1
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Parker C, Chambers AC, Flanagan DJ, Ho JWY, Collard TJ, Ngo G, Baird DM, Timms P, Morgan RG, Sansom OJ, Williams AC. BCL-3 loss sensitises colorectal cancer cells to DNA damage by targeting homologous recombination. DNA Repair (Amst) 2022; 115:103331. [PMID: 35468497 PMCID: PMC10618080 DOI: 10.1016/j.dnarep.2022.103331] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 03/28/2022] [Accepted: 04/13/2022] [Indexed: 11/11/2022]
Abstract
The proto-oncogene BCL-3 is upregulated in a subset of colorectal cancers (CRC), where it has been shown to enhance tumour cell survival. However, although increased expression correlates with poor patient prognosis, the role of BCL-3 in determining therapeutic response remains largely unknown. In this study, we use combined approaches in multiple cell lines and pre-clinical mouse models to investigate the function of BCL-3 in the DNA damage response. We show that suppression of BCL-3 increases γH2AX foci formation and decreases homologous recombination in CRC cells, resulting in reduced RAD51 foci number and increased sensitivity to PARP inhibition. Importantly, a similar phenotype is seen in Bcl3-/- mice, where Bcl3-/- mouse crypts also exhibit sensitivity to DNA damage with increased γH2AX foci compared to wild type mice. Additionally, Apc.Kras-mutant x Bcl3-/- mice are more sensitive to cisplatin chemotherapy compared to wild type mice. Taken together, our results identify BCL-3 as a regulator of the cellular response to DNA damage and suggests that elevated BCL-3 expression, as observed in CRC, could increase resistance of tumour cells to DNA damaging agents including radiotherapy. These findings offer a rationale for targeting BCL-3 in CRC as an adjunct to conventional therapies and suggest that BCL-3 expression in tumours could be a useful biomarker in stratification of rectal cancer patients for neo-adjuvant chemoradiotherapy.
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Affiliation(s)
- Christopher Parker
- Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Faculty of Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Adam C Chambers
- Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Faculty of Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK.
| | - Dustin J Flanagan
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD UK; Biomedicine Discovery Institute, Monash University, Melbourne 3800, Australia
| | - Jasmine Wing Yu Ho
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD UK
| | - Tracey J Collard
- Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Faculty of Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Greg Ngo
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN UK
| | - Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN UK
| | - Penny Timms
- Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Faculty of Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK
| | - Rhys G Morgan
- School of Life Sciences, University of Sussex, Sussex House, Falmer, Brighton BN1 9RH UK
| | - Owen J Sansom
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD UK
| | - Ann C Williams
- Colorectal Tumour Biology Group, School of Cellular and Molecular Medicine, Faculty of Life Sciences, Biomedical Sciences Building, University Walk, University of Bristol, Bristol BS8 1TD, UK.
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2
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Hua LL, Casas C, Mikawa T. Mitotic Antipairing of Homologous Chromosomes. Results Probl Cell Differ 2022; 70:191-220. [PMID: 36348108 PMCID: PMC9731508 DOI: 10.1007/978-3-031-06573-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chromosome organization is highly dynamic and plays an essential role during cell function. It was recently found that pairs of the homologous chromosomes are continuously separated at mitosis and display a haploid (1n) chromosome set, or "antipairing," organization in human cells. Here, we provide an introduction to the current knowledge of homologous antipairing in humans and its implications in human disease.
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Affiliation(s)
- Lisa L. Hua
- Department of Biology, Sonoma State University, San Francisco
| | - Christian Casas
- Department of Biology, Sonoma State University, San Francisco
| | - Takashi Mikawa
- Department of Anatomy, Cardiovascular Research Institute, University of California, San Francisco,Corresponding author:
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3
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Kubelac P, Genestie C, Auguste A, Mesnage S, Le Formal A, Pautier P, Gouy S, Morice P, Bentivegna E, Maulard A, Adam J, Achimas-Cadariu P, Leary A. Changes in DNA Damage Response Markers with Treatment in Advanced Ovarian Cancer. Cancers (Basel) 2020; 12:E707. [PMID: 32192091 PMCID: PMC7140046 DOI: 10.3390/cancers12030707] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 03/08/2020] [Accepted: 03/11/2020] [Indexed: 12/19/2022] Open
Abstract
Ovarian cancer (OC) is sensitive to upfront chemotherapy, which is likely attributable to defects in DNA damage repair (DDR). Unfortunately, patients relapse and the evolution of DDR competency are poorly described. We examined the expression of proposed effectors in homologous recombination (HR: RAD51, ATM, FANCD2), error-prone non-homologous end-joining (NHEJ: 53BP1), and base excision repair pathways (BER: PAR and PARP1) in a cohort of sequential OC samples obtained at diagnosis, after neoadjuvant chemotherapy (NACT), and/or at relapse from a total of 147 patients. Immunohistochemical (IHC) expression was quantified using the H-score (0-300), where H ≤ 10 defined negativity. Before NACT, a significant number of cases lacked the expression of some effectors: 60%, 60%, and 24% were PAR-, FANCD2-, or RAD51-negative, with a reassuringly similar proportion of negative biomarkers after NACT. In multivariate analysis, there was a poorer progression-free survival (PFS) and overall survival (OS) for cases with competent HR at diagnosis (PRE-NACT 53BP1-/RAD51+, hazard ratio (HR) 3.13, p = 0.009 and HR 2.78, p = 0.024) and after NACT (POST-NACT FANCD2+/RAD51+ HR 1.89, p = 0.05 and HR 2.38, p = 0.02; POST-NACT PARP-1+/RAD51+ HR 1.79, p = 0.038 and HR 2.04, p = 0.034), reflecting proficient DNA repair. Overall, HR-competent tumors appeared to have a dismal prognosis in comparison with tumors utilizing NHEJ, as assessed either at baseline or post-NACT. Accurate knowledge of the HR status during treatment is clinically important for the efficient timing of platinum-based and targeted therapies with poly(ADP-ribose) polymerase inhibitors (PARPi).
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Affiliation(s)
- Paul Kubelac
- Department of Oncology, Iuliu Hatieganu University of Medicine and Pharmacy, 400012 Cluj Napoca, Romania; (P.K.); (P.A.-C.)
- The Oncology Institute “Prof. Dr. Ion Chiricuta”, 400015 Cluj Napoca, Romania
| | - Catherine Genestie
- INSERM U981, Gustave Roussy Cancer Center, 94805 Villejuif, France; (C.G.); (A.A.); (S.M.); (A.L.F.)
