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Wu J, Song L, Lu M, Gao Q, Xu S, Zhou P, Ma T. The multifaceted functions of DNA-PKcs: implications for the therapy of human diseases. MedComm (Beijing) 2024; 5:e613. [PMID: 38898995 PMCID: PMC11185949 DOI: 10.1002/mco2.613] [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: 08/10/2023] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 06/21/2024] Open
Abstract
The DNA-dependent protein kinase (DNA-PK), catalytic subunit, also known as DNA-PKcs, is complexed with the heterodimer Ku70/Ku80 to form DNA-PK holoenzyme, which is well recognized as initiator in the nonhomologous end joining (NHEJ) repair after double strand break (DSB). During NHEJ, DNA-PKcs is essential for both DNA end processing and end joining. Besides its classical function in DSB repair, DNA-PKcs also shows multifaceted functions in various biological activities such as class switch recombination (CSR) and variable (V) diversity (D) joining (J) recombination in B/T lymphocytes development, innate immunity through cGAS-STING pathway, transcription, alternative splicing, and so on, which are dependent on its function in NHEJ or not. Moreover, DNA-PKcs deficiency has been proven to be related with human diseases such as neurological pathogenesis, cancer, immunological disorder, and so on through different mechanisms. Therefore, it is imperative to summarize the latest findings about DNA-PKcs and diseases for better targeting DNA-PKcs, which have shown efficacy in cancer treatment in preclinical models. Here, we discuss the multifaceted roles of DNA-PKcs in human diseases, meanwhile, we discuss the progresses of DNA-PKcs inhibitors and their potential in clinical trials. The most updated review about DNA-PKcs will hopefully provide insights and ideas to understand DNA-PKcs associated diseases.
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Affiliation(s)
- Jinghong Wu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Liwei Song
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Mingjun Lu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Qing Gao
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Shaofa Xu
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Ping‐Kun Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Teng Ma
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
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2
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Li Q, Qian W, Zhang Y, Hu L, Chen S, Xia Y. A new wave of innovations within the DNA damage response. Signal Transduct Target Ther 2023; 8:338. [PMID: 37679326 PMCID: PMC10485079 DOI: 10.1038/s41392-023-01548-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 06/01/2023] [Accepted: 06/27/2023] [Indexed: 09/09/2023] Open
Abstract
Genome instability has been identified as one of the enabling hallmarks in cancer. DNA damage response (DDR) network is responsible for maintenance of genome integrity in cells. As cancer cells frequently carry DDR gene deficiencies or suffer from replicative stress, targeting DDR processes could induce excessive DNA damages (or unrepaired DNA) that eventually lead to cell death. Poly (ADP-ribose) polymerase (PARP) inhibitors have brought impressive benefit to patients with breast cancer gene (BRCA) mutation or homologous recombination deficiency (HRD), which proves the concept of synthetic lethality in cancer treatment. Moreover, the other two scenarios of DDR inhibitor application, replication stress and combination with chemo- or radio- therapy, are under active clinical exploration. In this review, we revisited the progress of DDR targeting therapy beyond the launched first-generation PARP inhibitors. Next generation PARP1 selective inhibitors, which could maintain the efficacy while mitigating side effects, may diversify the application scenarios of PARP inhibitor in clinic. Albeit with unavoidable on-mechanism toxicities, several small molecules targeting DNA damage checkpoints (gatekeepers) have shown great promise in preliminary clinical results, which may warrant further evaluations. In addition, inhibitors for other DNA repair pathways (caretakers) are also under active preclinical or clinical development. With these progresses and efforts, we envision that a new wave of innovations within DDR has come of age.
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Affiliation(s)
- Qi Li
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China
| | - Wenyuan Qian
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China
| | - Yang Zhang
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China
| | - Lihong Hu
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China
| | - Shuhui Chen
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China
| | - Yuanfeng Xia
- Domestic Discovery Service Unit, WuXi AppTec, 200131, Shanghai, China.
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3
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Correction to 'PIDD mediates the association of DNA-pkcs and ATR at stalled replication forks to facilitate the ATR signaling pathway'. Nucleic Acids Res 2023:7151357. [PMID: 37140048 DOI: 10.1093/nar/gkad367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
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4
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Maresca L, Stecca B, Carrassa L. Novel Therapeutic Approaches with DNA Damage Response Inhibitors for Melanoma Treatment. Cells 2022; 11:1466. [PMID: 35563772 PMCID: PMC9099918 DOI: 10.3390/cells11091466] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/22/2022] [Accepted: 04/25/2022] [Indexed: 02/06/2023] Open
Abstract
Targeted therapies against components of the mitogen-activated protein kinase (MAPK) pathway and immunotherapies, which block immune checkpoints, have shown important clinical benefits in melanoma patients. However, most patients develop resistance, with consequent disease relapse. Therefore, there is a need to identify novel therapeutic approaches for patients who are resistant or do not respond to the current targeted and immune therapies. Melanoma is characterized by homologous recombination (HR) and DNA damage response (DDR) gene mutations and by high replicative stress, which increase the endogenous DNA damage, leading to the activation of DDR. In this review, we will discuss the current experimental evidence on how DDR can be exploited therapeutically in melanoma. Specifically, we will focus on PARP, ATM, CHK1, WEE1 and ATR inhibitors, for which preclinical data as single agents, taking advantage of synthetic lethal interactions, and in combination with chemo-targeted-immunotherapy, have been growing in melanoma, encouraging the ongoing clinical trials. The overviewed data are suggestive of considering DDR inhibitors as a valid therapeutic approach, which may positively impact the future of melanoma treatment.
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Affiliation(s)
- Luisa Maresca
- Tumor Cell Biology Unit, Core Research Laboratory, Institute for Cancer Research and Prevention (ISPRO), Viale Gaetano Pieraccini 6, 50139 Florence, Italy;
| | - Barbara Stecca
- Tumor Cell Biology Unit, Core Research Laboratory, Institute for Cancer Research and Prevention (ISPRO), Viale Gaetano Pieraccini 6, 50139 Florence, Italy;
| | - Laura Carrassa
- Fondazione Cesalpino, Arezzo Hospital, USL Toscana Sud-Est, Via Pietro Nenni 20, 52100 Arezzo, Italy
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5
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Cell cycle involvement in cancer therapy; WEE1 kinase, a potential target as therapeutic strategy. Mutat Res 2022; 824:111776. [PMID: 35247630 DOI: 10.1016/j.mrfmmm.2022.111776] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/22/2022]
Abstract
Mitosis is the process of cell division and is regulated by checkpoints in the cell cycle. G1-S, S, and G2-M are the three main checkpoints that prevent initiation of the next phase of the cell cycle phase until previous phase has completed. DNA damage leads to activation of the G2-M checkpoint, which can trigger a downstream DNA damage response (DDR) pathway to induce cell cycle arrest while the damage is repaired. If the DNA damage cannot be repaired, the replication stress response (RSR) pathway finally leads to cell death by apoptosis, in this case called mitotic catastrophe. Many cancer treatments (chemotherapy and radiotherapy) cause DNA damages based on SSBs (single strand breaks) or DSBs (double strand breaks), which cause cell death through mitotic catastrophe. However, damaged cells can activate WEE1 kinase (as a part of the DDR and RSR pathways), which prevents apoptosis and cell death by inducing cell cycle arrest at G2 phase. Therefore, inhibition of WEE1 kinase could sensitize cancer cells to chemotherapeutic drugs. This review focuses on the role of WEE1 kinase (as a biological macromolecule which has a molecular mass of 96 kDa) in the cell cycle, and its interactions with other regulatory pathways. In addition, we discuss the potential of WEE1 inhibition as a new therapeutic approach in the treatment of various cancers, such as melanoma, breast cancer, pancreatic cancer, cervical cancer, etc.
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6
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Choi SH, Cho K, Kim ES, Yoo HY. Proline-serine-threonine-repeat region of MDC1 mediates Chk1 phosphorylation and the DNA double-strand break repair. Int J Biochem Cell Biol 2021; 143:106152. [PMID: 34974185 DOI: 10.1016/j.biocel.2021.106152] [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: 09/10/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 11/29/2022]
Abstract
MDC1, a mediator of DNA damage response, recruits other repair proteins on double-strand break (DSB) sites. MDC1 is necessary for activating checkpoint kinases Chk1 and Chk2. It is unclear whether Chk1 interacts with MDC1. MDC1 also comprises many discrete domains. The role of the proline-serine-threonine (PST)-repeat domain of MDC1 in the DNA damage response is unclear. Here, we showed that MDC1 directly binds Chk1 through this PST-repeat region. Phosphorylation of Chk1 by ionizing radiation (IR) also required this PST-repeat domain. Degradation of intact MDC1 was accelerated depending on the PST-repeat domain after IR exposure. In the IR damage response, the PST-repeat-deleted MDC1 levels remained elevated with slow degradation. This abnormal regulation of MDC1 was F-box- and WD40 repeat-containing 7 (FBXW7)-dependent. The mutation of lysine 1413 within the PST-repeat of MDC1 deregulated MDC1 with or without damage. K1413R mutant and PST-deleted MDC1 displayed reduced ability to repair the damaged genome post-IR exposure. These results provide that the PST domain of MDC1 is involved in Chk1 and DNA repair activation. The findings suggest new insights into how MDC1 connects the checkpoint and DNA repair in the DNA damage response.
