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Wang M, Chen S, Ao D. Targeting DNA repair pathway in cancer: Mechanisms and clinical application. MedComm (Beijing) 2021; 2:654-691. [PMID: 34977872 PMCID: PMC8706759 DOI: 10.1002/mco2.103] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 11/21/2021] [Accepted: 11/22/2021] [Indexed: 02/05/2023] Open
Abstract
Over the last decades, the growing understanding on DNA damage response (DDR) pathways has broadened the therapeutic landscape in oncology. It is becoming increasingly clear that the genomic instability of cells resulted from deficient DNA damage response contributes to the occurrence of cancer. One the other hand, these defects could also be exploited as a therapeutic opportunity, which is preferentially more deleterious in tumor cells than in normal cells. An expanding repertoire of DDR-targeting agents has rapidly expanded to inhibitors of multiple members involved in DDR pathways, including PARP, ATM, ATR, CHK1, WEE1, and DNA-PK. In this review, we sought to summarize the complex network of DNA repair machinery in cancer cells and discuss the underlying mechanism for the application of DDR inhibitors in cancer. With the past preclinical evidence and ongoing clinical trials, we also provide an overview of the history and current landscape of DDR inhibitors in cancer treatment, with special focus on the combination of DDR-targeted therapies with other cancer treatment strategies.
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Affiliation(s)
- Manni Wang
- Department of BiotherapyCancer CenterWest China HospitalSichuan UniversityChengduChina
| | - Siyuan Chen
- Department of BiotherapyCancer CenterWest China HospitalSichuan UniversityChengduChina
| | - Danyi Ao
- Department of BiotherapyCancer CenterWest China HospitalSichuan UniversityChengduChina
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2
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Medová M, Medo M, Hovhannisyan L, Muñoz-Maldonado C, Aebersold DM, Zimmer Y. DNA-PK in human malignant disorders: Mechanisms and implications for pharmacological interventions. Pharmacol Ther 2020; 215:107617. [PMID: 32610116 DOI: 10.1016/j.pharmthera.2020.107617] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/15/2020] [Indexed: 12/12/2022]
Abstract
The DNA-PK holoenzyme is a fundamental element of the DNA damage response machinery (DDR), which is responsible for cellular genomic stability. Consequently, and predictably, over the last decades since its identification and characterization, numerous pre-clinical and clinical studies reported observations correlating aberrant DNA-PK status and activity with cancer onset, progression and responses to therapeutic modalities. Notably, various studies have established in recent years the role of DNA-PK outside the DDR network, corroborating its role as a pleiotropic complex involved in transcriptional programs that operate biologic processes as epithelial to mesenchymal transition (EMT), hypoxia, metabolism, nuclear receptors signaling and inflammatory responses. In particular tumor entities as prostate cancer, immense research efforts assisted mapping and describing the overall signaling networks regulated by DNA-PK that control metastasis and tumor progression. Correspondingly, DNA-PK emerges as an obvious therapeutic target in cancer and data pertaining to various pharmacological approaches have been published, largely in context of combination with DNA-damaging agents (DDAs) that act by inflicting DNA double strand breaks (DSBs). Currently, new generation inhibitors are tested in clinical trials. Several excellent reviews have been published in recent years covering the biology of DNA-PK and its role in cancer. In the current article we are aiming to systematically describe the main findings on DNA-PK signaling in major cancer types, focusing on both preclinical and clinical reports and present a detailed current status of the DNA-PK inhibitors repertoire.
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Abstract
DNA-dependent protein kinase (DNA-PK) is involved in many cellular pathways. It has a key role in the cellular response to DNA damage, in the repair of DNA double-strand break (DNA-DSBs) and as a consequence an important role in maintaining genomic integrity. In addition, DNA-PK has been shown to modulate transcription, to be involved in the development of the immune system and to protect telomeres. These pleotropic involvements and the fact that its expression is de-regulated in cancer have made DNA-PK an intriguing therapeutic target in cancer therapy, especially when combined with agents causing DNA-DSBs such as topoisomerase II inhibitors and ionizing radiation. Different small molecule inhibitors of DNA-PK have been recently synthesized and some are now being tested in clinical trials. This review discusses what is known about DNA-PK, its role in tumor biology, DNA repair and cancer therapy and critically discusses its inhibition as a potential therapeutic approach.
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Affiliation(s)
- Giovanna Damia
- Laboratory of Molecular Pharmacology, Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy.
