovery. Similar to poly-ADP-ribose polymerase (PARP) inhibitors, pharmacological inhibition of RAD52 is synthetically lethal with defects in genome caretakers BRCA1 and BRCA2 (∼25% of breast and ovarian cancers). Emerging structure activity relationships for RAD52 are complex, making it challenging to transform previously identified disruptors of the RAD52-ssDNA interaction into drug-like leads using traditional medicinal chemistry approaches. Using pharmacophoric informatics on the RAD52 complexation by epigallocatechin (EGC), and the Enamine in silico REAL database, we identified six distinct chemical scaffolds that occupy the same physical space on RAD52 as EGC. All six were RAD52 inhibitors (IC50 ∼23-1200 μM) with two of the compounds (Z56 and Z99) selectively killing BRCA-mutant cells and inhibiting cellular activities of RAD52 at micromolar inhibitor concentrations. While Z56 had no effect on the ssDNA-binding protein RPA and was toxic to BRCA-mutant cells only, Z99 inhibited both proteins and displayed toxicity towards BRCA-complemented cells. Optimization of the Z99 scaffold resulted in a set of more powerful and selective inhibitors (IC50 ∼1.3-8 μM), which were only toxic to BRCA-mutant cells. RAD52 complexation by Z56, Z99 and its more specific derivatives provide a roadmap for next generation of cancer therapeutics.
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Affiliation(s)
- Divya S Bhat
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Ludovica Di Biagi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Mortezaali Razzaghi
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Masayoshi Honda
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Kathryn F Hobbs
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
| | - Sarah R Hengel
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
- Naturis Informatika LLC, 401 Mullin Ave., Iowa City, IA 52246, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
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10
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Replication gap suppression depends on the double-strand DNA binding activity of BRCA2. Nat Commun 2023; 14:446. [PMID: 36707518 PMCID: PMC9883520 DOI: 10.1038/s41467-023-36149-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 01/17/2023] [Indexed: 01/28/2023] Open
Abstract
Replication stress (RS) is a major source of genomic instability and is intrinsic to cancer cells. RS is also the consequence of chemotherapeutic drugs for treating cancer. However, adaptation to RS is also a mechanism of resistance to chemotherapy. BRCA2 deficiency results in replication stress in human cells. BRCA2 protein's main functions include DNA repair by homologous recombination (HR) both at induced DNA double-strand breaks (DSB) and spontaneous replicative lesions. At stalled replication forks, BRCA2 protects the DNA from aberrant nucleolytic degradation and is thought to limit the appearance of ssDNA gaps by arresting replication and via post-replicative HR. However, whether and how BRCA2 acts to limit the formation of ssDNA gaps or mediate their repair, remains ill-defined. Here, we use breast cancer variants affecting different domains of BRCA2 to shed light on this function. We demonstrate that the N-terminal DNA binding domain (NTD), and specifically, its dsDNA binding activity, is required to prevent and repair/fill-in ssDNA gaps upon nucleotide depletion but not to limit PARPi-induced ssDNA gaps. Thus, these findings suggest that nucleotide depletion and PARPi trigger gaps via distinct mechanisms and that the NTD of BRCA2 prevents nucleotide depletion-induced ssDNA gaps.
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11
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Jackson LM, Moldovan GL. Mechanisms of PARP1 inhibitor resistance and their implications for cancer treatment. NAR Cancer 2022; 4:zcac042. [PMID: 36568963 PMCID: PMC9773381 DOI: 10.1093/narcan/zcac042] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
The discovery of synthetic lethality as a result of the combined loss of PARP1 and BRCA has revolutionized the treatment of DNA repair-deficient cancers. With the development of PARP inhibitors, patients displaying germline or somatic mutations in BRCA1 or BRCA2 were presented with a novel therapeutic strategy. However, a large subset of patients do not respond to PARP inhibitors. Furthermore, many of those who do respond eventually acquire resistance. As such, combating de novo and acquired resistance to PARP inhibitors remains an obstacle in achieving durable responses in patients. In this review, we touch on some of the key mechanisms of PARP inhibitor resistance, including restoration of homologous recombination, replication fork stabilization and suppression of single-stranded DNA gap accumulation, as well as address novel approaches for overcoming PARP inhibitor resistance.
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Affiliation(s)
- Lindsey M Jackson
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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12
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Pre-Existing and Acquired Resistance to PARP Inhibitor-Induced Synthetic Lethality. Cancers (Basel) 2022; 14:cancers14235795. [PMID: 36497275 PMCID: PMC9741207 DOI: 10.3390/cancers14235795] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
The advanced development of synthetic lethality has opened the doors for specific anti-cancer medications of personalized medicine and efficient therapies against cancers. One of the most popular approaches being investigated is targeting DNA repair pathways as the implementation of the PARP inhibitor (PARPi) into individual or combinational therapeutic schemes. Such treatment has been effectively employed against homologous recombination-defective solid tumors as well as hematopoietic malignancies. However, the resistance to PARPi has been observed in both preclinical research and clinical treatment. Therefore, elucidating the mechanisms responsible for the resistance to PARPi is pivotal for the further success of this intervention. Apart from mechanisms of acquired resistance, the bone marrow microenvironment provides a pre-existing mechanism to induce the inefficiency of PARPi in leukemic cells. Here, we describe the pre-existing and acquired mechanisms of the resistance to PARPi-induced synthetic lethality. We also discuss the potential rationales for developing effective therapies to prevent/repress the PARPi resistance in cancer cells.
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13
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Deshpande M, Paniza T, Jalloul N, Nanjangud G, Twarowski J, Koren A, Zaninovic N, Zhan Q, Chadalavada K, Malkova A, Khiabanian H, Madireddy A, Rosenwaks Z, Gerhardt J. Error-prone repair of stalled replication forks drives mutagenesis and loss of heterozygosity in haploinsufficient BRCA1 cells. Mol Cell 2022; 82:3781-3793.e7. [PMID: 36099913 DOI: 10.1016/j.molcel.2022.08.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 04/21/2022] [Accepted: 08/16/2022] [Indexed: 01/05/2023]
Abstract
Germline mutations in the BRCA genes are associated with a higher risk of carcinogenesis, which is linked to an increased mutation rate and loss of the second unaffected BRCA allele (loss of heterozygosity, LOH). However, the mechanisms triggering mutagenesis are not clearly understood. The BRCA genes contain high numbers of repetitive DNA sequences. We detected replication forks stalling, DNA breaks, and deletions at these sites in haploinsufficient BRCA cells, thus identifying the BRCA genes as fragile sites. Next, we found that stalled forks are repaired by error-prone pathways, such as microhomology-mediated break-induced replication (MMBIR) in haploinsufficient BRCA1 breast epithelial cells. We detected MMBIR mutations in BRCA1 tumor cells and noticed deletions-insertions (>50 bp) at the BRCA1 genes in BRCA1 patients. Altogether, these results suggest that under stress, error-prone repair of stalled forks is upregulated and induces mutations, including complex genomic rearrangements at the BRCA genes (LOH), in haploinsufficient BRCA1 cells.
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Affiliation(s)
- Madhura Deshpande
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Theodore Paniza
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Nahed Jalloul
- Rutgers Cancer Institute of New Jersey and Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08903, USA
| | - Gouri Nanjangud
- Molecular Cytogenetics Core Facility, Sloan Kettering Institute, New York, NY 10065, USA
| | - Jerzy Twarowski
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Nikica Zaninovic
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Qiansheng Zhan
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Kalyani Chadalavada
- Molecular Cytogenetics Core Facility, Sloan Kettering Institute, New York, NY 10065, USA
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
| | - Hossein Khiabanian
- Rutgers Cancer Institute of New Jersey and Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08903, USA
| | - Advaitha Madireddy
- Department of Pediatric Hematology/Oncology, Rutgers University, New Brunswick, NJ 08903, USA
| | - Zev Rosenwaks
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jeannine Gerhardt
- The Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY 10021, USA; Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY 10021, USA.
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14
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Xie T, Dickson KA, Yee C, Ma Y, Ford CE, Bowden NA, Marsh DJ. Targeting Homologous Recombination Deficiency in Ovarian Cancer with PARP Inhibitors: Synthetic Lethal Strategies That Impact Overall Survival. Cancers (Basel) 2022; 14:4621. [PMID: 36230543 PMCID: PMC9563432 DOI: 10.3390/cancers14194621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/09/2022] [Accepted: 09/21/2022] [Indexed: 11/23/2022] Open
Abstract
The advent of molecular targeted therapies has made a significant impact on survival of women with ovarian cancer who have defects in homologous recombination repair (HRR). High-grade serous ovarian cancer (HGSOC) is the most common histological subtype of ovarian cancer, with over 50% displaying defective HRR. Poly ADP ribose polymerases (PARPs) are a family of enzymes that catalyse the transfer of ADP-ribose to target proteins, functioning in fundamental cellular processes including transcription, chromatin remodelling and DNA repair. In cells with deficient HRR, PARP inhibitors (PARPis) cause synthetic lethality leading to cell death. Despite the major advances that PARPis have heralded for women with ovarian cancer, questions and challenges remain, including: can the benefits of PARPis be brought to a wider range of women with ovarian cancer; can other drugs in clinical use function in a similar way or with greater efficacy than currently clinically approved PARPis; what can we learn from long-term responders to PARPis; can PARPis sensitise ovarian cancer cells to immunotherapy; and can synthetic lethal strategies be employed more broadly to develop new therapies for women with ovarian cancer. We examine these, and other, questions with focus on improving outcomes for women with ovarian cancer.