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Affiliation(s)
- Seung Ho Choi
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06355, Korea; Samsung Biomedical Research Institute, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06355, Korea
| | - Kyoungjoo Cho
- Department of Life Science, College of Fusion Science, Kyonggi University, Suwon 16227, Korea
| | - Eun Seon Kim
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06355, Korea; Samsung Biomedical Research Institute, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06355, Korea
| | - Hae Yong Yoo
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06355, Korea; Samsung Biomedical Research Institute, Research Institute for Future Medicine, Samsung Medical Center, Seoul 06355, Korea.
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7
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Gorecki L, Andrs M, Korabecny J. Clinical Candidates Targeting the ATR-CHK1-WEE1 Axis in Cancer. Cancers (Basel) 2021; 13:795. [PMID: 33672884 PMCID: PMC7918546 DOI: 10.3390/cancers13040795] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 02/07/2023] Open
Abstract
Selective killing of cancer cells while sparing healthy ones is the principle of the perfect cancer treatment and the primary aim of many oncologists, molecular biologists, and medicinal chemists. To achieve this goal, it is crucial to understand the molecular mechanisms that distinguish cancer cells from healthy ones. Accordingly, several clinical candidates that use particular mutations in cell-cycle progressions have been developed to kill cancer cells. As the majority of cancer cells have defects in G1 control, targeting the subsequent intra‑S or G2/M checkpoints has also been extensively pursued. This review focuses on clinical candidates that target the kinases involved in intra‑S and G2/M checkpoints, namely, ATR, CHK1, and WEE1 inhibitors. It provides insight into their current status and future perspectives for anticancer treatment. Overall, even though CHK1 inhibitors are still far from clinical establishment, promising accomplishments with ATR and WEE1 inhibitors in phase II trials present a positive outlook for patient survival.
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Affiliation(s)
- Lukas Gorecki
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic; (L.G.); (M.A.)
| | - Martin Andrs
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic; (L.G.); (M.A.)
- Laboratory of Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 00 Prague, Czech Republic
| | - Jan Korabecny
- Biomedical Research Center, University Hospital Hradec Kralove, Sokolska 581, 500 05 Hradec Kralove, Czech Republic; (L.G.); (M.A.)
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Ma S, Rong Z, Liu C, Qin X, Zhang X, Chen Q. DNA damage promotes microtubule dynamics through a DNA-PK-AKT axis for enhanced repair. J Cell Biol 2021; 220:211656. [PMID: 33404607 PMCID: PMC7791344 DOI: 10.1083/jcb.201911025] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 11/01/2020] [Accepted: 12/02/2020] [Indexed: 01/09/2023] Open
Abstract
DNA double-strand breaks (DSBs) are mainly repaired by c-NHEJ and HR pathways. The enhanced DSB mobility after DNA damage is critical for efficient DSB repair. Although microtubule dynamics have been shown to regulate DSB mobility, the reverse effect of DSBs to microtubule dynamics remains elusive. Here, we uncovered a novel DSB-induced microtubule dynamics stress response (DMSR), which promotes DSB mobility and facilitates c-NHEJ repair. DMSR is accompanied by interphase centrosome maturation, which occurs in a DNA-PK-AKT-dependent manner. Depletion of PCM proteins attenuates DMSR and the mobility of DSBs, resulting in delayed c-NHEJ. Remarkably, DMSR occurs only in G1 or G0 cells and lasts around 6 h. Both inhibition of DNA-PK and depletion of 53BP1 abolish DMSR. Taken together, our study reveals a positive DNA repair mechanism in G1 or G0 cells in which DSBs actively promote microtubule dynamics and facilitate the c-NHEJ process.
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Affiliation(s)
- Shuyun Ma
- Department of Radiation and Medical Oncology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Zeming Rong
- Department of Radiation and Medical Oncology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Chen Liu
- Department of Radiation and Medical Oncology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Xiaobing Qin
- Department of Radiation and Medical Oncology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Xiaoyan Zhang
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, China,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Qiang Chen
- Department of Radiation and Medical Oncology, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan, China,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China,Correspondence to Qiang Chen:
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9
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Yue X, Bai C, Xie D, Ma T, Zhou PK. DNA-PKcs: A Multi-Faceted Player in DNA Damage Response. Front Genet 2020; 11:607428. [PMID: 33424929 PMCID: PMC7786053 DOI: 10.3389/fgene.2020.607428] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/01/2020] [Indexed: 12/17/2022] Open
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a member of the phosphatidylinositol 3-kinase related kinase family, which can phosphorylate more than 700 substrates. As the core enzyme, DNA-PKcs forms the active DNA-PK holoenzyme with the Ku80/Ku70 heterodimer to play crucial roles in cellular DNA damage response (DDR). Once DNA double strand breaks (DSBs) occur in the cells, DNA-PKcs is promptly recruited into damage sites and activated. DNA-PKcs is auto-phosphorylated and phosphorylated by Ataxia-Telangiectasia Mutated at multiple sites, and phosphorylates other targets, participating in a series of DDR and repair processes, which determine the cells' fates: DSBs NHEJ repair and pathway choice, replication stress response, cell cycle checkpoints, telomeres length maintenance, senescence, autophagy, etc. Due to the special and multi-faceted roles of DNA-PKcs in the cellular responses to DNA damage, it is important to precisely regulate the formation and dynamic of its functional complex and activities for guarding genomic stability. On the other hand, targeting DNA-PKcs has been considered as a promising strategy of exploring novel radiosensitizers and killing agents of cancer cells. Combining DNA-PKcs inhibitors with radiotherapy can effectively enhance the efficacy of radiotherapy, offering more possibilities for cancer therapy.
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Affiliation(s)
- Xiaoqiao Yue
- School of Public Health, University of South China, Hengyang, China.,Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Chenjun Bai
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Dafei Xie
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Teng Ma
- Department of Cellular and Molecular Biology, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
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Implications of CLSPN Variants in Cellular Function and Susceptibility to Cancer. Cancers (Basel) 2020; 12:cancers12092396. [PMID: 32847043 PMCID: PMC7565888 DOI: 10.3390/cancers12092396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/05/2020] [Accepted: 08/20/2020] [Indexed: 11/28/2022] Open
Abstract
Claspin is a multifunctional protein that participates in physiological processes essential for cell homeostasis that are often defective in cancer, namely due to genetic changes. It is conceivable that Claspin gene (CLSPN) alterations may contribute to cancer development. Therefore, CLSPN germline alterations were characterized in sporadic and familial breast cancer and glioma samples, as well as in six cancer cell lines. Their association to cancer susceptibility and functional impact were investigated. Eight variants were identified (c.-68C>T, c.17G>A, c.1574A>G, c.2230T>C, c.2028+16G>A, c.3595-3597del, and c.3839C>T). CLSPN c.1574A>G (p.Asn525Ser) was significantly associated with breast cancer and was shown to cause partial exon skipping and decreased Claspin expression and Chk1 activation in a minigene splicing assay and in signalling experiments, respectively. CLSPN c.2028+16G>A was significantly associated with familial breast cancer and glioma, whereas c.2230T>C (p.Ser744Pro), was exclusively detected in breast cancer and glioma patients, but not in healthy controls. The remaining variants lacked a significant association with cancer. Nevertheless, the c.-68C>T promoter variant increased transcriptional activity in a luciferase assay. In conclusion, some of the CLSPN variants identified in the present study appear to modulate Claspin’s function by altering CLSPN transcription and RNA processing, as well as Chk1 activation.
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11
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Wang CY, Tsai SW, Chien HH, Chen TY, Sheu SY, So EC, Huang BM. Cordycepin Inhibits Human Gestational Choriocarcinoma Cell Growth by Disrupting Centrosome Homeostasis. DRUG DESIGN DEVELOPMENT AND THERAPY 2020; 14:2987-3000. [PMID: 32801639 PMCID: PMC7394508 DOI: 10.2147/dddt.s252401] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 07/06/2020] [Indexed: 12/19/2022]
Abstract
Introduction Human gestational choriocarcinoma, a type of gestational trophoblastic disease, occurs after miscarriage, abortion, ectopic pregnancy, or molar pregnancy. Despite recent advances in the mechanism of anticancer drugs that induce human gestational choriocarcinoma apoptosis or block its growth, new therapeutic approaches are needed to be established. Cordycepin is an active anti-cancer component extracted from Cordyceps sinensis. It prevents cell proliferation both in vitro and in vivo. Materials and Methods Here, we examined cell growth by counting cell numbers, and performing a flow cytometry assay and EdU incorporation assay. Centrosome and cytoskeleton-related structures were observed by immunofluorescence assay. The DNA damage-related signaling was examined by Western blot assay. Results Here, we showed that cordycepin inhibited human gestational choriocarcinoma cell proliferation and induced cell death. In addition, treatment with cordycepin activated DNA-PK and ERK, thus inducing centrosome amplification and aberrant mitosis. These amplified centrosomes also disrupted microtubule arrays and actin networks, thus leading to defective cell adhesion. Furthermore, cordycepin induced autophagy for triggering cell death. Conclusion Thus, our study demonstrates that cordycepin inhibits cell proliferation and disrupts the cytoskeleton by triggering centrosome amplification.
