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Lin X, Soni A, Hessenow R, Sun Y, Mladenov E, Guberina M, Stuschke M, Iliakis G. Talazoparib enhances resection at DSBs and renders HR-proficient cancer cells susceptible to Polθ inhibition. Radiother Oncol 2024; 200:110475. [PMID: 39147034 DOI: 10.1016/j.radonc.2024.110475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 07/02/2024] [Accepted: 08/12/2024] [Indexed: 08/17/2024]
Abstract
BACKGROUND AND PURPOSE The PARP inhibitor (PARPi), Talazoparib (BMN673), effectively and specifically radiosensitizes cancer cells. Radiosensitization is mediated by a shift in the repair of ionizing radiation (IR)-induced DNA double-strand breaks (DSBs) toward PARP1-independent, alternative end-joining (alt-EJ). DNA polymerase theta (Polθ) is a key component of this PARP1-independent alt-EJ pathway and we show here that its inhibition can further radiosensitize talazoparib-treated cells. The purpose of the present work is to explore mechanisms and dynamics underpinning enhanced talazoparib radiosensitization by Polθ inhibitors in HR-proficient cancer cells. METHODS AND MATERIALS Radiosensitization to PARPis, talazoparib, olaparib, rucaparib and veliparib was assessed by clonogenic survival. Polθ-proficient and -deficient cells were treated with PARPis and/or with the Polθ inhibitors ART558 or novobiocin. The role of DNA end-resection was studied by down-regulating CtIP and MRE11 expression using siRNAs. DSB repair was assessed by scoring γH2AX foci. The formation of chromosomal abnormalities was assessed as evidence of alt-EJ function using G2-specific cytogenetic analysis. RESULTS Talazoparib exerted pronounced radiosensitization that varied among the tested cancer cell lines; however, radiosensitization was undetectable in normal cells. Other commonly used PARPis, olaparib, veliparib, or rucaparib were ineffective radiosensitizers under our experimental conditions. Although genetic ablation or pharmacological inhibition of Polθ only mildly radiosensitized cancer cells, talazoparib-treated cells were markedly further radiosensitized. Mechanistically, talazoparib shunted DSBs to Polθ-dependent alt-EJ by enhancing DNA end-resection in a CtIP- and MRE11-dependent manner - an effect detectable at low, but not high IR doses. Chromosomal translocation analysis in talazoparib-treated cells exposed to Polθ inhibitors suggested that PARP1- and Polθ-dependent alt-EJ pathways may complement, but also back up each other. CONCLUSION We propose that talazoparib promotes low-dose, CtIP/MRE11-dependent resection and increases the reliance of irradiated HR-proficient cancer cells, on Polθ-mediated alt-EJ. The combination of Polθ inhibitors with talazoparib suppresses this option and causes further radiosensitization. The results suggest that Polθ inhibition may be exploited to maximize talazoparib radiosensitization of HR-proficient tumors in the clinic.
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Affiliation(s)
- Xixi Lin
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany
| | - Aashish Soni
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany.
| | - Razan Hessenow
- West German Proton Therapy Center Essen (WPE), University of Duisburg-Essen, 45147, Essen, Germany
| | - Yanjie Sun
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; West German Proton Therapy Center Essen (WPE), University of Duisburg-Essen, 45147, Essen, Germany
| | - Emil Mladenov
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany
| | - Maja Guberina
- Department of Radiation Therapy, West German Cancer Center, University Hospital Essen, University Duisburg-Essen, 45147, Essen, Germany; German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147, Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Department of Radiation Therapy, West German Cancer Center, University Hospital Essen, University Duisburg-Essen, 45147, Essen, Germany; German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147, Essen, Germany
| | - George Iliakis
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany; Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147, Essen, Germany.
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Liu Y, Zhu J, Zhou S, Hou Y, Yan Z, Ao X, Wang P, Zhou L, Chen H, Liang X, Guan H, Gao S, Xie D, Gu Y, Zhou P. Low-dose ionizing radiation-induced RET/PTC1 rearrangement via the non-homologous end joining pathway to drive thyroid cancer. MedComm (Beijing) 2024; 5:e690. [PMID: 39135916 PMCID: PMC11318340 DOI: 10.1002/mco2.690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 07/14/2024] [Accepted: 07/16/2024] [Indexed: 08/15/2024] Open
Abstract
Thyroid cancer incidence increases worldwide annually, primarily due to factors such as ionizing radiation (IR), iodine intake, and genetics. Papillary carcinoma of the thyroid (PTC) accounts for about 80% of thyroid cancer cases. RET/PTC1 (coiled-coil domain containing 6 [CCDC6]-rearranged during transfection) rearrangement is a distinctive feature in over 70% of thyroid cancers who exposed to low doses of IR in Chernobyl and Hiroshima‒Nagasaki atomic bombings. This study aims to elucidate mechanism between RET/PTC1 rearrangement and IR in PTC. N-thy-ori-3-1 cells were subjected to varying doses of IR (2/1/0.5/0.2/0.1/0.05 Gy) of IR at different days, and result showed low-dose IR-induced RET/PTC1 rearrangement in a dose-dependent manner. RET/PTC1 has been observed to promote PTC both in vivo and in vitro. To delineate the role of different DNA repair pathways, SCR7, RI-1, and Olaparib were employed to inhibit non-homologous end joining (NHEJ), homologous recombination (HR), and microhomology-mediated end joining (MMEJ), respectively. Notably, inhibiting NHEJ enhanced HR repair efficiency and reduced IR-induced RET/PTC1 rearrangement. Conversely, inhibiting HR increased NHEJ repair efficiency and subsequent RET/PTC1 rearrangement. The MMEJ did not show a markable role in this progress. Additionally, inhibiting DNA-dependent protein kinase catalytic subunit (DNA-PKcs) decreased the efficiency of NHEJ and thus reduced IR-induced RET/PTC1 rearrangement. To conclude, the data suggest that NHEJ, rather than HR or MMEJ, is the critical cause of IR-induced RET/PTC1 rearrangement. Targeting DNA-PKcs to inhibit the NHEJ has emerged as a promising therapeutic strategy for addressing IR-induced RET/PTC1 rearrangement in PTC.
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Affiliation(s)
- Yuhao Liu
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Jiaojiao Zhu
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Shenghui Zhou
- Hengyang Medical CollegeUniversity of South ChinaHengyangChina
| | - Yifan Hou
- College of Life SciencesHebei UniversityBaodingChina
| | - Ziyan Yan
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Xingkun Ao
- Hengyang Medical CollegeUniversity of South ChinaHengyangChina
| | - Ping Wang
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Lin Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Huixi Chen
- Hengyang Medical CollegeUniversity of South ChinaHengyangChina
| | - Xinxin Liang
- Hengyang Medical CollegeUniversity of South ChinaHengyangChina
| | - Hua Guan
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Shanshan Gao
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Dafei Xie
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Yongqing Gu
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
- Hengyang Medical CollegeUniversity of South ChinaHengyangChina
- College of Life SciencesHebei UniversityBaodingChina
| | - Ping‐Kun Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
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Inanc B, Fang Q, Andrews JF, Zeng X, Clark J, Li J, Dey NB, Ibrahim M, Sykora P, Yu Z, Braganza A, Verheij M, Jonkers J, Yates NA, Vens C, Sobol RW. TRIP12 governs DNA Polymerase β involvement in DNA damage response and repair. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588474. [PMID: 38645048 PMCID: PMC11030427 DOI: 10.1101/2024.04.08.588474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
The multitude of DNA lesion types, and the nuclear dynamic context in which they occur, present a challenge for genome integrity maintenance as this requires the engagement of different DNA repair pathways. Specific 'repair controllers' that facilitate DNA repair pathway crosstalk between double strand break (DSB) repair and base excision repair (BER), and regulate BER protein trafficking at lesion sites, have yet to be identified. We find that DNA polymerase β (Polβ), crucial for BER, is ubiquitylated in a BER complex-dependent manner by TRIP12, an E3 ligase that partners with UBR5 and restrains DSB repair signaling. Here we find that, TRIP12, but not UBR5, controls cellular levels and chromatin loading of Polβ. Required for Polβ foci formation, TRIP12 regulates Polβ involvement after DNA damage. Notably, excessive TRIP12-mediated shuttling of Polβ affects DSB formation and radiation sensitivity, underscoring its precedence for BER. We conclude that the herein discovered trafficking function at the nexus of DNA repair signaling pathways, towards Polβ-directed BER, optimizes DNA repair pathway choice at complex lesion sites.
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Soni A, Lin X, Mladenov E, Mladenova V, Stuschke M, Iliakis G. BMN673 Is a PARP Inhibitor with Unique Radiosensitizing Properties: Mechanisms and Potential in Radiation Therapy. Cancers (Basel) 2022; 14:cancers14225619. [PMID: 36428712 PMCID: PMC9688666 DOI: 10.3390/cancers14225619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/10/2022] [Accepted: 11/13/2022] [Indexed: 11/17/2022] Open
Abstract
BMN673 is a relatively new PARP inhibitor (PARPi) that exhibits superior efficacy in vitro compared to olaparib and other clinically relevant PARPi. BMN673, similar to most clinical PARPi, inhibits the catalytic activities of PARP-1 and PARP-2 and shows impressive anticancer potential as monotherapy in several pre-clinical and clinical studies. Tumor resistance to PARPi poses a significant challenge in the clinic. Thus, combining PARPi with other treatment modalities, such as radiotherapy (RT), is being actively pursued to overcome such resistance. However, the modest to intermediate radiosensitization exerted by olaparib, rucaparib, and veliparib, limits the rationale and the scope of such combinations. The recently reported strong radiosensitizing potential of BMN673 forecasts a paradigm shift on this front. Evidence accumulates that BMN673 may radiosensitize via unique mechanisms causing profound shifts in the balance among DNA double-strand break (DSB) repair pathways. According to one of the emerging models, BMN673 strongly inhibits classical non-homologous end-joining (c-NHEJ) and increases reciprocally and profoundly DSB end-resection, enhancing error-prone DSB processing that robustly potentiates cell killing. In this review, we outline and summarize the work that helped to formulate this model of BMN673 action on DSB repair, analyze the causes of radiosensitization and discuss its potential as a radiosensitizer in the clinic. Finally, we highlight strategies for combining BMN673 with other inhibitors of DNA damage response for further improvements.
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Affiliation(s)
- Aashish Soni
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Xixi Lin
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Emil Mladenov
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Veronika Mladenova
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - George Iliakis
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
- Correspondence: ; Tel.: +49-201-723-4152
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Cheng Z, Wang Y, Guo L, Li J, Zhang W, Zhang C, Liu Y, Huang Y, Xu K. Ku70 affects the frequency of chromosome translocation in human lymphocytes after radiation and T-cell acute lymphoblastic leukemia. Radiat Oncol 2022; 17:144. [PMID: 35986335 PMCID: PMC9389784 DOI: 10.1186/s13014-022-02113-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 08/05/2022] [Indexed: 11/23/2022] Open
Abstract
Background As one of the most common chromosomal causes, chromosome translocation leads to T-cell acute lymphoblastic leukemia (T-ALL). Ku70 is one of the key factors of error-prone DNA repair and it may end in translocation. So far, the direct correlation between Ku70 and translocation has not been assessed. This study aimed to investigate the association between Ku70 and translocation in human lymphocytes after radiation and T-ALL. Methods Peripheral blood lymphocytes (PBLs) from volunteers and human lymphocyte cell line AHH-1 were irradiated with X-rays to form the chromosome translocations. Phytohemagglutinin (PHA) was used to stimulate lymphocytes. The frequency of translocation was detected by fluorescence in situ hybridization (FISH). Meanwhile, the expression of Ku70 was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. Furthermore, Ku70 interference, overexpression and chemical inhibition were used in AHH-1 cell lines to confirm the correlation. Finally, the expression of Ku70 in T-ALL samples with or without translocation was detected. Results The expression of Ku70 and frequencies of translocation were both significantly increased in PBLs after being irradiated by X-rays, and a positive correlation between the expression (both mRNA and protein level) of Ku70 and the frequency of translocation was detected (r = 0.4877, P = 0.004; r = 0.3038, P = 0.0358 respectively). Moreover, Ku70 interference decreased the frequency of translocations, while the frequency of translocations was not significantly affected after Ku70 overexpression. The expression of Ku70 and frequencies of translocation were both significantly increased in cells after irradiation, combined with chemical inhibition (P < 0.01). The protein level and mRNA level of Ku70 in T-ALL with translocation were obviously higher than T-ALL with normal karyotype (P = 0.009, P = 0.049 respectively). Conclusions Ku70 is closely associated with the frequency of chromosome translocation in human lymphocytes after radiation and T-ALL. Ku70 might be a radiation damage biomarker and a potential tumor therapy target. Supplementary Information The online version contains supplementary material available at 10.1186/s13014-022-02113-3.
