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Gutierrez R, Chan AYS, Lai SWT, Itoh S, Lee DH, Sun K, Battad A, Chen S, O'Connor TR, Shuck SC. Lack of mismatch repair enhances resistance to methylating agents for cells deficient in oxidative demethylation. J Biol Chem 2024; 300:107492. [PMID: 38925328 DOI: 10.1016/j.jbc.2024.107492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 05/21/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
The human alkylation B (AlkB) homologs, ALKBH2 and ALKBH3, respond to methylation damage to maintain genomic integrity and cellular viability. Both ALKBH2 and ALKBH3 are direct reversal repair enzymes that remove 1-methyladenine (1meA) and 3-methylcytosine (3meC) lesions commonly generated by alkylating chemotherapeutic agents. Thus, the existence of deficiencies in ALKBH proteins can be exploited in synergy with chemotherapy. In this study, we investigated possible interactions between ALKBH2 and ALKBH3 with other proteins that could alter damage response and discovered an interaction with the mismatch repair (MMR) system. To test whether the lack of active MMR impacts ALKBH2 and/or ALKBH3 response to methylating agents, we generated cells deficient in ALKBH2, ALKBH3, or both in addition to Mlh homolog 1 (MLH1), another MMR protein. We found that MLH1koALKBH3ko cells showed enhanced resistance toward SN1- and SN2-type methylating agents, whereas MLH1koALKBH2ko cells were only resistant to SN1-type methylating agents. Concomitant loss of ALKBH2 and ALKBH3 (ALKBH2ko3ko) rendered cells sensitive to SN1- and SN2-agents, but the additional loss of MLH1 enhanced resistance to both types of damage. We also showed that ALKBH2ko3ko cells have an ATR-dependent arrest at the G2/M checkpoint, increased apoptotic signaling, and replication fork stress in response to methylation. However, these responses were not observed with the loss of functional MLH1 in MLH1koALKBH2ko3ko cells. Finally, in MLH1koALKBH2ko3ko cells, we observed elevated mutant frequency in untreated and temozolomide treated cells. These results suggest that obtaining a more accurate prognosis of chemotherapeutic outcome requires information on the functionality of ALKBH2, ALKBH3, and MLH1.
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Affiliation(s)
- Roberto Gutierrez
- Department of Cancer Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Annie Yin S Chan
- Department of Cancer Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Seigmund Wai Tsuen Lai
- Department of Diabetes and Cancer Metabolism, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Shunsuke Itoh
- Department of Cancer Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Dong-Hyun Lee
- Department of Biological Sciences, College of Natural Sciences, Chonnam National University, Gwangju, South Korea
| | - Kelani Sun
- Department of Diabetes and Cancer Metabolism, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Alana Battad
- Department of Diabetes and Cancer Metabolism, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Shiuan Chen
- Department of Cancer Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute at the City of Hope, Duarte, California, USA
| | - Timothy R O'Connor
- Department of Cancer Biology, Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute at the City of Hope, Duarte, California, USA.
| | - Sarah C Shuck
- Department of Diabetes and Cancer Metabolism, Beckman Research Institute at the City of Hope, Duarte, California, USA.
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2
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Chen T, Xiao Z, Liu X, Wang T, Wang Y, Ye F, Su J, Yao X, Xiong L, Yang DH. Natural products for combating multidrug resistance in cancer. Pharmacol Res 2024; 202:107099. [PMID: 38342327 DOI: 10.1016/j.phrs.2024.107099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/22/2024] [Accepted: 02/05/2024] [Indexed: 02/13/2024]
Abstract
Cancer cells frequently develop resistance to chemotherapeutic therapies and targeted drugs, which has been a significant challenge in cancer management. With the growing advances in technologies in isolation and identification of natural products, the potential of natural products in combating cancer multidrug resistance has received substantial attention. Importantly, natural products can impact multiple targets, which can be valuable in overcoming drug resistance from different perspectives. In the current review, we will describe the well-established mechanisms underlying multidrug resistance, and introduce natural products that could target these multidrug resistant mechanisms. Specifically, we will discuss natural compounds such as curcumin, resveratrol, baicalein, chrysin and more, and their potential roles in combating multidrug resistance. This review article aims to provide a systematic summary of recent advances of natural products in combating cancer drug resistance, and will provide rationales for novel drug discovery.
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Affiliation(s)
- Ting Chen
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Zhicheng Xiao
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Xiaoyan Liu
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Tingfang Wang
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Yun Wang
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Fei Ye
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China
| | - Juan Su
- School of Pharmacy, Naval Medical University, Shanghai 200433, China.
| | - Xuan Yao
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China.
| | - Liyan Xiong
- Shanghai Engineering Research Center of Organ Repair, School of Medicine, Shanghai University, Shanghai 200444, China.
| | - Dong-Hua Yang
- New York College of Traditional Chinese Medicine, NY 11501, USA.
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3
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Bai P, Fan T, Sun G, Wang X, Zhao L, Zhong R. The dual role of DNA repair protein MGMT in cancer prevention and treatment. DNA Repair (Amst) 2023; 123:103449. [PMID: 36680944 DOI: 10.1016/j.dnarep.2023.103449] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
Alkylating agents are genotoxic chemicals that can induce and treat various types of cancer. This occurs through covalent bonding with cellular macromolecules, in particular DNA, leading to the loss of functional integrity under the persistence of modifications upon replication. O6-alkylguanine (O6-AlkylG) adducts are proposed to be the most potent DNA lesions induced by alkylating agents. If not repaired correctly, these adducts can result, at the molecular level, in DNA point mutations, chromosome aberrations, recombination, crosslinking, and single- and double-strand breaks (SSB/DSBs). At the cellular level, these lesions can result in malignant transformation, senescence, or cell death. O6-methylguanine-DNA methyltransferase (MGMT) is a DNA repair protein capable of removing the alkyl groups from O6-AlkylG adducts in a damage reversal process that can prevent the adverse biological effects of DNA damage caused by guanine O6-alkylation. MGMT can thereby defend normal cells against tumor initiation, however it can also protect tumor cells against the beneficial effects of chemotherapy. Hence, MGMT can play an important role in both the prevention and treatment of cancer; thus, it can be considered as a double-edged sword. From a clinical perspective, MGMT is a therapeutic target, and it is important to explore the rational development of its clinical exploitation.