- Gustave Roussy Cancer Center, Department of Pathology, Université Paris-Saclay, 94805 Villejuif, France;
| | - Aurelie Auguste
- INSERM U981, Gustave Roussy Cancer Center, 94805 Villejuif, France; (C.G.); (A.A.); (S.M.); (A.L.F.)
| | - Soizick Mesnage
- INSERM U981, Gustave Roussy Cancer Center, 94805 Villejuif, France; (C.G.); (A.A.); (S.M.); (A.L.F.)
| | - Audrey Le Formal
- INSERM U981, Gustave Roussy Cancer Center, 94805 Villejuif, France; (C.G.); (A.A.); (S.M.); (A.L.F.)
| | - Patricia Pautier
- Gustave Roussy Cancer Center, Department of Medical Oncology, Université Paris-Saclay, 94805 Villejuif, France;
| | - Sebastien Gouy
- Gustave Roussy Cancer Center, Department of Surgery, Université Paris-Saclay, 94805 Villejuif, France; (S.G.); (P.M.); (E.B.); (A.M.)
| | - Philippe Morice
- Gustave Roussy Cancer Center, Department of Surgery, Université Paris-Saclay, 94805 Villejuif, France; (S.G.); (P.M.); (E.B.); (A.M.)
| | - Enrica Bentivegna
- Gustave Roussy Cancer Center, Department of Surgery, Université Paris-Saclay, 94805 Villejuif, France; (S.G.); (P.M.); (E.B.); (A.M.)
| | - Amandine Maulard
- Gustave Roussy Cancer Center, Department of Surgery, Université Paris-Saclay, 94805 Villejuif, France; (S.G.); (P.M.); (E.B.); (A.M.)
| | - Julien Adam
- Gustave Roussy Cancer Center, Department of Pathology, Université Paris-Saclay, 94805 Villejuif, France;
| | - Patriciu Achimas-Cadariu
- Department of Oncology, Iuliu Hatieganu University of Medicine and Pharmacy, 400012 Cluj Napoca, Romania; (P.K.); (P.A.-C.)
- The Oncology Institute “Prof. Dr. Ion Chiricuta”, 400015 Cluj Napoca, Romania
| | - Alexandra Leary
- INSERM U981, Gustave Roussy Cancer Center, 94805 Villejuif, France; (C.G.); (A.A.); (S.M.); (A.L.F.)
- Gustave Roussy Cancer Center, Department of Medical Oncology, Université Paris-Saclay, 94805 Villejuif, France;
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4
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The dichotomous effects of caffeine on homologous recombination in mammalian cells. DNA Repair (Amst) 2020; 88:102805. [PMID: 32062581 DOI: 10.1016/j.dnarep.2020.102805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 01/15/2020] [Accepted: 01/19/2020] [Indexed: 11/23/2022]
Abstract
This study was initiated to examine the effects of caffeine on the DNA damage response (DDR) and homologous recombination (HR) in mammalian cells. A 5 mM caffeine treatment caused the cell cycle to stall at G2/M and cells eventually underwent apoptosis. Caffeine exposure also induced a strong DDR along with subsequent activation of wildtype p53 protein. An unexpected observation was the caffeine-induced depletion of Rad51 (and Brca2) proteins. Consequently, caffeine-treated cells were expected to be inefficient in HR. However, a dichotomy in the HR response of cells to caffeine treatment was revealed. Caffeine treatment rendered cells significantly better at performing the nascent DNA synthesis that accompanies the early strand invasion steps of HR. Additionally, caffeine treatment increased chromatin accessibility and elevated the efficiency of illegitimate recombination. Conversely, the increase in nascent DNA synthesis did not translate into a higher number of gene targeting events. Thus, prolonged caffeine exposure stalls the cell cycle, induces a p53-mediated apoptotic response and a down-regulation of critical HR proteins, and for reasons discussed, stimulates early steps of HR, but not the formation of complete recombination products.
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5
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Gachechiladze M, Škarda J, Kolek V, Grygárková I, Langová K, Bouchal J, Kolář Z, Baty F, Stahel R, Weder W, Soltermann A, Joerger M. Prognostic and predictive value of loss of nuclear RAD51 immunoreactivity in resected non-small cell lung cancer patients. Lung Cancer 2017; 105:31-38. [PMID: 28236982 DOI: 10.1016/j.lungcan.2017.01.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 01/09/2017] [Accepted: 01/13/2017] [Indexed: 02/06/2023]
Abstract
OBJECTIVES In response to DNA damage, recombination proteins are relocalized into sub-nuclear complexes that are microscopically detected as RAD51-containing nuclear foci. We aimed for assessing the prognostic and predictive value of loss of nuclear RAD51 immunoreactivity ('RAD51 loss') in 2 independent stage I to III non-small cell lung cancer (NSCLC) patient cohorts undergoing surgical resection and eventual perioperative chemo-/radiotherapy (CT/RT). MATERIALS AND METHODS The discovery set included 69 evaluable patients (19 adenocarcinomas, ADC, 50 squamous cell carcinomas, SCC) from Palacky University Hospital, 45/69 (65.2%) with additional platinum-based CT. The replication set entailed 845 evaluable patients (446 ADC, 399 SCC) from University Hospital Zurich, 308/845 (36.5%) with platinum based CT or RT. RAD51 loss was defined as ≤20% of tumor cell nuclei having any nuclear RAD51 expression. We assessed the prognostic value of RAD51 loss in all patients and its predictive value in patients receiving CT/RT. RESULTS RAD51 loss was observed in 40/69 (58.0%) and 439/845 (51.9%) evaluable tumors in the discovery and replication set, respectively (p=0.34). It was more frequent in ADC compared to SCC (57.2% vs 47.4%, p=0.003). RAD51 loss was significantly associated with worse OS in both the discovery (adjusted HR=2.39, p=0.039) and replication set (adjusted HR=1.31, p=0.008). The unfavourable prognostic effect of RAD51 loss seen in the overall population was not observed in patients receiving perioperative CT (adjusted HR=1.07, p=0.73) or perioperative RT (adjusted HR=1.05, p=0.82). CONCLUSION RAD51 loss has an unfavourable prognostic impact in NSCLC patients undergoing curative surgical resection, but it may have a favourable predictive value in the subgroup of patients receiving perioperative platinum-based CT or RT, most likely as a consequence of deficient DNA repair.
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Affiliation(s)
- Mariam Gachechiladze
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czechia.
| | - Josef Škarda
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czechia
| | - Vítězslav Kolek
- Department of Tuberculosis and Respiratory Diseases, Faculty of Medicine and Dentistry, Palacký University and University Hospital, Olomouc, Czechia
| | - Ivona Grygárková
- Department of Tuberculosis and Respiratory Diseases, Faculty of Medicine and Dentistry, Palacký University and University Hospital, Olomouc, Czechia
| | - Kateřina Langová
- Department of Medical Biophysics, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czechia
| | - Jan Bouchal
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czechia
| | - Zdeněk Kolář
- Department of Clinical and Molecular Pathology, Institute of Translational and Molecular Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Czechia
| | - Florent Baty
- Department of Pneumology, Cantonal Hospital, St. Gallen, Switzerland
| | - Rolf Stahel
- Clinic of Oncology, University Hospital, Zurich, Switzerland
| | - Walter Weder
- Department of Thoracic Surgery, University Hospital, Zurich, Switzerland
| | - Alex Soltermann
- Department of Pathology and Molecular Pathology, University Hospital, Zurich, Switzerland
| | - Markus Joerger
- Department of Medical Oncology and Hematology, Cantonal Hospital, CH-9007 St. Gallen, Switzerland.