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Accumulation of oncometabolite D-2-Hydroxyglutarate by SLC25A1 inhibition: A metabolic strategy for induction of HR-ness and radiosensitivity. Cell Death Dis 2022; 13:641. [PMID: 35869047 PMCID: PMC9307853 DOI: 10.1038/s41419-022-05098-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 01/21/2023]
Abstract
Oncogenic mutations in metabolic genes and associated oncometabolite accumulation support cancer progression but can also restrict cellular functions needed to cope with DNA damage. For example, gain-of-function mutations in isocitrate dehydrogenase (IDH) and the resulting accumulation of the oncometabolite D-2-hydroxyglutarate (D-2-HG) enhanced the sensitivity of cancer cells to inhibition of poly(ADP-ribose)-polymerase (PARP)1 and radiotherapy (RT). In our hand, inhibition of the mitochondrial citrate transport protein (SLC25A1) enhanced radiosensitivity of cancer cells and this was associated with increased levels of D-2-HG and a delayed repair of radiation-induced DNA damage. Here we aimed to explore the suggested contribution of D-2-HG-accumulation to disturbance of DNA repair, presumably homologous recombination (HR) repair, and enhanced radiosensitivity of cancer cells with impaired SLC25A1 function. Genetic and pharmacologic inhibition of SLC25A1 (SLC25A1i) increased D-2-HG-levels and sensitized lung cancer and glioblastoma cells to the cytotoxic action of ionizing radiation (IR). SLC25A1i-mediated radiosensitization was abrogated in MEFs with a HR-defect. D-2-HG-accumulation was associated with increased DNA damage and delayed resolution of IR-induced γH2AX and Rad51 foci. Combining SLC25A1i with PARP- or the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs)-inhibitors further potentiated IR-induced DNA damage, delayed DNA repair kinetics resulting in radiosensitization of cancer cells. Importantly, proof of concept experiments revealed that combining SLC25A1i with IR without and with PARPi also reduced tumor growth in the chorioallantoic membrane (CAM) model in vivo. Thereby SLC25A1i offers an innovative strategy for metabolic induction of context-dependent lethality approaches in combination with RT and clinically relevant inhibitors of complementary DNA repair pathways.
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Xiao H, Li F, Mladenov E, Soni A, Mladenova V, Pan B, Dueva R, Stuschke M, Timmermann B, Iliakis G. Increased Resection at DSBs in G2-Phase Is a Unique Phenotype Associated with DNA-PKcs Defects That Is Not Shared by Other Factors of c-NHEJ. Cells 2022; 11:cells11132099. [PMID: 35805183 PMCID: PMC9265841 DOI: 10.3390/cells11132099] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 01/27/2023] Open
Abstract
The load of DNA double-strand breaks (DSBs) induced in the genome of higher eukaryotes by different doses of ionizing radiation (IR) is a key determinant of DSB repair pathway choice, with homologous recombination (HR) and ATR substantially gaining ground at doses below 0.5 Gy. Increased resection and HR engagement with decreasing DSB-load generate a conundrum in a classical non-homologous end-joining (c-NHEJ)-dominated cell and suggest a mechanism adaptively facilitating resection. We report that ablation of DNA-PKcs causes hyper-resection, implicating DNA-PK in the underpinning mechanism. However, hyper-resection in DNA-PKcs-deficient cells can also be an indirect consequence of their c-NHEJ defect. Here, we report that all tested DNA-PKcs mutants show hyper-resection, while mutants with defects in all other factors of c-NHEJ fail to do so. This result rules out the model of c-NHEJ versus HR competition and the passive shift from c-NHEJ to HR as the causes of the increased resection and suggests the integration of DNA-PKcs into resection regulation. We develop a model, compatible with the results of others, which integrates DNA-PKcs into resection regulation and HR for a subset of DSBs. For these DSBs, we propose that the kinase remains at the break site, rather than the commonly assumed autophosphorylation-mediated removal from DNA ends.
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Affiliation(s)
- Huaping Xiao
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Fanghua Li
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK), 45147 Essen, Germany;
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Aashish Soni
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Veronika Mladenova
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Bing Pan
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
| | - Rositsa Dueva
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Institute of Physiology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
| | - Martin Stuschke
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - Beate Timmermann
- Department of Particle Therapy, University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK), 45147 Essen, Germany;
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, German Cancer Research Center (DKFZ), 45147 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; (H.X.); (F.L.); (E.M.); (A.S.); (V.M.); (B.P.); (R.D.)
- Division of Experimental Radiation Biology, Department of Radiation Therapy, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany;
- Correspondence: ; Tel.: +49-201-723-4152
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TCDD-inducible Poly (ADP-ribose) Polymerase Promotes Adipogenesis of Both Brown and White Preadipocytes. J Transl Int Med 2022; 10:246-254. [PMID: 36776241 PMCID: PMC9901556 DOI: 10.2478/jtim-2021-0032] [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] [Indexed: 11/20/2022] Open
Abstract
Background TCDD-inducible poly (ADP-ribose) polymerase (TiPARP) is a DNA repair enzyme with functions in energy metabolism, signal transduction, cell differentiation, and other biological processes, which may closely related to lipid metabolism and is highly expressed in adipose tissue. Adipose tissue can be divided into white adipose tissue (WAT) that stores energy and brown adipose tissue (BAT) that releases energy and generates heat. In the present study, we investigated whether TiPARP can affect adipogenesis in adipose tissue and thus participate in the development of obesity. Methods BAT primary cells or 3T3-L1 cells infected with adenovirus expressing TiPARP or TiPARP-targeted short hairpin RNA (shTiPARP) were cultured to induce adipogenic differentiation. The expression of TiPARP was detected by real-time PCR and Western blotting. The expression of specific BAT- and WAT-related markers was detected by real-time PCR. The accumulation of lipid droplets in differentiated cells was detected by Oil Red O staining. Results TiPARP was highly expressed in both subcutaneous WAT and BAT, and TiPARP mRNA level increased significantly along with adipogenic differentiation. Activation of TiPARP or overexpression of TiPARP upregulated BAT-related markers in primary BAT cells and WAT-related markers in 3T3-L1 cells, together with increased lipid accumulation. On the contrary, knockdown of TiPARP downregulated expression of specific markers in both BAT primary cells and 3T3-L1 cells, together with decreased lipid accumulation. Conclusion TiPARP regulates adipogenesis in both BAT primary cells and 3T3-L1 cells and therefore plays an important role in modulating maturity and lipid accumulation in brown and white adipocytes. These findings provide us with a new strategy for combating obesity.
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Derby SJ, Chalmers AJ, Carruthers RD. Radiotherapy-Poly(ADP-ribose) Polymerase Inhibitor Combinations: Progress to Date. Semin Radiat Oncol 2022; 32:15-28. [PMID: 34861992 DOI: 10.1016/j.semradonc.2021.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Radiation resistance remains a huge clinical problem for cancer patients and oncologists in the 21st century. In recent years, the mammalian DNA damage response (DDR) has been extensively characterized and shown to play a key role in determining cellular survival following ionizing radiation exposure. Genomic instability due to altered DDR is a hallmark of cancer, with many tumors exhibiting abnormal DNA repair or lack of redundancy in DDR. Targeting the abnormal DDR phenotype of tumor cells could lead to substantial gains in radiotherapy efficacy, improving local control and survival for patients with cancers that are refractory to current therapies. Poly(ADP-ribose) polymerase inhibitors (PARPi) are the most clinically advanced DDR inhibitors under investigation as radiosensitisers. Preclinical evidence suggests that PARPi may provide tumor specific radiosensitisation in certain contexts. In addition to inhibition of DNA single strand break repair, PARPi may offer other benefits in combination treatment including radiosensitisation of hypoxic cells and targeting of alternative repair pathways such as microhomology mediated end joining which are increasingly recognized to be upregulated in cancer. Several early phase clinical trials of PARPi with radiation have completed or are in progress. Early reports have highlighted tumor specific challenges, with tolerability dependent upon anatomical location and use of concomitant systemic therapies; these challenges were largely predicted by preclinical data. This review discusses the role of PARP in the cellular response to ionizing radiation, summarizes preclinical studies of PARPi in combination with radiotherapy and explores current early phase clinical trials that are evaluating these combinations.
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Affiliation(s)
- Sarah J Derby
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow, Scotland.
| | - Anthony J Chalmers
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow, Scotland
| | - Ross D Carruthers
- Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow, Scotland
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PARP Inhibitors and Myeloid Neoplasms: A Double-Edged Sword. Cancers (Basel) 2021; 13:cancers13246385. [PMID: 34945003 PMCID: PMC8699275 DOI: 10.3390/cancers13246385] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Poly(ADP-ribose) polymerase (PARP) inhibitors, which are medications approved to treat various solid tumors, including breast, prostate, ovarian, and prostate cancers, are being examined in hematological malignancies. This review summarizes the potential role of PARP inhibitors in the treatment of myeloid diseases, particularly acute myeloid leukemia (AML). We review ongoing clinical studies investigating the safety and efficacy of PARP inhibitors in the treatment of AML, focusing on specific molecular and genetic AML subgroups that could be particularly sensitive to PARP inhibitor treatment. We also discuss reports describing an increased risk of treatment-related myeloid neoplasms in patients receiving PARP inhibitors for solid tumors. Abstract Despite recent discoveries and therapeutic advances in aggressive myeloid neoplasms, there remains a pressing need for improved therapies. For instance, in acute myeloid leukemia (AML), while most patients achieve a complete remission with conventional chemotherapy or the combination of a hypomethylating agent and venetoclax, de novo or acquired drug resistance often presents an insurmountable challenge, especially in older patients. Poly(ADP-ribose) polymerase (PARP) enzymes, PARP1 and PARP2, are involved in detecting DNA damage and repairing it through multiple pathways, including base excision repair, single-strand break repair, and double-strand break repair. In the context of AML, PARP inhibitors (PARPi) could potentially exploit the frequently dysfunctional DNA repair pathways that, similar to deficiencies in homologous recombination in BRCA-mutant disease, set the stage for cell killing. PARPi appear to be especially effective in AML with certain gene rearrangements and molecular characteristics (RUNX1-RUNX1T1 and PML-RARA fusions, FLT3- and IDH1-mutated). In addition, PARPi can enhance the efficacy of other agents, particularly alkylating agents, TOP1 poisons, and hypomethylating agents, that induce lesions ordinarily repaired via PARP1-dependent mechanisms. Conversely, emerging reports suggest that long-term treatment with PARPi for solid tumors is associated with an increased incidence of myelodysplastic syndrome (MDS) and AML. Here, we (i) review the pre-clinical and clinical data on the role of PARPi, specifically olaparib, talazoparib, and veliparib, in aggressive myeloid neoplasms and (ii) discuss the reported risk of MDS/AML with PARPi, especially as the indications for PARPi use expand to include patients with potentially curable cancer.