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Affiliation(s)
- Peiying Bai
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Tengjiao Fan
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; Department of Medical Technology, Beijing Pharmaceutical University of Staff and Workers, Beijing 100079, China
| | - Guohui Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
| | - Xin Wang
- Department of Clinical Trials Center, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100029, China
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
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4
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Rikitake M, Fujikane R, Obayashi Y, Oka K, Ozaki M, Hidaka M. MLH1-mediated recruitment of FAN1 to chromatin for the induction of apoptosis triggered by O 6 -methylguanine. Genes Cells 2020; 25:175-186. [PMID: 31955481 DOI: 10.1111/gtc.12748] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/10/2020] [Accepted: 01/10/2020] [Indexed: 01/03/2023]
Abstract
O6 -Methylguanines (O6 -meG), which are produced in DNA by the action of alkylating agents, are mutagenic and cytotoxic, and induce apoptosis in a mismatch repair (MMR) protein-dependent manner. To understand the molecular mechanism of O6 -meG-induced apoptosis, we performed functional analyses of FANCD2 and FANCI-associated nuclease 1 (FAN1), which was identified as an interacting partner of MLH1. Immunoprecipitation analyses showed that FAN1 interacted with both MLH1 and MSH2 after treatment with N-methyl-N-nitrosourea (MNU), indicating the formation of a FAN1-MMR complex. In comparison with control cells, FAN1-knockdown cells were more resistant to MNU, and the appearances of a sub-G1 population and caspase-9 activation were suppressed. FAN1 formed nuclear foci in an MLH1-dependent manner after MNU treatment, and some were colocalized with both MLH1 foci and single-stranded DNA (ssDNA) created at damaged sites. Under the same condition, FANCD2 also formed nuclear foci, although it was dispensable for the formation of FAN1 foci and ssDNA. MNU-induced formation of ssDNA was dramatically suppressed in FAN1-knockdown cells. We therefore propose that FAN1 is loaded on chromatin through the interaction with MLH1 and produces ssDNA by its exonuclease activity, which contributes to the activation of the DNA damage response followed by the induction of apoptosis triggered by O6 -meG.
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Affiliation(s)
- Mihoko Rikitake
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.,Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan
| | - Ryosuke Fujikane
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.,Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Yuko Obayashi
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.,Department of Oral and Maxillofacial Surgery, Fukuoka Dental College, Fukuoka, Japan
| | - Kyoko Oka
- Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan
| | - Masao Ozaki
- Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka, Japan
| | - Masumi Hidaka
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.,Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
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5
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SMARCAD1-mediated recruitment of the DNA mismatch repair protein MutLα to MutSα on damaged chromatin induces apoptosis in human cells. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49915-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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6
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Takeishi Y, Fujikane R, Rikitake M, Obayashi Y, Sekiguchi M, Hidaka M. SMARCAD1-mediated recruitment of the DNA mismatch repair protein MutLα to MutSα on damaged chromatin induces apoptosis in human cells. J Biol Chem 2019; 295:1056-1065. [PMID: 31843968 DOI: 10.1074/jbc.ra119.008854] [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: 04/11/2019] [Revised: 12/12/2019] [Indexed: 12/12/2022] Open
Abstract
The mismatch repair (MMR) complex is composed of MutSα (MSH2-MSH6) and MutLα (MLH1-PMS2) and specifically recognizes mismatched bases during DNA replication. O 6-Methylguanine is produced by treatment with alkylating agents, such as N-methyl-N-nitrosourea (MNU), and during DNA replication forms a DNA mismatch (i.e. an O 6-methylguanine/thymine pair) and induces a G/C to A/T transition mutation. To prevent this outcome, cells carrying this DNA mismatch are eliminated by MMR-dependent apoptosis, but the underlying molecular mechanism is unclear. In this study, we provide evidence that the chromatin-regulatory and ATP-dependent nucleosome-remodeling protein SMARCAD1 is involved in the induction of MMR-dependent apoptosis in human cells. Unlike control cells, SMARCAD1-knockout cells (ΔSMARCAD1) were MNU-resistant, and the appearance of a sub-G1 population and caspase-9 activation were significantly suppressed in the ΔSMARCAD1 cells. Furthermore, the MNU-induced mutation frequencies were increased in these cells. Immunoprecipitation analyses revealed that the recruitment of MutLα to chromatin-bound MutSα, observed in SMARCAD1-proficient cells, is suppressed in ΔSMARCAD1 cells. Of note, the effect of SMARCAD1 on the recruitment of MutLα exclusively depended on the ATPase activity of the protein. On the basis of these findings, we propose that SMARCAD1 induces apoptosis via its chromatin-remodeling activity, which helps recruit MutLα to MutSα on damaged chromatin.
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Affiliation(s)
- Yukimasa Takeishi
- Advanced Science Research Center, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Ryosuke Fujikane
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Mihoko Rikitake
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan.,Department of Oral Growth and Development, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Yuko Obayashi
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan.,Department of Oral and Maxillofacial Surgery, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Mutsuo Sekiguchi
- Advanced Science Research Center, Fukuoka Dental College, Fukuoka 814-0193, Japan
| | - Masumi Hidaka
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka 814-0193, Japan
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7
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Itoh K, Masumori S, Mukai D, Sakakibara H, Yasuda M, Shimoi K. Dosage time affects alkylating agents induced micronuclei in mouse peripheral blood reticulocytes through the function of erythropoietin. J Toxicol Sci 2019; 44:273-282. [PMID: 30944280 DOI: 10.2131/jts.44.273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Previously, we reported that the frequency of micronucleated reticulocytes (MNRETs) in the peripheral blood of male C3H/He mice intraperitoneally administered ethylnitrosourea (ENU) (25 mg/kg body weight) in the dark period (zeitgeber time, ZT15) was higher than in the light period (ZT3). In this study, to clarify the mechanism underlying this phenomenon, we investigated the differences in micronucleus (MN) induction observed between ZT3 and ZT15 using five chemicals, methylnitrosourea (MNU), ethylmethane sulfonate (EMS), mitomycin C, cyclophosphamide and vincristin. MNU and EMS, monofunctional alkylating agents, showed higher frequencies of MNRETs in the ZT15 than the ZT3 treatment similar to ENU. However, no differences were observed for the other chemicals. In the comet assay, more DNA damage was induced by ENU in the ZT15 than the ZT3 treatment. Furthermore, the plasma erythropoietin (EPO) level, a known effector of MN induction with anti-apoptotic activity mediated by Bcl-xL expression, was higher in the dark than in the light period. EPO did not increase the frequency of MNRETs. However, in the ENU treatment group at ZT3 following EPO injection a significant increase of MNRETs was observed similar to the ZT15 treatment. Higher expression of apoptosis-related genes such as Bcl-xL was induced in bone marrow cells from mice treated with ENU at ZT15 compared with ZT3. From these results, it was speculated that the differences in MN induction in the peripheral blood of mice exposed to monofunctional alkylating agents such as ENU depend on apoptotic or anti-apoptotic conditions related to the circadian rhythms of EPO in bone marrow.