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6
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Parplys AC, Seelbach JI, Becker S, Behr M, Wrona A, Jend C, Mansour WY, Joosse SA, Stuerzbecher HW, Pospiech H, Petersen C, Dikomey E, Borgmann K. High levels of RAD51 perturb DNA replication elongation and cause unscheduled origin firing due to impaired CHK1 activation. Cell Cycle 2016; 14:3190-202. [PMID: 26317153 DOI: 10.1080/15384101.2015.1055996] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In response to replication stress ATR signaling through CHK1 controls the intra-S checkpoint and is required for the maintenance of genomic integrity. Homologous recombination (HR) comprises a series of interrelated pathways that function in the repair of DNA double strand breaks and interstrand crosslinks. In addition, HR, with its key player RAD51, provides critical support for the recovery of stalled forks during replication. High levels of RAD51 are regularly found in various cancers, yet little is known about the effect of the increased RAD51 expression on intra-S checkpoint signaling. Here, we describe a role for RAD51 in driving genomic instability caused by impaired replication and intra-S mediated CHK1 signaling by studying an inducible RAD51 overexpression model as well as 10 breast cancer cell lines. We demonstrate that an excess of RAD51 decreases I-Sce-I mediated HR despite formation of more RAD51 foci. Cells with high RAD51 levels display reduced elongation rates and excessive dormant origin firing during undisturbed growth and after damage, likely caused by impaired CHK1 activation. In consequence, the inability of cells with a surplus of RAD51 to properly repair complex DNA damage and to resolve replication stress leads to higher genomic instability and thus drives tumorigenesis.
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Affiliation(s)
- Ann Christin Parplys
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Jasna Irena Seelbach
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Saskia Becker
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Matthias Behr
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Agnieszka Wrona
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Camilla Jend
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Wael Yassin Mansour
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany.,b Tumor Biology Department; National Cancer Institute; Cairo University ; Cairo , Egypt
| | - Simon Andreas Joosse
- d Department of Tumor Biology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | | | - Helmut Pospiech
- f Leibniz Institute for Age Research - Fritz Lipmann Institute ; Jena , Germany.,g Faculty of Biochemistry and Molecular Medicine; University of Oulu ; Oulu , Finland
| | - Cordula Petersen
- c Department of Radiotherapy and Radiooncology ; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Ekkehard Dikomey
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
| | - Kerstin Borgmann
- a Laboratory of Radiobiology & Experimental Radiooncology; University Medical Center Hamburg-Eppendorf ; Hamburg , Germany
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Ozden O, Bishehsari F, Bauer J, Park SH, Jana A, Baik SH, Sporn JC, Staudacher JJ, Yazici C, Krett N, Jung B. Expression of an Oncogenic BARD1 Splice Variant Impairs Homologous Recombination and Predicts Response to PARP-1 Inhibitor Therapy in Colon Cancer. Sci Rep 2016; 6:26273. [PMID: 27197561 PMCID: PMC4873788 DOI: 10.1038/srep26273] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/26/2016] [Indexed: 01/30/2023] Open
Abstract
BRCA1-associated RING domain protein 1 (BARD1) stabilizes BRCA1 protein by forming a heterodimeric RING-RING complex, and impacts function of BRCA1, including homologous recombination (HR) repair. Although colon cancer cells usually express wild type BRCA1, presence of an oncogenic BARD1 splice variant (SV) in select cancers may render BRCA1 dysfunctional and allow cells to become sensitive to HR targeting therapies. We previously reported association of loss of full-length (FL) BARD1 with poor prognosis in colon cancer as well as expression of various BARD1 SVs with unknown function. Here we show that loss of BARD1 function through the expression of a BARD1 SV, BARD1β, results in a more malignant phenotype with decreased RAD51 foci formation, reduced BRCA1 E3 ubiquitin ligase activity, and decreased nuclear BRCA1 protein localization. BARD1β sensitizes colon cancer cells to poly ADP ribose polymerase 1 (PARP-1) inhibition even in a FL BRCA1 background. These results suggest that expression of BARD1β may serve as a future biomarker to assess suitability of colon cancers for HR targeting with PARP-1 inhibitors in treatment of advanced colon cancer.
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Affiliation(s)
- Ozkan Ozden
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Faraz Bishehsari
- Department of Internal Medicine, Division of Gastroenterology, Rush University Medical Center, Chicago, IL, 60612, U.S.A
| | - Jessica Bauer
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Seong-Hoon Park
- Department of Radiation Oncology, Robert Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, U.S.A
| | - Arundhati Jana
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Seung Hyun Baik
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Judith C Sporn
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Jonas J Staudacher
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Cemal Yazici
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Nancy Krett
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
| | - Barbara Jung
- Department of Medicine, Division of Gastroenterology, University of Illinois at Chicago, Chicago, IL 60612, U.S.A
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Abstract
Figuring out what is wrong in Fanconi anemia (FA) patient cells is critical to understanding the contributions of the FA pathway to DNA repair and tumor suppression. Although FA patients exhibit a wide range of disease manifestation as well as severity (asymptomatic to congenital abnormalities, bone marrow failure, and cancer), cells from FA patients share underlying defects in their ability to process DNA lesions that interfere with DNA replication. In particular, FA cells are very sensitive to agents that induce DNA interstrand crosslinks (ICLs). The cause of this pronounced ICL sensitivity is not fully understood, but has been linked to the aberrant activation of DNA damage repair proteins, checkpoints and pathways. Thus, regulation of these responses through coordination of repair processing at stalled replication forks is an essential function of the FA pathway. Here, we briefly summarize some of the aberrant DNA damage responses contributing to defects in FA cells, and detail the newly-identified relationship between FA and the mismatch repair protein, MSH2. Understanding the contribution of MSH2 and/or other proteins to the replication problem in FA cells will be key to assessing therapeutic options to improve the health of FA patients. Moreover, loss of these factors, if linked to improved replication, could be a key event in the progression of FA cells to cancer cells. Likewise, loss of these factors could synergize to enhance tumorigenesis or confer chemoresistance in tumors defective in FA-BRCA pathway proteins and provide a basis for biomarkers for disease progression and response.
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Affiliation(s)
- Sharon B Cantor
- a Department of Cancer Biology ; University of Massachusetts Medical School; UMASS Memorial Cancer Center ; Worcester , MA USA
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9
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Marchetti C, Ledermann JA, Benedetti Panici P. An overview of early investigational therapies for chemoresistant ovarian cancer. Expert Opin Investig Drugs 2015. [DOI: 10.1517/13543784.2015.1072168] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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10
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Yoshikawa Y, Morimatsu M, Ochiai K, Ishiguro-Oonuma T, Wada S, Orino K, Watanabe K. Reduced canine BRCA2 expression levels in mammary gland tumors. BMC Vet Res 2015. [PMID: 26202431 PMCID: PMC4512014 DOI: 10.1186/s12917-015-0483-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mammary tumors are the most common tumor type in intact female dogs. Recently, the breast cancer 2 early onset (BRCA2) gene was proposed to be associated with tumorigenesis in dogs. The expression level of BRCA2 is important for its DNA repair function in mammalian cells, and its expression level is linked to tumorigenesis in mammary tissue. However, the expression of canine BRCA2 in mammary tumors is unclear. RESULTS BRCA2 mRNA levels were compared between seven mammary gland samples and seventeen mammary tumor samples isolated from dogs. The expression level of canine BRCA2 in mammary tumor samples was lower than levels in mammary gland samples. We attempted to identify why the BRCA2 expression level was decreased in mammary tumor samples by promoter sequencing analysis; however, we did not find any mutations in the canine BRCA2 promoter that altered BRCA2 transcription levels. We did detect two types of BRCA2 splice variants in 8 mammary tumor samples. One of the variants induced a frame-shift mutation that could lead to nonsense-mediated mRNA decay, a ubiquitous cellular mechanism that eliminates mRNA containing a premature termination codon. CONCLUSIONS Reduced expression of canine BRCA2 mRNA in mammary tumor samples is a possible mechanism to explain mammary tumor development in dogs. One possible reason for reduced BRCA2 mRNA levels in these tumor samples was nonsense-mediated mRNA decay, not mutations in the BRCA2 promoter region. While it remains unclear why canine BRCA2 expression levels are reduced in mammary tumor samples, this study found that the expression level of BRCA2 was associated with canine mammary tumorigenesis.