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Affiliation(s)
- Tao Xie
- Translational Oncology Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Kristie-Ann Dickson
- Translational Oncology Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Christine Yee
- Translational Oncology Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Yue Ma
- Translational Oncology Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Caroline E. Ford
- School of Clinical Medicine, Faculty of Medicine and Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Nikola A. Bowden
- Centre for Drug Repurposing and Medicines Research, University of Newcastle, Newcastle, NSW 2289, Australia
- School of Medicine and Public Health, University of Newcastle, Newcastle, NSW 2289, Australia
- Hunter Medical Research Institute, Newcastle, NSW 2289, Australia
| | - Deborah J. Marsh
- Translational Oncology Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
- Northern Clinical School, Faculty of Medicine and Health, University of Sydney, Camperdown, NSW 2006, Australia
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15
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Costanza A, Guaragnella N, Bobba A, Manzari C, L'Abbate A, Giudice CL, Picardi E, D'Erchia AM, Pesole G, Giannattasio S. Yeast as a Model to Unravel New BRCA2 Functions in Cell Metabolism. Front Oncol 2022; 12:908442. [PMID: 35734584 PMCID: PMC9207209 DOI: 10.3389/fonc.2022.908442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/06/2022] [Indexed: 11/13/2022] Open
Abstract
Mutations in BRCA2 gene increase the risk for breast cancer and for other cancer types, including pancreatic and prostate cancer. Since its first identification as an oncosupressor in 1995, the best-characterized function of BRCA2 is in the repair of DNA double-strand breaks (DSBs) by homologous recombination. BRCA2 directly interacts with both RAD51 and single-stranded DNA, mediating loading of RAD51 recombinase to sites of single-stranded DNA. In the absence of an efficient homologous recombination pathway, DSBs accumulate resulting in genome instability, thus supporting tumorigenesis. Yet the precise mechanism by which BRCA2 exerts its tumor suppressor function remains unclear. BRCA2 has also been involved in other biological functions including protection of telomere integrity and stalled replication forks, cell cycle progression, transcriptional control and mitophagy. Recently, we and others have reported a role of BRCA2 in modulating cell death programs through a molecular mechanism conserved in yeast and mammals. Here we hypothesize that BRCA2 is a multifunctional protein which exerts specific functions depending on cell stress response pathway. Based on a differential RNA sequencing analysis carried out on yeast cells either growing or undergoing a regulated cell death process, either in the absence or in the presence of BRCA2, we suggest that BRCA2 causes central carbon metabolism reprogramming in response to death stimuli and encourage further investigation on the role of metabolic reprogramming in BRCA2 oncosuppressive function.
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Affiliation(s)
- Alessandra Costanza
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
| | - Nicoletta Guaragnella
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy.,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Antonella Bobba
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
| | - Caterina Manzari
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Alberto L'Abbate
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
| | - Claudio Lo Giudice
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Ernesto Picardi
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy.,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Anna Maria D'Erchia
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy.,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Graziano Pesole
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy.,Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro", Bari, Italy
| | - Sergio Giannattasio
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, Bari, Italy
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16
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Zong C, Zhu T, He J, Huang R, Jia R, Shen J. PARP mediated DNA damage response, genomic stability and immune responses. Int J Cancer 2021; 150:1745-1759. [PMID: 34952967 DOI: 10.1002/ijc.33918] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 11/11/2022]
Abstract
Poly (ADP-ribose) polymerase (PARP) enzymes, especially PARP1, play important roles in the DNA damage response and in the maintenance of genome stability, which makes PARPis a classic synthetic lethal therapy for BRCA-deficient tumors. Conventional mechanisms suggest that PARPis exert their effects via catalytic inhibition and PARP-DNA trapping. Recently, PARP1 has been found to play a role in the immune modulation of tumors. The blockade of PARP1 is able to induce innate immunity through a series of molecular mechanisms, thus allowing the prediction of the feasibility of PARPis combined with immune agents in the treatment of tumors. PARPis combined with immunomodulators may have a stronger tumor suppressive effect on inhibiting tumor growth and blocking immune escape. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Chunyan Zong
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Tianyu Zhu
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Jie He
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Rui Huang
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Renbing Jia
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
| | - Jianfeng Shen
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, P. R. China.,Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
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17
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Hernández-Suárez B, Gillespie DA, Pawlak A. DNA Damage Response (DDR) proteins in canine cancer as potential research targets in comparative oncology. Vet Comp Oncol 2021; 20:347-361. [PMID: 34923737 PMCID: PMC9304296 DOI: 10.1111/vco.12795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 11/22/2022]
Abstract
The DNA damage response (DDR) is a complex signal transduction network that is activated when endogenous or exogenous genotoxins damage or interfere with the replication of genomic DNA. Under such conditions, the DDR promotes DNA repair and ensures accurate replication and division of the genome. High levels of genomic instability are frequently observed in cancers and can stem from germline loss‐of‐function mutations in certain DDR genes, such as BRCA1, BRCA2, and p53, that form the basis of human cancer predisposition syndromes. In addition, mutation and/or aberrant expression of multiple DDR genes are frequently observed in sporadic human cancers. As a result, the DDR is considered to represent a viable target for cancer therapy in humans and a variety of strategies are under investigation. Cancer is also a significant cause of mortality in dogs, a species that offers certain advantages for experimental oncology. Domestic dogs present numerous inbred lines, many of which display predisposition to specific forms of cancer and the study of which may provide insight into the biological basis of this susceptibility. In addition, clinical trials are possible in dogs and may lead to therapeutic insights that could ultimately be extended to humans. Here we review what is known specifically about the DDR in dogs and discuss how this knowledge could be extended and exploited to advance experimental oncology in this species.
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Affiliation(s)
- Beatriz Hernández-Suárez
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Poland
| | - David A Gillespie
- Instituto de Tecnologías Biomédicas, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, La Laguna 38071, Tenerife, Spain
| | - Aleksandra Pawlak
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Poland
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18
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Homologous Recombination as a Fundamental Genome Surveillance Mechanism during DNA Replication. Genes (Basel) 2021; 12:genes12121960. [PMID: 34946909 PMCID: PMC8701046 DOI: 10.3390/genes12121960] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/28/2022] Open
Abstract
Accurate and complete genome replication is a fundamental cellular process for the proper transfer of genetic material to cell progenies, normal cell growth, and genome stability. However, a plethora of extrinsic and intrinsic factors challenge individual DNA replication forks and cause replication stress (RS), a hallmark of cancer. When challenged by RS, cells deploy an extensive range of mechanisms to safeguard replicating genomes and limit the burden of DNA damage. Prominent among those is homologous recombination (HR). Although fundamental to cell division, evidence suggests that cancer cells exploit and manipulate these RS responses to fuel their evolution and gain resistance to therapeutic interventions. In this review, we focused on recent insights into HR-mediated protection of stress-induced DNA replication intermediates, particularly the repair and protection of daughter strand gaps (DSGs) that arise from discontinuous replication across a damaged DNA template. Besides mechanistic underpinnings of this process, which markedly differ depending on the extent and duration of RS, we highlight the pathophysiological scenarios where DSG repair is naturally silenced. Finally, we discuss how such pathophysiological events fuel rampant mutagenesis, promoting cancer evolution, but also manifest in adaptative responses that can be targeted for cancer therapy.
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19
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Cantor SB. Revisiting the BRCA-pathway through the lens of replication gap suppression: "Gaps determine therapy response in BRCA mutant cancer". DNA Repair (Amst) 2021; 107:103209. [PMID: 34419699 PMCID: PMC9049047 DOI: 10.1016/j.dnarep.2021.103209] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 08/06/2021] [Accepted: 08/07/2021] [Indexed: 12/12/2022]
Abstract
The toxic lesion emanating from chemotherapy that targets the DNA was initially debated, but eventually the DNA double strand break (DSB) ultimately prevailed. The reasoning was in part based on the perception that repairing a fractured chromosome necessitated intricate processing or condemned the cell to death. Genetic evidence for the DSB model was also provided by the extreme sensitivity of cells that were deficient in DSB repair. In particular, sensitivity characterized cells harboring mutations in the hereditary breast/ovarian cancer genes, BRCA1 or BRCA2, that function in the repair of DSBs by homologous recombination (HR). Along with functions in HR, BRCA proteins were found to prevent DSBs by protecting stalled replication forks from nuclease degradation. Coming full-circle, BRCA mutant cancer cells that gained resistance to genotoxic chemotherapy often displayed restored DNA repair by HR and/or restored fork protection (FP) implicating that the therapy was tolerated when DSB repair was intact or DSBs were prevented. Despite this well-supported paradigm that has been the impetus for targeted cancer therapy, here we argue that the toxic DNA lesion conferring response is instead single stranded DNA (ssDNA) gaps. We discuss the evidence that persistent ssDNA gaps formed in the wake of DNA replication rather than DSBs are responsible for cell killing following treatment with genotoxic chemotherapeutic agents. We also highlight that proteins, such as BRCA1, BRCA2, and RAD51 known for canonical DSB repair also have critical roles in normal replication as well as replication gap suppression (RGS) and repair. We review the literature that supports the idea that widespread gap induction proximal to treatment triggers apoptosis in a process that does not need or stem from DSB induction. Lastly, we discuss the clinical evidence for gaps and how to exploit them to enhance genotoxic chemotherapy response.