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Affiliation(s)
- Keiichi Itoh
- Graduate School of Integrated Pharmaceutical and Nutritional Science, University of Shizuoka.,Biosafety Research Center Inc. (BSRC)
| | | | | | | | - Michiko Yasuda
- Department of Human Nutrition, Sugiyama Jogakuen University
| | - Kayoko Shimoi
- Graduate School of Integrated Pharmaceutical and Nutritional Science, University of Shizuoka
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8
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Li GC, Zhang L, Yu M, Jia H, Tian T, Wang J, Wang F, Zhou L. Identification of novel biomarker and therapeutic target candidates for acute intracerebral hemorrhage by quantitative plasma proteomics. Clin Proteomics 2017; 14:14. [PMID: 28450824 PMCID: PMC5406897 DOI: 10.1186/s12014-017-9149-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/14/2017] [Indexed: 12/19/2022] Open
Abstract
Background The systematic mechanisms of acute intracerebral hemorrhage are still unknown and unverified, although many recent researches have indicated the secondary insults. This study was aimed to disclose the pathological mechanism and identify novel biomarker and therapeutic target candidates by plasma proteome. Methods Patients with AICH (n = 8) who demographically matched healthy controls (n = 4) were prospectively enrolled, and their plasma samples were obtained. The TMT-LC–MS/MS-based proteomics approach was used to quantify the differential proteome across plasma samples, and the results were analyzed by Ingenuity Pathway Analysis to explore canonical pathways and the relationship involved in the uploaded data. Results Compared with healthy controls, there were 31 differentially expressed proteins in the ICH group (P < 0.05), of which 21 proteins increased while 10 proteins decreased in abundance. These proteins are involved in 21 canonical pathways. One network with high confidence level was selected by the function network analysis, in which 23 proteins, P38MAPK and NFκB signaling pathways participated. Upstream regulator analysis found two regulators, IL6 and TNF, with an activation z-score. Seven biomarker candidates: APCS, FGB, LBP, MGMT, IGFBP2, LYZ, and APOA4 were found. Six candidate proteins were selected to assess the validity of the results by subsequent Western blotting analysis. Conclusion Our analysis provided several intriguing pathways involved in ICH, like LXR/RXR activation, acute phase response signaling, and production of NO and ROS in macrophages pathways. The three upstream regulators: IL-6, TNF, LPS, and seven biomarker candidates: APCS, APOA4, FGB, IGFBP2, LBP, LYZ, and MGMT were uncovered. LPS, APOA4, IGFBP2, LBP, LYZ, and MGMT are novel potential biomarkers in ICH development. The identified proteins and pathways provide new perspectives to the potential pathological mechanism and therapeutic targets underlying ICH. Electronic supplementary material The online version of this article (doi:10.1186/s12014-017-9149-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Guo-Chun Li
- College of Medicine and Life Sciences, Nanjing University of Chinese Medicine, Nanjing, 210023 People's Republic of China
| | - Lina Zhang
- The Third Hospital of Zhangzhou, Zhangzhou, 363005 People's Republic of China
| | - Ming Yu
- Department of Neurology, Affiliated Hospital of Jiangsu University, Zhenjiang, 212001 People's Republic of China
| | - Haiyu Jia
- Department of Neurology, Affiliated Hospital of Jiangsu University, Zhenjiang, 212001 People's Republic of China
| | - Ting Tian
- College of Medicine and Life Sciences, Nanjing University of Chinese Medicine, Nanjing, 210023 People's Republic of China
| | - Junqin Wang
- College of Medicine and Life Sciences, Nanjing University of Chinese Medicine, Nanjing, 210023 People's Republic of China
| | - Fuqiang Wang
- School of Public Health, Nanjing Medical University, Nanjing, 211166 People's Republic of China
| | - Ling Zhou
- School of Public Health, Nanjing Medical University, Nanjing, 211166 People's Republic of China
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9
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Function of high-mobility group A proteins in the DNA damage signaling for the induction of apoptosis. Sci Rep 2016; 6:31714. [PMID: 27538817 PMCID: PMC4990841 DOI: 10.1038/srep31714] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 07/25/2016] [Indexed: 11/29/2022] Open
Abstract
O6-Methylguanine produced in DNA can pair with thymine during DNA replication, thus leading to a G-to-A transition mutation. To prevent such outcomes, cells harboring O6-methylguanine-containing mispair undergo apoptosis that requires the function of mismatch repair (MMR) protein complex. To identify the genes involved in the induction of apoptosis, we performed gene-trap mutagenesis and isolated a clone of mouse cells exhibiting an increased resistance to the killing effect of an alkylating agent, N-methyl-N-nitrosourea (MNU). The mutant carries an insertion in the Hmga2 gene, which belongs to a gene family encoding the high-mobility group A non-histone chromatin proteins. To elucidate the function of HMGA proteins in the apoptosis pathway, we introduced siRNAs for HMGA1 and/or HMGA2 into human HeLa MR cells defective in O6-methylguanine-DNA methyltransferase. HMGA1- and HMGA2-single knockdown cells showed an increased resistance to MNU, and HMGA1/HMGA2-double knockdown cells exhibited further increased tolerance compared to the control. The phosphorylation of ATR and CHK1, the appearance of a sub-G1 population, and caspase-9 activation were suppressed in the knockdown cells, although the formation of mismatch recognition complex was unaffected. These results suggest that HMGA family proteins function at the step following the damage recognition in the process of apoptosis triggered by O6-methylguanine.