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Abstract
The DNA-dependent protein kinase (DNA-PK) plays an instrumental role in the overall survival and proliferation of cells. As a member of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, DNA-PK is best known as a mediator of the cellular response to DNA damage. In this context, DNA-PK has emerged as an intriguing therapeutic target in the treatment of a variety of cancers, especially when used in conjunction with genotoxic chemotherapy or ionizing radiation. Beyond the DNA damage response, DNA-PK activity is necessary for multiple cellular functions, including the regulation of transcription, progression of the cell cycle, and in the maintenance of telomeres. Here, we review what is currently known about DNA-PK regarding its structure and established roles in DNA repair. We also discuss its lesser-known functions, the pharmacotherapies inhibiting its function in DNA repair, and its potential as a therapeutic target in a broader context.
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Affiliation(s)
- Ismail S Mohiuddin
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Min H Kang
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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Cao Z, Goyal D, Meiler SE, Zhou Y, Dynan WS. Platforms for delivery of macromolecules to sites of DNA double-strand break repair. Artificial Cells, Nanomedicine, and Biotechnology 2019; 47:2196-2204. [PMID: 31159605 DOI: 10.1080/21691401.2019.1622553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Zhen Cao
- Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, USA
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
- Hubei Cancer Clinical Study Centre, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
| | - Deepika Goyal
- Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, USA
| | - Steffen E. Meiler
- Department of Anesthesiology and Perioperative Medicine, Georgia Health Sciences University, Augusta, Georgia, USA
| | - Yunfeng Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
- Hubei Cancer Clinical Study Centre, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, P. R. China
| | - William S. Dynan
- Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, USA
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, USA
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6
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George VC, Ansari SA, Chelakkot VS, Chelakkot AL, Chelakkot C, Menon V, Ramadan W, Ethiraj KR, El-Awady R, Mantso T, Mitsiogianni M, Panagiotidis MI, Dellaire G, Vasantha Rupasinghe HP. DNA-dependent protein kinase: Epigenetic alterations and the role in genomic stability of cancer. Mutat Res Rev Mutat Res 2018; 780:92-105. [PMID: 31395353 DOI: 10.1016/j.mrrev.2018.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/13/2018] [Indexed: 12/28/2022]
Abstract
DNA-dependent protein kinase (DNA-PK), a member of phosphatidylinositol-kinase family, is a key protein in mammalian DNA double-strand break (DSB) repair that helps to maintain genomic integrity. DNA-PK also plays a central role in immune cell development and protects telomerase during cellular aging. Epigenetic deregulation due to endogenous and exogenous factors may affect the normal function of DNA-PK, which in turn could impair DNA repair and contribute to genomic instability. Recent studies implicate a role for epigenetics in the regulation of DNA-PK expression in normal and cancer cells, which may impact cancer progression and metastasis as well as provide opportunities for treatment and use of DNA-PK as a novel cancer biomarker. In addition, several small molecules and biological agents have been recently identified that can inhibit DNA-PK function or expression, and thus hold promise for cancer treatments. This review discusses the impact of epigenetic alterations and the expression of DNA-PK in relation to the DNA repair mechanisms with a focus on its differential levels in normal and cancer cells.
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Affiliation(s)
- Vazhappilly Cijo George
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Shabbir Ahmed Ansari
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Vipin Shankar Chelakkot
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | | | - Chaithanya Chelakkot
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Varsha Menon
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Wafaa Ramadan
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Raafat El-Awady
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates; Cancer Biology Department, National Cancer Institute and College of Medicine, Cairo University, Cairo, Egypt
| | - Theodora Mantso
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Melina Mitsiogianni
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Mihalis I Panagiotidis
- Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Graham Dellaire
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - H P Vasantha Rupasinghe
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.
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Abstract
Cancer is a disease attributed to the accumulation of DNA damages due to incapacitation of DNA repair pathways resulting in genomic instability and a mutator phenotype. Among the DNA lesions, double stranded breaks (DSBs) are the most toxic forms of DNA damage which may arise as a result of extrinsic DNA damaging agents or intrinsic replication stress in fast proliferating cancer cells. Accurate repair of DSBs is therefore paramount to the cell survival, and several classes of proteins such as kinases, nucleases, helicases or core recombinational proteins have pre-defined jobs in precise execution of DSB repair pathways. On one hand, the proper functioning of these proteins ensures maintenance of genomic stability in normal cells, and on the other hand results in resistance to various drugs employed in cancer therapy and therefore presents a suitable opportunity for therapeutic targeting. Higher relapse and resistance in cancer patients due to non-specific, cytotoxic therapies is an alarming situation and it is becoming more evident to employ personalized treatment based on the genetic landscape of the cancer cells. For the success of personalized treatment, it is of immense importance to identify more suitable targetable proteins in DSB repair pathways and also to explore new synthetic lethal interactions with these pathways. Here we review the various alternative approaches to target the various protein classes termed as cancer TARGETases in DSB repair pathway to obtain more beneficial and selective therapy.