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Affiliation(s)
- Sharon B Cantor
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, LRB 415, 364 Plantation St., Worcester, MA 01605, USA.
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20
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Somyajit K, Spies J, Coscia F, Kirik U, Rask MB, Lee JH, Neelsen KJ, Mund A, Jensen LJ, Paull TT, Mann M, Lukas J. Homology-directed repair protects the replicating genome from metabolic assaults. Dev Cell 2021; 56:461-477.e7. [PMID: 33621493 DOI: 10.1016/j.devcel.2021.01.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 10/14/2020] [Accepted: 01/20/2021] [Indexed: 12/18/2022]
Abstract
Homology-directed repair (HDR) safeguards DNA integrity under various forms of stress, but how HDR protects replicating genomes under extensive metabolic alterations remains unclear. Here, we report that besides stalling replication forks, inhibition of ribonucleotide reductase (RNR) triggers metabolic imbalance manifested by the accumulation of increased reactive oxygen species (ROS) in cell nuclei. This leads to a redox-sensitive activation of the ATM kinase followed by phosphorylation of the MRE11 nuclease, which in HDR-deficient settings degrades stalled replication forks. Intriguingly, nascent DNA degradation by the ROS-ATM-MRE11 cascade is also triggered by hypoxia, which elevates signaling-competent ROS and attenuates functional HDR without arresting replication forks. Under these conditions, MRE11 degrades daughter-strand DNA gaps, which accumulate behind active replisomes and attract error-prone DNA polymerases to escalate mutation rates. Thus, HDR safeguards replicating genomes against metabolic assaults by restraining mutagenic repair at aberrantly processed nascent DNA. These findings have implications for cancer evolution and tumor therapy.
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Affiliation(s)
- Kumar Somyajit
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.
| | - Julian Spies
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Fabian Coscia
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Ufuk Kirik
- Disease Systems Biology Program, Novo Nordisk Foundation Center for Protein, Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Maj-Britt Rask
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Ji-Hoon Lee
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Kai John Neelsen
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Andreas Mund
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Lars Juhl Jensen
- Disease Systems Biology Program, Novo Nordisk Foundation Center for Protein, Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Tanya T Paull
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Matthias Mann
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - Jiri Lukas
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.
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21
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Le HP, Heyer WD, Liu J. Guardians of the Genome: BRCA2 and Its Partners. Genes (Basel) 2021; 12:genes12081229. [PMID: 34440403 PMCID: PMC8394001 DOI: 10.3390/genes12081229] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 12/28/2022] Open
Abstract
The tumor suppressor BRCA2 functions as a central caretaker of genome stability, and individuals who carry BRCA2 mutations are predisposed to breast, ovarian, and other cancers. Recent research advanced our mechanistic understanding of BRCA2 and its various interaction partners in DNA repair, DNA replication support, and DNA double-strand break repair pathway choice. In this review, we discuss the biochemical and structural properties of BRCA2 and examine how these fundamental properties contribute to DNA repair and replication fork stabilization in living cells. We highlight selected BRCA2 binding partners and discuss their role in BRCA2-mediated homologous recombination and fork protection. Improved mechanistic understanding of how BRCA2 functions in genome stability maintenance can enable experimental evidence-based evaluation of pathogenic BRCA2 mutations and BRCA2 pseudo-revertants to support targeted therapy.
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Affiliation(s)
- Hang Phuong Le
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA; (H.P.L.); (W.-D.H.)
- Correspondence: ; Tel.: +1-530-752-3016
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22
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The evolving role of PARP inhibitors in advanced ovarian cancer. FORUM OF CLINICAL ONCOLOGY 2021. [DOI: 10.2478/fco-2021-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
The field of ovarian cancer has been revolutionized with the use of poly (ADP-ribose) polymerase (PARP) inhibitors, which present greater inhibition effect in epithelial subtype due to high rates of homologous recombination deficiency. PARP inhibition exploits this cancer pitfall by disrupting DNA repair, leading to genomic instability and apoptosis. Three PARP inhibitors (olaparib, niraparib, and rucaparib) are now approved for use in women with epithelial ovarian cancer, while others are under development. Among women with BRCA1/2 mutations, maintenance PARP therapy has led to a nearly fourfold prolongation of PFS, while those without BRCA1/2 mutations experience an approximately twofold increase in PFS. Differences in trial design, patient selection and primary analysis population affect the conclusions on PARP inhibitors. Limited OS data have been published and there is also limited experience regarding long-term safety. With regard to toxicity profile, there are no differences in serious adverse events between the experimental and control groups. However, combining adverse event data from maintenance phases, a trend towards more events in the experimental group, compared with controls, has been shown. The mechanisms of PARP-inhibitor resistance include restoration of HR through reversion mutations in HR genes, leading to resumed HR function. Other mechanisms that sustain sufficient DNA repair are discussed as well. PARP inhibitors play a pivotal role in the management of ovarian cancer, affecting the future treatment choices. Defining exactly which patients will benefit from them is a challenge and the need for HRD testing to define ‘BRCA-ness’ will add additional costs to treatment.
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23
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Cong K, Peng M, Kousholt AN, Lee WTC, Lee S, Nayak S, Krais J, VanderVere-Carozza PS, Pawelczak KS, Calvo J, Panzarino NJ, Turchi JJ, Johnson N, Jonkers J, Rothenberg E, Cantor SB. Replication gaps are a key determinant of PARP inhibitor synthetic lethality with BRCA deficiency. Mol Cell 2021; 81:3128-3144.e7. [PMID: 34216544 PMCID: PMC9089372 DOI: 10.1016/j.molcel.2021.06.011] [Citation(s) in RCA: 145] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/19/2021] [Accepted: 06/09/2021] [Indexed: 01/04/2023]
Abstract
Mutations in BRCA1 or BRCA2 (BRCA) is synthetic lethal with poly(ADP-ribose) polymerase inhibitors (PARPi). Lethality is thought to derive from DNA double-stranded breaks (DSBs) necessitating BRCA function in homologous recombination (HR) and/or fork protection (FP). Here, we report instead that toxicity derives from replication gaps. BRCA1- or FANCJ-deficient cells, with common repair defects but distinct PARPi responses, reveal gaps as a distinguishing factor. We further uncouple HR, FP, and fork speed from PARPi response. Instead, gaps characterize BRCA-deficient cells, are diminished upon resistance, restored upon resensitization, and, when exposed, augment PARPi toxicity. Unchallenged BRCA1-deficient cells have elevated poly(ADP-ribose) and chromatin-associated PARP1, but aberrantly low XRCC1 consistent with defects in backup Okazaki fragment processing (OFP). 53BP1 loss resuscitates OFP by restoring XRCC1-LIG3 that suppresses the sensitivity of BRCA1-deficient cells to drugs targeting OFP or generating gaps. We highlight gaps as a determinant of PARPi toxicity changing the paradigm for synthetic lethal interactions.
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Affiliation(s)
- Ke Cong
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Min Peng
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Arne Nedergaard Kousholt
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Wei Ting C Lee
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Silviana Lee
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Sumeet Nayak
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - John Krais
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | | | - Jennifer Calvo
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Nicholas J Panzarino
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - John J Turchi
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; NERx Biosciences, 212 W. 10th St., Suite A480, Indianapolis, IN 46202, USA
| | - Neil Johnson
- Molecular Therapeutics Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Jos Jonkers
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Sharon B Cantor
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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24
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Renaudin X, Lee M, Shehata M, Surmann EM, Venkitaraman AR. BRCA2 deficiency reveals that oxidative stress impairs RNaseH1 function to cripple mitochondrial DNA maintenance. Cell Rep 2021; 36:109478. [PMID: 34348152 PMCID: PMC8356021 DOI: 10.1016/j.celrep.2021.109478] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 06/16/2021] [Accepted: 07/13/2021] [Indexed: 01/07/2023] Open
Abstract
Oxidative stress is a ubiquitous cellular challenge implicated in aging, neurodegeneration, and cancer. By studying pathogenic mutations in the tumor suppressor BRCA2, we identify a general mechanism by which oxidative stress restricts mitochondrial (mt)DNA replication. BRCA2 inactivation induces R-loop accumulation in the mtDNA regulatory region and diminishes mtDNA replication initiation. In BRCA2-deficient cells, intracellular reactive oxygen species (ROS) are elevated, and ROS scavengers suppress the mtDNA defects. Conversely, wild-type cells exposed to oxidative stress by pharmacologic or genetic manipulation phenocopy these defects. Mechanistically, we find that 8-oxoguanine accumulation in mtDNA caused by oxidative stress suffices to impair recruitment of the mitochondrial enzyme RNaseH1 to sites of R-loop accrual, restricting mtDNA replication initiation. Thus, oxidative stress impairs RNaseH1 function to cripple mtDNA maintenance. Our findings highlight a molecular mechanism that links oxidative stress to mitochondrial dysfunction and is elicited by the inactivation of genes implicated in neurodegeneration and cancer. BRCA2-deficient cells accumulate mtDNA R-loops due to oxidative stress This stress creates 8-oxoguanine lesions impairing RNaseH1 recruitment to mtDNA RNaseH1 impairment triggers R-loop formation and restricts mtDNA replication Other sources of oxidative stress also cripple mtDNA maintenance via this mechanism
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Affiliation(s)
- Xavier Renaudin
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Miyoung Lee
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Mona Shehata
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Eva-Maria Surmann
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK.