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Affiliation(s)
- Yasunaga Yoshikawa
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Aomori, 034-8628, Japan.
| | - Masami Morimatsu
- Laboratory of Laboratory Animal Science and Medicine, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan.
| | - Kazuhiko Ochiai
- Department of Basic Science, School of Veterinary Nursing and Technology, Nippon Veterinary and Life Science University, Tokyo, 180-8602, Japan.
| | - Toshina Ishiguro-Oonuma
- Department of Biological Resources, Integrated Center for Science, Ehime University, Ehime, 791-0295, Japan.
| | - Seiichi Wada
- Laboratory of Veterinary Radiology and Radiation Biology, School of Veterinary Medicine, Kitasato University, Aomori, 034-8628, Japan.
| | - Koichi Orino
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Aomori, 034-8628, Japan.
| | - Kiyotaka Watanabe
- Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Aomori, 034-8628, Japan.
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11
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Lee JM, Gordon N, Trepel JB, Lee MJ, Yu M, Kohn EC. Development of a multiparameter flow cytometric assay as a potential biomarker for homologous recombination deficiency in women with high-grade serous ovarian cancer. J Transl Med 2015; 13:239. [PMID: 26198537 PMCID: PMC4508767 DOI: 10.1186/s12967-015-0604-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/13/2015] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVES PARP inhibitors (PARPi) are a novel class of drugs with activity in patients with acquired or germline homologous recombination (HR) deficiency-associated high-grade serous ovarian cancer (HGSOC). We hypothesized that measuring γH2AX as an indicator of DNA double-strand breaks (DSB), and MRE11 or RAD51 as an indicator of DSB repair, would reflect HR status and predict response to PARPi-based therapy. Our aim was to develop and use high-throughput multiparametric flow cytometry to quantify γH2AX with MRE11 or RAD51 in PBMCs as a readily available surrogate. METHODS Healthy donor PBMCs were used for assay development and optimization. We validated induction of γH2AX, MRE11 and RAD51 by staining with fluorophore-conjugated antibodies. The multiparameter flow cytometric method was applied to PBMC samples from recurrent HGSOC patients who were treated with PARPi, olaparib and carboplatin. RESULTS Stimulation was necessary for quantification of a DNA damage response to olaparib/carboplatin in healthy donor PBMCs. The flow cytometric protocol could not distinguish between cytoplasmic and nuclear RAD51, erroneously indicating activation in response to injury. Thus, MRE11 was selected as the marker of DSB repair. PBMCs from 15 recurrent HGSOC patients were then examined. Patients who did not respond to PARPi therapy had a significantly higher pre-treatment level of γH2AX (p = 0.01), and a higher ratio of γH2AX/MRE11 (11.0 [3.5-13.2] v. 3.3 [2.8-9.9], p < 0.03) compared with responders. CONCLUSIONS We successfully developed and applied a multiparameter flow cytometry assay to measure γH2AX and MRE11 in PBMCs. Prospective studies will be required to validate this surrogate biomarker assay as a potential predictive biomarker of PARPi-based therapy.
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Affiliation(s)
- Jung-Min Lee
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, 10 Center Dr. MSC1906, Building 10, Room 12N/226, Bethesda, MD, 20892-1906, USA.
| | - Nicolas Gordon
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, 10 Center Dr. MSC1906, Building 10, Room 12N/226, Bethesda, MD, 20892-1906, USA.
| | - Jane B Trepel
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.
| | - Min-Jung Lee
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.
| | - Minshu Yu
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, 10 Center Dr. MSC1906, Building 10, Room 12N/226, Bethesda, MD, 20892-1906, USA.
| | - Elise C Kohn
- Women's Malignancies Branch, Center for Cancer Research, National Cancer Institute, 10 Center Dr. MSC1906, Building 10, Room 12N/226, Bethesda, MD, 20892-1906, USA.
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12
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Zhang J. Poly (ADP-ribose) polymerase inhibitor: an evolving paradigm in the treatment of prostate cancer. Asian J Androl 2014; 16:401-6. [PMID: 24589464 PMCID: PMC4023365 DOI: 10.4103/1008-682x.123684] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Recent phase I studies have reported single-agent activities of poly (ADP-ribose) polymerase (PARP) inhibitor in sporadic and in BRCA-mutant prostate cancers. Two of the most common genetic alterations in prostate cancer, ETS gene rearrangement and loss of PTEN, have been linked to increased sensitivity to PARP inhibitor in preclinical models. Emerging evidence also suggests that PARP1 plays an important role in mediating the transcriptional activities of androgen receptor (AR) and ETS gene rearrangement. In this article, the preclinical work and early-phase clinical trials in developing PARP inhibitor-based therapy as a new treatment paradigm for metastatic prostate cancer are reviewed.
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Affiliation(s)
- Jingsong Zhang
- Department of Genitourinary Oncology and Department of Cancer Imaging and Metabolism, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
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13
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Shahid T, Soroka J, Kong E, Malivert L, McIlwraith MJ, Pape T, West SC, Zhang X. Structure and mechanism of action of the BRCA2 breast cancer tumor suppressor. Nat Struct Mol Biol 2014; 21:962-968. [PMID: 25282148 PMCID: PMC4222816 DOI: 10.1038/nsmb.2899] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/04/2014] [Indexed: 02/06/2023]
Abstract
Mutations in BRCA2 increase susceptibility to breast, ovarian and prostate cancers. The product of human BRCA2, BRCA2 protein, has a key role in the repair of DNA double-strand breaks and interstrand cross-links by RAD51-mediated homologous recombination. Here, we present a biochemical and structural characterization of full-length (3,418 amino acid) BRCA2, alone and in complex with RAD51. We show that BRCA2 facilitates nucleation of RAD51 filaments at multiple sites on single-stranded DNA. Three-dimensional EM reconstructions revealed that BRCA2 exists as a dimer and that two oppositely oriented sets of RAD51 molecules bind the dimer. Single-stranded DNA binds along the long axis of BRCA2, such that only one set of RAD51 monomers can form a productive complex with DNA and establish filament formation. Our data define the molecular mechanism by which this tumor suppressor facilitates RAD51-mediated homologous-recombinational repair.