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10
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Dacarbazine as a minor groove binder of DNA: Spectroscopic, biophysical and molecular docking studies. Int J Biol Macromol 2015; 79:193-200. [DOI: 10.1016/j.ijbiomac.2015.04.055] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 04/23/2015] [Accepted: 04/25/2015] [Indexed: 11/19/2022]
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11
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Su Y, Yin L, Liu R, Sheng J, Yang M, Wang Y, Pan E, Guo W, Pu Y, Zhang J, Liang G. Promoter methylation status of MGMT, hMSH2, and hMLH1 and its relationship to corresponding protein expression and TP53 mutations in human esophageal squamous cell carcinoma. Med Oncol 2013; 31:784. [PMID: 24366688 DOI: 10.1007/s12032-013-0784-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/22/2013] [Indexed: 12/12/2022]
Abstract
To determine the relevance of O-6-methylguanine-DNA methyltransferase (MGMT), human mutS homolog 2 (hMSH2), and human mutL homolog 1 (hMLH1) in TP53 mutations in esophageal squamous cell carcinoma, we employed methylation-sensitive high-resolution melting technology and methylation-specific polymerase chain reaction (PCR) to analyze promoter hypermethylation of MGMT, hMSH2, and hMLH1, respectively, in 51 paired tumors and their adjacent normal tissues. The protein expression of the three proteins was also evaluated by Western blot analysis, and the PCR products of TP53, from exon 5 to exon 8, were directly sequenced to measure the mutation spectrum. Esophageal tumor tissues embraced statistically higher MGMT and hMSH2 promoter methylation level than normal tissue. The promoter methylation status of MGMT and hMSH2 corresponds positively with the protein expression level of MGMT and hMSH2. However, such relevance was not found for hMLH1. Furthermore, TP53 mutation status was well associated with MGMT and hMSH2 promoter methylation status, indicating that silencing of the two genes could lead to TP53 mutation in ESCC.
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Affiliation(s)
- Yaoyao Su
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
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12
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Quintavalle C, Mangani D, Roscigno G, Romano G, Diaz-Lagares A, Iaboni M, Donnarumma E, Fiore D, De Marinis P, Soini Y, Esteller M, Condorelli G. MiR-221/222 target the DNA methyltransferase MGMT in glioma cells. PLoS One 2013; 8:e74466. [PMID: 24147153 PMCID: PMC3798259 DOI: 10.1371/journal.pone.0074466] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/31/2013] [Indexed: 11/19/2022] Open
Abstract
Glioblastoma multiforme (GBM) is one of the most deadly types of cancer. To date, the best clinical approach for treatment is based on administration of temozolomide (TMZ) in combination with radiotherapy. Much evidence suggests that the intracellular level of the alkylating enzyme O6-methylguanine–DNA methyltransferase (MGMT) impacts response to TMZ in GBM patients. MGMT expression is regulated by the methylation of its promoter. However, evidence indicates that this is not the only regulatory mechanism present. Here, we describe a hitherto unknown microRNA-mediated mechanism of MGMT expression regulation. We show that miR-221 and miR-222 are upregulated in GMB patients and that these paralogues target MGMT mRNA, inducing greater TMZ-mediated cell death. However, miR-221/miR-222 also increase DNA damage and, thus, chromosomal rearrangements. Indeed, miR-221 overexpression in glioma cells led to an increase in markers of DNA damage, an effect rescued by re-expression of MGMT. Thus, chronic miR-221/222-mediated MGMT downregulation may render cells unable to repair genetic damage. This, associated also to miR-221/222 oncogenic potential, may poor GBM prognosis.
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Affiliation(s)
- Cristina Quintavalle
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
- IEOS, CNR, Naples, Italy
| | - Davide Mangani
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
| | - Giuseppina Roscigno
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
- IEOS, CNR, Naples, Italy
| | | | - Angel Diaz-Lagares
- Epigenetic and Cancer Biology Program (PEBC) IDIBELL, Hospital Duran i Reynals, Barcelona, Spain
| | - Margherita Iaboni
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
| | | | - Danilo Fiore
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
| | | | - Ylermi Soini
- Department of Pathology and Forensic Medicine, Institute of Clinical Medicine, Pathology and Forensic Medicine, School of Medicine, Cancer Center of Eastern Finland, University of Eastern Finland, Kuopio, Finland
| | - Manel Esteller
- Epigenetic and Cancer Biology Program (PEBC) IDIBELL, Hospital Duran i Reynals, Barcelona, Spain
| | - Gerolama Condorelli
- Department of Molecular Medicine and Medical Biotechnology, "Federico II” University ofNaples, Naples, Italy
- IEOS, CNR, Naples, Italy
- * E-mail:
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13
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Noonan EM, Shah D, Yaffe MB, Lauffenburger DA, Samson LD. O6-Methylguanine DNA lesions induce an intra-S-phase arrest from which cells exit into apoptosis governed by early and late multi-pathway signaling network activation. Integr Biol (Camb) 2013; 4:1237-55. [PMID: 22892544 DOI: 10.1039/c2ib20091k] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The O(6)-methylguanine (O(6)MeG) DNA lesion is well known for its mutagenic, carcinogenic, and cytotoxic properties, and understanding how a cell processes such damage is of critical importance for improving current cancer therapy. Here we use human cells differing only in their O(6)MeG DNA methyltransferase (MGMT) or mismatch repair (MMR) status to explore the O(6)MeG/MMR-dependent molecular and cellular responses to treatment with the methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). We find that O(6)MeG triggers MMR-dependent cell cycle perturbations in both the first and second cell cycle post treatment. At lower levels of damage, we show that a transient arrest in the second S-phase precedes survival and progression into subsequent cell cycles. However, at higher levels of damage, arrest in the second S-phase coincides with a cessation of DNA replication followed by initiation of apoptotic cell death. Further, we show that entry into apoptotic cell death is specifically from S-phase of the second cell cycle. Finally, we demonstrate the key role of an O(6)MeG/MMR-dependent multi-pathway, multi-time-scale signaling network activation, led by early ATM, H2AX, CHK1, and p53 phosphorylation and followed by greatly amplified late phosphorylation of the early pathway nodes along with activation of the CHK2 kinase and the stress-activated JNK kinase.