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25
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Palleschi M, Tedaldi G, Sirico M, Virga A, Ulivi P, De Giorgi U. Moving beyond PARP Inhibition: Current State and Future Perspectives in Breast Cancer. Int J Mol Sci 2021; 22:ijms22157884. [PMID: 34360649 PMCID: PMC8346118 DOI: 10.3390/ijms22157884] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/15/2021] [Accepted: 07/20/2021] [Indexed: 12/27/2022] Open
Abstract
Breast cancer is the most frequent and lethal tumor in women and finding the best therapeutic strategy for each patient is an important challenge. PARP inhibitors (PARPis) are the first, clinically approved drugs designed to exploit synthetic lethality in tumors harboring BRCA1/2 mutations. Recent evidence indicates that PARPis have the potential to be used both in monotherapy and combination strategies in breast cancer treatment. In this review, we show the mechanism of action of PARPis and discuss the latest clinical applications in different breast cancer treatment settings, including the use as neoadjuvant and adjuvant approaches. Furthermore, as a class, PARPis show many similarities but also certain critical differences which can have essential clinical implications. Finally, we report the current knowledge about the resistance mechanisms to PARPis. A systematic PubMed search, using the entry terms “PARP inhibitors” and “breast cancer”, was performed to identify all published clinical trials (Phase I-II-III) and ongoing trials (ClinicalTrials.gov), that have been reported and discussed in this review.
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Affiliation(s)
- Michela Palleschi
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (M.P.); (M.S.); (U.D.G.)
| | - Gianluca Tedaldi
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (A.V.); (P.U.)
- Correspondence: ; Tel.: +39-0543-739232; Fax: +39-0543-739221
| | - Marianna Sirico
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (M.P.); (M.S.); (U.D.G.)
| | - Alessandra Virga
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (A.V.); (P.U.)
| | - Paola Ulivi
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (A.V.); (P.U.)
| | - Ugo De Giorgi
- Department of Medical Oncology, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) “Dino Amadori”, 47014 Meldola, Italy; (M.P.); (M.S.); (U.D.G.)
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26
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Missense Variants of Uncertain Significance: A Powerful Genetic Tool for Function Discovery with Clinical Implications. Cancers (Basel) 2021; 13:cancers13153719. [PMID: 34359619 PMCID: PMC8345083 DOI: 10.3390/cancers13153719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/19/2021] [Accepted: 07/21/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Variants of uncertain significance in the breast cancer susceptibility gene BRCA2 represent 50–80% of the results from genetic testing. These mutations may lead to the dysfunction of the gene, thus conferring breast cancer predisposition; however, because they are rare and their impact on the function is not easy to predict, their classification into benign or pathogenic variants remains a challenge. By focusing on three specific rare missense variants identified in breast cancer patients, in this review, we discuss how the functional evaluation of this type of variants can be used to reveal novel activities of BRCA2. Based on these findings, we suggest additional functional tests that might be required for accurate variant classification and how their characterization may be leveraged to find novel clinical strategies for patients bearing these mutations. Abstract The breast cancer susceptibility gene BRCA2 encodes a multifunctional protein required for the accurate repair of DNA double-strand breaks and replicative DNA lesions. In addition, BRCA2 exhibits emerging important roles in mitosis. As a result, mutations in BRCA2 may affect chromosomal integrity in multiple ways. However, many of the BRCA2 mutations found in breast cancer patients and their families are single amino acid substitutions, sometimes unique, and their relevance in cancer risk remains difficult to assess. In this review, we focus on three recent reports that investigated variants of uncertain significance (VUS) located in the N-terminal region of BRCA2. In this framework, we make the case for how the functional evaluation of VUS can be a powerful genetic tool not only for revealing novel aspects of BRCA2 function but also for re-evaluating cancer risk. We argue that other functions beyond homologous recombination deficiency or “BRCAness” may influence cancer risk. We hope our discussion will help the reader appreciate the potential of these functional studies in the prevention and diagnostics of inherited breast and ovarian cancer. Moreover, these novel aspects in BRCA2 function might help find new therapeutic strategies.
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27
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Paul MW, Sidhu A, Liang Y, van Rossum-Fikkert SE, Odijk H, Zelensky AN, Kanaar R, Wyman C. Role of BRCA2 DNA-binding and C-terminal domain in its mobility and conformation in DNA repair. eLife 2021; 10:e67926. [PMID: 34254584 PMCID: PMC8324294 DOI: 10.7554/elife.67926] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 07/12/2021] [Indexed: 11/30/2022] Open
Abstract
Breast cancer type two susceptibility protein (BRCA2) is an essential protein in genome maintenance, homologous recombination (HR), and replication fork protection. Its function includes multiple interaction partners and requires timely localization to relevant sites in the nucleus. We investigated the importance of the highly conserved DNA-binding domain (DBD) and C-terminal domain (CTD) of BRCA2. We generated BRCA2 variants missing one or both domains in mouse embryonic stem (ES) cells and defined their contribution in HR function and dynamic localization in the nucleus, by single-particle tracking of BRCA2 mobility. Changes in molecular architecture of BRCA2 induced by binding partners of purified BRCA2 were determined by scanning force microscopy. BRCA2 mobility and DNA-damage-induced increase in the immobile fraction were largely unaffected by C-terminal deletions. The purified proteins missing CTD and/or DBD were defective in architectural changes correlating with reduced HR function in cells. These results emphasize BRCA2 activity at sites of damage beyond promoting RAD51 delivery.
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Affiliation(s)
- Maarten W Paul
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
| | - Arshdeep Sidhu
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
- Department of Radiation Oncology, Erasmus University Medical CenterRotterdamNetherlands
| | - Yongxin Liang
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
| | - Sarah E van Rossum-Fikkert
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
- Department of Radiation Oncology, Erasmus University Medical CenterRotterdamNetherlands
| | - Hanny Odijk
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
| | - Alex N Zelensky
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
| | - Claire Wyman
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical CenterRotterdamNetherlands
- Department of Radiation Oncology, Erasmus University Medical CenterRotterdamNetherlands
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28
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Lee M, Shorthouse D, Mahen R, Hall BA, Venkitaraman AR. Cancer-causing BRCA2 missense mutations disrupt an intracellular protein assembly mechanism to disable genome maintenance. Nucleic Acids Res 2021; 49:5588-5604. [PMID: 33978741 PMCID: PMC8191791 DOI: 10.1093/nar/gkab308] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/11/2021] [Accepted: 04/28/2021] [Indexed: 12/13/2022] Open
Abstract
Cancer-causing missense mutations in the 3418 amino acid BRCA2 breast and ovarian cancer suppressor protein frequently affect a short (∼340 residue) segment in its carboxyl-terminal domain (DBD). Here, we identify a shared molecular mechanism underlying their pathogenicity. Pathogenic BRCA2 missense mutations cluster in the DBD’s helical domain (HD) and OB1-fold motifs, which engage the partner protein DSS1. Pathogenic - but not benign – DBD mutations weaken or abolish DSS1-BRCA2 assembly, provoking mutant BRCA2 oligomers that are excluded from the cell nucleus, and disable DNA repair by homologous DNA recombination (HDR). DSS1 inhibits the intracellular oligomerization of wildtype, but not mutant, forms of BRCA2. Remarkably, DSS1 expression corrects defective HDR in cells bearing pathogenic BRCA2 missense mutants with weakened, but not absent, DSS1 binding. Our findings identify a DSS1-mediated intracellular protein assembly mechanism that is disrupted by cancer-causing BRCA2 missense mutations, and suggest an approach for its therapeutic correction.
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Affiliation(s)
- Miyoung Lee
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - David Shorthouse
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Robert Mahen
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Benjamin A Hall
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK
| | - Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Hills Road, Cambridge CB2 0XZ, UK.,The Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599 & Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove 138648, Singapore
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29
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Andreassen PR, Seo J, Wiek C, Hanenberg H. Understanding BRCA2 Function as a Tumor Suppressor Based on Domain-Specific Activities in DNA Damage Responses. Genes (Basel) 2021; 12:genes12071034. [PMID: 34356050 PMCID: PMC8307705 DOI: 10.3390/genes12071034] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/23/2021] [Accepted: 06/29/2021] [Indexed: 01/14/2023] Open
Abstract
BRCA2 is an essential genome stability gene that has various functions in cells, including roles in homologous recombination, G2 checkpoint control, protection of stalled replication forks, and promotion of cellular resistance to numerous types of DNA damage. Heterozygous mutation of BRCA2 is associated with an increased risk of developing cancers of the breast, ovaries, pancreas, and other sites, thus BRCA2 acts as a classic tumor suppressor gene. However, understanding BRCA2 function as a tumor suppressor is severely limited by the fact that ~70% of the encoded protein has not been tested or assigned a function in the cellular DNA damage response. Remarkably, even the specific role(s) of many known domains in BRCA2 are not well characterized, predominantly because stable expression of the very large BRCA2 protein in cells, for experimental purposes, is challenging. Here, we review what is known about these domains and the assay systems that are available to study the cellular roles of BRCA2 domains in DNA damage responses. We also list criteria for better testing systems because, ultimately, functional assays for assessing the impact of germline and acquired mutations identified in genetic screens are important for guiding cancer prevention measures and for tailored cancer treatments.