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11
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Disruption of Chromatin Dynamics by Hypotonic Stress Suppresses HR and Shifts DSB Processing to Error-Prone SSA. Int J Mol Sci 2021; 22:ijms222010957. [PMID: 34681628 PMCID: PMC8535785 DOI: 10.3390/ijms222010957] [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: 08/24/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 11/17/2022] Open
Abstract
The processing of DNA double-strand breaks (DSBs) depends on the dynamic characteristics of chromatin. To investigate how abrupt changes in chromatin compaction alter these dynamics and affect DSB processing and repair, we exposed irradiated cells to hypotonic stress (HypoS). Densitometric and chromosome-length analyses show that HypoS transiently decompacts chromatin without inducing histone modifications known from regulated local chromatin decondensation, or changes in Micrococcal Nuclease (MNase) sensitivity. HypoS leaves undisturbed initial stages of DNA-damage-response (DDR), such as radiation-induced ATM activation and H2AX-phosphorylation. However, detection of ATM-pS1981, γ-H2AX and 53BP1 foci is reduced in a protein, cell cycle phase and cell line dependent manner; likely secondary to chromatin decompaction that disrupts the focal organization of DDR proteins. While HypoS only exerts small effects on classical nonhomologous end-joining (c-NHEJ) and alternative end-joining (alt-EJ), it markedly suppresses homologous recombination (HR) without affecting DNA end-resection at DSBs, and clearly enhances single-strand annealing (SSA). These shifts in pathway engagement are accompanied by decreases in HR-dependent chromatid-break repair in the G2-phase, and by increases in alt-EJ and SSA-dependent chromosomal translocations. Consequently, HypoS sensitizes cells to ionizing radiation (IR)-induced killing. We conclude that HypoS-induced global chromatin decompaction compromises regulated chromatin dynamics and genomic stability by suppressing DSB-processing by HR, and allowing error-prone processing by alt-EJ and SSA.
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12
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Amirifar P, Mehrmohamadi M, Ranjouri MR, Akrami SM, Rezaei N, Saberi A, Yazdani R, Abolhassani H, Aghamohammadi A. Genetic Risk Variants for Class Switching Recombination Defects in Ataxia-Telangiectasia Patients. J Clin Immunol 2021; 42:72-84. [PMID: 34628594 PMCID: PMC8821084 DOI: 10.1007/s10875-021-01147-8] [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: 08/10/2021] [Accepted: 09/27/2021] [Indexed: 11/04/2022]
Abstract
Background Ataxia-telangiectasia (A-T) is a rare autosomal recessive disorder caused by mutations in the ataxia telangiectasia mutated (ATM) gene. A-T patients manifest considerable variability in clinical and immunological features, suggesting the presence of genetic modifying factors. A striking heterogeneity has been observed in class switching recombination (CSR) in A-T patients which cannot be explained by the severity of ATM mutations. Methods To investigate the cause of variable CSR in A-T patients, we applied whole-exome sequencing (WES) in 20 A-T patients consisting of 10 cases with CSR defect (CSR-D) and 10 controls with normal CSR (CSR-N). Comparative analyses on modifier variants found in the exomes of these two groups of patients were performed. Results For the first time, we identified some variants in the exomes of the CSR-D group that were significantly associated with antigen processing and presentation pathway. Moreover, in this group of patients, the variants in four genes involved in DNA double-strand breaks (DSB) repair signaling, in particular, XRCC3 were observed, suggesting an association with CSR defect. Conclusion Additional impact of certain variants, along with ATM mutations, may explain the heterogeneity in CSR defect phenotype among A-T patients. It can be concluded that genetic modulators play an important role in the course of A-T disease and its clinical severity. Supplementary Information The online version contains supplementary material available at 10.1007/s10875-021-01147-8.
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Affiliation(s)
- Parisa Amirifar
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran
| | - Mahya Mehrmohamadi
- Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | - Mohammad Reza Ranjouri
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran
| | - Seyed Mohammad Akrami
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran.,Primary Immunodeficiency Diseases Network (PIDNet), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Ali Saberi
- Department of Computer Engineering, Sharif University of Technology, Tehran, Iran
| | - Reza Yazdani
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran.,Primary Immunodeficiency Diseases Network (PIDNet), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Hassan Abolhassani
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran. .,Division of Clinical Immunology, Department of Biosciences and Nutrition, NEO, Karolinska Institute, Blickagangen 16, 14157, Stockholm, Sweden. .,Division of Clinical Immunology, Department of Laboratory Medicine, Karolinska Institute at Karolinska University Hospital Huddinge, Stockholm, Sweden.
| | - Asghar Aghamohammadi
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran. .,Children's Medical Center Hospital, 62 Qarib St., Keshavarz Blvd, 14194, Tehran, Iran.
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13
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Scarpa M, Kapoor S, Tvedte ES, Doshi KA, Zou YS, Singh P, Lee JK, Chatterjee A, Ali MKM, Bromley RE, Hotopp JCD, Rassool FV, Baer MR. Pim kinase inhibitor co-treatment decreases alternative non-homologous end-joining DNA repair and genomic instability induced by topoisomerase 2 inhibitors in cells with FLT3 internal tandem duplication. Oncotarget 2021; 12:1763-1779. [PMID: 34504649 PMCID: PMC8416564 DOI: 10.18632/oncotarget.28042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 07/28/2021] [Indexed: 01/11/2023] Open
Abstract
Acute myeloid leukemia (AML) with fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) relapses with new chromosome abnormalities following chemotherapy, implicating genomic instability. Error-prone alternative non-homologous end-joining (Alt-NHEJ) DNA double-strand break (DSB) repair is upregulated in FLT3-ITD-expresssing cells, driven by c-Myc. The serine/threonine kinase Pim-1 is upregulated downstream of FLT3-ITD, and inhibiting Pim increases topoisomerase 2 (TOP2) inhibitor chemotherapy drug induction of DNA DSBs and apoptosis. We hypothesized that Pim inhibition increases DNA DSBs by downregulating Alt-NHEJ, also decreasing genomic instability. Alt-NHEJ activity, measured with a green fluorescent reporter construct, increased in FLT3-ITD-transfected Ba/F3-ITD cells treated with TOP2 inhibitors, and this increase was abrogated by Pim kinase inhibitor AZD1208 co-treatment. TOP2 inhibitor and AZD1208 co-treatment downregulated cellular and nuclear expression of c-Myc and Alt-NHEJ repair pathway proteins DNA polymerase θ, DNA ligase 3 and XRCC1 in FLT3-ITD cell lines and AML patient blasts. ALT-NHEJ protein downregulation was preceded by c-Myc downregulation, inhibited by c-Myc overexpression and induced by c-Myc knockdown or inhibition. TOP2 inhibitor treatment increased chromosome breaks in metaphase spreads in FLT3-ITD-expressing cells, and AZD1208 co-treatment abrogated these increases. Thus Pim kinase inhibitor co-treatment both enhances TOP2 inhibitor cytotoxicity and decreases TOP2 inhibitor-induced genomic instability in cells with FLT3-ITD.
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Affiliation(s)
- Mario Scarpa
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shivani Kapoor
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | | | - Kshama A. Doshi
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Ying S. Zou
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Prerna Singh
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Jonelle K. Lee
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Aditi Chatterjee
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Moaath K. Mustafa Ali
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Julie C. Dunning Hotopp
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Institute for Genome Sciences, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Feyruz V. Rassool
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Maria R. Baer
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Veterans Affairs Medical Center, Baltimore, MD, USA
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Magin S, Meher PK, Iliakis G. Nucleoside Analogs Radiosensitize G0 Cells by Activating DNA End Resection and Alternative End-Joining. Radiat Res 2021; 195:412-426. [PMID: 33755161 DOI: 10.1667/rade-20-00195.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 02/22/2021] [Indexed: 11/03/2022]
Abstract
Alternative end-joining (alt-EJ) is a DNA end resection-dependent, error-prone pathway utilized by vertebrate cells to repair DNA double-strand breaks (DSBs), but its engagement is linked to chromosomal translocations and genomic instability. Here, we report that when proliferating cells are exposed to ionizing radiation, treatment with nucleoside analogs (NAs) causes strong radiosensitization by increasing engagement of alt-EJ, while at the same time suppressing homologous recombination (HR) in S- and G2phase cells. This NA-mediated pathway shift may reflect a passive compensatory engagement of alt-EJ following HR suppression that is specific for S- and G2-phase cells, and/or the direct activation of alt-EJ throughout the cell cycle. To distinguish between these possibilities, we utilize here a cell culture model that exploits genetic and cell cycle-dependent inactivation of DSB repair pathways, to exclusively study alt-EJ and its modulation by NAs in murine and human cell lines. To this end, we allow LIG4-/--deficient cells to accumulate in G1/G0 phase by transfer to serum-deprived media and obtain cells deficient in c-NHEJ owing to the genetic LIG4 knockout, deficient in HR owing to the absence of S- or G2-phase cells, and compromised in their ability to carry out alt-EJ owing to their accumulation in G0. We find that in these cells irradiation and treatment with the NA, β-arabinofuranosyladenine (araA), and to a lesser degree with other NAs, promptly activates suppressed alt-EJ that now functions at levels approximating those of c-NHEJ in wild-type cells. Results at high dose (20 Gy) generated using pulsed-field gel electrophoresis (PFGE) are corroborated by results at low dose (1 Gy) generated by scoring 53BP1 foci. Strikingly, araA treatment activates a normally undetectable DNA-end-resection at DSBs, which requires ATR activity, but proceeds unimpeded after CtIP knockdown. Treatment with araA increases the formation of chromosomal aberrations and enhances radiation-induced cell killing. The results support direct stimulation of resection by NAs and alt-EJ as a mechanism of their documented radiosensitizing potential. We propose that this stimulation also occurs in repair-proficient cells and that it occurs throughout the cell cycle. It may therefore be harnessed to develop protocols combining NAs with radiation to treat human cancer.
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Affiliation(s)
- Simon Magin
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Prabodha Kumar Meher
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
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15
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Huang R, Zhou PK. DNA damage repair: historical perspectives, mechanistic pathways and clinical translation for targeted cancer therapy. Signal Transduct Target Ther 2021; 6:254. [PMID: 34238917 PMCID: PMC8266832 DOI: 10.1038/s41392-021-00648-7] [Citation(s) in RCA: 260] [Impact Index Per Article: 86.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 04/28/2021] [Accepted: 05/13/2021] [Indexed: 02/06/2023] Open
Abstract
Genomic instability is the hallmark of various cancers with the increasing accumulation of DNA damage. The application of radiotherapy and chemotherapy in cancer treatment is typically based on this property of cancers. However, the adverse effects including normal tissues injury are also accompanied by the radiotherapy and chemotherapy. Targeted cancer therapy has the potential to suppress cancer cells' DNA damage response through tailoring therapy to cancer patients lacking specific DNA damage response functions. Obviously, understanding the broader role of DNA damage repair in cancers has became a basic and attractive strategy for targeted cancer therapy, in particular, raising novel hypothesis or theory in this field on the basis of previous scientists' findings would be important for future promising druggable emerging targets. In this review, we first illustrate the timeline steps for the understanding the roles of DNA damage repair in the promotion of cancer and cancer therapy developed, then we summarize the mechanisms regarding DNA damage repair associated with targeted cancer therapy, highlighting the specific proteins behind targeting DNA damage repair that initiate functioning abnormally duo to extrinsic harm by environmental DNA damage factors, also, the DNA damage baseline drift leads to the harmful intrinsic targeted cancer therapy. In addition, clinical therapeutic drugs for DNA damage and repair including therapeutic effects, as well as the strategy and scheme of relative clinical trials were intensive discussed. Based on this background, we suggest two hypotheses, namely "environmental gear selection" to describe DNA damage repair pathway evolution, and "DNA damage baseline drift", which may play a magnified role in mediating repair during cancer treatment. This two new hypothesis would shed new light on targeted cancer therapy, provide a much better or more comprehensive holistic view and also promote the development of new research direction and new overcoming strategies for patients.