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Affiliation(s)
- Taha Shahid
- Centre for Structural Biology, Imperial College, London, U.K
| | - Joanna Soroka
- London Research Institute, Clare Hall Laboratories, South Mimms, U.K
| | - Eric Kong
- Centre for Structural Biology, Imperial College, London, U.K
| | - Laurent Malivert
- London Research Institute, Clare Hall Laboratories, South Mimms, U.K
| | | | - Tillman Pape
- Centre for Structural Biology, Imperial College, London, U.K
| | - Stephen C. West
- London Research Institute, Clare Hall Laboratories, South Mimms, U.K
| | - Xiaodong Zhang
- Centre for Structural Biology, Imperial College, London, U.K
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14
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Abstract
Ovarian cancer is the leading cause of gynecologic cancer death in women. Our understanding of the treatment of ovarian cancer has evolved over the last decade, with the use neo-adjuvant chemotherapy, combined intravenous-intraperitoneal (IV-IP) chemotherapy, as well as dose dense paclitaxel. Despite significant improvements in overall survival, the majority of patients succumb to recurrent chemotherapy resistant disease. Given the above, an emphasis has been placed on exploring alternate therapeutics. Recent research efforts have improved our understanding of the molecular biology of ovarian cancer and novel targeted treatment strategies have emerged. With the discovery of BRCA1 and BRCA2 gene mutations, and a more comprehensive assessment of heredity ovarian cancer syndrome, targeted interventions exploiting this biologic susceptibility have emerged. To date, the most studied of these have been PARP inhibitors. The purpose of this review will be to discuss PARP inhibition in advanced stage ovarian cancer, highlighting recent scientific advancements.
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Affiliation(s)
- Ramez N Eskander
- Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, University of California Irvine Medical Center, Building 56 Room 260, 101 The City Dr., Orange, CA 92868, USA
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15
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Wu M, Wang X, McGregor N, Pienta KJ, Zhang J. Dynamic regulation of Rad51 by E2F1 and p53 in prostate cancer cells upon drug-induced DNA damage under hypoxia. Mol Pharmacol 2014; 85:866-76. [PMID: 24627085 PMCID: PMC4014666 DOI: 10.1124/mol.113.090688] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 03/13/2014] [Indexed: 01/06/2023] Open
Abstract
Intratumoral hypoxia has been proposed to create a "mutator" phenotype through downregulation of DNA repair, leading to increased genomic instability and drug resistance. Such downregulation of DNA repair has been proposed to sensitize hypoxic cancer cells to DNA-damaging agents and inhibitors of DNA repair. Here, we showed that prostate cancer cells with mutant p53 were resistant to the poly(ADP-ribose) polymerase inhibitor, veliparib (2-[(2R)-2-methylpyrrolidin-2-yl]-1H-benzimidazole-4-carboxamide, dihydrochloride; Abbott Laboratories, Abbott Park, IL), and the DNA-damaging topoisomerase I inhibitor camptothecin-11 (CPT-11) or SN38 (7-ethyl-10-hydroxycamptothecin) under hypoxia. Upregulation of Rad51 by E2F1 upon DNA damage under hypoxia contributed to such resistance, which was reversed by either inhibiting RAD51 transcription with small interfering RNA or by expressing wild-type p53 in the p53 null prostate cancer line. Accumulation of endogenous p53 but not E2F1 and suppressed RAD51 transcription was observed in prostate cancer line with wild-type p53 after DNA damage under hypoxia. Combining veliparib with CPT-11 significantly enhanced DNA damage and apoptosis under both hypoxic and normoxic culture conditions. Such enhanced DNA damage and antitumor activities were seen in the presence of Rad51 upregulation and confirmed in vivo with PC3 mouse xenografts. These data illustrate a dynamic regulation of Rad51 by E2F1 and p53 in prostate cancer cells' response to hypoxia and DNA damage. The veliparib and CPT-11 combination can be further explored as a treatment of metastatic castration-resistant prostate cancers that have frequent p53 mutations and enriched genomic instability.
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Affiliation(s)
- Minghui Wu
- Department of Genitourinary Oncology and Department of Cancer Imaging and Metabolism, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida (M.W., X.W., J.Z.); and University of Michigan Comprehensive Cancer Center, Ann Arbor, Michigan (N.M., K.J.P.)
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16
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Mason JM, Logan HL, Budke B, Wu M, Pawlowski M, Weichselbaum RR, Kozikowski AP, Bishop DK, Connell PP. The RAD51-stimulatory compound RS-1 can exploit the RAD51 overexpression that exists in cancer cells and tumors. Cancer Res 2014; 74:3546-55. [PMID: 24753542 DOI: 10.1158/0008-5472.can-13-3220] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RAD51 is the central protein that catalyzes DNA repair via homologous recombination, a process that ensures genomic stability. RAD51 protein is commonly expressed at high levels in cancer cells relative to their noncancerous precursors. High levels of RAD51 expression can lead to the formation of genotoxic RAD51 protein complexes on undamaged chromatin. We developed a therapeutic approach that exploits this potentially toxic feature of malignancy, using compounds that stimulate the DNA-binding activity of RAD51 to promote cancer cell death. A panel of immortalized cell lines was challenged with the RAD51-stimulatory compound RS-1. Resistance to RS-1 tended to occur in cells with higher levels of RAD54L and RAD54B, which are Swi2/Snf2-related translocases known to dissociate RAD51 filaments from dsDNA. In PC3 prostate cancer cells, RS-1-induced lethality was accompanied by the formation of microscopically visible RAD51 nuclear protein foci occurring in the absence of any DNA-damaging treatment. Treatment with RS-1 promoted significant antitumor responses in a mouse model, providing proof-of-principle for this novel therapeutic strategy.
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Affiliation(s)
- Jennifer M Mason
- Authors' Affiliations: Department of Radiation and Cellular Oncology
| | - Hillary L Logan
- Authors' Affiliations: Department of Radiation and Cellular Oncology
| | - Brian Budke
- Authors' Affiliations: Department of Radiation and Cellular Oncology
| | - Megan Wu
- Authors' Affiliations: Department of Radiation and Cellular Oncology
| | - Michal Pawlowski
- Department of Medicinal Chemistry and Pharmacognosy, Drug Discovery Program, University of Illinois at Chicago, Chicago, Illinois
| | - Ralph R Weichselbaum
- Authors' Affiliations: Department of Radiation and Cellular Oncology, Ludwig Center for Metastasis Research
| | - Alan P Kozikowski
- Department of Medicinal Chemistry and Pharmacognosy, Drug Discovery Program, University of Illinois at Chicago, Chicago, Illinois
| | - Douglas K Bishop
- Authors' Affiliations: Department of Radiation and Cellular Oncology, Department of Molecular Genetics and Cell Biology, University of Chicago; and
| | - Philip P Connell
- Authors' Affiliations: Department of Radiation and Cellular Oncology,
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17
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Nascent DNA synthesis during homologous recombination is synergistically promoted by the rad51 recombinase and DNA homology. Genetics 2014; 197:107-19. [PMID: 24583581 DOI: 10.1534/genetics.114.161455] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In this study, we exploited a plasmid-based assay that detects the new DNA synthesis (3' extension) that accompanies Rad51-mediated homology searching and strand invasion steps of homologous recombination to investigate the interplay between Rad51 concentration and homology length. Mouse hybridoma cells that express endogenous levels of Rad51 display an approximate linear increase in the frequency of 3' extension for homology lengths of 500 bp to 2 kb. At values below ∼500 bp, the frequency of 3' extension declines markedly, suggesting that this might represent the minimal efficient processing segment for 3' extension. Overexpression of wild-type Rad51 stimulated the frequency of 3' extension by ∼3-fold for homology lengths <900 bp, but when homology was >2 kb, 3' extension frequency increased by as much as 10-fold. Excess wild-type Rad51 did not increase the average 3' extension tract length. Analysis of cell lines expressing N-terminally FLAG-tagged Rad51 polymerization mutants F86E, A89E, or F86E/A89E established that the 3' extension process requires Rad51 polymerization activity. Mouse hybridoma cells that have reduced Brca2 (Breast cancer susceptibility 2) due to stable expression of small interfering RNA show a significant reduction in 3' extension efficiency; expression of wild-type human BRCA2, but not a BRCA2 variant devoid of BRC repeats 1-8, rescues the 3' extension defect in these cells. Our results suggest that increased Rad51 concentration and homology length interact synergistically to promote 3' extension, presumably as a result of enhanced Brca2-mediated Rad51 polymerization.