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Affiliation(s)
- Paul R. Andreassen
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
- Correspondence: ; Tel.: +1-(513)-636-0499
| | - Joonbae Seo
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
| | - Helmut Hanenberg
- Department of Otorhinolaryngology and Head/Neck Surgery, Heinrich Heine University, 40225 Düsseldorf, Germany; (C.W.); (H.H.)
- Department of Pediatrics III, Children’s Hospital, University of Duisburg-Essen, 45122 Essen, Germany
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30
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Mukherjee J, Pandita A, Kamalakar C, Johannessen TC, Ohba S, Tang Y, Dalle-Ore CL, Bjerkvig R, Pieper RO. RETRACTED: A subset of PARP inhibitors induces lethal telomere fusion in ALT-dependent tumor cells. Sci Transl Med 2021; 13:13/592/eabc7211. [PMID: 33952676 DOI: 10.1126/scitranslmed.abc7211] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/07/2020] [Accepted: 02/26/2021] [Indexed: 12/30/2022]
Abstract
About 10% of all tumors, including most lower-grade astrocytoma, rely on the alternative lengthening of telomere (ALT) mechanism to resolve telomeric shortening and avoid limitations on their growth. Here, we found that dependence on the ALT mechanism made cells hypersensitive to a subset of poly(ADP-ribose) polymerase inhibitors (PARPi). We found that this hypersensitivity was not associated with PARPi-created genomic DNA damage as in most PARPi-sensitive populations but rather with PARPi-induced telomere fusion. Mechanistically, we determined that PARP1 was recruited to the telomeres of ALT-dependent cells as part of a DNA damage response. By recruiting MRE11 and BRCC3 to stabilize TRF2 at the ends of telomeres, PARP1 blocked chromosomal fusion. Exposure of ALT-dependent tumor cells to a subset of PARPi induced a conformational change in PARP1 that limited binding to MRE11 and BRCC3 and delayed release of the TRF2-mediated block on lethal telomeric fusion. These results therefore provide a basis for PARPi treatment of ALT-dependent tumors, as well as establish chromosome fusion as a biomarker of their activity.
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Affiliation(s)
- Joydeep Mukherjee
- Department of Neurosurgery and The Brain Tumor Center, University of California-San Francisco, San Francisco, CA 94158, USA
| | - Ajay Pandita
- Core Diagnostics, 3535 Breakwater Avenue, Hayward, CA 94545, USA
| | - Chatla Kamalakar
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Tor-Christian Johannessen
- The Kristian Gerhard Jebsen Brain Tumor Research Centre, Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, 5019, Bergen, Norway
| | - Shigeo Ohba
- Department of Neurosurgery, Fujita Health University, Toyoake 4701192, Aichi, Japan
| | - Yongjian Tang
- Department of Neurosurgery and The Brain Tumor Center, University of California-San Francisco, San Francisco, CA 94158, USA
| | - Cecilia L Dalle-Ore
- Department of Neurosurgery and The Brain Tumor Center, University of California-San Francisco, San Francisco, CA 94158, USA
| | - Rolf Bjerkvig
- The Kristian Gerhard Jebsen Brain Tumor Research Centre, Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, 5019, Bergen, Norway.,Department of Oncology, Luxembourg Institute of Health, 84, Val Fleuri, L-1526, Luxembourg
| | - Russell O Pieper
- Department of Neurosurgery and The Brain Tumor Center, University of California-San Francisco, San Francisco, CA 94158, USA.
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31
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Canman CE. Which Holds the Key to BRCAness: Inability to Repair the Break, Protect the Fork, or Prevent the Gap? Cancer Res 2021; 81:1214-1215. [PMID: 33822743 DOI: 10.1158/0008-5472.can-20-4340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 11/16/2022]
Abstract
Defects in genes crucial for the process of DNA repair by homology-directed DNA repair (HDR), such as BRCA1 and BRCA2, are well-known contributors to cancer pathogenesis as well as an Achilles' heel that can be exploited therapeutically. BRCA1/2-deficient cells are exquisitely sensitive to agents that stall replication forks, such as PARP inhibitors and platinating drugs, presumably due to the inability to repair double-stranded breaks that form as a consequence of replication fork collapse. BRCA1/2 also promote tolerance to DNA replication stress by protecting replication forks from nucleolytic degradation. Both biological endpoints involve the deposition of RAD51 onto single-stranded DNA (ssDNA) for homology searching and strand exchange during HDR repair, as well as protection of newly synthesized DNA from nucleolytic degradation (i.e., replication fork protection). In this issue of Cancer Research, Panzarino and colleagues performed multiple separation-of-function studies and identify the lesion most associated with intolerance to replication stress in BRCA1/2-deficient cells is persistent ssDNA gaps in newly synthesized DNA, resulting from a failure to restrain DNA replication. Mechanisms that suppress gap formation are closely associated with chemoresistance, and the authors' findings challenge the paradigm that lack of HR repair or fork protection underlie the phenotype known as BRCAness.See related article by Panzarino et al., p. 1388.
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Affiliation(s)
- Christine E Canman
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan.
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32
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Panzarino NJ, Krais JJ, Cong K, Peng M, Mosqueda M, Nayak SU, Bond SM, Calvo JA, Doshi MB, Bere M, Ou J, Deng B, Zhu LJ, Johnson N, Cantor SB. Replication Gaps Underlie BRCA Deficiency and Therapy Response. Cancer Res 2020; 81:1388-1397. [PMID: 33184108 PMCID: PMC8026497 DOI: 10.1158/0008-5472.can-20-1602] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/02/2020] [Accepted: 11/09/2020] [Indexed: 11/16/2022]
Abstract
Defects in DNA repair and the protection of stalled DNA replication forks are thought to underlie the chemosensitivity of tumors deficient in the hereditary breast cancer genes BRCA1 and BRCA2 (BRCA). Challenging this assumption are recent findings that indicate chemotherapies, such as cisplatin used to treat BRCA-deficient tumors, do not initially cause DNA double-strand breaks (DSB). Here, we show that ssDNA replication gaps underlie the hypersensitivity of BRCA-deficient cancer and that defects in homologous recombination (HR) or fork protection (FP) do not. In BRCA-deficient cells, ssDNA gaps developed because replication was not effectively restrained in response to stress. Gap suppression by either restoration of fork restraint or gap filling conferred therapy resistance in tissue culture and BRCA patient tumors. In contrast, restored FP and HR could be uncoupled from therapy resistance when gaps were present. Moreover, DSBs were not detected after therapy when apoptosis was inhibited, supporting a framework in which DSBs are not directly induced by genotoxic agents, but rather are induced from cell death nucleases and are not fundamental to the mechanism of action of genotoxic agents. Together, these data indicate that ssDNA replication gaps underlie the BRCA cancer phenotype, "BRCAness," and we propose they are fundamental to the mechanism of action of genotoxic chemotherapies. SIGNIFICANCE: This study suggests that ssDNA replication gaps are fundamental to the toxicity of genotoxic agents and underlie the BRCA-cancer phenotype "BRCAness," yielding promising biomarkers, targets, and opportunities to resensitize refractory disease.See related commentary by Canman, p. 1214.
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Affiliation(s)
| | - John J Krais
- Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Ke Cong
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Min Peng
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Michelle Mosqueda
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Sumeet U Nayak
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Samuel M Bond
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jennifer A Calvo
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Mihir B Doshi
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Matt Bere
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jianhong Ou
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Bin Deng
- The University of Vermont, Burlington, Vermont
| | - Lihua J Zhu
- University of Massachusetts Medical School, Worcester, Massachusetts
| | - Neil Johnson
- Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Sharon B Cantor
- University of Massachusetts Medical School, Worcester, Massachusetts.
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33
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Kühbacher U, Duxin JP. How to fix DNA-protein crosslinks. DNA Repair (Amst) 2020; 94:102924. [PMID: 32683310 PMCID: PMC7511601 DOI: 10.1016/j.dnarep.2020.102924] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 12/18/2022]
Abstract
Proteins that act on DNA, or are in close proximity to it, can become inadvertently crosslinked to DNA and form highly toxic lesions, known as DNA-protein crosslinks (DPCs). DPCs are generated by different chemotherapeutics, environmental or endogenous sources of crosslinking agents, or by lesions on DNA that stall the catalytic cycle of certain DNA processing enzymes. These bulky adducts impair processes on DNA such as DNA replication or transcription, and therefore pose a serious threat to genome integrity. The large diversity of DPCs suggests that there is more than one canonical mechanism to repair them. Indeed, many different enzymes have been shown to act on DPCs by either processing the protein, the DNA or the crosslink itself. In addition, the cell cycle stage or cell type are likely to dictate pathway choice. In recent years, a detailed understanding of DPC repair during S phase has started to emerge. Here, we review the current knowledge on the mechanisms of replication-coupled DPC repair, and describe and also speculate on possible pathways that remove DPCs outside of S phase. Moreover, we highlight a recent paradigm shifting finding that indicates that DPCs are not always detrimental, but can also play a protective role, preserving the genome from more deleterious forms of DNA damage.