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Affiliation(s)
- Ruixue Huang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha, Hunan, China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, AMMS, Beijing, China.
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16
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Analysis of chromatid-break-repair detects a homologous recombination to non-homologous end-joining switch with increasing load of DNA double-strand breaks. Mutat Res 2021; 867:503372. [PMID: 34266628 DOI: 10.1016/j.mrgentox.2021.503372] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/28/2021] [Accepted: 06/09/2021] [Indexed: 11/24/2022]
Abstract
We recently reported that when low doses of ionizing radiation induce low numbers of DNA double-strand breaks (DSBs) in G2-phase cells, about 50 % of them are repaired by homologous recombination (HR) and the remaining by classical non-homologous end-joining (c-NHEJ). However, with increasing DSB-load, the contribution of HR drops to undetectable (at ∼10 Gy) as c-NHEJ dominates. It remains unknown whether the approximately equal shunting of DSBs between HR and c-NHEJ at low radiation doses and the predominant shunting to c-NHEJ at high doses, applies to every DSB, or whether the individual characteristics of each DSB generate processing preferences. When G2-phase cells are irradiated, only about 10 % of the induced DSBs break the chromatids. This breakage allows analysis of the processing of this specific subset of DSBs using cytogenetic methods. Notably, at low radiation doses, these DSBs are almost exclusively processed by HR, suggesting that chromatin characteristics awaiting characterization underpin chromatid breakage and determine the preferential engagement of HR. Strikingly, we also discovered that with increasing radiation dose, a pathway switch to c-NHEJ occurs in the processing of this subset of DSBs. Here, we confirm and substantially extend our initial observations using additional methodologies. Wild-type cells, as well as HR and c-NHEJ mutants, are exposed to a broad spectrum of radiation doses and their response analyzed specifically in G2 phase. Our results further consolidate the observation that at doses <2 Gy, HR is the main option in the processing of the subset of DSBs generating chromatid breaks and that a pathway switch at doses between 4-6 Gy allows the progressive engagement of c-NHEJ. PARP1 inhibition, irrespective of radiation dose, leaves chromatid break repair unaffected suggesting that the contribution of alternative end-joining is undetectable under these experimental conditions.
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17
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Ku70 suppresses alternative end joining in G1-arrested progenitor B cells. Proc Natl Acad Sci U S A 2021; 118:2103630118. [PMID: 34006647 DOI: 10.1073/pnas.2103630118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Classical nonhomologous end joining (C-NHEJ) repairs DNA double-strand breaks (DSBs) throughout interphase but predominates in G1 phase when homologous recombination is unavailable. Complexes containing the Ku70/80 ("Ku") and XRCC4/ligase IV (Lig4) core C-NHEJ factors are required, respectively, for sensing and joining DSBs. While XRCC4/Lig4 are absolutely required for joining RAG1/2 endonuclease ("RAG")-initiated DSBs during V(D)J recombination in G1-phase progenitor lymphocytes, cycling cells deficient for XRCC4/Lig4 also can join chromosomal DSBs by alternative end-joining (A-EJ) pathways. Restriction of V(D)J recombination by XRCC4/Lig4-mediated joining has been attributed to RAG shepherding V(D)J DSBs exclusively into the C-NHEJ pathway. Here, we report that A-EJ of DSB ends generated by RAG1/2, Cas9:gRNA, and Zinc finger endonucleases in Lig4-deficient G1-arrested progenitor B cell lines is suppressed by Ku. Thus, while diverse DSBs remain largely as free broken ends in Lig4-deficient G1-arrested progenitor B cells, deletion of Ku70 increases DSB rejoining and translocation levels to those observed in Ku70-deficient counterparts. Correspondingly, while RAG-initiated V(D)J DSB joining is abrogated in Lig4-deficient G1-arrested progenitor B cell lines, joining of RAG-generated DSBs in Ku70-deficient and Ku70/Lig4 double-deficient lines occurs through a translocation-like A-EJ mechanism. Thus, in G1-arrested, Lig4-deficient progenitor B cells are functionally end-joining suppressed due to Ku-dependent blockage of A-EJ, potentially in association with G1-phase down-regulation of Lig1. Finally, we suggest that differential impacts of Ku deficiency versus Lig4 deficiency on V(D)J recombination, neuronal apoptosis, and embryonic development results from Ku-mediated inhibition of A-EJ in the G1 cell cycle phase in Lig4-deficient developing lymphocyte and neuronal cells.
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18
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London RE. XRCC1 - Strategies for coordinating and assembling a versatile DNA damage response. DNA Repair (Amst) 2021; 93:102917. [PMID: 33087283 DOI: 10.1016/j.dnarep.2020.102917] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
X-ray cross complementing protein 1 (XRCC1) is a DNA repair scaffold that supports base excision repair and single strand break repair, and is also a participant in other repair pathways. It also serves as an important co-transporter for several other repair proteins, including aprataxin and PNKP-like factor (APLF), and DNA Ligase 3α (LIG3). By combining highly specialized regions that help to organize specific repair functions with recruitment of additional enzymes whose contribution is dependent on the details of the damaged site, XRCC1 is able to handle an expanded range of problems that may arise as the repair progresses or in connection with other repair pathways with which it interfaces. This review discusses the interplay between these functions and considers some possible interactions that underlie its reported repair activities.
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Affiliation(s)
- Robert E London
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, 111 T. W. Alexander Dr, NC, 27709, United States.
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19
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Soni A, Mladenov E, Iliakis G. Proficiency in homologous recombination repair is prerequisite for activation of G 2-checkpoint at low radiation doses. DNA Repair (Amst) 2021; 101:103076. [PMID: 33640756 DOI: 10.1016/j.dnarep.2021.103076] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/30/2020] [Accepted: 02/13/2021] [Indexed: 10/22/2022]
Abstract
Pathways of repair of DNA double strand breaks (DSBs) cooperate with DNA damage cell cycle checkpoints to safeguard genomic stability when cells are exposed to ionizing radiation (IR). It is widely accepted that checkpoints facilitate the function of DSB repair pathways. Whether DSB repair proficiency feeds back into checkpoint activation is less well investigated. Here, we study activation of the G2-checkpoint in cells deficient in homologous recombination repair (HRR) after exposure to low IR doses (∼1 Gy) in the G2-phase. We report that in the absence of functional HRR, activation of the G2-checkpoint is severely impaired. This response is specific for HRR, as cells deficient in classical non-homologous end joining (c-NHEJ) develop a similar or stronger G2-checkpoint than wild-type (WT) cells. Inhibition of ATM or ATR leaves largely unaffected residual G2-checkpoint in HRR-deficient cells, suggesting that the G2-checkpoint engagement of ATM/ATR is coupled to HRR. HRR-deficient cells show in G2-phase reduced DSB-end-resection, as compared to WT-cells or c-NHEJ mutants, confirming the reported link between resection and G2-checkpoint activation. Strikingly, at higher IR doses (≥4 Gy) HRR-deficient cells irradiated in G2-phase activate a weak but readily detectable ATM/ATR-dependent G2-checkpoint, whereas HRR-deficient cells irradiated in S-phase develop a stronger G2-checkpoint than WT-cells. We conclude that HRR and the ATM/ATR-dependent G2-checkpoint are closely intertwined in cells exposed to low IR-doses in G2-phase, where HRR dominates; they uncouple as HRR becomes suppressed at higher IR doses. Notably, this coupling is specific for cells irradiated in G2-phase, and cells irradiated in S-phase utilize a different mechanistic setup.
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Affiliation(s)
- Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany.
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20
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Eki R, She J, Parlak M, Benamar M, Du KP, Kumar P, Abbas T. A robust CRISPR-Cas9-based fluorescent reporter assay for the detection and quantification of DNA double-strand break repair. Nucleic Acids Res 2020; 48:e126. [PMID: 33068408 PMCID: PMC7708081 DOI: 10.1093/nar/gkaa897] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 09/25/2020] [Accepted: 09/30/2020] [Indexed: 12/30/2022] Open
Abstract
DNA double-strand breaks (DSBs) are highly cytotoxic lesions that can lead to chromosome rearrangements, genomic instability and cell death. Consequently, cells have evolved multiple mechanisms to efficiently repair DSBs to preserve genomic integrity. We have developed a DSB repair assay system, designated CDDR (CRISPR-Cas9-based Dual-fluorescent DSB Repair), that enables the detection and quantification of DSB repair outcomes in mammalian cells with high precision. CDDR is based on the introduction and subsequent resolution of one or two DSB(s) in an intrachromosomal fluorescent reporter following the expression of Cas9 and sgRNAs targeting the reporter. CDDR can discriminate between high-fidelity (HF) and error-prone non-homologous end-joining (NHEJ), as well as between proximal and distal NHEJ repair. Furthermore, CDDR can detect homology-directed repair (HDR) with high sensitivity. Using CDDR, we found HF-NHEJ to be strictly dependent on DNA Ligase IV, XRCC4 and XLF, members of the canonical branch of NHEJ pathway (c-NHEJ). Loss of these genes also stimulated HDR, and promoted error-prone distal end-joining. Deletion of the DNA repair kinase ATM, on the other hand, stimulated HF-NHEJ and suppressed HDR. These findings demonstrate the utility of CDDR in characterizing the effect of repair factors and in elucidating the balance between competing DSB repair pathways.
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Affiliation(s)
- Rebeka Eki
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
| | - Jane She
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Mahmut Parlak
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Mouadh Benamar
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA
| | - Kang-Ping Du
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA
| | - Pankaj Kumar
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA
| | - Tarek Abbas
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA 22908, USA.,Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.,Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA.,Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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21
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Ahmed EA, Alzahrani AM, Scherthan H. Parp1-Dependent DNA Double-Strand Break Repair in Irradiated Late Pachytene Spermatocytes. DNA Cell Biol 2020; 40:209-218. [PMID: 33337266 DOI: 10.1089/dna.2020.5727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Poly (ADP-ribose) polymerase-1 (Parp1) is a member of nuclear enzymes family involved in to the response to genotoxic stresses, DNA repair, and is critical for the maintenance of genome stability. During gametogenesis, genome stability is essential for inheritance and formation of healthy gametes. The latter involves DNA double-strand break (DSB)-driven pairing of homologous chromosomes in first meiotic prophase. By analysis of DSB repair kinetics in male meiotic prophase cells of homologous recombination (HR) and nonhomologous end joining (NHEJ)-deficient mouse models, we previously demonstrated an interplay between HR and the conventional NHEJ repair pathway. In the current work, we evaluate the relative contribution of Parp1-dependent NHEJ to the repair of ectopic ionizing radiation (IR)-induced DSBs in control and Parp1-inhibited mouse pachytene spermatocytes before and after the completion of meiotic recombination in stages VI-XI. The disappearance of large, exogenous DSB-related γ-H2AX foci was quantified 1 and 8 h after 1 Gy γ-irradiation of control and 3,4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2H)quinolinone (DPQ) Parp1-inhibited mice. Late pachytene control spermatocytes obtained 8 h after IR had repaired >80% of DSBs observed at 1 h after IR. However, only 64% of DSBs were repaired in late spermatocytes of DPQ-treated (Parp1-inhibited) mice. Thus, it appears that Parp1 contributes to the repair of a fraction of DSBs in late prophase I, providing further insights in DNA repair pathway choreography during spermatogenic differentiation.