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Affiliation(s)
- Chia-Yih Wang
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Shih-Wei Tsai
- Department of Obstetrics and Gynecology, An Nan Hospital, China Medical University, Tainan, Taiwan
| | - Han-Hsiang Chien
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ting-Yu Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Shi-Yuan Sheu
- School of Chinese Medicine for Post-Baccalaureate, I-Shou University, Kaohsiung, Taiwan.,Department of Chinese Medicine, E-Da Cancer Hospital, Kaohsiung, Taiwan
| | - Edmund Cheung So
- Department of Anesthesia & Medical Research, An Nan Hospital, China Medical University, Tainan, Taiwan.,Graduate Institute of Medical Sciences, Chang Jung Christian University Tainan, Tainan, Taiwan
| | - Bu-Miin Huang
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Medical Research, China Medical University, Taichung, Taiwan
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12
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Brunner A, Suryo Rahmanto A, Johansson H, Franco M, Viiliäinen J, Gazi M, Frings O, Fredlund E, Spruck C, Lehtiö J, Rantala JK, Larsson LG, Sangfelt O. PTEN and DNA-PK determine sensitivity and recovery in response to WEE1 inhibition in human breast cancer. eLife 2020; 9:57894. [PMID: 32628111 PMCID: PMC7338058 DOI: 10.7554/elife.57894] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/22/2020] [Indexed: 12/12/2022] Open
Abstract
Inhibition of WEE1 kinase by AZD1775 has shown promising results in clinical cancer trials, but markers predicting AZD1775 response are lacking. Here we analysed AZD1775 response in a panel of human breast cancer (BC) cell lines by global proteome/transcriptome profiling and identified two groups of basal-like BC (BLBCs): ‘PTEN low’ BLBCs were highly sensitive to AZD1775 and failed to recover following removal of AZD1775, while ‘PTEN high’ BLBCs recovered. AZD1775 induced phosphorylation of DNA-PK, protecting cells from replication-associated DNA damage and promoting cellular recovery. Deletion of DNA-PK or PTEN, or inhibition of DNA-PK sensitized recovering BLBCs to AZD1775 by abrogating replication arrest, allowing replication despite DNA damage. This was linked to reduced CHK1 activation, increased cyclin E levels and apoptosis. In conclusion, we identified PTEN and DNA-PK as essential regulators of replication checkpoint arrest in response to AZD1775 and defined PTEN as a promising biomarker for efficient WEE1 cancer therapy.
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Affiliation(s)
- Andrä Brunner
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | | | - Henrik Johansson
- Cancer Proteomics Mass Spectrometry, Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Marcela Franco
- Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Stockholm, Sweden
| | - Johanna Viiliäinen
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Mohiuddin Gazi
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Oliver Frings
- Cancer Proteomics Mass Spectrometry, Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Erik Fredlund
- Cancer Proteomics Mass Spectrometry, Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Charles Spruck
- Tumor Initiation and Maintenance Program, NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
| | - Janne Lehtiö
- Cancer Proteomics Mass Spectrometry, Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Juha K Rantala
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Lars-Gunnar Larsson
- Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Stockholm, Sweden
| | - Olle Sangfelt
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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13
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Protective Mechanisms Against DNA Replication Stress in the Nervous System. Genes (Basel) 2020; 11:genes11070730. [PMID: 32630049 PMCID: PMC7397197 DOI: 10.3390/genes11070730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/25/2020] [Accepted: 06/25/2020] [Indexed: 02/06/2023] Open
Abstract
The precise replication of DNA and the successful segregation of chromosomes are essential for the faithful transmission of genetic information during the cell cycle. Alterations in the dynamics of genome replication, also referred to as DNA replication stress, may lead to DNA damage and, consequently, mutations and chromosomal rearrangements. Extensive research has revealed that DNA replication stress drives genome instability during tumorigenesis. Over decades, genetic studies of inherited syndromes have established a connection between the mutations in genes required for proper DNA repair/DNA damage responses and neurological diseases. It is becoming clear that both the prevention and the responses to replication stress are particularly important for nervous system development and function. The accurate regulation of cell proliferation is key for the expansion of progenitor pools during central nervous system (CNS) development, adult neurogenesis, and regeneration. Moreover, DNA replication stress in glial cells regulates CNS tumorigenesis and plays a role in neurodegenerative diseases such as ataxia telangiectasia (A-T). Here, we review how replication stress generation and replication stress response (RSR) contribute to the CNS development, homeostasis, and disease. Both cell-autonomous mechanisms, as well as the evidence of RSR-mediated alterations of the cellular microenvironment in the nervous system, were discussed.
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Sui J, Zhang S, Chen BPC. DNA-dependent protein kinase in telomere maintenance and protection. Cell Mol Biol Lett 2020; 25:2. [PMID: 31988640 PMCID: PMC6969447 DOI: 10.1186/s11658-020-0199-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
This review focuses on DNA-dependent protein kinase (DNA-PK), which is the key regulator of canonical non-homologous end-joining (NHEJ), the predominant mechanism of DNA double-strand break (DSB) repair in mammals. DNA-PK consists of the DNA-binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs. They assemble at DNA ends, forming the active DNA-PK complex, which initiates NHEJ-mediated DSB repair. Paradoxically, both Ku and DNA-PKcs are associated with telomeres, and they play crucial roles in protecting the telomere against fusions. Herein, we discuss possible mechanisms and contributions of Ku and DNA-PKcs in telomere regulation.
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Affiliation(s)
- Jiangdong Sui
- 1Radiation Oncology Center, Chongqing University Cancer Hospital, Chongqing, 400030 China
| | - Shichuan Zhang
- 2Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, China
| | - Benjamin P C Chen
- 3Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd., Dallas, TX 75390-9187 USA
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15
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The Replisome Mediates A-NHEJ Repair of Telomeres Lacking POT1-TPP1 Independently of MRN Function. Cell Rep 2019; 29:3708-3725.e5. [PMID: 31825846 PMCID: PMC7001145 DOI: 10.1016/j.celrep.2019.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/22/2019] [Accepted: 11/04/2019] [Indexed: 02/07/2023] Open
Abstract
Telomeres use shelterin to protect chromosome ends from activating the DNA damage sensor MRE11-RAD50-NBS1 (MRN), repressing ataxia-telangiectasia, mutated (ATM) and ATM and Rad3-related (ATR) dependent DNA damage checkpoint responses. The MRE11 nuclease is thought to be essential for the resection of the 5′ C-strand to generate the microhomologies necessary for alternative non-homologous end joining (A-NHEJ) repair. In the present study, we uncover DNA damage signaling and repair pathways engaged by components of the replisome complex to repair dysfunctional telomeres. In cells lacking MRN, single-stranded telomeric overhangs devoid of POT1-TPP1 do not recruit replication protein A (RPA), ATR-interacting protein (ATRIP), and RAD 51. Rather, components of the replisome complex, including Claspin, Proliferating cell nuclear antigen (PCNA), and Downstream neighbor of SON (DONSON), initiate DNA-PKcs-mediated p-CHK1 activation and A-NHEJ repair. In addition, Claspin directly interacts with TRF2 and recruits EXO1 to newly replicated telomeres to promote 5′ end resection. Our data indicate that MRN is dispensable for the repair of dysfunctional telomeres lacking POT1-TPP1 and highlight the contributions of the replisome in telomere repair. Rai et al. define roles for the DNA replisome components Claspin, PCNA, and DONSON in the sensing and repair of telomeres lacking POT1-TPP1. In cells lacking MRN, CPD initiates DNA-PKcs-mediated p-CHK1 activation and A-NHEJ repair. Claspin directly interacts with TRF2 and recruits EXO1 to promote 5′ C-strand end resection.