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18
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Lee JM, Ledermann JA, Kohn EC. PARP Inhibitors for BRCA1/2 mutation-associated and BRCA-like malignancies. Ann Oncol 2014; 25:32-40. [PMID: 24225019 PMCID: PMC3868320 DOI: 10.1093/annonc/mdt384] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 08/02/2013] [Accepted: 08/14/2013] [Indexed: 12/11/2022] Open
Abstract
Poly(ADP-ribose)polymerase inhibitors (PARPis) have shown promising activity in patients with BRCA1/2 mutation-associated (BRCA1/2(MUT+)) ovarian and breast cancers. Accumulating evidence suggests that PARPi may have a wider application in the treatment of sporadic high-grade serous ovarian cancer, and cancers defective in DNA repair pathways, such as prostate, endometrial, and pancreatic cancers. Several PARPis are currently in phase 1/2 clinical investigation, with registration trials now being designed. Olaparib, one of the most studied PARPis, has demonstrated activity in BRCA1/2(MUT+) and BRCA-like sporadic ovarian and breast cancers, and looks promising in prostate and pancreatic cancers. Understanding more about the molecular abnormalities involved in BRCA-like tumors, exploring novel therapeutic trial strategies and drug combinations, and defining potential predictive biomarkers, is critical to rapidly advancing the field of PARPi therapy and improve clinical outcomes.
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Affiliation(s)
- J-m. Lee
- Molecular Signaling Section, Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, USA
| | | | - E. C. Kohn
- Molecular Signaling Section, Medical Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, USA
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19
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Arbini AA, Guerra F, Greco M, Marra E, Gandee L, Xiao G, Lotan Y, Gasparre G, Hsieh JT, Moro L. Mitochondrial DNA depletion sensitizes cancer cells to PARP inhibitors by translational and post-translational repression of BRCA2. Oncogenesis 2013; 2:e82. [PMID: 24336406 PMCID: PMC3940862 DOI: 10.1038/oncsis.2013.45] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/25/2013] [Accepted: 10/29/2013] [Indexed: 12/15/2022] Open
Abstract
Previous studies have shown that pharmacologic inhibition of poly (ADP-ribose) polymerase (PARP), a nuclear protein that is crucial in signaling single-strand DNA breaks, is synthetically lethal to cancer cells from patients with genetic deficiency in the DNA repair proteins BRCA1 and BRCA2. Herein, we demonstrate that depletion of the mitochondrial genome (mtDNA) in breast, prostate and thyroid transformed cells resulted in elevated steady-state cytosolic calcium concentration and activation of calcineurin/PI3-kinase/AKT signaling leading to upregulation of miR-1245 and the ubiquitin ligase Skp2, two potent negative regulators of the tumor suppressor protein BRCA2, thus resulting in BRCA2 protein depletion, severe reduction in homologous recombination (HR) and increased sensitivity to the PARP inhibitor rucaparib. Treatment of mtDNA-depleted cells with the PI3-kinase inhibitor LY294002, the calmodulin antagonist W-7, the calcineurin inhibitor FK506, the calcium chelator BAPTA-AM, or suppression of AKT activity by AKT small-interfering RNA (siRNA) enhanced BRCA2 protein levels as well as HR. Decreasing the intracellular calcium levels using BAPTA, or direct reconstitution of BRCA2 protein levels either by recombinant expression or by small molecule inhibition of both Skp2 and miR-1245 restored sensitivity to rucaparib to wild-type levels. Furthermore, by studying prostate tissue specimens from prostate carcinoma patients we found a direct correlation between the presence of mtDNA large deletions and loss of BRCA2 protein in vivo, suggesting that mtDNA status may serve as a marker to predict therapeutic efficacy to PARP inhibitors. In summary, our results uncover a novel mechanism by which mtDNA depletion restrains HR, and highlight the role of mtDNA in regulating sensitivity to PARP inhibitors in transformed cells.
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Affiliation(s)
- A A Arbini
- Department of Pathology, New York University Medical Center, New York, NY, USA
| | - F Guerra
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - M Greco
- Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Italy
| | - E Marra
- Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Italy
| | - L Gandee
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - G Xiao
- Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Y Lotan
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - G Gasparre
- Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - J-T Hsieh
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - L Moro
- 1] Department of Pathology, New York University Medical Center, New York, NY, USA [2] Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Italy [3] Department of Urology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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20
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Magwood AC, Malysewich MJ, Cealic I, Mundia MM, Knapp J, Baker MD. Endogenous levels of Rad51 and Brca2 are required for homologous recombination and regulated by homeostatic re-balancing. DNA Repair (Amst) 2013; 12:1122-33. [PMID: 24210700 DOI: 10.1016/j.dnarep.2013.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 10/15/2013] [Indexed: 12/17/2022]
Abstract
Stable expression of Rad51 siRNA was used to generate mouse hybridoma cell lines in which endogenous Rad51 levels were depleted by as much as 60%. Stable Rad51 knockdowns feature reduced homologous recombination responses. The relative ease with which stable Rad51 knockdowns were recovered was surprising, given the embryonic lethality of Rad51 ablation. Interestingly, Rad51-depleted hybridoma cell lines are characterized by reduced levels of p53 protein. Completely unexpected, was the finding that Rad51-depleted hybridoma cell lines are also reduced for the breast cancer susceptibility 2 (Brca2) protein. Additionally, hybridoma cell lines that are siRNA depleted for mouse Brca2 show a corresponding reduction in Rad51 and p53 proteins. Furthermore, cellular levels of Rad51, Brca2 and p53 can be elevated in these cell lines by ectopic expression of wild-type human Rad51 and wild-type human BRCA2. In marked contrast, hybridoma cell lines that are siRNA depleted for mouse p53 feature relatively normal Rad51 and Brca2 levels. These results suggest that cellular levels of Brca2 and Rad51 are mutually dependent on each other, and that low levels of these proteins provide selective pressure for reduction of p53, which permits cell growth.