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Affiliation(s)
- Ericka M Noonan
- Biological Engineering Department, Biology Department, Center for Environmental Health Sciences, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Ho KL, Chong PP, Yazan LS, Ismail M. Vanillin differentially affects azoxymethane-injected rat colon carcinogenesis and gene expression. J Med Food 2012; 15:1096-102. [PMID: 23216109 DOI: 10.1089/jmf.2012.2245] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Vanillin is the substance responsible for the flavor and smell of vanilla, a widely used flavoring agent. Previous studies reported that vanillin is a good antimutagen and anticarcinogen. However, there are also some contradicting findings showing that vanillin was a comutagen and cocarcinogen. This study investigated whether vanillin is an anticarcinogen or a cocarcinogen in rats induced with azoxymethane (AOM). Rats induced with AOM will develop aberrant crypt foci (ACF). AOM-challenged rats were treated with vanillin orally and intraperitoneally at low and high concentrations and ACF density, multiplicity, and distribution were observed. The gene expression of 14 colorectal cancer-related genes was also studied. Results showed that vanillin consumed orally had no effect on ACF. However, high concentrations (300 mg/kg body weight) of vanillin administered through intraperitoneal injection could increase ACF density and ACF multiplicity. ACF were mainly found in the distal colon rather than in the mid-section and proximal colon. The expression of colorectal cancer biomarkers, protooncogenes, recombinational repair, mismatch repair, and cell cycle arrest, and tumor suppressor gene expression were also affected by vanillin. Vanillin was not cocarcinogenic when consumed orally. However, it was cocarcinogenic when being administered intraperitoneally at high concentration. Hence, the use of vanillin in food should be safe but might have cocarcinogenic potential when it is used in high concentration for therapeutic purposes.
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Affiliation(s)
- Ket Li Ho
- Nutrigenomic Program, Laboratory of Molecular Biomedicine, Institute of Bioscience, University Putra Malaysia, Serdang, Malaysia
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15
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Sano S, Sakagami R, Sekiguchi M, Hidaka M. Stabilization of MAPO1 by specific binding with folliculin and AMP-activated protein kinase in O⁶-methylguanine-induced apoptosis. Biochem Biophys Res Commun 2012. [PMID: 23201403 DOI: 10.1016/j.bbrc.2012.11.064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
When DNA is damaged by alkylating agents, apoptosis is induced to exclude cells carrying DNA lesions in order to prevent mutations and cancer. MAPO1, identified as a component involved in the induction of apoptosis, interacts with AMP-activated protein kinase (AMPK) and folliculin (FLCN). We herein report that MAPO1 is stabilized during the course of apoptosis, triggered by alkylation-induced O(6)-methylguanine in DNA. An immunoblotting analysis revealed that the amount of MAPO1 increased gradually after treatment with N-methyl-N-nitrosourea (MNU), although the level of mRNA for MAPO1 was unchanged. When cells were exposed to a proteasome inhibitor, MG132, the MAPO1 level significantly increased. On the other hand, application of a protein synthesis inhibitor, cycloheximide, caused a decrease in the MAPO1 content, implying that proteasome-mediated degradation is involved. In FLCN-knockdown cells, the MAPO1 level decreased, and no increases occurred even after MNU treatment. In contrast, stabilization of MAPO1 occurred in AMPKα-knockdown cells even without MNU treatment. While MAPO1 retains its ability to stably bind to FLCN, it dissociates gradually from AMPK after exposure to MNU. It seems that the proapoptotic function of MAPO1 may be regulated by AMPK and FLCN through stabilization of MAPO1 itself.
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Affiliation(s)
- Shiori Sano
- Department of Odontology, Fukuoka Dental College, Fukuoka 814-0193, Japan
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16
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Affiliation(s)
- Mutsuo Sekiguchi
- Fukuoka Dental College, Frontier Research Center, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan.
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17
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Fujikane R, Sanada M, Sekiguchi M, Hidaka M. The identification of a novel gene, MAPO2, that is involved in the induction of apoptosis triggered by O⁶-methylguanine. PLoS One 2012; 7:e44817. [PMID: 23028632 PMCID: PMC3454368 DOI: 10.1371/journal.pone.0044817] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 08/14/2012] [Indexed: 01/21/2023] Open
Abstract
O6-Methylguanine, one of alkylated DNA bases, is especially mutagenic. Cells containing this lesion are eliminated by induction of apoptosis, associated with the function of mismatch repair (MMR) proteins. A retrovirus-mediated gene-trap mutagenesis was used to isolate new genes related to the induction of apoptosis, triggered by the treatment with an alkylating agent, N-methyl-N-nitrosourea (MNU). This report describes the identification of a novel gene, MAPO2 (O6-methylguanine-induced apoptosis 2), which is originally annotated as C1orf201. The MAPO2 gene is conserved among a wide variety of multicellular organisms and encodes a protein containing characteristic PxPxxY repeats. To elucidate the function of the gene product in the apoptosis pathway, a human cell line derived from HeLa MR cells, in which the MAPO2 gene was stably knocked down by expressing specific miRNA, was constructed. The knockdown cells grew at the same rate as HeLa MR, thus indicating that MAPO2 played no role in the cellular growth. After exposure to MNU, HeLa MR cells and the knockdown cells underwent cell cycle arrest at G2/M phase, however, the production of the sub-G1 population in the knockdown cells was significantly suppressed in comparison to that in HeLa MR cells. Moreover, the activation of BAK and caspase-3, and depolarization of mitochondrial membrane, hallmarks for the induction of apoptosis, were also suppressed in the knockdown cells. These results suggest that the MAPO2 gene product might positively contribute to the induction of apoptosis triggered by O6-methylguanine.