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Affiliation(s)
- Pounami Samadder
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital in Brno, 60200 Brno, Czech Republic
| | - Rakesh Aithal
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; Department of Biology, Masaryk University, 62500 Brno, Czech Republic
| | - Ondrej Belan
- Department of Biology, Masaryk University, 62500 Brno, Czech Republic
| | - Lumir Krejci
- National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital in Brno, 60200 Brno, Czech Republic; Department of Biology, Masaryk University, 62500 Brno, Czech Republic.
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Nikitaki Z, Michalopoulos I, Georgakilas AG. Molecular inhibitors of DNA repair: searching for the ultimate tumor killing weapon. Future Med Chem 2015; 7:1543-58. [DOI: 10.4155/fmc.15.95] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
DNA repair (DR) inhibitors are small molecules that interact with DR proteins in order to disrupt their function and induce a ‘strike’ to the high fidelity of the mammalian DNA repair systems. Many anticancer therapies aim to harm the DNA of the usually highly proliferative cancer cell, causing it to undergo apoptosis. In response to this, cancer cells attempt to fix the induced lesion and reconstitute its genomic integrity, in turn reducing the efficacy of treatment. To overcome this, DR inhibitors suppress DNA repair proteins’ function, increasing the potency and tumor killing effect of chemotherapy or radiotherapy. In this review, we discuss clinically applied novel inhibitors under translational investigation and we apply bioinformatic tools in order to identify repair proteins implicated in more than two phenomenically distinct DNA repair pathways (e.g., base excision repair and nonhomologous end joining), that is, the concept of ‘synthetic lethality’. Our study can aid towards the optimization of this therapeutic strategy and, therefore, maximizing treatment effectiveness like in the case of radiation therapy.
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Li Y, Li H, Peng W, He XY, Huang M, Qiu D, Xue YB, Lu L. DNA-dependent protein kinase catalytic subunit inhibitor reverses acquired radioresistance in lung adenocarcinoma by suppressing DNA repair. Mol Med Rep 2015; 12:1328-34. [PMID: 25815686 DOI: 10.3892/mmr.2015.3505] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 02/24/2015] [Indexed: 11/06/2022] Open
Abstract
The mechanisms underlying lung cancer radioresistance remain to be fully elucidated. The DNA repair pathway is a predominant target of radiotherapy, which is considered to be involved in the acquired radioresistance of cancer cells. The present study aimed to establish a radioresistant cell model using the A549 human lung cancer cell line, and to further investigate the potential mechanisms underlying the radioresistance. The A549R radioresistant lung cancer cell variant was established by exposing the parental A549 cells to repeated γ-ray irradiation at a total dose of 60 Gy. Colony formation assays were then used to determine cell survival following γ-ray exposure. The established radioresistant cells were subsequently treated with or without the NU7026 DNA-PKcs inhibitor. The levels of DNA damage were determined by counting the number of fluorescent γ-H2AX foci in the cells. The cellular capacity for DNA repair was assessed using antibodies for the detection of various DNA repair pathway proteins. The radioresistant sub-clones exhibited significantly decreased survival following NU7026 treatment, compared with the parental cells, as determined by colony formation assays (P<0.05), and this finding was found to be dose-dependent. Treatment with the DNA-dependent protein kinase (DNA-PK) inhibitor significantly reduced γ-H2AX foci formation (P<0.05) following acute radiation exposure in the radioresistant sub-clones, compared with the parental control cells. The decreased levels of γ-H2AX were accompanied by an increase in the percentage of apoptotic cells in the radioresistant cell line following post-radiation treatment with the DNA-PKcs inhibitor. The expression levels of proteins associated with the DNA repair pathway were altered markedly in the cells treated with NU7026. The results of the present study suggested that radioresistance may be associated with enhanced DNA repair following exposure to radiation, resulting in reduced apoptosis. Therefore, the quantity of γ-H2AX determines the radioresistance of cells. The DNA repair pathway is important in mediating radioresistance, and treatment with the DNA-PKcs inhibitor, NU7026 restored the acquired radiation resistance.