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Affiliation(s)
- Ulrike Kühbacher
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Julien P Duxin
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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Nguyen DD, Kim EY, Sang PB, Chai W. Roles of OB-Fold Proteins in Replication Stress. Front Cell Dev Biol 2020; 8:574466. [PMID: 33043007 PMCID: PMC7517361 DOI: 10.3389/fcell.2020.574466] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/25/2020] [Indexed: 12/20/2022] Open
Abstract
Accurate DNA replication is essential for maintaining genome stability. However, this stability becomes vulnerable when replication fork progression is stalled or slowed - a condition known as replication stress. Prolonged fork stalling can cause DNA damage, leading to genome instabilities. Thus, cells have developed several pathways and a complex set of proteins to overcome the challenge at stalled replication forks. Oligonucleotide/oligosaccharide binding (OB)-fold containing proteins are a group of proteins that play a crucial role in fork protection and fork restart. These proteins bind to single-stranded DNA with high affinity and prevent premature annealing and unwanted nuclease digestion. Among these OB-fold containing proteins, the best studied in eukaryotic cells are replication protein A (RPA) and breast cancer susceptibility protein 2 (BRCA2). Recently, another RPA-like protein complex CTC1-STN1-TEN1 (CST) complex has been found to counter replication perturbation. In this review, we discuss the latest findings on how these OB-fold containing proteins (RPA, BRCA2, CST) cooperate to safeguard DNA replication and maintain genome stability.
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Affiliation(s)
| | | | | | - Weihang Chai
- Department of Cancer Biology, Cardinal Bernardin Cancer Center, Loyola University Chicago Stritch School of Medicine, Maywood, IL, United States
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Zhou P, Wang J, Mishail D, Wang CY. Recent advancements in PARP inhibitors-based targeted cancer therapy. PRECISION CLINICAL MEDICINE 2020; 3:187-201. [PMID: 32983586 PMCID: PMC7501589 DOI: 10.1093/pcmedi/pbaa030] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/27/2020] [Accepted: 08/27/2020] [Indexed: 12/11/2022] Open
Abstract
Poly(ADP-ribose) polymerase inhibitors (PARPi) are a new class of agents with unparalleled clinical achievement for driving synthetic lethality in BRCA-deficient cancers. Recent FDA approval of PARPi has motivated clinical trials centered around the optimization of PARPi-associated therapies in a variety of BRCA-deficient cancers. This review highlights recent advancements in understanding the molecular mechanisms of PARP ‘trapping’ and synthetic lethality. Particular attention is placed on the potential extension of PARPi therapies from BRCA-deficient patients to populations with other homologous recombination-deficient backgrounds, and common characteristics of PARPi and non-homologous end-joining have been elucidated. The synergistic antitumor effect of combining PARPi with various immune checkpoint blockades has been explored to evaluate the potential of combination therapy in attaining greater therapeutic outcome. This has shed light onto the differing classifications of PARPi as well as the factors that result in altered PARPi activity. Lastly, acquired chemoresistance is a crucial issue for clinical application of PARPi. The molecular mechanisms underlying PARPi resistance and potential overcoming strategies are discussed.
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Affiliation(s)
- Ping Zhou
- Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA 90095, USA
| | - Justin Wang
- Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA 90095, USA
| | - Daniel Mishail
- Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA 90095, USA
| | - Cun-Yu Wang
- Laboratory of Molecular Signaling, Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA 90095, USA
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Combining PARP with ATR inhibition overcomes PARP inhibitor and platinum resistance in ovarian cancer models. Nat Commun 2020; 11:3726. [PMID: 32709856 PMCID: PMC7381609 DOI: 10.1038/s41467-020-17127-2] [Citation(s) in RCA: 162] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 06/04/2020] [Indexed: 02/03/2023] Open
Abstract
Ovarian cancer (OVCA) inevitably acquires resistance to platinum chemotherapy and PARP inhibitors (PARPi). We show that acquisition of PARPi-resistance is accompanied by increased ATR-CHK1 activity and sensitivity to ATR inhibition (ATRi). However, PARPi-resistant cells are remarkably more sensitive to ATRi when combined with PARPi (PARPi-ATRi). Sensitivity to PARPi-ATRi in diverse PARPi and platinum-resistant models, including BRCA1/2 reversion and CCNE1-amplified models, correlate with synergistic increases in replication fork stalling, double-strand breaks, and apoptosis. Surprisingly, BRCA reversion mutations and an ability to form RAD51 foci are frequently not observed in models of acquired PARPi-resistance, suggesting the existence of alternative resistance mechanisms. However, regardless of the mechanisms of resistance, complete and durable therapeutic responses to PARPi-ATRi that significantly increase survival are observed in clinically relevant platinum and acquired PARPi-resistant patient-derived xenografts (PDXs) models. These findings indicate that PARPi-ATRi is a highly promising strategy for OVCAs that acquire resistance to PARPi and platinum.
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Sato K, Brandsma I, van Rossum-Fikkert SE, Verkaik N, Oostra AB, Dorsman JC, van Gent DC, Knipscheer P, Kanaar R, Zelensky AN. HSF2BP negatively regulates homologous recombination in DNA interstrand crosslink repair. Nucleic Acids Res 2020; 48:2442-2456. [PMID: 31960047 PMCID: PMC7049687 DOI: 10.1093/nar/gkz1219] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 02/06/2023] Open
Abstract
The tumor suppressor BRCA2 is essential for homologous recombination (HR), replication fork stability and DNA interstrand crosslink (ICL) repair in vertebrates. We show that ectopic production of HSF2BP, a BRCA2-interacting protein required for meiotic HR during mouse spermatogenesis, in non-germline human cells acutely sensitize them to ICL-inducing agents (mitomycin C and cisplatin) and PARP inhibitors, resulting in a phenotype characteristic of cells from Fanconi anemia (FA) patients. We biochemically recapitulate the suppression of ICL repair and establish that excess HSF2BP compromises HR by triggering the removal of BRCA2 from the ICL site and thereby preventing the loading of RAD51. This establishes ectopic expression of a wild-type meiotic protein in the absence of any other protein-coding mutations as a new mechanism that can lead to an FA-like cellular phenotype. Naturally occurring elevated production of HSF2BP in tumors may be a source of cancer-promoting genomic instability and also a targetable vulnerability.
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Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Inger Brandsma
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Sari E van Rossum-Fikkert
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Nicole Verkaik
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Anneke B Oostra
- Department of Clinical Genetics, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Josephine C Dorsman
- Department of Clinical Genetics, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Dik C van Gent
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Alex N Zelensky
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
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38
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Physiological and Pathological Roles of RAD52 at DNA Replication Forks. Cancers (Basel) 2020; 12:cancers12020402. [PMID: 32050645 PMCID: PMC7072239 DOI: 10.3390/cancers12020402] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 02/07/2023] Open
Abstract
Understanding basic molecular mechanisms underlying the biology of cancer cells is of outmost importance for identification of novel therapeutic targets and biomarkers for patient stratification and better therapy selection. One of these mechanisms, the response to replication stress, fuels cancer genomic instability. It is also an Achille’s heel of cancer. Thus, identification of pathways used by the cancer cells to respond to replication-stress may assist in the identification of new biomarkers and discovery of new therapeutic targets. Alternative mechanisms that act at perturbed DNA replication forks and involve fork degradation by nucleases emerged as crucial for sensitivity of cancer cells to chemotherapeutics agents inducing replication stress. Despite its important role in homologous recombination and recombinational repair of DNA double strand breaks in lower eukaryotes, RAD52 protein has been considered dispensable in human cells and the full range of its cellular functions remained unclear. Very recently, however, human RAD52 emerged as an important player in multiple aspects of replication fork metabolism under physiological and pathological conditions. In this review, we describe recent advances on RAD52’s key functions at stalled or collapsed DNA replication forks, in particular, the unexpected role of RAD52 as a gatekeeper, which prevents unscheduled processing of DNA. Last, we will discuss how these functions can be exploited using specific inhibitors in targeted therapy or for an informed therapy selection.
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Abstract
In this review, Slade provides an overview of the molecular mechanisms and cellular consequences of PARP and PARG inhibition. The author also highlights the clinical performance of four PARP inhibitors used in cancer therapy (olaparib, rucaparib, niraparib, and talazoparib) and discusses the predictive biomarkers of inhibitor sensitivity and mechanisms of resistance as well as the means of overcoming them through combination therapy. Oxidative and replication stress underlie genomic instability of cancer cells. Amplifying genomic instability through radiotherapy and chemotherapy has been a powerful but nonselective means of killing cancer cells. Precision medicine has revolutionized cancer therapy by putting forth the concept of selective targeting of cancer cells. Poly(ADP-ribose) polymerase (PARP) inhibitors represent a successful example of precision medicine as the first drugs targeting DNA damage response to have entered the clinic. PARP inhibitors act through synthetic lethality with mutations in DNA repair genes and were approved for the treatment of BRCA mutated ovarian and breast cancer. PARP inhibitors destabilize replication forks through PARP DNA entrapment and induce cell death through replication stress-induced mitotic catastrophe. Inhibitors of poly(ADP-ribose) glycohydrolase (PARG) exploit and exacerbate replication deficiencies of cancer cells and may complement PARP inhibitors in targeting a broad range of cancer types with different sources of genomic instability. Here I provide an overview of the molecular mechanisms and cellular consequences of PARP and PARG inhibition. I highlight clinical performance of four PARP inhibitors used in cancer therapy (olaparib, rucaparib, niraparib, and talazoparib) and discuss the predictive biomarkers of inhibitor sensitivity, mechanisms of resistance as well as the means of overcoming them through combination therapy.