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Affiliation(s)
- Emad A Ahmed
- Biological Sciences Department, Faculty of Science, King Faisal University, Al-Ahsa, Saudi Arabia.,Laboratory of Molecular Physiology, Zoology Department, Faculty of Science, Assiut University, Assiut, Egypt
| | - Abdullah M Alzahrani
- Biological Sciences Department, Faculty of Science, King Faisal University, Al-Ahsa, Saudi Arabia
| | - Harry Scherthan
- Institut für Radiobiologie der Bundeswehr in Verb. mit der Universität Ulm, Munich, Germany
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22
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Dueva R, Iliakis G. Replication protein A: a multifunctional protein with roles in DNA replication, repair and beyond. NAR Cancer 2020; 2:zcaa022. [PMID: 34316690 PMCID: PMC8210275 DOI: 10.1093/narcan/zcaa022] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
Single-stranded DNA (ssDNA) forms continuously during DNA replication and is an important intermediate during recombination-mediated repair of damaged DNA. Replication protein A (RPA) is the major eukaryotic ssDNA-binding protein. As such, RPA protects the transiently formed ssDNA from nucleolytic degradation and serves as a physical platform for the recruitment of DNA damage response factors. Prominent and well-studied RPA-interacting partners are the tumor suppressor protein p53, the RAD51 recombinase and the ATR-interacting proteins ATRIP and ETAA1. RPA interactions are also documented with the helicases BLM, WRN and SMARCAL1/HARP, as well as the nucleotide excision repair proteins XPA, XPG and XPF–ERCC1. Besides its well-studied roles in DNA replication (restart) and repair, accumulating evidence shows that RPA is engaged in DNA activities in a broader biological context, including nucleosome assembly on nascent chromatin, regulation of gene expression, telomere maintenance and numerous other aspects of nucleic acid metabolism. In addition, novel RPA inhibitors show promising effects in cancer treatment, as single agents or in combination with chemotherapeutics. Since the biochemical properties of RPA and its roles in DNA repair have been extensively reviewed, here we focus on recent discoveries describing several non-canonical functions.
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Affiliation(s)
- Rositsa Dueva
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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23
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Huang RX, Zhou PK. DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer. Signal Transduct Target Ther 2020; 5:60. [PMID: 32355263 PMCID: PMC7192953 DOI: 10.1038/s41392-020-0150-x] [Citation(s) in RCA: 488] [Impact Index Per Article: 122.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/20/2020] [Accepted: 03/16/2020] [Indexed: 12/19/2022] Open
Abstract
Radiotherapy is one of the most common countermeasures for treating a wide range of tumors. However, the radioresistance of cancer cells is still a major limitation for radiotherapy applications. Efforts are continuously ongoing to explore sensitizing targets and develop radiosensitizers for improving the outcomes of radiotherapy. DNA double-strand breaks are the most lethal lesions induced by ionizing radiation and can trigger a series of cellular DNA damage responses (DDRs), including those helping cells recover from radiation injuries, such as the activation of DNA damage sensing and early transduction pathways, cell cycle arrest, and DNA repair. Obviously, these protective DDRs confer tumor radioresistance. Targeting DDR signaling pathways has become an attractive strategy for overcoming tumor radioresistance, and some important advances and breakthroughs have already been achieved in recent years. On the basis of comprehensively reviewing the DDR signal pathways, we provide an update on the novel and promising druggable targets emerging from DDR pathways that can be exploited for radiosensitization. We further discuss recent advances identified from preclinical studies, current clinical trials, and clinical application of chemical inhibitors targeting key DDR proteins, including DNA-PKcs (DNA-dependent protein kinase, catalytic subunit), ATM/ATR (ataxia-telangiectasia mutated and Rad3-related), the MRN (MRE11-RAD50-NBS1) complex, the PARP (poly[ADP-ribose] polymerase) family, MDC1, Wee1, LIG4 (ligase IV), CDK1, BRCA1 (BRCA1 C terminal), CHK1, and HIF-1 (hypoxia-inducible factor-1). Challenges for ionizing radiation-induced signal transduction and targeted therapy are also discussed based on recent achievements in the biological field of radiotherapy.
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Affiliation(s)
- Rui-Xue Huang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, 410078, Changsha, People's Republic of China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, AMMS, 100850, Beijing, People's Republic of China.
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory, Guangzhou Medical University, 511436, Guangzhou, People's Republic of China.
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24
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Soni A, Murmann-Konda T, Siemann-Loekes M, Pantelias GE, Iliakis G. Chromosome breaks generated by low doses of ionizing radiation in G 2-phase are processed exclusively by gene conversion. DNA Repair (Amst) 2020; 89:102828. [PMID: 32143127 DOI: 10.1016/j.dnarep.2020.102828] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/31/2020] [Accepted: 02/21/2020] [Indexed: 02/07/2023]
Abstract
Four repair pathways process DNA double-strand breaks (DSBs). Among these pathways the homologous recombination repair (HRR) subpathway of gene conversion (GC) affords error-free processing, but functions only in S- and G2-phases of the cell cycle. Classical non-homologous end-joining (c-NHEJ) operates throughout the cell cycle, but causes small deletions and translocations. Similar deficiencies in exaggerated form, combined with reduced efficiency, are associated with alternative end-joining (alt-EJ). Finally, single-strand annealing (SSA) causes large deletions and possibly translocations. Thus, processing of a DSB by any pathway, except GC, poses significant risks to the genome, making the mechanisms navigating pathway-engagement critical to genome stability. Logically, the cell ought to attempt engagement of the pathway ensuring preservation of the genome, while accommodating necessities generated by the types of DSBs induced. Thereby, inception of DNA end-resection will be key determinant for GC, SSA and alt-EJ engagement. We reported that during G2-phase, where all pathways are active, GC engages in the processing of almost 50 % of DSBs, at low DSB-loads in the genome, and that this contribution rapidly drops to nearly zero with increasing DSB-loads. At the transition between these two extremes, SSA and alt-EJ compensate, but at extremely high DSB-loads resection-dependent pathways are suppressed and c-NHEJ remains mainly active. We inquired whether in this processing framework all DSBs have similar fates. Here, we analyze in G2-phase the processing of a subset of DSBs defined by their ability to break chromosomes. Our results reveal an absolute requirement for GC in the processing of chromatid breaks at doses in the range of 1 Gy. Defects in c-NHEJ delay significantly the inception of processing by GC, but leave processing kinetics unchanged. These results delineate the essential role of GC in chromatid break repair before mitosis and classify DSBs that underpin this breakage as the exclusive substrate of GC.
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Affiliation(s)
- Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Tamara Murmann-Konda
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Maria Siemann-Loekes
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Gabriel E Pantelias
- Institute of Nuclear Technology and Radiation Protection, National Centre for Scientific Research "Demokritos,''Aghia Paraskevi Attikis, Athens, Greece
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany.
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25
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Li W, Bai X, Li J, Zhao Y, Liu J, Zhao H, Liu L, Ding M, Wang Q, Shi FY, Hou M, Ji J, Gao G, Guo R, Sun Y, Liu Y, Xu D. The nucleoskeleton protein IFFO1 immobilizes broken DNA and suppresses chromosome translocation during tumorigenesis. Nat Cell Biol 2019; 21:1273-1285. [DOI: 10.1038/s41556-019-0388-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/09/2019] [Indexed: 01/19/2023]
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26
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27
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Ray S, Breuer G, DeVeaux M, Zelterman D, Bindra R, Sweasy JB. DNA polymerase beta participates in DNA End-joining. Nucleic Acids Res 2019; 46:242-255. [PMID: 29161447 PMCID: PMC5758893 DOI: 10.1093/nar/gkx1147] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/31/2017] [Indexed: 12/21/2022] Open
Abstract
DNA double strand breaks (DSBs) are one of the most deleterious lesions and if left unrepaired, they lead to cell death, genomic instability and carcinogenesis. Cells combat DSBs by two pathways: homologous recombination (HR) and non-homologous end-joining (NHEJ), wherein the two DNA ends are re-joined. Recently a back-up NHEJ pathway has been reported and is referred to as alternative NHEJ (aNHEJ), which joins ends but results in deletions and insertions. NHEJ requires processing enzymes including nucleases and polymerases, although the roles of these enzymes are poorly understood. Emerging evidence indicates that X family DNA polymerases lambda (Pol λ) and mu (Pol μ) promote DNA end-joining. Here, we show that DNA polymerase beta (Pol β), another member of the X family of DNA polymerases, plays a role in aNHEJ. In the absence of DNA Pol β, fewer small deletions are observed. In addition, depletion of Pol β results in cellular sensitivity to bleomycin and DNA protein kinase catalytic subunit inhibitors due to defective repair of DSBs. In summary, our results indicate that Pol β in functions in aNHEJ and provide mechanistic insight into its role in this process.
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Affiliation(s)
- Sreerupa Ray
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Gregory Breuer
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Pathology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Michelle DeVeaux
- School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Daniel Zelterman
- School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Ranjit Bindra
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Pathology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Joann B Sweasy
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Genetics, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
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28
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Gothe HJ, Bouwman BAM, Gusmao EG, Piccinno R, Petrosino G, Sayols S, Drechsel O, Minneker V, Josipovic N, Mizi A, Nielsen CF, Wagner EM, Takeda S, Sasanuma H, Hudson DF, Kindler T, Baranello L, Papantonis A, Crosetto N, Roukos V. Spatial Chromosome Folding and Active Transcription Drive DNA Fragility and Formation of Oncogenic MLL Translocations. Mol Cell 2019; 75:267-283.e12. [DOI: 10.1016/j.molcel.2019.05.015] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/14/2019] [Accepted: 05/09/2019] [Indexed: 01/21/2023]
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29
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Iliakis G, Mladenova V, Sharif M, Chaudhary S, Mavragani IV, Soni A, Saha J, Schipler A, Mladenov E. DEFINED BIOLOGICAL MODELS OF HIGH-LET RADIATION LESIONS. RADIATION PROTECTION DOSIMETRY 2019; 183:60-68. [PMID: 30566664 DOI: 10.1093/rpd/ncy248] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Indexed: 06/09/2023]
Abstract
DNA double-strand break (DSB) complexity is invoked to explain the increased efficacy of high-linear energy transfer (LET) radiation. Complexity is usually defined as presence of additional lesions in the immediate proximity of the DSB. DSB-clusters represent a different level of complexity that can jeopardize processing by destabilizing chromatin in the vicinity of the cluster. DSB-clusters are generated after exposure of cells to ionizing radiation (IR), particularly high-LET radiation, and have been considered as particularly consequential in several mathematical models of IR action. Yet, experimental demonstration of their relevance to the adverse IR effects, as well as information on the mechanisms underpinning their severity as DNA lesions is lacking. We addressed this void by developing cell lines with especially designed, multiply integrated constructs modeling defined combinations of DSB-clusters through appropriately engineered I-SceI meganuclease recognition sites. Using this model system, we demonstrate efficient activation of the DNA damage response, as well as a markedly increased potential of DSB-clusters, as compared to single-DSBs, to kill cells, and cause Parp1- dependent chromosomal translocations. We propose that DSB repair relying on first line DSB-processing pathways (canonical non-homologous end joining and to some degree homologous recombination repair) is compromised within DSB clusters, presumably through the associated chromatin destabilization, leaving alternative end joining as last option and translocation formation as a natural consequence. Our observations offer a mechanistic explanation for the increased efficacy of high-LET radiation.