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Vanillin derivative VND3207 activates DNA-PKcs conferring protection against radiation-induced intestinal epithelial cells injury in vitro and in vivo. Toxicol Appl Pharmacol 2019; 387:114855. [PMID: 31830491 DOI: 10.1016/j.taap.2019.114855] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/05/2019] [Accepted: 12/07/2019] [Indexed: 12/20/2022]
Abstract
Vanillin is a natural compound endowed with antioxidant and anti-mutagenic properties. We previously identified the vanillin derivative VND3207 with strong radio-protective and antioxidant effects and found that VND3207 confers survival benefit and protection against radiation-induced intestinal injury (RIII) in mice. We also observed that VND3207 treatment enhanced the expression level of the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs) in human lymphoblastoid cells with or without γ-irradiation. DNA-PKcs is a critical component of DNA double strand break repair pathway and also regulates mitotic progression by stabilizing spindle formation and preventing mitotic catastrophe in response to DNA damage. In the present study, we found that VND3207 protected intestinal epithelial cells in vitro against ionizing radiation by promoting cell proliferation and inhibiting cell apoptosis. In addition, VND3207 promoted DNA-PKcs activity by increasing autophosphorylation at S2056 site. Consistent with this, VND3207 significantly decreased the number of γH2AX foci and mitotic catastrophe after radiation. DNA-PKcs deficiency abolished these VND3207 radio-protective effects, indicating that DNA-PKcs activation is essential for VND3207 activity. In conclusion, VND3207 promoted intestinal repair following radiation injury by regulating the DNA-PKcs pathway.
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AZD7648 is a potent and selective DNA-PK inhibitor that enhances radiation, chemotherapy and olaparib activity. Nat Commun 2019; 10:5065. [PMID: 31699977 PMCID: PMC6838110 DOI: 10.1038/s41467-019-12836-9] [Citation(s) in RCA: 178] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 10/04/2019] [Indexed: 02/05/2023] Open
Abstract
DNA-dependent protein kinase (DNA-PK) is a critical player in the DNA damage response (DDR) and instrumental in the non-homologous end-joining pathway (NHEJ) used to detect and repair DNA double-strand breaks (DSBs). We demonstrate that the potent and highly selective DNA-PK inhibitor, AZD7648, is an efficient sensitizer of radiation- and doxorubicin-induced DNA damage, with combinations in xenograft and patient-derived xenograft (PDX) models inducing sustained regressions. Using ATM-deficient cells, we demonstrate that AZD7648, in combination with the PARP inhibitor olaparib, increases genomic instability, resulting in cell growth inhibition and apoptosis. AZD7648 enhanced olaparib efficacy across a range of doses and schedules in xenograft and PDX models, enabling sustained tumour regression and providing a clear rationale for its clinical investigation. Through its differentiated mechanism of action as an NHEJ inhibitor, AZD7648 complements the current armamentarium of DDR-targeted agents and has potential in combination with these agents to achieve deeper responses to current therapies. DNA-dependent protein kinase (DNA-PK) plays a major role in the DNA damage response upon double-strand break formation. Here, the authors show that the DNA-PK inhibitor AZD7648, enhances the activity of radiotherapy, chemotherapy and the PARP inhibitor olaparib in multiple mouse tumour models.
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Mladenov E, Fan X, Paul-Konietzko K, Soni A, Iliakis G. DNA-PKcs and ATM epistatically suppress DNA end resection and hyperactivation of ATR-dependent G 2-checkpoint in S-phase irradiated cells. Sci Rep 2019; 9:14597. [PMID: 31601897 PMCID: PMC6787047 DOI: 10.1038/s41598-019-51071-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 09/20/2019] [Indexed: 11/29/2022] Open
Abstract
We previously reported that cells exposed to low doses of ionizing radiation (IR) in the G2-phase of the cell cycle activate a checkpoint that is epistatically regulated by ATM and ATR operating as an integrated module. In this module, ATR interphases exclusively with the cell cycle to implement the checkpoint, mainly using CHK1. The ATM/ATR module similarly regulates DNA end-resection at low IR-doses. Strikingly, at high IR-doses, the ATM/ATR coupling relaxes and each kinase exerts independent contributions to resection and the G2-checkpoint. DNA-PKcs links to the ATM/ATR module and defects cause hyper-resection and hyperactivation of G2-checkpoint at all doses examined. Surprisingly, our present report reveals that cells irradiated in S-phase utilize a different form of wiring between DNA-PKcs/ATM/ATR: The checkpoint activated in G2-phase is regulated exclusively by ATR/CHK1; similarly at high and low IR-doses. DNA end-resection supports ATR-activation, but inhibition of ATR leaves resection unchanged. DNA-PKcs and ATM link now epistatically to resection and their inhibition causes hyper-resection and ATR-dependent G2-checkpoint hyperactivation at all IR-doses. We propose that DNA-PKcs, ATM and ATR form a modular unit to regulate DSB processing with their crosstalk distinctly organized in S- and G2- phase, with strong dependence on DSB load only in G2-phase.
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Affiliation(s)
- Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany.
| | - Xiaoxiang Fan
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany
| | - Katja Paul-Konietzko
- 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
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122, Essen, Germany.
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Habiel DM, Hohmann MS, Espindola MS, Coelho AL, Jones I, Jones H, Carnibella R, Pinar I, Werdiger F, Hogaboam CM. DNA-PKcs modulates progenitor cell proliferation and fibroblast senescence in idiopathic pulmonary fibrosis. BMC Pulm Med 2019; 19:165. [PMID: 31464599 PMCID: PMC6716822 DOI: 10.1186/s12890-019-0922-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 08/19/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Recent studies have highlighted the contribution of senescent mesenchymal and epithelial cells in Idiopathic Pulmonary Fibrosis (IPF), but little is known regarding the molecular mechanisms that regulate the accumulation of senescent cells in this disease. Therefore, we addressed the hypothesis that the loss of DNA repair mechanisms mediated by DNA protein kinase catalytic subunit (DNA-PKcs) in IPF, promoted the accumulation of mesenchymal progenitors and progeny, and the expression of senescent markers by these cell types. METHODS Surgical lung biopsy samples and lung fibroblasts were obtained from patients exhibiting slowly, rapidly or unknown progressing IPF and lung samples lacking any evidence of fibrotic disease (i.e. normal; NL). The expression of DNA-Pkcs in lung tissue was assessed by quantitative immunohistochemical analysis. Chronic inhibition of DNA-PKcs kinase activity was mimicked using a highly specific small molecule inhibitor, Nu7441. Proteins involved in DNA repair (stage-specific embryonic antigen (SSEA)-4+ cells) were determined by quantitative Ingenuity Pathway Analysis of transcriptomic datasets (GSE103488). Lastly, the loss of DNA-PKc was modeled in a humanized model of pulmonary fibrosis in NSG SCID mice genetically deficient in PRKDC (the transcript for DNA-PKcs) and treated with Nu7441. RESULTS DNA-PKcs expression was significantly reduced in IPF lung tissues. Chronic inhibition of DNA-PKcs by Nu7441 promoted the proliferation of SSEA4+ mesenchymal progenitor cells and a significant increase in the expression of senescence-associated markers in cultured lung fibroblasts. Importantly, mesenchymal progenitor cells and their fibroblast progeny derived from IPF patients showed a loss of transcripts encoding for DNA damage response and DNA repair components. Further, there was a significant reduction in transcripts encoding for PRKDC (the transcript for DNA-PKcs) in SSEA4+ mesenchymal progenitor cells from IPF patients compared with normal lung donors. In SCID mice lacking DNA-PKcs activity receiving IPF lung explant cells, treatment with Nu7441 promoted the expansion of progenitor cells, which was observed as a mass of SSEA4+ CgA+ expressing cells. CONCLUSIONS Together, our results show that the loss of DNA-PKcs promotes the expansion of SSEA4+ mesenchymal progenitors, and the senescence of their mesenchymal progeny.
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Affiliation(s)
- David M Habiel
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA
| | - Miriam S Hohmann
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA.
| | - Milena S Espindola
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA
| | - Ana Lucia Coelho
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA
| | - Isabelle Jones
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA
| | - Heather Jones
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA
| | - Richard Carnibella
- Laboratory of Dynamic Imaging, Mechanical and Aerospace Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Isaac Pinar
- Laboratory of Dynamic Imaging, Mechanical and Aerospace Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Freda Werdiger
- Laboratory of Dynamic Imaging, Mechanical and Aerospace Engineering, Monash University, Clayton, VIC, 3800, Australia
| | - Cory M Hogaboam
- Department of Medicine, Cedars-Sinai Medical Center, Women's Guild Lung Institute, 127 S San Vicente Blvd., AHSP A9315, Los Angeles, CA, 90048, USA.