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Affiliation(s)
- Dea Slade
- Department of Biochemistry, Max Perutz Labs, Vienna Biocenter (VBC), University of Vienna, 1030 Vienna, Austria
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Zheng F, Zhang Y, Chen S, Weng X, Rao Y, Fang H. Mechanism and current progress of Poly ADP-ribose polymerase (PARP) inhibitors in the treatment of ovarian cancer. Biomed Pharmacother 2020; 123:109661. [PMID: 31931287 DOI: 10.1016/j.biopha.2019.109661] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 11/03/2019] [Accepted: 11/06/2019] [Indexed: 12/22/2022] Open
Abstract
Ovarian cancer is the most lethal gynecologic malignancy and the fifth most lethal cancer type overall in women. Ovarian cancer often presents genome instability, with almost half of the ovarian cancers harbor defects in one or more of the six DNA repair pathways, most of them in homologous recombination (HR). Targeting DNA repair genes has becoming a unique strategy to combat HR-deficient cancers in recent years. The multi-functional enzyme Poly ADP ribose polymerase (PARP) plays an impart role in DNA damage repair and genome stability. PARP inhibitors inhibit DNA repair pathways and cause apoptosis of cancer cells, especially in homologous recombination (HR)-deficient cells. PARP inhibitors (PARPi) have drawn increasing amount of attention due to their remarkable efficacy and low toxicity in treating HR-deficient ovarian cancers (i.e. BRCA1/2 mutated). To date, three PARP inhibitor drugs have been approved for treating ovarian cancer by FDA in United States, namely Olaparib, Rucaparib, and Niraparib. In this review, we summarized the current research progress of PARPi from basic science to clinical studies. We discussed the mechanism of action of PARP inhibitors and the exciting results from the clinical studies of the FDA-approved PARP inhibitors. We also highlighted the current research progress on PARP inhibitor resistance, which has become a challenge in clinics.
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Affiliation(s)
- Feiyue Zheng
- Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China; The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China
| | - Yi Zhang
- The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China
| | - Shuang Chen
- Hangzhou Obstetrics and Gynecology Hospital, Hangzhou, 310000, China
| | - Xiang Weng
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Yuefeng Rao
- The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China.
| | - Hongmei Fang
- Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China.
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41
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Venkitaraman AR. How do mutations affecting the breast cancer genes BRCA1 and BRCA2 cause cancer susceptibility? DNA Repair (Amst) 2019; 81:102668. [PMID: 31337537 PMCID: PMC6765401 DOI: 10.1016/j.dnarep.2019.102668] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The inheritance of monoallelic germline mutations affecting BRCA1 or BRCA2 predisposes with a high penetrance to several forms of epithelial malignancy. The large, nuclear-localized BRCA proteins act as custodians of chromosome integrity through distinct functions in the assembly and activity of macromolecular complexes that mediate DNA repair, replication reactivation and mitotic progression. The loss of these tumour suppressive functions following biallelic BRCA gene inactivation has long been thought to provoke genomic instability and carcinogenesis. However, recent studies not only identify new functions for BRCA1 and BRCA2 in the regulation of transcription and RNA processing potentially relevant to their tumour suppressive activity, but also suggest that monoallelic BRCA2 gene mutations suffice for carcinogenesis. This emerging evidence opens fresh lines of enquiry concerning tissue-specific cancer evolution in BRCA mutation carriers. Collectively, these insights engender new models to explain how BRCA gene mutations cause cancer susceptibility in specific tissues.
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Affiliation(s)
- Ashok R Venkitaraman
- Medical Research Council Cancer Unit, University of Cambridge, Box 197, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XZ, United Kingdom.
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Mateo J, Lord CJ, Serra V, Tutt A, Balmaña J, Castroviejo-Bermejo M, Cruz C, Oaknin A, Kaye SB, de Bono JS. A decade of clinical development of PARP inhibitors in perspective. Ann Oncol 2019; 30:1437-1447. [PMID: 31218365 PMCID: PMC6771225 DOI: 10.1093/annonc/mdz192] [Citation(s) in RCA: 419] [Impact Index Per Article: 83.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Genomic instability is a hallmark of cancer, and often is the result of altered DNA repair capacities in tumour cells. DNA damage repair defects are common in different cancer types; these alterations can also induce tumour-specific vulnerabilities that can be exploited therapeutically. In 2009, a first-in-man clinical trial of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib clinically validated the synthetic lethal interaction between inhibition of PARP1, a key sensor of DNA damage, and BRCA1/BRCA2 deficiency. In this review, we summarize a decade of PARP inhibitor clinical development, a work that has resulted in the registration of several PARP inhibitors in breast (olaparib and talazoparib) and ovarian cancer (olaparib, niraparib and rucaparib, either alone or following platinum chemotherapy as maintenance therapy). Over the past 10 years, our knowledge on the mechanism of action of PARP inhibitor as well as how tumours become resistant has been extended, and we summarise this work here. We also discuss opportunities for expanding the precision medicine approach with PARP inhibitors, identifying a wider population who could benefit from this drug class. This includes developing and validating better predictive biomarkers for patient stratification, mainly based on homologous recombination defects beyond BRCA1/BRCA2 mutations, identifying DNA repair deficient tumours in other cancer types such as prostate or pancreatic cancer, or by designing combination therapies with PARP inhibitors.
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Affiliation(s)
- J Mateo
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona; Vall d´Hebron University Hospital, Barcelona, Spain
| | - C J Lord
- The CRUK Gene Function Laboratory; The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London
| | - V Serra
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona
| | - A Tutt
- The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London; The Breast Cancer Now Research Unit, Guy's Cancer Centre, Kings College, London
| | - J Balmaña
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona; Vall d´Hebron University Hospital, Barcelona, Spain
| | | | - C Cruz
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona; Vall d´Hebron University Hospital, Barcelona, Spain
| | - A Oaknin
- Vall d'Hebron Institute of Oncology (VHIO), Barcelona; Vall d´Hebron University Hospital, Barcelona, Spain
| | - S B Kaye
- The Royal Marsden NHS Foundation Trust, London; The Institute of Cancer Research, London, UK
| | - J S de Bono
- The Royal Marsden NHS Foundation Trust, London; The Institute of Cancer Research, London, UK.
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Sun J, Chen J, Wang Z, Deng Y, Liu L, Liu X. [Expression of NUF2 in breast cancer and its clinical significance]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2019; 39:591-597. [PMID: 31140425 DOI: 10.12122/j.issn.1673-4254.2019.05.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To investigate the expression of the cell division- associated gene NUF2 in breast cancer and its clinical significance. METHODS The expression of NUF2 in breast cancer tissues was analyzed using Oncomine database. The relationship between the expression of NUF2 and the prognosis of breast cancer was analyzed using the Kaplan-Meier Plotter database. Gene set enrichment analysis (GSEA) and GEO database were used to investigate the effect of NUF2 on gene enrichment. The String database was utilized to analyze the proteins associated with NUF2. The TIMER database was analyzed to assess the correlations of NUF2 with BUB1, MAD2L1 and MYC. The expressions of NUF2 mRNA in 8 pairs of breast cancer tissues and adjacent tissues were verified by q-PCR. RESULTS Compared with that in normal breast tissue, NUF2 was significantly overexpressed in breast cancer (P < 0.001). The overall survival time (HR = 1.52, P = 0.015) and the recurrence-free survival time (HR = 1.85, P = 3.2e-14) of the patients with high NUF2 expression were significantly shorter than those of patients with low NUF2 expression. In patients with high NUF2 expression, the enriched genes were involved mainly in cell cycle, P53, G2/M, DNA repair, MYC, and PI3K-AKT-MTOR signaling pathways, which were associated with tumor proliferation, invasion, metastasis and stemness. Combination of the results of String database, gene enrichment and TIMER database analyses suggested that NUF2 interacted directly with BUB1, MAD2L1, and MYC, which could promote the progression of breast cancer. The results of q-PCR showed that NUF2 expression was up-regulated in 6 cancer tissues and down-regulated in 2 cancer tissues. CONCLUSIONS NUF2 gene is overexpressed in breast cancer, and its expression level is important in predicting the prognosis of breast cancer.