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Affiliation(s)
- Ryosuke Fujikane
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Masayuki Sanada
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Mutsuo Sekiguchi
- Advanced Science Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Masumi Hidaka
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
- * E-mail:
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Manikandan M, Raksha G, Munirajan AK. Haploinsufficiency of Tumor Suppressor Genes is Driven by the Cumulative Effect of microRNAs, microRNA Binding Site Polymorphisms and microRNA Polymorphisms: An In silico Approach. Cancer Inform 2012; 11:157-71. [PMID: 23032637 PMCID: PMC3433856 DOI: 10.4137/cin.s10176] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Haploinsufficiency of tumor suppressor genes, wherein the reduced production and activity of proteins results in the inability of the cell to maintain normal cellular function, is one among the various causes of cancer. However the precise molecular mechanisms underlying this condition remain unclear. Here we hypothesize that single nucleotide polymorphisms (SNPs) in the 3′untranslated region (UTR) of mRNAs and microRNA seed sequence (miR-SNPs) may cause haploinsufficiency at the level of proteins through altered binding specificity of microRNAs (miRNAs). Bioinformatics analysis of haploinsufficient genes for variations in their 3′UTR showed that the occurrence of SNPs result in the creation of new binding sites for miRNAs, thereby bringing the respective mRNA variant under the control of more miRNAs. In addition, 19 miR-SNPs were found to result in non-specific binding of microRNAs to tumor suppressors. Networking analysis suggests that the haploinsufficient tumor suppressor genes strongly interact with one another, and any subtle alterations in this network will contribute to tumorigenesis.
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Affiliation(s)
- Mayakannan Manikandan
- Department of Genetics, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai - 600113, Tamil Nadu, India
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19
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Cabelof DC. Haploinsufficiency in mouse models of DNA repair deficiency: modifiers of penetrance. Cell Mol Life Sci 2012; 69:727-40. [PMID: 21952828 PMCID: PMC11114761 DOI: 10.1007/s00018-011-0839-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 08/08/2011] [Accepted: 09/15/2011] [Indexed: 11/24/2022]
Abstract
Mouse models of DNA repair deficiency are useful tools for determining susceptibility to disease. Cancer predisposition and premature aging are commonly impacted by deficiencies in DNA repair, presumably as a function of reduced genomic fitness. In this review, a comprehensive analysis of all DNA repair mutant mouse models has been completed in order to assess the importance of haploinsufficiency for these genes. This analysis brings to light a clear role for haploinsufficiency in disease predisposition. Unfortunately, much of the data on heterozygous models are buried or underinvestigated. In light of a better understanding that the role of DNA repair haploinsufficiency may play in penetrance of other oncogenic or disease causing factors, it may be in the interest of human health and disease prevention to further investigate the phenotypes in many of these mouse models.
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Affiliation(s)
- Diane C Cabelof
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48201, USA.
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20
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Lim TH, Fujikane R, Sano S, Sakagami R, Nakatsu Y, Tsuzuki T, Sekiguchi M, Hidaka M. Activation of AMP-activated protein kinase by MAPO1 and FLCN induces apoptosis triggered by alkylated base mismatch in DNA. DNA Repair (Amst) 2011; 11:259-66. [PMID: 22209521 DOI: 10.1016/j.dnarep.2011.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/09/2011] [Accepted: 11/28/2011] [Indexed: 10/14/2022]
Abstract
O₆-methylguanine produced in DNA by the action of simple alkylating agents, such as N-methyl-N-nitrosourea (MNU), causes base-mispairing during DNA replication, thus leading to mutations and cancer. To prevent such outcomes, the cells carrying O⁶-methylguanine undergo apoptosis in a mismatch repair protein-dependent manner. We previously identified MAPO1 as one of the components required for the induction of apoptosis triggered by O⁶-methylguanine. MAPO1, also known as FNIP2 and FNIPL, forms a complex with AMP-activated protein kinase (AMPK) and folliculin (FLCN), which is encoded by the BHD tumor suppressor gene. We describe here the involvement of the AMPK-MAPO1-FLCN complex in the signaling pathway of apoptosis induced by O⁶-methylguanine. By the introduction of siRNAs specific for these genes, the transition of cells to a population with sub-G₁ DNA content following MNU treatment was significantly suppressed. After MNU exposure, phosphorylation of AMPKα occurred in an MLH1-dependent manner, and this activation of AMPK was not observed in cells in which the expression of either the Mapo1 or the Flcn gene was downregulated. When cells were treated with AICA-ribose (AICAR), a specific activator of AMPK, activation of AMPK was also observed in a MAPO1- and FLCN-dependent manner, thus leading to cell death which was accompanied by the depolarization of the mitochondrial membrane, a hallmark of the apoptosis induction. It is therefore likely that MAPO1, in its association with FLCN, may regulate the activation of AMPK to control the induction of apoptosis triggered by O⁶-methylguanine.
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Affiliation(s)
- Teik How Lim
- Department of Medical Biophysics and Radiation Biology, Faculty of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan
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Mazon G, Philippin G, Cadet J, Gasparutto D, Modesti M, Fuchs RP. Alkyltransferase-like protein (eATL) prevents mismatch repair-mediated toxicity induced by O6-alkylguanine adducts in Escherichia coli. Proc Natl Acad Sci U S A 2010; 107:18050-5. [PMID: 20921378 PMCID: PMC2964255 DOI: 10.1073/pnas.1008635107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
O(6)-alkylG adducts are highly mutagenic due to their capacity to efficiently form O(6)-alkylG:T mispairs during replication, thus triggering G→A transitions. Mutagenesis is largely prevented by repair strategies such as reversal by alkyltransferases or excision by nucleotide excision repair (NER). Moreover, methyl-directed mismatch repair (MMR) is known to trigger sensitivity to methylating agents via a mechanism that involves recognition by MutS of the O(6)-mG:T replication intermediates. We wanted to investigate the mechanism by which MMR controls the genotoxicity of environmentally relevant O(6)-alkylG adducts formed by ethylene oxide and propylene oxide. Recently, the alkyltransferase-like gene ybaZ (eATL) was shown to enhance repair of these slightly larger O(6)-alkylG adducts by NER. We analyzed the toxicity and mutagenesis induced by these O(6)-alkylG adducts using single-adducted plasmid probes. We show that the eATL gene product prevents MMR-mediated attack of the O(6)-alkylG:T replication intermediate for the larger alkyl groups but not for methyl. In vivo data are compatible with the occurrence of repeated cycles of MMR attack of the O(6)-alkylG:T intermediate. In addition, in vitro, the eATL protein efficiently prevents binding of MutS to the O(6)-alkylG:T mispairs formed by the larger alkyl groups but not by methyl. In conclusion, eATL not only enhances the efficiency of repair of these larger adducts by NER, it also shields these adducts from MMR-mediated toxicity.