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20
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Michelena J, Gatti M, Teloni F, Imhof R, Altmeyer M. Basal CHK1 activity safeguards its stability to maintain intrinsic S-phase checkpoint functions. J Cell Biol 2019; 218:2865-2875. [PMID: 31366665 PMCID: PMC6719454 DOI: 10.1083/jcb.201902085] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 06/12/2019] [Accepted: 07/08/2019] [Indexed: 12/11/2022] Open
Abstract
The essential kinase CHK1 controls cell cycle checkpoint signaling and S-phase progression. Michelena et al. reveal that steady-state activity of CHK1 is required to sustain its own stability and that failure to do so results in CHK1 degradation and sensitizes cells to replication stress. The DNA replication machinery frequently encounters impediments that slow replication fork progression and threaten timely and error-free replication. The CHK1 protein kinase is essential to deal with replication stress (RS) and ensure genome integrity and cell survival, yet how basal levels and activity of CHK1 are maintained under physiological, unstressed conditions is not well understood. Here, we reveal that CHK1 stability is controlled by its steady-state activity during unchallenged cell proliferation. This autoactivatory mechanism, which depends on ATR and its coactivator ETAA1 and is tightly associated with CHK1 autophosphorylation at S296, counters CHK1 ubiquitylation and proteasomal degradation, thereby preventing attenuation of S-phase checkpoint functions and a compromised capacity to respond to RS. Based on these findings, we propose that steady-state CHK1 activity safeguards its stability to maintain intrinsic checkpoint functions and ensure genome integrity and cell survival.
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Affiliation(s)
- Jone Michelena
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Marco Gatti
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Federico Teloni
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.,Molecular Life Sciences Program, Life Science Zurich Graduate School, Zurich, Switzerland
| | - Ralph Imhof
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
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21
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Lin YF, Shih HY, Shang ZF, Kuo CT, Guo J, Du C, Lee H, Chen BPC. PIDD mediates the association of DNA-PKcs and ATR at stalled replication forks to facilitate the ATR signaling pathway. Nucleic Acids Res 2019; 46:1847-1859. [PMID: 29309644 PMCID: PMC5829747 DOI: 10.1093/nar/gkx1298] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/19/2017] [Indexed: 12/13/2022] Open
Abstract
The DNA-dependent protein kinase (DNA-PK), consisting of the DNA binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs, has been well characterized in the non-homologous end-joining mechanism for DNA double strand break (DSB) repair and radiation resistance. Besides playing a role in DSB repair, DNA-PKcs is required for the cellular response to replication stress and participates in the ATR-Chk1 signaling pathway. However, the mechanism through which DNA-PKcs is recruited to stalled replication forks is still unclear. Here, we report that the apoptosis mediator p53-induced protein with a death domain (PIDD) is required to promote DNA-PKcs activity in response to replication stress. PIDD is known to interact with PCNA upon UV-induced replication stress. Our results demonstrate that PIDD is required to recruit DNA-PKcs to stalled replication forks through direct binding to DNA-PKcs at the N’ terminal region. Disruption of the interaction between DNA-PKcs and PIDD not only compromises the ATR association and regulation of DNA-PKcs, but also the ATR signaling pathway, intra-S-phase checkpoint and cellular resistance to replication stress. Taken together, our results indicate that PIDD, but not the Ku heterodimer, mediates the DNA-PKcs activity at stalled replication forks and facilitates the ATR signaling pathway in the cellular response to replication stress.
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Affiliation(s)
- Yu-Fen Lin
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Hung-Ying Shih
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Zeng-Fu Shang
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Ching-Te Kuo
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.,Department of Life Science, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Jiaming Guo
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.,Department of Radiation Medicine, Faculty of Naval Medicine, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Chunying Du
- Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Hsinyu Lee
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan, Republic of China
| | - Benjamin P C Chen
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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22
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Radiation-dose-dependent functional synergisms between ATM, ATR and DNA-PKcs in checkpoint control and resection in G 2-phase. Sci Rep 2019; 9:8255. [PMID: 31164689 PMCID: PMC6547644 DOI: 10.1038/s41598-019-44771-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/23/2019] [Indexed: 12/31/2022] Open
Abstract
Using data generated with cells exposed to ionizing-radiation (IR) in G2-phase of the cell cycle, we describe dose-dependent interactions between ATM, ATR and DNA-PKcs revealing unknown mechanistic underpinnings for two key facets of the DNA damage response: DSB end-resection and G2-checkpoint activation. At low IR-doses that induce low DSB-numbers in the genome, ATM and ATR regulate epistatically the G2-checkpoint, with ATR at the output-node, interfacing with the cell-cycle predominantly through Chk1. Strikingly, at low IR-doses, ATM and ATR epistatically regulate also resection, and inhibition of either activity fully suppresses resection. At high IR-doses that induce high DSB-numbers in the genome, the tight ATM/ATR coupling relaxes and independent outputs to G2-checkpoint and resection occur. Consequently, both kinases must be inhibited to fully suppress checkpoint activation and resection. DNA-PKcs integrates to the ATM/ATR module by regulating resection at all IR-doses, with defects in DNA-PKcs causing hyper-resection and G2-checkpoint hyper-activation. Notably, hyper-resection is absent from other c-NHEJ mutants. Thus, DNA-PKcs specifically regulates resection and adjusts the activation of the ATM/ATR module. We propose that selected DSBs are shepherd by DNA-PKcs from c-NHEJ to resection-dependent pathways for processing under the regulatory supervision of the ATM/ATR module.
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23
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Kermi C, Aze A, Maiorano D. Preserving Genome Integrity During the Early Embryonic DNA Replication Cycles. Genes (Basel) 2019; 10:genes10050398. [PMID: 31137726 PMCID: PMC6563053 DOI: 10.3390/genes10050398] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 05/15/2019] [Indexed: 02/06/2023] Open
Abstract
During the very early stages of embryonic development chromosome replication occurs under rather challenging conditions, including a very short cell cycle, absence of transcription, a relaxed DNA damage response and, in certain animal species, a highly contracted S-phase. This raises the puzzling question of how the genome can be faithfully replicated in such a peculiar metabolic context. Recent studies have provided new insights into this issue, and unveiled that embryos are prone to accumulate genetic and genomic alterations, most likely due to restricted cellular functions, in particular reduced DNA synthesis quality control. These findings may explain the low rate of successful development in mammals and the occurrence of diseases, such as abnormal developmental features and cancer. In this review, we will discuss recent findings in this field and put forward perspectives to further study this fascinating question.
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Affiliation(s)
- Chames Kermi
- Laboratoire Surveillance et Stabilité du Génome, Institut de Génétique Humaine, UMR9002, CNRS, Université de Montpellier, 34090 Montpellier, France.
- Department of Chemical and Systems Biology, Stanford University School of Medicine, 318 Campus Drive, Stanford, CA 94305-5441, USA.
| | - Antoine Aze
- Laboratoire Surveillance et Stabilité du Génome, Institut de Génétique Humaine, UMR9002, CNRS, Université de Montpellier, 34090 Montpellier, France.
| | - Domenico Maiorano
- Laboratoire Surveillance et Stabilité du Génome, Institut de Génétique Humaine, UMR9002, CNRS, Université de Montpellier, 34090 Montpellier, France.
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24
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Bourgeois A, Bonnet S, Breuils-Bonnet S, Habbout K, Paradis R, Tremblay E, Lampron MC, Orcholski ME, Potus F, Bertero T, Peterlini T, Chan SY, Norris KA, Paulin R, Provencher S, Boucherat O. Inhibition of CHK 1 (Checkpoint Kinase 1) Elicits Therapeutic Effects in Pulmonary Arterial Hypertension. Arterioscler Thromb Vasc Biol 2019; 39:1667-1681. [PMID: 31092016 DOI: 10.1161/atvbaha.119.312537] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Pulmonary arterial hypertension (PAH) is a debilitating disease associated with progressive vascular remodeling of distal pulmonary arteries leading to elevation of pulmonary artery pressure, right ventricular hypertrophy, and death. Although presenting high levels of DNA damage that normally jeopardize their viability, pulmonary artery smooth muscle cells (PASMCs) from patients with PAH exhibit a cancer-like proproliferative and apoptosis-resistant phenotype accounting for vascular lumen obliteration. In cancer cells, overexpression of the serine/threonine-protein kinase CHK1 (checkpoint kinase 1) is exploited to counteract the excess of DNA damage insults they are exposed to. This study aimed to determine whether PAH-PASMCs have developed an orchestrated response mediated by CHK1 to overcome DNA damage, allowing cell survival and proliferation. Approach and Results: We demonstrated that CHK1 expression is markedly increased in isolated PASMCs and distal PAs from patients with PAH compared with controls, as well as in multiple complementary animal models recapitulating the disease, including monocrotaline rats and the simian immunodeficiency virus-infected macaques. Using a pharmacological and molecular loss of function approach, we showed that CHK1 promotes PAH-PASMCs proliferation and resistance to apoptosis. In addition, we found that inhibition of CHK1 induces downregulation of the DNA repair protein RAD 51 and severe DNA damage. In vivo, we provided evidence that pharmacological inhibition of CHK1 significantly reduces vascular remodeling and improves hemodynamic parameters in 2 experimental rat models of PAH. CONCLUSIONS Our results show that CHK1 exerts a proproliferative function in PAH-PASMCs by mitigating DNA damage and suggest that CHK1 inhibition may, therefore, represent an attractive therapeutic option for patients with PAH.