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Affiliation(s)
- Jingbo Sun
- Department of General Surgery, Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, China
| | - Jiawei Chen
- Southern Medical University, Guangzhou 510515, China
| | - Zhizhi Wang
- Southern Medical University, Guangzhou 510515, China
| | - Yunyao Deng
- Department of General Surgery, Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, China
| | - Lixin Liu
- Department of General Surgery, Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, China
| | - Xiaolong Liu
- Department of General Surgery, Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, China
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Abstract
Genome replication involves dealing with obstacles that can result from DNA damage but also from chromatin alterations, topological stress, tightly bound proteins or non-B DNA structures such as R loops. Experimental evidence reveals that an engaged transcription machinery at the DNA can either enhance such obstacles or be an obstacle itself. Thus, transcription can become a potentially hazardous process promoting localized replication fork hindrance and stress, which would ultimately cause genome instability, a hallmark of cancer cells. Understanding the causes behind transcription-replication conflicts as well as how the cell resolves them to sustain genome integrity is the aim of this review.
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45
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Gorodetska I, Kozeretska I, Dubrovska A. BRCA Genes: The Role in Genome Stability, Cancer Stemness and Therapy Resistance. J Cancer 2019; 10:2109-2127. [PMID: 31205572 PMCID: PMC6548160 DOI: 10.7150/jca.30410] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 02/20/2019] [Indexed: 12/14/2022] Open
Abstract
Carcinogenesis is a multistep process, and tumors frequently harbor multiple mutations regulating genome integrity, cell division and death. The integrity of cellular genome is closely controlled by the mechanisms of DNA damage signaling and DNA repair. The association of breast cancer susceptibility genes BRCA1 and BRCA2 with breast and ovarian cancer development was first demonstrated over 20 years ago. Since then the germline mutations within these genes were linked to genomic instability and increased risk of many other cancer types. Genomic instability is an engine of the oncogenic transformation of non-tumorigenic cells into tumor-initiating cells and further tumor evolution. In this review we discuss the biological functions of BRCA1 and BRCA2 genes and the role of BRCA mutations in tumor initiation, regulation of cancer stemness, therapy resistance and tumor progression.
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Affiliation(s)
- Ielizaveta Gorodetska
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Iryna Kozeretska
- Department of General and Medical Genetics, ESC "The Institute of Biology and Medicine", Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | - Anna Dubrovska
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany; German Cancer Consortium (DKTK), Partner site Dresden, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany
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Ca 2+-Stimulated AMPK-Dependent Phosphorylation of Exo1 Protects Stressed Replication Forks from Aberrant Resection. Mol Cell 2019; 74:1123-1137.e6. [PMID: 31053472 DOI: 10.1016/j.molcel.2019.04.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/04/2019] [Accepted: 03/29/2019] [Indexed: 12/22/2022]
Abstract
Abnormal processing of stressed replication forks by nucleases can cause fork collapse, genomic instability, and cell death. Despite its importance, it is poorly understood how the cell properly controls nucleases to prevent detrimental fork processing. Here, we report a signaling pathway that controls the activity of exonuclease Exo1 to prevent aberrant fork resection during replication stress. Our results indicate that replication stress elevates intracellular Ca2+ concentration ([Ca2+]i), leading to activation of CaMKK2 and the downstream kinase 5' AMP-activated protein kinase (AMPK). Following activation, AMPK directly phosphorylates Exo1 at serine 746 to promote 14-3-3 binding and inhibit Exo1 recruitment to stressed replication forks, thereby avoiding unscheduled fork resection. Disruption of this signaling pathway results in excessive ssDNA, chromosomal instability, and hypersensitivity to replication stress inducers. These findings reveal a link between [Ca2+]i and the replication stress response as well as a function of the Ca2+-CaMKK2-AMPK signaling axis in safeguarding fork structure to maintain genome stability.
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47
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Deveryshetty J, Peterlini T, Ryzhikov M, Brahiti N, Dellaire G, Masson JY, Korolev S. Novel RNA and DNA strand exchange activity of the PALB2 DNA binding domain and its critical role for DNA repair in cells. eLife 2019; 8:44063. [PMID: 31017574 PMCID: PMC6533086 DOI: 10.7554/elife.44063] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 04/23/2019] [Indexed: 12/14/2022] Open
Abstract
BReast Cancer Associated proteins 1 and 2 (BRCA1, -2) and Partner and Localizer of BRCA2 (PALB2) protein are tumour suppressors linked to a spectrum of malignancies, including breast cancer and Fanconi anemia. PALB2 coordinates functions of BRCA1 and BRCA2 during homology-directed repair (HDR) and interacts with several chromatin proteins. In addition to protein scaffold function, PALB2 binds DNA. The functional role of this interaction is poorly understood. We identified a major DNA-binding site of PALB2, mutations in which reduce RAD51 foci formation and the overall HDR efficiency in cells by 50%. PALB2 N-terminal DNA-binding domain (N-DBD) stimulates the function of RAD51 recombinase. Surprisingly, it possesses the strand exchange activity without RAD51. Moreover, N-DBD stimulates the inverse strand exchange and can use DNA and RNA substrates. Our data reveal a versatile DNA interaction property of PALB2 and demonstrate a critical role of PALB2 DNA binding for chromosome repair in cells.
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Affiliation(s)
- Jaigeeth Deveryshetty
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
| | - Thibaut Peterlini
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | - Mikhail Ryzhikov
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
| | - Nadine Brahiti
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | | | - Jean-Yves Masson
- Genome Stability LaboratoryCHU de Québec-Université Laval, Oncology Division, Laval University Cancer Research CenterQuébec CityCanada
| | - Sergey Korolev
- Edward A Doisy Department of Biochemistry and Molecular BiologySaint Louis University School of MedicineSaint LouisUnited States
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48
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Zhao W, Wiese C, Kwon Y, Hromas R, Sung P. The BRCA Tumor Suppressor Network in Chromosome Damage Repair by Homologous Recombination. Annu Rev Biochem 2019; 88:221-245. [PMID: 30917004 DOI: 10.1146/annurev-biochem-013118-111058] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations in the BRCA1 and BRCA2 genes predispose afflicted individuals to breast, ovarian, and other cancers. The BRCA-encoded products form complexes with other tumor suppressor proteins and with the recombinase enzyme RAD51 to mediate chromosome damage repair by homologous recombination and also to protect stressed DNA replication forks against spurious nucleolytic attrition. Understanding how the BRCA tumor suppressor network executes its biological functions would provide the foundation for developing targeted cancer therapeutics, but progress in this area has been greatly hampered by the challenge of obtaining purified BRCA complexes for mechanistic studies. In this article, we review how recent effort begins to overcome this technical challenge, leading to functional and structural insights into the biochemical attributes of these complexes and the multifaceted roles that they fulfill in genome maintenance. We also highlight the major mechanistic questions that remain.
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Affiliation(s)
- Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Claudia Wiese
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Youngho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
| | - Robert Hromas
- Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, USA.,Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229, USA; ,
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49
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Kwon M, Lee JJ, Min J, Hwang K, Park SG, Kim E, Kim BC, Bhak J, Lee H. Brca2 abrogation engages with the alternative lengthening of telomeres via break‐induced replication. FEBS J 2019; 286:1841-1858. [DOI: 10.1111/febs.14796] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/21/2019] [Accepted: 02/25/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Mi‐Sun Kwon
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Jennifer J. Lee
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Jaewon Min
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Kwangwoo Hwang
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
| | - Seung Gu Park
- Department of Biomedical Engineering UNIST Ulsan Korea
| | - Eun‐Hye Kim
- Department of Biomedical Engineering UNIST Ulsan Korea
| | | | - Jong Bhak
- Department of Biomedical Engineering UNIST Ulsan Korea
- Clinomics Inc. Ulsan Korea
| | - Hyunsook Lee
- Department of Biological Sciences Institute of Molecular Biology and Genetics (IMBG) Seoul National University South Korea
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50
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Mengwasser KE, Adeyemi RO, Leng Y, Choi MY, Clairmont C, D'Andrea AD, Elledge SJ. Genetic Screens Reveal FEN1 and APEX2 as BRCA2 Synthetic Lethal Targets. Mol Cell 2019. [PMID: 30686591 DOI: 10.1016/j.molcel.2018.12.008]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BRCA1 or BRCA2 inactivation drives breast and ovarian cancer but also creates vulnerability to poly(ADP-ribose) polymerase (PARP) inhibitors. To search for additional targets whose inhibition is synthetically lethal in BRCA2-deficient backgrounds, we screened two pairs of BRCA2 isogenic cell lines with DNA-repair-focused small hairpin RNA (shRNA) and CRISPR (clustered regularly interspaced short palindromic repeats)-based libraries. We found that BRCA2-deficient cells are selectively dependent on multiple pathways including base excision repair, ATR signaling, and splicing. We identified APEX2 and FEN1 as synthetic lethal genes with both BRCA1 and BRCA2 loss of function. BRCA2-deficient cells require the apurinic endonuclease activity and the PCNA-binding domain of Ape2 (APEX2), but not Ape1 (APEX1). Furthermore, BRCA2-deficient cells require the 5' flap endonuclease but not the 5'-3' exonuclease activity of Fen1, and chemically inhibiting Fen1 selectively targets BRCA-deficient cells. Finally, we developed a microhomology-mediated end-joining (MMEJ) reporter and showed that Fen1 participates in MMEJ, underscoring the importance of MMEJ as a collateral repair pathway in the context of homologous recombination (HR) deficiency.
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Affiliation(s)
- Kristen E Mengwasser
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Richard O Adeyemi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Yumei Leng
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Mei Yuk Choi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Connor Clairmont
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Stephen J Elledge
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA.
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