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Affiliation(s)
- Gerard Mazon
- Centre National de la Recherche Scientifique (CNRS), Unité Propre de Recherche 3081, Genome Instability and Carcinogenesis, Conventionné par l'Université d'Aix-Marseille 2, 13402 Marseille Cedex 20, France; and
| | - Gaëlle Philippin
- Centre National de la Recherche Scientifique (CNRS), Unité Propre de Recherche 3081, Genome Instability and Carcinogenesis, Conventionné par l'Université d'Aix-Marseille 2, 13402 Marseille Cedex 20, France; and
| | - Jean Cadet
- Institut Nanosciences et Cryogénie/Service de Chimie Inorganique et Biologique-Unité Mixte de Recherche E3 Commissariat à l'Énergie Atomique (CEA)-Université Joseph Fourier, Federation de Recherche en Evolution 3200 CEA-CNRS/CEA Grenoble, F-38054 Grenoble Cedex 9, France
| | - Didier Gasparutto
- Institut Nanosciences et Cryogénie/Service de Chimie Inorganique et Biologique-Unité Mixte de Recherche E3 Commissariat à l'Énergie Atomique (CEA)-Université Joseph Fourier, Federation de Recherche en Evolution 3200 CEA-CNRS/CEA Grenoble, F-38054 Grenoble Cedex 9, France
| | - Mauro Modesti
- Centre National de la Recherche Scientifique (CNRS), Unité Propre de Recherche 3081, Genome Instability and Carcinogenesis, Conventionné par l'Université d'Aix-Marseille 2, 13402 Marseille Cedex 20, France; and
| | - Robert P. Fuchs
- Centre National de la Recherche Scientifique (CNRS), Unité Propre de Recherche 3081, Genome Instability and Carcinogenesis, Conventionné par l'Université d'Aix-Marseille 2, 13402 Marseille Cedex 20, France; and
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22
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Komori K, Takagi Y, Sanada M, Lim TH, Nakatsu Y, Tsuzuki T, Sekiguchi M, Hidaka M. A novel protein, MAPO1, that functions in apoptosis triggered by O6-methylguanine mispair in DNA. Oncogene 2009; 28:1142-50. [PMID: 19137017 DOI: 10.1038/onc.2008.462] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
O(6)-Methylguanine produced in DNA induces mutation due to its ambiguous base-pairing properties during DNA replication. To suppress such an outcome, organisms possess a mechanism to eliminate cells carrying O(6)-methylguanine by inducing apoptosis that requires the function of mismatch repair proteins. To identify other factors involved in this apoptotic process, we performed retrovirus-mediated gene-trap mutagenesis and isolated a mutant that acquired resistance to a simple alkylating agent, N-methyl-N-nitrosourea (MNU). However, it was still sensitive to methyl methanesulfonate, 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea, etoposide and ultraviolet irradiation. Moreover, the mutant exhibited an increased mutant frequency after exposure to MNU. The gene responsible was identified and designated Mapo1 (O(6)-methylguanine-induced apoptosis 1). When the expression of the gene was inhibited by small interfering RNA, MNU-induced apoptosis was significantly suppressed. In the Mapo1-defective mutant cells treated with MNU, the mitochondrial membrane depolarization and caspase-3 activation were severely suppressed, although phosphorylation of p53, CHK1 and histone H2AX was observed. The orthologs of the Mapo1 gene are present in various organisms from nematode to humans. Both mouse and human MAPO1 proteins expressed in cells localize in the cytoplasm. We therefore propose that MAPO1 may play a role in the signal-transduction pathway of apoptosis induced by O(6)-methylguanine-mispaired lesions.
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Affiliation(s)
- K Komori
- Department of Molecular Biology, Biomolecular Engineering Research Institute, Suita, Japan
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O6-methylguanine-induced cell death involves exonuclease 1 as well as DNA mismatch recognition in vivo. Proc Natl Acad Sci U S A 2009; 106:576-81. [PMID: 19124772 DOI: 10.1073/pnas.0811991106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Alkylation-induced O(6)-methylguanine (O(6)MeG) DNA lesions can be mutagenic or cytotoxic if unrepaired by the O(6)MeG-DNA methyltransferase (Mgmt) protein. O(6)MeG pairs with T during DNA replication, and if the O(6)MeG:T mismatch persists, a G:C to A:T transition mutation is fixed at the next replication cycle. O(6)MeG:T mismatch detection by MutSalpha and MutLalpha leads to apoptotic cell death, but the mechanism by which this occurs has been elusive. To explore how mismatch repair mediates O(6)MeG-dependent apoptosis, we used an Mgmt-null mouse model combined with either the Msh6-null mutant (defective in mismatch recognition) or the Exo1-null mutant (impaired in the excision step of mismatch repair). Mouse embryonic fibroblasts and bone marrow cells derived from Mgmt-null mice were much more alkylation-sensitive than wild type, as expected. However, ablation of either Msh6 or Exo1 function rendered these Mgmt-null cells just as resistant to alkylation-induced cytotoxicity as wild-type cells. Rapidly proliferating tissues in Mgmt-null mice (bone marrow, thymus, and spleen) are extremely sensitive to apoptosis induced by O(6)MeG-producing agents. Here, we show that ablation of either Msh6 or Exo1 function in the Mgmt-null mouse renders these rapidly proliferating tissues alkylation-resistant. However, whereas the Msh6 defect confers total alkylation resistance, the Exo1 defect leads to a variable tissue-specific alkylation resistance phenotype. Our results indicate that Exo1 plays an important role in the induction of apoptosis by unrepaired O(6)MeGs.