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Affiliation(s)
- Alice Bourgeois
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Sébastien Bonnet
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.).,Department of Medicine, Université Laval, QC, Canada (S.P., O.B., S.B.)
| | - Sandra Breuils-Bonnet
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Karima Habbout
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Renée Paradis
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Eve Tremblay
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Marie-Claude Lampron
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Mark E Orcholski
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Francois Potus
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Thomas Bertero
- University Côte d'Azur, CNRS UMR7284, INSERM U1081, Institute for Research on Cancer and Aging Nice (IRCAN), University Côte d'Azur, France (T.B.)
| | - Thibaut Peterlini
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Stephen Y Chan
- Center for Pulmonary Vascular Biology and Medicine, Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine and University of Pittsburgh Medical Center, PA (S.Y.C.)
| | - Karen A Norris
- Center for Vaccines and Immunology, University of Georgia, Athens (K.A.N.)
| | - Roxane Paulin
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.)
| | - Steeve Provencher
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.).,Department of Medicine, Université Laval, QC, Canada (S.P., O.B., S.B.)
| | - Olivier Boucherat
- From the Pulmonary Hypertension Research Group, Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Canada (A.B., S.B., S.B-B., K.H., R.P., E.T., M.C.L., M.E.O., F.P., T.P., R.P., S.P., O.B.).,Department of Medicine, Université Laval, QC, Canada (S.P., O.B., S.B.)
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25
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Azenha D, Lopes MC, Martins TC. Claspin: From replication stress and DNA damage responses to cancer therapy. DNA Repair (Amst) 2019; 115:203-246. [DOI: 10.1016/bs.apcsb.2018.10.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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26
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Huang TH, Fowler F, Chen CC, Shen ZJ, Sleckman B, Tyler JK. The Histone Chaperones ASF1 and CAF-1 Promote MMS22L-TONSL-Mediated Rad51 Loading onto ssDNA during Homologous Recombination in Human Cells. Mol Cell 2018; 69:879-892.e5. [PMID: 29478807 DOI: 10.1016/j.molcel.2018.01.031] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 11/27/2017] [Accepted: 01/23/2018] [Indexed: 10/18/2022]
Abstract
The access-repair-restore model for the role of chromatin in DNA repair infers that chromatin is a mere obstacle to DNA repair. However, here we show that blocking chromatin assembly, via knockdown of the histone chaperones ASF1 or CAF-1 or a mutation that prevents ASF1A binding to histones, hinders Rad51 loading onto ssDNA during homologous recombination. This is a consequence of reduced recruitment of the Rad51 loader MMS22L-TONSL to ssDNA, resulting in persistent RPA foci, extensive DNA end resection, persistent activation of the ATR-Chk1 pathway, and cell cycle arrest. In agreement, histones occupy ssDNA during DNA repair in yeast. We also uncovered DNA-PKcs-dependent DNA damage-induced ASF1A phosphorylation, which enhances chromatin assembly, promoting MMS22L-TONSL recruitment and, hence, Rad51 loading. We propose that transient assembly of newly synthesized histones onto ssDNA serves to recruit MMS22L-TONSL to efficiently form the Rad51 nucleofilament for strand invasion, suggesting an active role of chromatin assembly in homologous recombination.
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Affiliation(s)
- Ting-Hsiang Huang
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY 10065, USA
| | - Faith Fowler
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY 10065, USA
| | - Chin-Chuan Chen
- Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan
| | - Zih-Jie Shen
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY 10065, USA
| | - Barry Sleckman
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY 10065, USA
| | - Jessica K Tyler
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY 10065, USA.
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27
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Lan T, Zhao Z, Qu Y, Zhang M, Wang H, Zhang Z, Zhou W, Fan X, Yu C, Zhan Q, Song Y. Targeting hyperactivated DNA-PKcs by KU0060648 inhibits glioma progression and enhances temozolomide therapy via suppression of AKT signaling. Oncotarget 2018; 7:55555-55571. [PMID: 27487130 PMCID: PMC5342436 DOI: 10.18632/oncotarget.10864] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 06/29/2016] [Indexed: 12/01/2022] Open
Abstract
The overall survival remains undesirable in clinical glioma treatment. Inhibition of DNA-PKcs activity by its inhibitors suppresses tumor growth and enhances chemosensitivity of several tumors to chemotherapy. However, whether DNA-PKcs could be a potential target in glioma therapy remains unknown. In this study, we reported that the hyperactivated DNA-PKcs was profoundly correlated with glioma malignancy and observe a significant association between DNA-PKcs activation and survival of the glioma patients. Our data also found that inhibition of DNA-PKcs by its inhibitor KU0060648 sensitized glioma cells to TMZ in vitro. Specifically, we demonstrated that KU0060648 interrupted the formation of DNA-PKcs/AKT complex, leading to suppression of AKT signaling and resultantly enhanced TMZ efficacy. Combination of KU0060648 and TMZ substantially inhibited downstream effectors of AKT. The in vivo results were similar to those obtained in vitro. In conclusion, this study indicated that inhibition of DNA-PKcs activity could suppress glioma malignancies and increase TMZ efficacy, which was mainly through regulation of the of AKT signaling. Therefore, DNA-PKcs/AKT axis may be a promising target for improving current glioma therapy.
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Affiliation(s)
- Tian Lan
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Zitong Zhao
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yanming Qu
- Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Mingshan Zhang
- Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Haoran Wang
- Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Zhihua Zhang
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Wei Zhou
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xinyi Fan
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Chunjiang Yu
- Department of Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Qimin Zhan
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yongmei Song
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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28
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Saki M, Makino H, Javvadi P, Tomimatsu N, Ding LH, Clark JE, Gavin E, Takeda K, Andrews J, Saha D, Story MD, Burma S, Nirodi CS. EGFR Mutations Compromise Hypoxia-Associated Radiation Resistance through Impaired Replication Fork-Associated DNA Damage Repair. Mol Cancer Res 2017; 15:1503-1516. [PMID: 28801308 PMCID: PMC5668182 DOI: 10.1158/1541-7786.mcr-17-0136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/29/2017] [Accepted: 08/03/2017] [Indexed: 12/20/2022]
Abstract
EGFR signaling has been implicated in hypoxia-associated resistance to radiation or chemotherapy. Non-small cell lung carcinomas (NSCLC) with activating L858R or ΔE746-E750 EGFR mutations exhibit elevated EGFR activity and downstream signaling. Here, relative to wild-type (WT) EGFR, mutant (MT) EGFR expression significantly increases radiosensitivity in hypoxic cells. Gene expression profiling in human bronchial epithelial cells (HBEC) revealed that MT-EGFR expression elevated transcripts related to cell cycle and replication in aerobic and hypoxic conditions and downregulated RAD50, a critical component of nonhomologous end joining and homologous recombination DNA repair pathways. NSCLCs and HBEC with MT-EGFR revealed elevated basal and hypoxia-induced γ-H2AX-associated DNA lesions that were coincident with replication protein A in the S-phase nuclei. DNA fiber analysis showed that, relative to WT-EGFR, MT-EGFR NSCLCs harbored significantly higher levels of stalled replication forks and decreased fork velocities in aerobic and hypoxic conditions. EGFR blockade by cetuximab significantly increased radiosensitivity in hypoxic cells, recapitulating MT-EGFR expression and closely resembling synthetic lethality of PARP inhibition.Implications: This study demonstrates that within an altered DNA damage response of hypoxic NSCLC cells, mutant EGFR expression, or EGFR blockade by cetuximab exerts a synthetic lethality effect and significantly compromises radiation resistance in hypoxic tumor cells. Mol Cancer Res; 15(11); 1503-16. ©2017 AACR.
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Affiliation(s)
- Mohammad Saki
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama
| | - Haruhiko Makino
- Division of Medical Oncology and Molecular Respirology, Faculty of Medicine Tottori University, Yonago, Tottori, Japan
| | - Prashanthi Javvadi
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Nozomi Tomimatsu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Liang-Hao Ding
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jennifer E Clark
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama
| | - Elaine Gavin
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama
| | - Kenichi Takeda
- Division of Medical Oncology and Molecular Respirology, Faculty of Medicine Tottori University, Yonago, Tottori, Japan
| | - Joel Andrews
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama
| | - Debabrata Saha
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Michael D Story
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Sandeep Burma
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Chaitanya S Nirodi
- Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama.