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Affiliation(s)
- Yong Li
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Hang Li
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Wen Peng
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Xin-Yun He
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Min Huang
- Department of Occupational and Environmental Health, School of Public Health, Ningxia Medical University, Ningxia 750004, P.R. China
| | - Dong Qiu
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Ying-Bo Xue
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Liang Lu
- Department of Oncology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
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Ramzan Z, Nassri AB, Huerta S. Genotypic characteristics of resistant tumors to pre-operative ionizing radiation in rectal cancer. World J Gastrointest Oncol 2014; 6:194-210. [PMID: 25024812 PMCID: PMC4092337 DOI: 10.4251/wjgo.v6.i7.194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/19/2014] [Accepted: 05/08/2014] [Indexed: 02/05/2023] Open
Abstract
Due to a wide range of clinical response in patients undergoing neo-adjuvant chemoradiation for rectal cancer it is essential to understand molecular factors that lead to the broad response observed in patients receiving the same form of treatment. Despite extensive research in this field, the exact mechanisms still remain elusive. Data raging from DNA-repair to specific molecules leading to cell survival as well as resistance to apoptosis have been investigated. Individually, or in combination, there is no single pathway that has become clinically applicable to date. In the following review, we describe the current status of various pathways that might lead to resistance to the therapeutic applications of ionizing radiation in rectal cancer.
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Vignard J, Mirey G, Salles B. Ionizing-radiation induced DNA double-strand breaks: a direct and indirect lighting up. Radiother Oncol 2013; 108:362-9. [PMID: 23849169 DOI: 10.1016/j.radonc.2013.06.013] [Citation(s) in RCA: 181] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/10/2013] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
The occurrence of DNA double-strand breaks (DSBs) induced by ionizing radiation has been extensively studied by biochemical or cell imaging techniques. Cell imaging development relies on technical advances as well as our knowledge of the cell DNA damage response (DDR) process. The DDR involves a complex network of proteins that initiate and coordinate DNA damage signaling and repair activities. As some DDR proteins assemble at DSBs in an established spatio-temporal pattern, visible nuclear foci are produced. In addition, post-translational modifications are important for the signaling and the recruitment of specific partners at damaged chromatin foci. We briefly review here the most widely used methods to study DSBs. We also discuss the development of indirect methods, using reporter expression or intra-nuclear antibodies, to follow the production of DSBs in real time and in living cells.
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Affiliation(s)
- Julien Vignard
- INRA, UMR1331, Université de Toulouse, TOXALIM (Research Centre in Food Toxicology), F-31027 Toulouse, France
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Yan L, Xu G, Qiao T, Chen W, Yuan S, Li X. CpG-ODN 7909 increases radiation sensitivity of radiation-resistant human lung adenocarcinoma cell line by overexpression of Toll-like receptor 9. Cancer Biother Radiopharm 2013; 28:559-64. [PMID: 23705865 DOI: 10.1089/cbr.2012.1450] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Radioresistance is one of the main reasons for the failure of radiotherapy in lung cancer. The aim of this study was to establish a radiation-resistant lung cancer cell line, to evaluate whether CpG oligodeoxyribonucleotide (CpG-ODN) 7909 could increase its radiosensitivity and to explore the relevant mechanisms. The radioresistant cell line, referred to as R-A549, was generated by reduplicative fractionated irradiation from the human lung adenocarcinoma cell line A549. The radioresistance of R-A549 cells were confirmed by the Cell Counting Kit-8 (CCK-8), cell viability assay, and clonogenic assay. Cell growth kinetics, morphological feature, and radiosensitivity were compared between the original A549 cells and R-A549 cells treated with or without CpG-ODN 7909 or radiation. To further explore the potential mechanisms of radiosensitivity, the cell cycle distributions and the expression of Toll-like receptor 9 (TLR-9) were examined by Western blot and flow cytometry. The R-A549 cell line was generated and its radioresistance was further confirmed. CpG-ODN 7909 was found to increase much more radiosensitivity of R-A549 cells under combined treatments with CpG-ODN 7909 and radiation compared with its control group without any treatments. They presented their respective D0 1.33 ± 0.20 Gy versus 1.76 ± 0.25 Gy with N 3.44 ± 1.01 versus 4.96 ± 0.32. Further, there was a larger cell population of R-A549 cells under combined treatment in the G2/M phase compared with the control group after treatment with CpG-ODN7909 or radiation alone at 24 and 48 hour. The expression level of TLR-9 in R-A549 cells was found higher than in A549 cells. These results suggested that CpG-ODN 7909 increased the radiosensitivity of R-A549 cells, which might be mediated via the upregulated TLR-9 and prolonged cell cycle arrest in the G2/M phase compared with A549 cells.