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Affiliation(s)
- Alissa C Magwood
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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21
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Optimize radiochemotherapy in pancreatic cancer: PARP inhibitors a new therapeutic opportunity. Mol Oncol 2012; 7:308-22. [PMID: 23148997 DOI: 10.1016/j.molonc.2012.10.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 10/09/2012] [Accepted: 10/10/2012] [Indexed: 12/17/2022] Open
Abstract
Cancer cells may use PARP enzymes and Homologous Recombination to repair single and double strand breaks caused by genotoxic insults. In this study, the PARP-1 inhibitor Rucaparib was utilized to increase the sensitivity to chemoradiotherapy treatment in BRCA-2-deficient and -proficient pancreatic cancer cells. We used the pancreatic cancer cell lines, Capan-1 with mutated BRCA-2 and Panc-1, AsPC-1 and MiaPaCa-2 with BRCA-1/2 wild type. Cells were treated with Rucaparib and/or radiotherapy (4-10 Gy) plus Gemcitabine then the capability to proliferate was evaluated by colony formation, cell counting and MTT assays. Flow cytometry, immunocytochemistry and western blotting were utilized to assess cell response to Rucaparib plus irradiation. The antitumour effectiveness of combining the PARP-1 inhibitor before, together and after radiotherapy evidenced the first as the optimal schedule in blocking cell growth. Pre-exposure to Rucaparib increased the cytotoxicity of Gemcitabine plus radiotherapy by heavily inducing the accumulation of cells in G2/M phase, impairing mitosis and finally inducing apoptosis and authophagy. The upregulation of p-Akt and downregulation of p53 were evidenced in MiaPaCa-2 which displayed replication stress features. For the first time, the rationale of using a PARP inhibitor as chemoradiosensitizer in pancreatic cancer models has been hypothesized and demonstrated.
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22
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Marchetti C, Imperiale L, Gasparri ML, Palaia I, Pignata S, Boni T, Bellati F, Benedetti Panici P. Olaparib, PARP1 inhibitor in ovarian cancer. Expert Opin Investig Drugs 2012; 21:1575-84. [PMID: 22788971 DOI: 10.1517/13543784.2012.707189] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Ovarian cancer is the most important cause of gynecological cancer-related mortality. Conventional treatments for advanced or recurrent disease offer limited results in terms of long-term responses and survival. Researches have recently focused on target therapies, which represent a new, promising, therapeutic approach, able to maximizing tumor kill and minimizing toxicity. The family of polyadenosine diphosphate-ribose polymerase (PARP) inhibitors is currently one of the most hopeful and investigated alternatives. AREAS COVERED Preclinical and clinical studies of Olaparib , the most investigated PARP inhibitor in ovarian cancer, are analyzed and discussed. Data were obtained by searching for all English peer-reviewed articles on Medline, on Cochrane Database and all on-going Phase I and II studies registered on National Cancer Institute Clinical Trials; also any related abstracts recently presented on Olaparib at major international congresses will be included. EXPERT OPINION Bad prognosis and drug resistance usually affect ovarian cancer. Recent trends toward the knowledge of molecular-specific pathways have produced new target drugs. PARP inhibition mediated by Olaparib in BRCA1 (breast cancer 1) and BRCA2 (breast cancer 2)-mutated and in sporadic ovarian cancer represents a promising field of investigation. Further studies are needed to confirm initial exciting results.
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Affiliation(s)
- Claudia Marchetti
- Sapienza University of Rome, Department of Gynecologic-Obstetrical and Urologic Sciences, Viale del Policlinico, 155 - 00161, Rome, Italy.
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Abstract
RAD51 is important for restarting stalled replication forks and for repairing DNA double-strand breaks (DSBs) through a pathway called homology-directed repair (HDR). However, analysis of the consequences of specific RAD51 mutants has been difficult since they are toxic. Here we report on the dominant effects of two human RAD51 mutants defective for ATP binding (K133A) or ATP hydrolysis (K133R) expressed in mouse embryonic stem (ES) cells that also expressed normal mouse RAD51 from the other chromosome. These cells were defective for restarting stalled replication forks and repairing breaks. They were also hypersensitive to camptothecin, a genotoxin that generates breaks specifically at the replication fork. In addition, these cells exhibited a wide range of structural chromosomal changes that included multiple breakpoints within the same chromosome. Thus, ATP binding and hydrolysis are essential for chromosomal maintenance. Fusion of RAD51 to a fluorescent tag (enhanced green fluorescent protein [eGFP]) allowed visualization of these proteins at sites of replication and repair. We found very low levels of mutant protein present at these sites compared to normal protein, suggesting that low levels of mutant protein were sufficient for disruption of RAD51 activity and generation of chromosomal rearrangements.
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24
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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25
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Magwood AC, Mundia MM, Baker MD. High levels of wild-type BRCA2 suppress homologous recombination. J Mol Biol 2012; 421:38-53. [PMID: 22579622 DOI: 10.1016/j.jmb.2012.05.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 04/23/2012] [Accepted: 05/03/2012] [Indexed: 11/26/2022]
Abstract
Endogenous levels of the BRCA2 (breast cancer susceptibility 2) protein promote homologous recombination by regulating the essential strand exchange protein RAD51. To examine BRCA2 function in homologous recombination, we expressed human BRCA2 in control mouse hybridoma cells, as well as those that were depleted of endogenous Brca2 by small interfering RNA. With moderate human BRCA2 expression, homologous recombination was stimulated. Conversely, a higher level of BRCA2 reduced homologous recombination and DNA-damage-induced Rad51 foci formation. Cells expressing high levels of BRCA2 feature normal growth, increased sensitivity to mitomycin C, and increased illegitimate recombination. BRCA2-overexpressing cells are also characterized by suppression of p53 transcriptional regulation and a corresponding reduction in the expression of the p53-responsive genes Noxa and p21. Notably, in cells expressing high levels of BRCA2, small interfering RNA depletion of human BRCA2 or ectopic expression of Rad51 increases homologous recombination and decreases illegitimate recombination. Thus, high levels of wild-type BRCA2 perturb Rad51-mediated homologous recombination, and relatively normal recombination responses can be restored by rebalancing recombination factors.
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Affiliation(s)
- Alissa C Magwood
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Yata K, Lloyd J, Maslen S, Bleuyard JY, Skehel M, Smerdon S, Esashi F. Plk1 and CK2 act in concert to regulate Rad51 during DNA double strand break repair. Mol Cell 2012; 45:371-83. [PMID: 22325354 PMCID: PMC3280358 DOI: 10.1016/j.molcel.2011.12.028] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 10/27/2011] [Accepted: 12/13/2011] [Indexed: 02/06/2023]
Abstract
Homologous recombination (HR) plays an important role in the maintenance of genome integrity. HR repairs broken DNA during S and G2 phases of the cell cycle but its regulatory mechanisms remain elusive. Here, we report that Polo-like kinase 1 (Plk1), which is vital for cell proliferation and is frequently upregulated in cancer cells, phosphorylates the essential Rad51 recombinase at serine 14 (S14) during the cell cycle and in response to DNA damage. Strikingly, S14 phosphorylation licenses subsequent Rad51 phosphorylation at threonine 13 (T13) by casein kinase 2 (CK2), which in turn triggers direct binding to the Nijmegen breakage syndrome gene product, Nbs1. This mechanism facilitates Rad51 recruitment to damage sites, thus enhancing cellular resistance to genotoxic stresses. Our results uncover a role of Plk1 in linking DNA damage recognition with HR repair and suggest a molecular mechanism for cancer development associated with elevated activity of Plk1.