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29
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Ashton NW, Paquet N, Shirran SL, Bolderson E, Kariawasam R, Touma C, Fallahbaghery A, Gamsjaeger R, Cubeddu L, Botting C, Pollock PM, O'Byrne KJ, Richard DJ. hSSB1 phosphorylation is dynamically regulated by DNA-PK and PPP-family protein phosphatases. DNA Repair (Amst) 2017; 54:30-39. [PMID: 28448822 DOI: 10.1016/j.dnarep.2017.03.006] [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: 01/10/2017] [Revised: 02/28/2017] [Accepted: 03/24/2017] [Indexed: 11/16/2022]
Abstract
The maintenance of genomic stability is essential for cellular viability and the prevention of diseases such as cancer. Human single-stranded DNA-binding protein 1 (hSSB1) is a protein with roles in the stabilisation and restart of stalled DNA replication forks, as well as in the repair of oxidative DNA lesions and double-strand DNA breaks. In the latter process, phosphorylation of threonine 117 by the ATM kinase is required for hSSB1 stability and efficient DNA repair. The regulation of hSSB1 in other DNA repair pathways has however remained unclear. Here we report that hSSB1 is also directly phosphorylated by DNA-PK at serine residue 134. While this modification is largely suppressed in undamaged cells by PPP-family protein phosphatases, S134 phosphorylation is enhanced following the disruption of replication forks and promotes cellular survival. Together, these data thereby represent a novel mechanism for hSSB1 regulation following the inhibition of replication.
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Affiliation(s)
- Nicholas W Ashton
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Nicolas Paquet
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Sally L Shirran
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Emma Bolderson
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Ruvini Kariawasam
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Christine Touma
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Azadeh Fallahbaghery
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Roland Gamsjaeger
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Liza Cubeddu
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Catherine Botting
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Pamela M Pollock
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Kenneth J O'Byrne
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Derek J Richard
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
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30
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Zeng L, Beggs RR, Cooper TS, Weaver AN, Yang ES. Combining Chk1/2 Inhibition with Cetuximab and Radiation Enhances In Vitro and In Vivo Cytotoxicity in Head and Neck Squamous Cell Carcinoma. Mol Cancer Ther 2017; 16:591-600. [PMID: 28138028 PMCID: PMC5560482 DOI: 10.1158/1535-7163.mct-16-0352] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 12/21/2022]
Abstract
EGFR inhibition and radiotherapy are potent inducers of DNA damage. Checkpoint kinases 1 and 2 (Chk1/2) are critical regulators of the DNA-damage response, controlling cell-cycle checkpoints that may permit recovery from therapy-associated genomic stress. We hypothesized that Chk1/2 inhibition (CHKi) with prexasertib may enhance cytotoxicity from EGFR inhibition plus radiotherapy in head and neck squamous cell carcinoma (HNSCC). In this study, we found that the addition of CHKi to the EGFR inhibitor cetuximab with and without radiotherapy significantly decreased cell proliferation and survival fraction in human papillomavirus virus (HPV)-positive and HPV-negative HNSCC cell lines. Reduced proliferation was accompanied by decreased checkpoint activation, induced S-phase accumulation, persistent DNA damage, and increased caspase cleavage and apoptosis. Importantly, a significant tumor growth delay was observed in vivo in both HPV-positive and HPV-negative cell line xenografts receiving triple combination therapy with CHKi, cetuximab, and radiotherapy without a concomitant increase in toxicity as assessed by mouse body weight. Taken together, the combination of CHKi with cetuximab plus irradiation displayed significant antitumor effects in HNSCCs both in vitro and in vivo, suggesting that this combination therapy may increase clinical benefit. A clinical trial to test this treatment for patients with head and neck cancer is currently ongoing (NCT02555644).
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Affiliation(s)
- Ling Zeng
- Department of Radiation Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama
| | - Reena R Beggs
- Department of Radiation Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama
| | - Tiffiny S Cooper
- Department of Radiation Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama
| | - Alice N Weaver
- Department of Radiation Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama
| | - Eddy S Yang
- Department of Radiation Oncology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama. .,Department of Pharmacology and Toxiology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama.,Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama.,Comprehensive Cancer Center, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama
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31
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Mimmler M, Peter S, Kraus A, Stroh S, Nikolova T, Seiwert N, Hasselwander S, Neitzel C, Haub J, Monien BH, Nicken P, Steinberg P, Shay JW, Kaina B, Fahrer J. DNA damage response curtails detrimental replication stress and chromosomal instability induced by the dietary carcinogen PhIP. Nucleic Acids Res 2016; 44:10259-10276. [PMID: 27599846 PMCID: PMC5137439 DOI: 10.1093/nar/gkw791] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 07/28/2016] [Accepted: 08/27/2016] [Indexed: 11/13/2022] Open
Abstract
PhIP is an abundant heterocyclic aromatic amine (HCA) and important dietary carcinogen. Following metabolic activation, PhIP causes bulky DNA lesions at the C8-position of guanine. Although C8-PhIP-dG adducts are mutagenic, their interference with the DNA replication machinery and the elicited DNA damage response (DDR) have not yet been studied. Here, we analyzed PhIP-triggered replicative stress and elucidated the role of the apical DDR kinases ATR, ATM and DNA-PKcs in the cellular defense response. First, we demonstrate that PhIP induced C8-PhIP-dG adducts and DNA strand breaks. This stimulated ATR-CHK1 signaling, phosphorylation of histone 2AX and the formation of RPA foci. In proliferating cells, PhIP treatment increased the frequency of stalled replication forks and reduced fork speed. Inhibition of ATR in the presence of PhIP-induced DNA damage strongly promoted the formation of DNA double-strand breaks, activation of the ATM-CHK2 pathway and hyperphosphorylation of RPA. The abrogation of ATR signaling potentiated the cell death response and enhanced chromosomal aberrations after PhIP treatment, while ATM and DNA-PK inhibition had only marginal effects. These results strongly support the notion that ATR plays a key role in the defense against cancer formation induced by PhIP and related HCAs.
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Affiliation(s)
| | - Simon Peter
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Alexander Kraus
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Svenja Stroh
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Teodora Nikolova
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Nina Seiwert
- Department of Toxicology, University Medical Center, Mainz, Germany
| | | | - Carina Neitzel
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Jessica Haub
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Bernhard H Monien
- Department of Food Safety, Federal Institute for Risk Assessment (BfR), Berlin, Germany
- Research Group Genotoxic Food Contaminants, German Institute of Human Nutrition (DIfE), Potsdam-Rehbrücke, Germany
| | - Petra Nicken
- Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Pablo Steinberg
- Institute for Food Toxicology and Analytical Chemistry, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bernd Kaina
- Department of Toxicology, University Medical Center, Mainz, Germany
| | - Jörg Fahrer
- Department of Toxicology, University Medical Center, Mainz, Germany
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32
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Lysines 3241 and 3260 of DNA-PKcs are important for genomic stability and radioresistance. Biochem Biophys Res Commun 2016; 477:235-40. [PMID: 27297111 DOI: 10.1016/j.bbrc.2016.06.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/09/2016] [Indexed: 11/22/2022]
Abstract
DNA-dependent protein kinase (DNA-PK) is a serine/threonine kinase that plays an essential role in the repair of DNA double-strand breaks (DSBs) in the non-homologous end-joining (NHEJ) pathway. The DNA-PK holoenzyme consists of a catalytic subunit (DNA-PKcs) and DNA-binding subunit (Ku70/80, Ku). Ku is a molecular sensor for double-stranded DNA and once bound to DSB ends it recruits DNA-PKcs to the DSB site. Subsequently, DNA-PKcs is activated and heavily phosphorylated, with these phosphorylations modulating DNA-PKcs. Although phosphorylation of DNA-PKcs is well studied, other post-translational modifications of DNA-PKcs are not. In this study, we aimed to determine if acetylation of DNA-PKcs regulates DNA-PKcs-dependent DSB repair. We report that DNA-PKcs is acetylated in vivo and identified two putative acetylation sites, lysine residues 3241 and 3260. Mutating these sites to block potential acetylation results in increased radiosensitive, a slight decrease in DSB repair capacity as assessed by γH2AX resolution, and increased chromosomal aberrations, especially quadriradial chromosomes. Together, our results provide evidence that acetylation potentially regulates DNA-PKcs.