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Affiliation(s)
- Li Yan
- Department of Oncology, Jinshan Hospital, Fudan University, Shanghai, China
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Wang C, Lees-Miller SP. Detection and repair of ionizing radiation-induced DNA double strand breaks: new developments in nonhomologous end joining. Int J Radiat Oncol Biol Phys. 2013;86:440-449. [PMID: 23433795 DOI: 10.1016/j.ijrobp.2013.01.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/07/2013] [Indexed: 01/13/2023]
Abstract
DNA damage can occur as a result of endogenous metabolic reactions and replication stress or from exogenous sources such as radiation therapy and chemotherapy. DNA double strand breaks are the most cytotoxic form of DNA damage, and defects in their repair can result in genome instability, a hallmark of cancer. The major pathway for the repair of ionizing radiation-induced DSBs in human cells is nonhomologous end joining. Here we review recent advances on the mechanism of nonhomologous end joining, as well as new findings on its component proteins and regulation.
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Davidson D, Amrein L, Panasci L, Aloyz R. Small Molecules, Inhibitors of DNA-PK, Targeting DNA Repair, and Beyond. Front Pharmacol 2013; 4:5. [PMID: 23386830 PMCID: PMC3560216 DOI: 10.3389/fphar.2013.00005] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/08/2013] [Indexed: 12/13/2022] Open
Abstract
Many current chemotherapies function by damaging genomic DNA in rapidly dividing cells ultimately leading to cell death. This therapeutic approach differentially targets cancer cells that generally display rapid cell division compared to normal tissue cells. However, although these treatments are initially effective in arresting tumor growth and reducing tumor burden, resistance and disease progression eventually occur. A major mechanism underlying this resistance is increased levels of cellular DNA repair. Most cells have complex mechanisms in place to repair DNA damage that occurs due to environmental exposures or normal metabolic processes. These systems, initially overwhelmed when faced with chemotherapy induced DNA damage, become more efficient under constant selective pressure and as a result chemotherapies become less effective. Thus, inhibiting DNA repair pathways using target specific small molecule inhibitors may overcome cellular resistance to DNA damaging chemotherapies. Non-homologous end joining a major mechanism for the repair of double-strand breaks (DSB) in DNA is regulated in part by the serine/threonine kinase, DNA dependent protein kinase (DNA-PK). The DNA-PK holoenzyme acts as a scaffold protein tethering broken DNA ends and recruiting other repair molecules. It also has enzymatic activity that may be involved in DNA damage signaling. Because of its’ central role in repair of DSBs, DNA-PK has been the focus of a number of small molecule studies. In these studies specific DNA-PK inhibitors have shown efficacy in synergizing chemotherapies in vitro. However, compounds currently known to specifically inhibit DNA-PK are limited by poor pharmacokinetics: these compounds have poor solubility and have high metabolic lability in vivo leading to short serum half-lives. Future improvement in DNA-PK inhibition will likely be achieved by designing new molecules based on the recently reported crystallographic structure of DNA-PK. Computer based drug design will not only assist in identifying novel functional moieties to replace the metabolically labile morpholino group but will also facilitate the design of molecules to target the DNA-PKcs/Ku80 interface or one of the autophosphorylation sites.
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Affiliation(s)
- David Davidson
- Department of Oncology, Segal Cancer Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University Montreal, QC, Canada
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16
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Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a key component of the non-homologous end-joining (NHEJ) pathway, is involved in DNA double-strand break repair, immunocompetence, genomic integrity, and epidermal growth factor receptor signaling. Clinical studies indicate that expression and activity of DNA-PKcs is correlated with cancer progression and response to treatment. Various anti-DNA-PKcs strategies have been developed and tested in preclinical studies to exploit the benefit of DNA-PKcs inhibition in sensitization of radiotherapy and in combined modality therapy with other antitumor agents. In this article, we review the association between DNA-PKcs and cancer development and discuss current approaches and mechanisms for inhibition of DNA-PKcs. The future challenges are to understand how DNA-PKcs activity is correlated with cancer susceptibility and to identify those patients who would most benefit from DNA-PKcs inhibition.
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Affiliation(s)
- Feng-Ming Hsu
- Department of Oncology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
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