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Affiliation(s)
- Keiko Yata
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Janette Lloyd
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway NW7 1AA, UK
| | - Sarah Maslen
- Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
| | - Jean-Yves Bleuyard
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Mark Skehel
- Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
| | - Stephen J. Smerdon
- Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway NW7 1AA, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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Meike S, Yamamori T, Yasui H, Eitaki M, Matsuda A, Morimatsu M, Fukushima M, Yamasaki Y, Inanami O. A nucleoside anticancer drug, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (TAS106), sensitizes cells to radiation by suppressing BRCA2 expression. Mol Cancer 2011; 10:92. [PMID: 21798026 PMCID: PMC3161955 DOI: 10.1186/1476-4598-10-92] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 07/28/2011] [Indexed: 11/30/2022] Open
Abstract
Background A novel anticancer drug 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine (ECyd, TAS106) has been shown to radiosensitize tumor cells and to improve the therapeutic efficiency of X-irradiation. However, the effect of TAS106 on cellular DNA repair capacity has not been elucidated. Our aim in this study was to examine whether TAS106 modified the repair capacity of DNA double-strand breaks (DSBs) in tumor cells. Methods Various cultured cell lines treated with TAS106 were irradiated and then survival fraction was examined by the clonogenic survival assays. Repair of sublethal damage (SLD), which indicates DSBs repair capacity, was measured as an increase of surviving cells after split dose irradiation with an interval of incubation. To assess the effect of TAS106 on the DSBs repair activity, the time courses of γ-H2AX and 53BP1 foci formation were examined by using immunocytochemistry. The expression of DNA-repair-related proteins was also examined by Western blot analysis and semi-quantitative RT-PCR analysis. Results In clonogenic survival assays, pretreatment of TAS106 showed radiosensitizing effects in various cell lines. TAS106 inhibited SLD repair and delayed the disappearance of γ-H2AX and 53BP1 foci, suggesting that DSB repair occurred in A549 cells. Western blot analysis demonstrated that TAS106 down-regulated the expression of BRCA2 and Rad51, which are known as keys among DNA repair proteins in the homologous recombination (HR) pathway. Although a significant radiosensitizing effect of TAS106 was observed in the parental V79 cells, pretreatment with TAS106 did not induce any radiosensitizing effects in BRCA2-deficient V-C8 cells. Conclusions Our results indicate that TAS106 induces the down-regulation of BRCA2 and the subsequent abrogation of the HR pathway, leading to a radiosensitizing effect. Therefore, this study suggests that inhibition of the HR pathway may be useful to improve the therapeutic efficiency of radiotherapy for solid tumors.
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Affiliation(s)
- Shunsuke Meike
- Laboratory of Radiation Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
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Mukhopadhyay A, Elattar A, Cerbinskaite A, Wilkinson SJ, Drew Y, Kyle S, Los G, Hostomsky Z, Edmondson RJ, Curtin NJ. Development of a functional assay for homologous recombination status in primary cultures of epithelial ovarian tumor and correlation with sensitivity to poly(ADP-ribose) polymerase inhibitors. Clin Cancer Res 2010; 16:2344-51. [PMID: 20371688 DOI: 10.1158/1078-0432.ccr-09-2758] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Poly(ADP-ribose) polymerase (PARP) inhibitors selectively target homologous recombination (HR)-defective cells and show good clinical activity in hereditary breast and ovarian cancer associated with BRCA1 or BRCA2 mutations. A high proportion (up to 50%) of sporadic epithelial ovarian cancers (EOC) could be deficient in HR due to genetic or epigenetic inactivation of BRCA1/BRCA2 or other HR genes. Therefore, there is a potential for extending the use of PARP inhibitors to these patients if HR status can be identified. We developed a functional assay of HR status in primary cultures of EOCs based on Rad51 focus formation that correlates well with sensitivity to the potent PARP inhibitor AG014699. EXPERIMENTAL DESIGN Primary cultures were derived from ascitic fluid from patients with EOCs. HR status was investigated by gammaH2AX and Rad51 focus formation by immunofluorescence. Cytotoxicity to PARP inhibitors was tested by sulforhodamine B and survival assay. RESULTS Twenty-five cultures were evaluated for HR status and cytotoxicity to PARP inhibitor. Following exposure to AG014699, there was an increase in Rad51 foci (HR competent) in 9 of 24 (36%) but no increase (HR deficient) in 16 of 24 (64%) cultures. Cytotoxicity was observed in 15 of 16 (93%) HR-deficient samples but not in 9 of 9 HR-competent samples following 24-hour exposure to 10 mumol/L AG014699. CONCLUSION HR status can be determined in primary cancer samples by Rad51 focus formation, and this correlates with in vitro response to PARP inhibition. Use of this assay as a biomarker now needs testing in the setting of a clinical trial.
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Affiliation(s)
- Asima Mukhopadhyay
- Northern Gynaecological Oncology Centre, Queen Elizabeth Hospital, Gateshead, UK
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Schild D, Wiese C. Overexpression of RAD51 suppresses recombination defects: a possible mechanism to reverse genomic instability. Nucleic Acids Res 2009; 38:1061-70. [PMID: 19942681 PMCID: PMC2831301 DOI: 10.1093/nar/gkp1063] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
RAD51, a key protein in the homologous recombinational DNA repair (HRR) pathway, is the major strand-transferase required for mitotic recombination. An important early step in HRR is the formation of single-stranded DNA (ss-DNA) coated by RPA (a ss-DNA-binding protein). Displacement of RPA by RAD51 is highly regulated and facilitated by a number of different proteins known as the 'recombination mediators'. To assist these recombination mediators, a second group of proteins also is required and we are defining these proteins here as 'recombination co-mediators'. Defects in either recombination mediators or co-mediators, including BRCA1 and BRCA2, lead to impaired HRR that can genetically be complemented for (i.e. suppressed) by overexpression of RAD51. Defects in HRR have long been known to contribute to genomic instability leading to tumor development. Since genomic instability also slows cell growth, precancerous cells presumably require genomic re-stabilization to gain a growth advantage. RAD51 is overexpressed in many tumors, and therefore, we hypothesize that the complementing ability of elevated levels of RAD51 in tumors with initial HRR defects limits genomic instability during carcinogenic progression. Of particular interest, this model may also help explain the high frequency of TP53 mutations in human cancers, since wild-type p53 represses RAD51 expression.
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Affiliation(s)
- David Schild
- Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
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Gildemeister OS, Sage JM, Knight KL. Cellular redistribution of Rad51 in response to DNA damage: novel role for Rad51C. J Biol Chem 2009; 284:31945-52. [PMID: 19783859 DOI: 10.1074/jbc.m109.024646] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Exposure of cells to DNA-damaging agents results in a rapid increase in the formation of subnuclear complexes containing Rad51. To date, it has not been determined to what extent DNA damage-induced cytoplasmic to nuclear transport of Rad51 may contribute to this process. We have analyzed subcellular fractions of HeLa and HCT116 cells and found a significant increase in nuclear Rad51 levels following exposure to a modest dose of ionizing radiation (2 grays). We also observed a DNA damage-induced increase in nuclear Rad51 in the Brca2-defective cell line Capan-1. To address a possible Brca2-independent mechanism for Rad51 nuclear transport, we analyzed subcellular fractions for two other Rad51-interacting proteins, Rad51C and Xrcc3. Rad51C has a functional nuclear localization signal, and although we found that the subcellular distribution of Xrcc3 was not significantly affected by DNA damage, there was a damage-induced increase in nuclear Rad51C. Furthermore, RNA interference-mediated depletion of Rad51C in HeLa and Capan-1 cells resulted in lower steady-state levels of nuclear Rad51 as well as a diminished DNA damage-induced increase. Our results provide important insight into the cellular regulation of Rad51 nuclear entry and a role for Rad51C in this process.
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Affiliation(s)
- Otto S Gildemeister
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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