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33
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Awate S, De Benedetti A. TLK1B mediated phosphorylation of Rad9 regulates its nuclear/cytoplasmic localization and cell cycle checkpoint. BMC Mol Biol 2016; 17:3. [PMID: 26860083 PMCID: PMC4746922 DOI: 10.1186/s12867-016-0056-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 01/26/2016] [Indexed: 01/09/2023] Open
Abstract
Background The Tousled like kinase 1B (TLK1B) is critical for DNA repair and survival of cells. Upon DNA damage, Chk1 phosphorylates TLK1B at S457 leading to its transient inhibition. Once TLK1B regains its kinase activity it phosphorylates Rad9 at S328. In this work we investigated the significance of this mechanism by overexpressing mutant TLK1B in which the inhibitory phosphorylation site was eliminated. Results and discussion These cells expressing TLK1B resistant to DNA damage showed constitutive phosphorylation of Rad9 S328 that occurred even in the presence of hydroxyurea (HU), and this resulted in a delayed checkpoint recovery. One possible explanation was that premature phosphorylation of Rad9 caused its dissociation from 9-1-1 at stalled replication forks, resulting in their collapse and prolonged activation of the S-phase checkpoint. We found that phosphorylation of Rad9 at S328 results in its dissociation from chromatin and redistribution to the cytoplasm. This results in double stranded breaks formation with concomitant activation of ATM and phosphorylation of H2AX. Furthermore, a Rad9 (S328D) phosphomimic mutant was exclusively localized to the cytoplasm and not the chromatin. Another Rad9 phosphomimic mutant (T355D), which is also a site phosphorylated by TLK1, localized normally. In cells expressing the mutant TLK1B treated with HU, Rad9 association with Hus1 and WRN was greatly reduced, suggesting again that its phosphorylation causes its premature release from stalled forks. Conclusions We propose that normally, the inactivation of TLK1B following replication arrest and genotoxic stress functions to allow the retention of 9-1-1 at the sites of damage or stalled forks. Following reactivation of TLK1B, whose synthesis is concomitantly induced by genotoxins, Rad9 is hyperphosphorylated at S328, resulting in its dissociation and inactivation of the checkpoint that occurs once repair is complete. Electronic supplementary material The online version of this article (doi:10.1186/s12867-016-0056-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sanket Awate
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA.
| | - Arrigo De Benedetti
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA.
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34
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Kwok M, Davies N, Agathanggelou A, Smith E, Oldreive C, Petermann E, Stewart G, Brown J, Lau A, Pratt G, Parry H, Taylor M, Moss P, Hillmen P, Stankovic T. ATR inhibition induces synthetic lethality and overcomes chemoresistance in TP53- or ATM-defective chronic lymphocytic leukemia cells. Blood 2016; 127:582-95. [PMID: 26563132 DOI: 10.1182/blood-2015-05-644872] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 10/31/2015] [Indexed: 12/31/2022] Open
Abstract
TP53 and ataxia telangiectasia mutated (ATM) defects are associated with genomic instability, clonal evolution, and chemoresistance in chronic lymphocytic leukemia (CLL). Currently, therapies capable of providing durable remissions in relapsed/refractory TP53- or ATM-defective CLL are lacking. Ataxia telangiectasia and Rad3-related (ATR) mediates response to replication stress, the absence of which leads to collapse of stalled replication forks into chromatid fragments that require resolution through the ATM/p53 pathway. Here, using AZD6738, a novel ATR kinase inhibitor, we investigated ATR inhibition as a synthetically lethal strategy to target CLL cells with TP53 or ATM defects. Irrespective of TP53 or ATM status, induction of CLL cell proliferation upregulated ATR protein, which then became activated in response to replication stress. In TP53- or ATM-defective CLL cells, inhibition of ATR signaling by AZD6738 led to an accumulation of unrepaired DNA damage, which was carried through into mitosis because of defective cell cycle checkpoints, resulting in cell death by mitotic catastrophe. Consequently, AZD6738 was selectively cytotoxic to both TP53- and ATM-defective CLL cell lines and primary cells. This was confirmed in vivo using primary xenograft models of TP53- or ATM-defective CLL, where treatment with AZD6738 resulted in decreased tumor load and reduction in the proportion of CLL cells with such defects. Moreover, AZD6738 sensitized TP53- or ATM-defective primary CLL cells to chemotherapy and ibrutinib. Our findings suggest that ATR is a promising therapeutic target for TP53- or ATM-defective CLL that warrants clinical investigation.
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MESH Headings
- Adenine/analogs & derivatives
- Animals
- Ataxia Telangiectasia Mutated Proteins/antagonists & inhibitors
- Ataxia Telangiectasia Mutated Proteins/genetics
- Ataxia Telangiectasia Mutated Proteins/metabolism
- DNA Damage/drug effects
- Drug Resistance, Neoplasm/drug effects
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Mice, Inbred NOD
- Piperidines
- Protein Kinase Inhibitors/pharmacology
- Protein Kinase Inhibitors/therapeutic use
- Pyrazoles/pharmacology
- Pyrazoles/therapeutic use
- Pyrimidines/pharmacology
- Pyrimidines/therapeutic use
- Tumor Cells, Cultured
- Tumor Suppressor Protein p53/genetics
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Affiliation(s)
- Marwan Kwok
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom; Centre for Clinical Haematology, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Nicholas Davies
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | | | - Edward Smith
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Ceri Oldreive
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Eva Petermann
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Grant Stewart
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Jeff Brown
- Oncology iMed, AstraZeneca Pharmaceuticals, Waltham, MA
| | - Alan Lau
- R&D Oncology iMed, AstraZeneca Pharmaceuticals, Alderley Park, United Kingdom
| | - Guy Pratt
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom; Birmingham Heartlands Hospital, Birmingham, United Kingdom; and
| | - Helen Parry
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom; Centre for Clinical Haematology, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Malcolm Taylor
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Paul Moss
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom; Centre for Clinical Haematology, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
| | - Peter Hillmen
- Section of Experimental Haematology, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, United Kingdom
| | - Tatjana Stankovic
- School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom; Centre for Clinical Haematology, Queen Elizabeth Hospital Birmingham, Birmingham, United Kingdom
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35
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Alonso-de Vega I, Martín Y, Smits VAJ. USP7 controls Chk1 protein stability by direct deubiquitination. Cell Cycle 2015; 13:3921-6. [PMID: 25483066 DOI: 10.4161/15384101.2014.973324] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Chk1, an essential checkpoint kinase in the DNA damage response pathway (DDR), is tightly regulated by both ATR-dependent phosphorylation and proteasome-mediated degradation. Here we identify ubiquitin hydrolase USP7 as a novel regulator of Chk1 protein stability. USP7 was shown before to regulate other DDR proteins such as p53, Hdm2 and Claspin, an adaptor protein in the ATR-Chk1 pathway required for Chk1 activation. Depletion or inhibition of USP7 leads to lower Chk1 levels. The decreased Chk1 protein after USP7 knock down cannot be rescued by simultaneously elevating Claspin levels, demonstrating that the effect of USP7 on Chk1 is independent of its known effect on Claspin. Conversely, overexpression of USP7 wild type, but not a catalytic mutant version, elevates Chk1 levels and increases the half-life of Chk1 protein. Importantly, wild type, but not catalytic mutant USP7 can deubiquitinate Chk1 in vivo and in vitro, confirming that USP7 directly regulates Chk1 protein levels. Finally we show that USP7 catalytic mutant is (mono-)ubiquitinated, which suggests auto-deubiquitination by this ubiquitin hydrolase, possibly important for its regulation.
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Affiliation(s)
- Ignacio Alonso-de Vega
- a Unidad de Investigación ; Hospital Universitario de Canarias ; Instituto de Tecnologías Biomédicas ; Tenerife , Spain
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36
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Taricani L, Shanahan F, Malinao MC, Beaumont M, Parry D. A functional approach reveals a genetic and physical interaction between ribonucleotide reductase and CHK1 in mammalian cells. PLoS One 2014; 9:e111714. [PMID: 25375241 PMCID: PMC4222937 DOI: 10.1371/journal.pone.0111714] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 10/07/2014] [Indexed: 11/30/2022] Open
Abstract
Ribonucleotide reductase (RNR) enzyme is composed of the homodimeric RRM1 and RRM2 subunits, which together form a heterotetramic active enzyme that catalyzes the de novo reduction of ribonucleotides to generate deoxyribonucleotides (dNTPs), which are required for DNA replication and DNA repair processes. In this study, we show that ablation of RRM1 and RRM2 by siRNA induces G1/S phase arrest, phosphorylation of Chk1 on Ser345 and phosphorylation of γ-H2AX on S139. Combinatorial ablation of RRM1 or RRM2 and Chk1 causes a dramatic accumulation of γ-H2AX, a marker of double-strand DNA breaks, suggesting that activation of Chk1 in this context is essential for suppression of DNA damage. Significantly, we demonstrate for the first time that Chk1 and RNR subunits co-immunoprecipitate from native cell extracts. These functional genomic studies suggest that RNR is a critical mediator of replication checkpoint activation.
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Affiliation(s)
- Lorena Taricani
- Merck Research Laboratories, Palo Alto, California, United States of America
| | - Frances Shanahan
- Merck Research Laboratories, Palo Alto, California, United States of America
| | | | - Maribel Beaumont
- Merck Research Laboratories, Palo Alto, California, United States of America
| | - David Parry
- Merck Research Laboratories, Palo Alto, California, United States of America
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37
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Affiliation(s)
- Donal P McLornan
- From King's College Hospital NHS Foundation Trust, London (D.P.M., G.J.M.); and Moffitt Cancer Center, Tampa, FL (A.L.)
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