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Affiliation(s)
- George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Mortoga Sharif
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Shipra Chaudhary
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Ifigeneia V Mavragani
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Janapriya Saha
- University of Texas Southwestern Medical Center, UT, Department of Radiation Oncology, Dallas, Texas
| | - Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
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30
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Soni A, Murmann-Konda T, Magin S, Iliakis G. A method for the cell-cycle-specific analysis of radiation-induced chromosome aberrations and breaks. Mutat Res 2019; 815:10-19. [PMID: 30999232 DOI: 10.1016/j.mrfmmm.2019.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 03/30/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
The classical G2-assay is widely used to assess cell-radiosensitivity and cancer phenotype: Cells are exposed to low doses of ionizing-radiation (IR) and collected for cytogenetic- analysis ˜1.5 h later. In this way, chromosome-damage is measured in cells irradiated in G2-phase, without retrieving information regarding kinetics of chromosome-break-repair. Modification of the assay to include analysis at multiple time-points after IR, has enabled kinetic-analysis of chromatid-break-repair and assessment of damage in a larger proportion of G2-phase cells. This modification, however, increases the probability that at later time points not only cells irradiated in G2-phase, but also cells irradiated in S-phase will reach metaphase. However, the response of cells irradiated in G2-phase can be mechanistically different from that of cells irradiated in S-phase. Therefore, indiscriminate analysis may confound the interpretation of experiments designed to elucidate mechanisms of chromosome-break-repair and the contributions of the different DSB-repair-pathways in this response. Here we report an EdU based modification of the assay that enables S- and G2-phase specific analysis of chromatid break repair. Our results show that the majority of metaphases captured during the first 2 h after IR originate from cells irradiated in G2-phase (EdU- metaphases) in both rodent and human cells. Metaphases originating from cells irradiated in S-phase (EdU+ metaphases) start appearing at 2 h and 4 h after IR in rodent and human cells, respectively. The kinetics of chromatid-break-repair are similar in cells irradiated in G2- and S-phase of the cell-cycle, both in rodent and human cells. The protocol is applicable to classical-cytogenetic experiments and allows the cell-cycle specific analysis of chromosomal-aberrations. Finally, the protocol can be applied to the kinetic analysis of chromosome-breaks in prematurely-condensed-chromosomes of G2-phase cells. In summary, the developed protocol provides means to enhance the analysis of IR-induced-cytogenetic-damage by providing information on the cell-cycle phase where DNA damage is inflicted.
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Affiliation(s)
- Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Tamara Murmann-Konda
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - Simon Magin
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Essen, Germany.
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31
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Lee K, Ji JH, Yoon K, Che J, Seol JH, Lee SE, Shim EY. Microhomology Selection for Microhomology Mediated End Joining in Saccharomyces cerevisiae. Genes (Basel) 2019; 10:genes10040284. [PMID: 30965655 PMCID: PMC6523938 DOI: 10.3390/genes10040284] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/26/2019] [Accepted: 03/28/2019] [Indexed: 12/03/2022] Open
Abstract
Microhomology-mediated end joining (MMEJ) anneals short, imperfect microhomologies flanking DNA breaks, producing repair products with deletions in a Ku- and RAD52-independent fashion. Puzzlingly, MMEJ preferentially selects certain microhomologies over others, even when multiple microhomologies are available. To define rules and parameters for microhomology selection, we altered the length, the position, and the level of mismatches to the microhomologies flanking homothallic switching (HO) endonuclease-induced breaks and assessed their effect on MMEJ frequency and the types of repair product formation. We found that microhomology of eight to 20 base pairs carrying no more than 20% mismatches efficiently induced MMEJ. Deletion of MSH6 did not impact MMEJ frequency. MMEJ preferentially chose a microhomology pair that was more proximal from the break. Interestingly, MMEJ events preferentially retained the centromere proximal side of the HO break, while the sequences proximal to the telomere were frequently deleted. The asymmetry in the deletional profile among MMEJ products was reduced when HO was induced on the circular chromosome. The results provide insight into how cells search and select microhomologies for MMEJ in budding yeast.
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Affiliation(s)
- Kihoon Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Jae-Hoon Ji
- Genomic Instability Research Center, Ajou University School of Medicine. 164, World Cup-ro, Yeongtong-gu, Suwon 16499, Korea.
| | - Kihoon Yoon
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Jun Che
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Ja-Hwan Seol
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Sang Eun Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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32
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Harvey A, Mielke N, Grimstead JW, Jones RE, Nguyen T, Mueller M, Baird DM, Hendrickson EA. PARP1 is required for preserving telomeric integrity but is dispensable for A-NHEJ. Oncotarget 2018; 9:34821-34837. [PMID: 30410680 PMCID: PMC6205175 DOI: 10.18632/oncotarget.26201] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 09/15/2018] [Indexed: 01/07/2023] Open
Abstract
Poly-ADP ribose polymerase 1 (PARP1) is clinically important because of its synthetic lethality with breast cancer allele 1 and 2 mutations, which are causative for inherited breast and ovarian cancers. Biochemically, PARP1 is a single-stranded DNA break repair protein that is needed for preserving genomic integrity. In addition, PARP1 has been implicated in a veritable plethora of additional cellular pathways and thus its precise contribution(s) to human biology has remained obscure. To help address this deficiency, we utilized gene editing to construct genetically-null PARP1 human cancer cells. We found a minor role for PARP1 in an alternative form of DNA double-strand break (DSB) repair, but only when these cells were deficient for the classical form of DSB repair. Despite being proficient for DSB repair, however, cell cycle progression defects and elevated endogenous DNA damage signaling were observed. These deficiencies were instead linked to telomere defects, where PARP1 -/- cells had short telomeres that co-localized with markers of endogenous DNA damage and were compromised in their ability to escape a telomere-driven crisis. Our data suggest that while PARP1 does not participate significantly in DNA DSB repair itself, it does prevent the incidence of telomeric DSBs, which, in turn, can drive genomic instability.
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Affiliation(s)
- Adam Harvey
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Nicholas Mielke
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Julia W. Grimstead
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Rhiannon E. Jones
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Thanh Nguyen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Matthew Mueller
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Duncan M. Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Eric A. Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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33
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Rodriguez-Berriguete G, Granata G, Puliyadi R, Tiwana G, Prevo R, Wilson RS, Yu S, Buffa F, Humphrey TC, McKenna WG, Higgins GS. Nucleoporin 54 contributes to homologous recombination repair and post-replicative DNA integrity. Nucleic Acids Res 2018; 46:7731-7746. [PMID: 29986057 PMCID: PMC6125679 DOI: 10.1093/nar/gky569] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 05/25/2018] [Accepted: 06/14/2018] [Indexed: 12/21/2022] Open
Abstract
The nuclear pore complex (NPC) machinery is emerging as an important determinant in the maintenance of genome integrity and sensitivity to DNA double-strand break (DSB)-inducing agents, such as ionising radiation (IR). In this study, using a high-throughput siRNA screen, we identified the central channel NPC protein Nup54, and concomitantly its molecular partners Nup62 and Nup58, as novel factors implicated in radiosensitivity. Nup54 depletion caused an increase in cell death by mitotic catastrophe after IR, and specifically enhanced both the duration of the G2 arrest and the radiosensitivity of cells that contained replicated DNA at the time of IR exposure. Nup54-depleted cells also exhibited increased formation of chromosome aberrations arisen from replicated DNA. Interestingly, we found that Nup54 is epistatic with the homologous recombination (HR) factor Rad51. Moreover, using specific DNA damage repair reporters, we observed a decreased HR repair activity upon Nup54 knockdown. In agreement with a role in HR repair, we also demonstrated a decreased formation of HR-linked DNA synthesis foci and sister chromatid exchanges after IR in cells depleted of Nup54. Our study reveals a novel role for Nup54 in the response to IR and the maintenance of HR-mediated genome integrity.
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Affiliation(s)
- Gonzalo Rodriguez-Berriguete
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Giovanna Granata
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Rathi Puliyadi
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Gaganpreet Tiwana
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Remko Prevo
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Rhodri S Wilson
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Sheng Yu
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Francesca Buffa
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Timothy C Humphrey
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - W Gillies McKenna
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Geoff S Higgins
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK
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Exposure to galactic cosmic radiation compromises DNA repair and increases the potential for oncogenic chromosomal rearrangement in bronchial epithelial cells. Sci Rep 2018; 8:11038. [PMID: 30038404 PMCID: PMC6056477 DOI: 10.1038/s41598-018-29350-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 06/04/2018] [Indexed: 01/05/2023] Open
Abstract
Participants in deep space missions face protracted exposure to galactic cosmic radiation (GCR). In this setting, lung cancer is a significant component of the overall risk of radiation-exposure induced death. Here we investigate persistent effects of GCR exposure on DNA repair capacity in lung-derived epithelial cells, using an enzyme-stimulated chromosomal rearrangement as an endpoint. Replicate cell cultures were irradiated with energetic 48Ti ions (a GCR component) or reference γ-rays. After a six-day recovery, they were challenged by expression of a Cas9/sgRNA pair that creates double-strand breaks simultaneously in the EML4 and ALK loci, misjoining of which creates an EML4-ALK fusion oncogene. Misjoining was significantly elevated in 48Ti-irradiated populations, relative to the baseline rate in mock-irradiated controls. The effect was not seen in γ-ray irradiated populations exposed to equal or higher radiation doses. Sequence analysis of the EML4-ALK joints from 48Ti-irradiated cultures showed that they were far more likely to contain deletions, sometimes flanked by short microhomologies, than equivalent samples from mock-irradiated cultures, consistent with a shift toward error-prone alternative nonhomologous end joining repair. Results suggest a potential mechanism by which a persistent physiological effect of GCR exposure may increase lung cancer risk.
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Bi Y, Verginadis II, Dey S, Lin L, Guo L, Zheng Y, Koumenis C. Radiosensitization by the PARP inhibitor olaparib in BRCA1-proficient and deficient high-grade serous ovarian carcinomas. Gynecol Oncol 2018; 150:534-544. [PMID: 30025822 DOI: 10.1016/j.ygyno.2018.07.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/27/2018] [Accepted: 07/01/2018] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Approximately 15-25% of high-grade serous ovarian carcinomas (HGSOC) harbor BRCA1/2 mutations. Inhibition of Poly (ADP-ribose) polymerase (PARP) is synthetically lethal to cells and tumors with BRCA1/2 mutation. Our goal was to investigate the radiosensitizing effects of PARP inhibitor olaparib in HGSOC with different BRCA1 status. METHODS The radiosensitizing effects of olaparib were tested on BRCA1-proficient and deficient HGSOC by clonogenic survival and tumor growth assays. The effects of olaparib and radiation on DNA damage, PARP activity, and apoptosis were determined. RESULTS BRCA1-deficient HGSOC cells were more sensitive to RT alone and exhibited significantly higher levels of olaparib-mediated radiosensitization compared to BRCA1-proficient cells. Furthermore, when combined with RT, olaparib inhibited DNA damage repair and PARP1 activity, increased apoptosis, decreased growth of HGSOC xenografts and increased overall host survival. The growth-inhibitory effects of the combined olaparib and RT treatment were more pronounced in mice bearing BRCA1-deficient tumors compared to BRCA1-proficient tumors. CONCLUSIONS These results provide a preclinical rationale for improved treatment modalities using olaparib as an effective radiosensitizer in HGSOC, particularly in tumors with BRCA1-deficiencies.
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Affiliation(s)
- Yue Bi
- Oncology Center, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong 510280, China; Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ioannis I Verginadis
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Souvik Dey
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lilie Lin
- MD Anderson Cancer Center, Division of Radiation Oncology, Houston, TX 77054, USA
| | - Linlang Guo
- Oncology Center, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong 510280, China
| | - Yanfang Zheng
- Oncology Center, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong 510280, China.
| | - Constantinos Koumenis
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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36
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Soni A, Li F, Wang Y, Grabos M, Krieger LM, Chaudhary S, Hasan MSM, Ahmed M, Coleman CN, Teicher BA, Piekarz RL, Wang D, Iliakis GE. Inhibition of Parp1 by BMN673 Effectively Sensitizes Cells to Radiotherapy by Upsetting the Balance of Repair Pathways Processing DNA Double-Strand Breaks. Mol Cancer Ther 2018; 17:2206-2216. [DOI: 10.1158/1535-7163.mct-17-0836] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/04/2018] [Accepted: 06/28/2018] [Indexed: 11/16/2022]
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Luteijn RD, Drexler I, Smith GL, Lebbink RJ, Wiertz EJHJ. Mutagenic repair of double-stranded DNA breaks in vaccinia virus genomes requires cellular DNA ligase IV activity in the cytosol. J Gen Virol 2018; 99:790-804. [PMID: 29676720 PMCID: PMC7614823 DOI: 10.1099/jgv.0.001034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Poxviruses comprise a group of large dsDNA viruses that include members relevant to human and animal health, such as variola virus, monkeypox virus, cowpox virus and vaccinia virus (VACV). Poxviruses are remarkable for their unique replication cycle, which is restricted to the cytoplasm of infected cells. The independence from the host nucleus requires poxviruses to encode most of the enzymes involved in DNA replication, transcription and processing. Here, we use the CRISPR/Cas9 genome engineering system to induce DNA damage to VACV (strain Western Reserve) genomes. We show that targeting CRISPR/Cas9 to essential viral genes limits virus replication efficiently. Although VACV is a strictly cytoplasmic pathogen, we observed extensive viral genome editing at the target site; this is reminiscent of a non-homologous end-joining DNA repair mechanism. This pathway was not dependent on the viral DNA ligase, but critically involved the cellular DNA ligase IV. Our data show that DNA ligase IV can act outside of the nucleus to allow repair of dsDNA breaks in poxvirus genomes. This pathway might contribute to the introduction of mutations within the genome of poxviruses and may thereby promote the evolution of these viruses.
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Affiliation(s)
- Rutger David Luteijn
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands.,Present address: Department of Molecular and Cell Biology, University of California, Berkeley, USA
| | - Ingo Drexler
- Institute for Virology, University Hospital Düsseldorf, Düsseldorf, Germany
| | | | - Robert Jan Lebbink
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Emmanuel J H J Wiertz
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
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38
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Hu Y, Lin J, Fang H, Fang J, Li C, Chen W, Liu S, Ondrejka S, Gong Z, Reu F, Maciejewski J, Yi Q, Zhao JJ. Targeting the MALAT1/PARP1/LIG3 complex induces DNA damage and apoptosis in multiple myeloma. Leukemia 2018; 32:2250-2262. [PMID: 29632340 PMCID: PMC6151178 DOI: 10.1038/s41375-018-0104-2] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 02/12/2018] [Accepted: 03/05/2018] [Indexed: 12/12/2022]
Abstract
Metastasis-associated lung adenocarcinoma transcript 1(MALAT1) is a highly conserved long non-coding RNA (lncRNA). Overexpression of MALAT1 has been demonstrated to related to poor prognosis of multiple myeloma(MM) patients. Here, we demonstrated that MALAT1 plays important roles in MM DNA repair and cell death. We found bone marrow plasma cells from patients with monoclonal gammopathy of undetermined significance (MGUS) and MM express elevated MALAT1 and involve in alternative-non-homozygous end joining (A-NHEJ) pathway by binding to PARP1 and LIG3, two key components of the A-NHEJ protein complex. Degradation of the MALAT1 RNA by RNase H using antisense gapmer DNA oligos in MM cells stimulated poly-ADP-ribosylation of nuclear proteins, defected the DNA repair pathway, and further provoked apoptotic pathways. Anti-MALAT1 therapy combined with PARP1 inhibitor or proteasome inhibitor in MM cells showed a synergistic effect in vitro. Furthermore, using novel single wall carbon nanotube (SWCNT) conjugated with anti-MALAT1 oligos, we successfully knocked down MALAT1 RNA in cultured MM cell lines and xenograft murine models. Most importantly, anti-MALAT1 therapy induced DNA damage and cell apoptosis in vivo, indicating that MALAT1 could serve as a potential novel therapeutic target for MM treatment.
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Affiliation(s)
- Yi Hu
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Jianhong Lin
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, 02215, USA
| | - Hua Fang
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Oncology, Fu Xing Hospital, Capital Medical University, Beijing, 100038, China
| | - Jing Fang
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Chen Li
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,College of Food Science and Technology, Agricultural University of Hebei, Baoding, Hebei, 071000, China
| | - Wei Chen
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.,Department of Ultrasound, The Fourth Hospital of Hebei Medical University, Shijiazhuang, 050011, China
| | - Shuang Liu
- Department of Pathology, Norman Bethune International Peace Hospital, Shijiazhuang, Hebei, 050082, China
| | - Sarah Ondrejka
- Department of Laboratory Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Zihua Gong
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Frederic Reu
- Department of Translational Hematology & Oncology Research, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Jaroslaw Maciejewski
- Department of Translational Hematology & Oncology Research, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Qing Yi
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Jian-Jun Zhao
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
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Sallmyr A, Tomkinson AE. Repair of DNA double-strand breaks by mammalian alternative end-joining pathways. J Biol Chem 2018. [PMID: 29530982 DOI: 10.1074/jbc.tm117.000375] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alternative end-joining (a-EJ) pathways, which repair DNA double-strand breaks (DSBs), are initiated by end resection that generates 3' single strands. This reaction is shared, at least in part, with homologous recombination but distinguishes a-EJ from the major nonhomologous end-joining pathway. Although the a-EJ pathways make only a minor and poorly understood contribution to DSB repair in nonmalignant cells, there is growing interest in these pathways, as they generate genomic rearrangements that are hallmarks of cancer cells. Here, we review and discuss the current understanding of the mechanisms and regulation of a-EJ pathways, the role of a-EJ in human disease, and the potential utility of a-EJ as a therapeutic target in cancer.
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Affiliation(s)
- Annahita Sallmyr
- From the Departments of Internal Medicine and Molecular Genetics and Microbiology, University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, New Mexico 87131
| | - Alan E Tomkinson
- From the Departments of Internal Medicine and Molecular Genetics and Microbiology, University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, New Mexico 87131
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40
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Brunet E, Jasin M. Induction of Chromosomal Translocations with CRISPR-Cas9 and Other Nucleases: Understanding the Repair Mechanisms That Give Rise to Translocations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1044:15-25. [PMID: 29956288 DOI: 10.1007/978-981-13-0593-1_2] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Chromosomal translocations are associated with several tumor types, including hematopoietic malignancies, sarcomas, and solid tumors of epithelial origin, due to their activation of a proto-oncogene or generation of a novel fusion protein with oncogenic potential. In many cases, the availability of suitable human models has been lacking because of the difficulty in recapitulating precise expression of the fusion protein or other reasons. Further, understanding how translocations form mechanistically has been a goal, as it may suggest ways to prevent their occurrence. Chromosomal translocations arise when DNA ends from double-strand breaks (DSBs) on two heterologous chromosomes are improperly joined. This review provides a summary of DSB repair mechanisms and their contribution to translocation formation, the various programmable nuclease platforms that have been used to generate translocations, and the successes that have been achieved in this area.
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Affiliation(s)
- Erika Brunet
- Genome Dynamics in the Immune System Laboratory, Institut Imagine, INSERM UMR 1163, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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41
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Day TA, Layer JV, Cleary JP, Guha S, Stevenson KE, Tivey T, Kim S, Schinzel AC, Izzo F, Doench J, Root DE, Hahn WC, Price BD, Weinstock DM. PARP3 is a promoter of chromosomal rearrangements and limits G4 DNA. Nat Commun 2017; 8:15110. [PMID: 28447610 PMCID: PMC5414184 DOI: 10.1038/ncomms15110] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 02/28/2017] [Indexed: 12/24/2022] Open
Abstract
Chromosomal rearrangements are essential events in the pathogenesis of both malignant and nonmalignant disorders, yet the factors affecting their formation are incompletely understood. Here we develop a zinc-finger nuclease translocation reporter and screen for factors that modulate rearrangements in human cells. We identify UBC9 and RAD50 as suppressors and 53BP1, DDB1 and poly(ADP)ribose polymerase 3 (PARP3) as promoters of chromosomal rearrangements across human cell types. We focus on PARP3 as it is dispensable for murine viability and has druggable catalytic activity. We find that PARP3 regulates G quadruplex (G4) DNA in response to DNA damage, which suppresses repair by nonhomologous end-joining and homologous recombination. Chemical stabilization of G4 DNA in PARP3-/- cells leads to widespread DNA double-strand breaks and synthetic lethality. We propose a model in which PARP3 suppresses G4 DNA and facilitates DNA repair by multiple pathways.
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Affiliation(s)
- Tovah A. Day
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Jacob V. Layer
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - J. Patrick Cleary
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Srijoy Guha
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Kristen E. Stevenson
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Trevor Tivey
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Sunhee Kim
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - Anna C. Schinzel
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - Francesca Izzo
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - John Doench
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - David E. Root
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - William C. Hahn
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - Brendan D. Price
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
| | - David M. Weinstock
- Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, USA
- Genetic Perturbation Platform, Broad Institute of MIT and Harvard University, 415 Main Street, Cambridge, Massachusetts 02142, USA
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Deregulated BCL-2 family proteins impact on repair of DNA double-strand breaks and are targets to overcome radioresistance in lung cancer. J Cancer Res Clin Oncol 2017; 143:1733-1744. [PMID: 28432456 DOI: 10.1007/s00432-017-2427-1] [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: 04/08/2017] [Accepted: 04/13/2017] [Indexed: 12/25/2022]
Abstract
PURPOSE DNA damage-induced cell death is a major effector mechanism of radiotherapy. Aberrant expression of anti-apoptotic BCL-2 family proteins is frequently observed in lung cancers. Against this background, we studied radioresistance mediated by BCL-2 family proteins at the mechanistic level and its potential as target for radiochemotherapy. METHODS Lung cancer models stably expressing BCL-xL or MCL-1 were irradiated to study cell death, clonogenic survival, and DNA repair kinetics in vitro, and growth suppression of established tumors in vivo. Additionally, endogenous BCL-xL and MCL-1 were targeted by shRNA or pharmacologic agents prior to irradiation. RESULTS Radiation exposure induced apoptosis at negligible levels. Yet, anti-apoptotic BCL-xL and MCL-1 expression conferred short-term and long-term radioresistance in vitro and in vivo. Radioresistance correlated with pertubations in homologous recombination repair and repair of DNA double-strand breaks by error-prone, alternative end-joining. Notably, genetic or pharmacologic targeting of BCL-xL or MCL-1 effectively sensitized lung cancer cells to radiotherapy. CONCLUSIONS In addition to directly suppressing apoptosis, BCL-2 family proteins confer long-term survival benefits to irradiated cancer cells associated with utilization of error-prone repair pathways. Targeting BCL-xL and MCL-1 is an attractive strategy for improving lung cancer radiotherapy.
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43
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So A, Le Guen T, Lopez BS, Guirouilh-Barbat J. Genomic rearrangements induced by unscheduled DNA double strand breaks in somatic mammalian cells. FEBS J 2017; 284:2324-2344. [PMID: 28244221 DOI: 10.1111/febs.14053] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/02/2017] [Accepted: 02/24/2017] [Indexed: 12/13/2022]
Abstract
DNA double-strand breaks (DSBs) are highly toxic lesions that can lead to profound genome rearrangements and/or cell death. They routinely occur in genomes due to endogenous or exogenous stresses. Efficient repair systems, canonical non-homologous end-joining and homologous recombination exist in the cell and not only ensure the maintenance of genome integrity but also, via specific programmed DNA double-strand breaks, permit its diversity and plasticity. However, these repair systems need to be tightly controlled because they can also generate genomic rearrangements. Thus, when DSB repair is not properly regulated, genome integrity is no longer guaranteed. In this review, we will focus on non-programmed genome rearrangements generated by DSB repair, in somatic cells. We first discuss genome rearrangements induced by homologous recombination and end-joining. We then discuss recently described rearrangement mechanisms, driven by microhomologies, that do not involve the joining of DNA ends but rather initiate DNA synthesis (microhomology-mediated break-induced replication, fork stalling and template switching and microhomology-mediated template switching). Finally, we discuss chromothripsis, which is the shattering of a localized region of the genome followed by erratic rejoining.
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Affiliation(s)
- Ayeong So
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Tangui Le Guen
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Bernard S Lopez
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
| | - Josée Guirouilh-Barbat
- CNRS UMR 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Saclay, Equipe Labellisée Ligue Contre le Cancer, Villejuif, France
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44
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Herskind C, Ma L, Liu Q, Zhang B, Schneider F, Veldwijk MR, Wenz F. Biology of high single doses of IORT: RBE, 5 R's, and other biological aspects. Radiat Oncol 2017; 12:24. [PMID: 28107823 PMCID: PMC5251326 DOI: 10.1186/s13014-016-0750-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 12/21/2016] [Indexed: 01/14/2023] Open
Abstract
Intraoperative radiotherapy differs from conventional, fractionated radiotherapy in several aspects that may influence its biological effect. The radiation quality influences the relative biologic effectiveness (RBE), and the role of the five R’s of radiotherapy (reassortment, repair, reoxygenation, repopulation, radiosensitivity) is different. Furthermore, putative special biological effects and the small volume receiving a high single dose may be important. The present review focuses on RBE, repair, and repopulation, and gives an overview of the other factors that potentially contribute to the efficacy. The increased RBE should be taken into account for low-energy X-rays while evidence of RBE < 1 for high-energy electrons at higher doses is presented. Various evidence supports a hypothesis that saturation of the primary DNA double-strand break (DSB) repair mechanisms leads to increasing use of an error-prone backup repair system leading to genomic instability that may contribute to inactivate tumour cells at high single doses. Furthermore, the elimination of repopulation of residual tumour cells in the tumour bed implies that some patients are likely to have very few residual tumour cells which may be cured even by low doses to the tumour bed. The highly localised dose distribution of IORT has the potential to inactivate tumour cells while sparing normal tissue by minimising the volume exposed to high doses. Whether special effects of high single doses also contribute to the efficacy will require further experimental and clinical studies.
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Affiliation(s)
- Carsten Herskind
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
| | - Lin Ma
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.,Present Address: Department of Radiation Oncology, University of California, San Francisco, CA, USA
| | - Qi Liu
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.,Present Address: Department of Radiation Oncology, University of California, San Francisco, CA, USA
| | - Bo Zhang
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.,Present Address: Department of Oncology at No. 2 Hospital Anhui Medical University, and School of Life Sciences, Anhui Medical University, Hefei, Anhui, China
| | - Frank Schneider
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Marlon R Veldwijk
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Frederik Wenz
- Department of Radiation Oncology, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
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Konecny GE, Kristeleit RS. PARP inhibitors for BRCA1/2-mutated and sporadic ovarian cancer: current practice and future directions. Br J Cancer 2016; 115:1157-1173. [PMID: 27736844 PMCID: PMC5104889 DOI: 10.1038/bjc.2016.311] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 08/02/2016] [Accepted: 09/01/2016] [Indexed: 12/12/2022] Open
Abstract
Poly(ADP-ribose) polymerase (PARP) inhibitors cause targeted tumour cell death in homologous recombination (HR)-deficient cancers, including BRCA-mutated tumours, by exploiting synthetic lethality. PARP inhibitors are being evaluated in late-stage clinical trials of ovarian cancer (OC). Recently, olaparib was the first PARP inhibitor approved in the European Union and United States for the treatment of advanced BRCA-mutated OC. This paper reviews the role of BRCA mutations for tumorigenesis and PARP inhibitor sensitivity, and summarises the clinical development of PARP inhibitors for the treatment of patients diagnosed with OC. Among the five key PARP inhibitors currently in clinical development, olaparib has undergone the most extensive clinical investigation. PARP inhibitors have demonstrated durable antitumour activity in BRCA-mutated advanced OC as a single agent in the treatment and maintenance setting, particularly in platinum-sensitive disease. PARP inhibitors are well tolerated; however, further careful assessment of moderate and late-onset toxicity is mandatory in the maintenance and adjuvant setting, respectively. PARP inhibitors are also being evaluated in combination with chemotherapeutic and novel targeted agents to potentiate antitumour activities. Current research is extending the use of PARP inhibitors beyond BRCA mutations to other sensitising molecular defects that result in HR-deficient cancer, and is defining an HR-deficiency signature. Trials are underway to determine whether such a signature will predict sensitivity to PARP inhibitors in women with sporadic OC.
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Affiliation(s)
- G E Konecny
- Division of Hematology-Oncology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, 2825 Santa Monica Blvd., Suite 200, Santa Monica, CA 90404–2429, USA
| | - R S Kristeleit
- Department of Oncology, University College London Cancer Institute, University College London, Paul Gorman Building, Huntley Street, London, WC1E 6BT, UK
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Woods ML, Barnes CP. Mechanistic Modelling and Bayesian Inference Elucidates the Variable Dynamics of Double-Strand Break Repair. PLoS Comput Biol 2016; 12:e1005131. [PMID: 27741226 PMCID: PMC5065155 DOI: 10.1371/journal.pcbi.1005131] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 09/05/2016] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution. Here we present a new method to model the combined activation of non-homologous end joining, single strand annealing and alternative end joining, following exposure to ionising radiation. We use Bayesian statistics to integrate eight biological data sets of double-strand break repair curves under varying genetic knockouts and confirm that our model is predictive by re-simulating and comparing to additional data. Analysis of the model suggests that there are at least three disjoint modes of repair, which we assign as fast, slow and intermediate. Our results show that when multiple data sets are combined, the rate for intermediate repair is variable amongst genetic knockouts. Further analysis suggests that the ratio between slow and intermediate repair depends on the presence or absence of DNA-PKcs and Ku70, which implies that non-homologous end joining and alternative end joining are not independent. Finally, we consider the proportion of double-strand breaks within each mechanism as a time series and predict activity as a function of repair rate. We outline how our insights can be directly tested using imaging and sequencing techniques and conclude that there is evidence of variable dynamics in alternative repair pathways. Our approach is an important step towards providing a unifying theoretical framework for the dynamics of DNA repair processes.
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Affiliation(s)
- Mae L. Woods
- Department of Cell and Developmental Biology, University College London, London, England
| | - Chris P. Barnes
- Department of Cell and Developmental Biology, University College London, London, England
- Department of Genetics, Evolution and Environment, University College London, London, England
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Ahrabi S, Sarkar S, Pfister SX, Pirovano G, Higgins GS, Porter ACG, Humphrey TC. A role for human homologous recombination factors in suppressing microhomology-mediated end joining. Nucleic Acids Res 2016; 44:5743-57. [PMID: 27131361 PMCID: PMC4937322 DOI: 10.1093/nar/gkw326] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 04/13/2016] [Accepted: 04/14/2016] [Indexed: 12/22/2022] Open
Abstract
DNA double-strand breaks (DSBs) are toxic lesions, which if improperly repaired can result in cell death or genomic instability. DSB repair is usually facilitated by the classical non-homologous end joining (C-NHEJ), or homologous recombination (HR) pathways. However, a mutagenic alternative NHEJ pathway, microhomology-mediated end joining (MMEJ), can also be deployed. While MMEJ is suppressed by C-NHEJ, the relationship between HR and MMEJ is less clear. Here, we describe a role for HR genes in suppressing MMEJ in human cells. By monitoring DSB mis-repair using a sensitive HPRT assay, we found that depletion of HR proteins, including BRCA2, BRCA1 or RPA, resulted in a distinct mutational signature associated with significant increases in break-induced mutation frequencies, deletion lengths and the annealing of short regions of microhomology (2-6 bp) across the break-site. This signature was dependent on CtIP, MRE11, POLQ and PARP, and thus indicative of MMEJ. In contrast to CtIP or MRE11, depletion of BRCA1 resulted in increased partial resection and MMEJ, thus revealing a functional distinction between these early acting HR factors. Together these findings indicate that HR factors suppress mutagenic MMEJ following DSB resection.
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Affiliation(s)
- Sara Ahrabi
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Sovan Sarkar
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Sophia X Pfister
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Giacomo Pirovano
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Geoff S Higgins
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Andrew C G Porter
- Gene Targeting Group, Centre for Haematology, Imperial College Faculty of Medicine, London W12 0NN, UK
| | - Timothy C Humphrey
- CRUK MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, OX3 7DQ, UK
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48
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DNA Damage and Pulmonary Hypertension. Int J Mol Sci 2016; 17:ijms17060990. [PMID: 27338373 PMCID: PMC4926518 DOI: 10.3390/ijms17060990] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/01/2016] [Accepted: 06/16/2016] [Indexed: 01/21/2023] Open
Abstract
Pulmonary hypertension (PH) is defined by a mean pulmonary arterial pressure over 25 mmHg at rest and is diagnosed by right heart catheterization. Among the different groups of PH, pulmonary arterial hypertension (PAH) is characterized by a progressive obstruction of distal pulmonary arteries, related to endothelial cell dysfunction and vascular cell proliferation, which leads to an increased pulmonary vascular resistance, right ventricular hypertrophy, and right heart failure. Although the primary trigger of PAH remains unknown, oxidative stress and inflammation have been shown to play a key role in the development and progression of vascular remodeling. These factors are known to increase DNA damage that might favor the emergence of the proliferative and apoptosis-resistant phenotype observed in PAH vascular cells. High levels of DNA damage were reported to occur in PAH lungs and remodeled arteries as well as in animal models of PH. Moreover, recent studies have demonstrated that impaired DNA-response mechanisms may lead to an increased mutagen sensitivity in PAH patients. Finally, PAH was linked with decreased breast cancer 1 protein (BRCA1) and DNA topoisomerase 2-binding protein 1 (TopBP1) expression, both involved in maintaining genome integrity. This review aims to provide an overview of recent evidence of DNA damage and DNA repair deficiency and their implication in PAH pathogenesis.
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Schipler A, Mladenova V, Soni A, Nikolov V, Saha J, Mladenov E, Iliakis G. Chromosome thripsis by DNA double strand break clusters causes enhanced cell lethality, chromosomal translocations and 53BP1-recruitment. Nucleic Acids Res 2016; 44:7673-90. [PMID: 27257076 PMCID: PMC5027484 DOI: 10.1093/nar/gkw487] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 05/19/2016] [Indexed: 01/04/2023] Open
Abstract
Chromosome translocations are hallmark of cancer and of radiation-induced cell killing, reflecting joining of incongruent DNA-ends that alter the genome. Translocation-formation requires DNA end-joining mechanisms and incompletely characterized, permissive chromatin conditions. We show that chromatin destabilization by clusters of DNA double-strand-breaks (DSBs) generated by the I-SceI meganuclease at multiple, appropriately engineered genomic sites, compromises c-NHEJ and markedly increases cell killing and translocation-formation compared to single-DSBs. Translocation-formation from DSB-clusters utilizes Parp1 activity, implicating alt-EJ in their formation. Immunofluorescence experiments show that single-DSBs and DSB-clusters uniformly provoke the formation of single γ-H2AX foci, suggesting similar activation of early DNA damage response (DDR). Live-cell imaging also shows similar single-focus recruitment of the early-response protein MDC1, to single-DSBs and DSB-clusters. Notably, the late DDR protein, 53BP1 shows in live-cell imaging strikingly stronger recruitment to DSB-clusters as compared to single-DSBs. This is the first report that chromatin thripsis, in the form of engineered DSB-clusters, compromises first-line DSB-repair pathways, allowing alt-EJ to function as rescuing-backup. DSB-cluster-formation is indirectly linked to the increased biological effectiveness of high ionization-density radiations, such as the alpha-particles emitted by radon gas or the heavy-ions utilized in cancer therapy. Our observations provide the first direct mechanistic explanation for this long-known effect.
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Affiliation(s)
- Agnes Schipler
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Veronika Mladenova
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Aashish Soni
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Vladimir Nikolov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Janapriya Saha
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
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DNA double-strand-break repair in higher eukaryotes and its role in genomic instability and cancer: Cell cycle and proliferation-dependent regulation. Semin Cancer Biol 2016; 37-38:51-64. [DOI: 10.1016/j.semcancer.2016.03.003] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 03/11/2016] [Accepted: 03/21/2016] [Indexed: 12/18/2022]
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