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Takagi Y, Hidaka M, Sanada M, Yoshida H, Sekiguchi M. Different initial steps of apoptosis induced by two types of antineoplastic drugs. Biochem Pharmacol 2008; 76:303-11. [PMID: 18573489 DOI: 10.1016/j.bcp.2008.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 05/05/2008] [Indexed: 11/26/2022]
Abstract
O6-Methylguanine and O6-chloroethylguanine are primary DNA lesions produced by two types of antineoplastic drugs, 8-carbamoyl-3-methylimidazo[5,1-d]-1,2,3,5-tetrazin-4(3H)-one (temozolomide, TMZ) and 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), respectively. They can be repaired by O6-methylguanine-DNA methyltransferase, coded by the Mgmt gene. Otherwise, these two types of lesions induce apoptosis in different ways. O6-Chloroethylguanine blocks DNA replication thereby inducing apoptosis. On the other hand, O6-methylguanine does not block DNA replication and the resulting O6-methylguanine-thymine mispair is recognized by mismatch repair-related proteins, including MLH1, thereby inducing apoptosis. Reflecting this, mouse cells lacking both MGMT and MLH1 are resistant to TMZ, but not to ACNU. The translocation of phosphatidylserine in cell membrane as well as a change of mitochondrial transmembrane potentials occurred in an MLH1-dependent manner after treatment with TMZ, but no such MLH1 dependency was observed in the case of ACNU treatment. By using cell lines defective in both APAF-1 and MGMT, it was revealed that the APAF-1 function is required for execution of apoptosis induced by either TMZ or ACNU. There is almost 12h delay in occurrence of apoptosis-related mitochondrial depolarization in TMZ-treated cells in comparison to those of ACNU-treated cells, reflecting the fact that at least one cycle of DNA replication is required to trigger apoptosis in the former case, but not in the latter.
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Affiliation(s)
- Yasumitsu Takagi
- Frontier Research Center, Fukuoka Dental College, 2-15-1, Tamura, Sawara-ku, Fukuoka, 814-0193, Japan.
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25
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Contribution of DNA repair mechanisms to determining chemotherapy response in high-grade glioma. J Clin Neurosci 2008; 15:1-8. [DOI: 10.1016/j.jocn.2007.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 05/23/2007] [Indexed: 01/07/2023]
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Tubbs JL, Pegg AE, Tainer JA. DNA binding, nucleotide flipping, and the helix-turn-helix motif in base repair by O6-alkylguanine-DNA alkyltransferase and its implications for cancer chemotherapy. DNA Repair (Amst) 2007; 6:1100-15. [PMID: 17485252 PMCID: PMC1993358 DOI: 10.1016/j.dnarep.2007.03.011] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
O(6)-Alkylguanine-DNA alkyltransferase (AGT) is a crucial target both for the prevention of cancer and for chemotherapy, since it repairs mutagenic lesions in DNA, and it limits the effectiveness of alkylating chemotherapies. AGT catalyzes the unique, single-step, direct damage reversal repair of O(6)-alkylguanines by selectively transferring the O(6)-alkyl adduct to an internal cysteine residue. Recent crystal structures of human AGT alone and in complex with substrate DNA reveal a two-domain alpha/beta fold and a bound zinc ion. AGT uses its helix-turn-helix motif to bind substrate DNA via the minor groove. The alkylated guanine is then flipped out from the base stack into the AGT active site for repair by covalent transfer of the alkyl adduct to Cys145. An asparagine hinge (Asn137) couples the helix-turn-helix DNA binding and active site motifs. An arginine finger (Arg128) stabilizes the extrahelical DNA conformation. With this newly improved structural understanding of AGT and its interactions with biologically relevant substrates, we can now begin to unravel the role it plays in preserving genetic integrity and discover how it promotes resistance to anticancer therapies.
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Affiliation(s)
- Julie L. Tubbs
- The Scripps Research Institute, The Skaggs Institute for Chemical Biology and Department of Molecular Biology, 10550 North Torrey Pines Road, MB4, La Jolla, CA 92037
| | - Anthony E. Pegg
- Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey, PA 17033
| | - John A. Tainer
- The Scripps Research Institute, The Skaggs Institute for Chemical Biology and Department of Molecular Biology, 10550 North Torrey Pines Road, MB4, La Jolla, CA 92037
- Life Sciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- *To whom correspondence should be addressed: Tel: +1-858-784-8119; fax: +1-858-784-2289;
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27
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Kaina B, Christmann M, Naumann S, Roos WP. MGMT: key node in the battle against genotoxicity, carcinogenicity and apoptosis induced by alkylating agents. DNA Repair (Amst) 2007; 6:1079-99. [PMID: 17485253 DOI: 10.1016/j.dnarep.2007.03.008] [Citation(s) in RCA: 444] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
O(6)-methylguanine-DNA methyltransferase (MGMT) plays a crucial role in the defense against alkylating agents that generate, among other lesions, O(6)-alkylguanine in DNA (collectively termed O(6)-alkylating agents [O(6)AA]). The defense is highly important, since O(6)AA are common environmental carcinogens, are formed endogenously during normal cellular metabolism and possibly inflammation, and are being used in cancer therapy. O(6)AA induced DNA damage is subject to repair, which is executed by MGMT, AlkB homologous proteins (ABH) and base excision repair (BER). Although this review focuses on MGMT, the mechanism of repair by ABH and BER will also be discussed. Experimental systems, in which MGMT has been modulated, revealed that O(6)-methylguanine (O(6)MeG) and O(6)-chloroethylguanine are major mutagenic, carcinogenic, recombinogenic, clastogenic and killing lesions. O(6)MeG-induced clastogenicity and cell death require MutS alpha-dependent mismatch repair (MMR), whereas O(6)-chloroethylguanine-induced killing occurs independently of MMR. Extensive DNA replication is required for O(6)MeG to provoke cytotoxicity. In MGMT depleted cells, O(6)MeG induces apoptosis almost exclusively, barely any necrosis, which is presumably due to the remarkable ability of secondarily formed DNA double-strand breaks (DSBs) to trigger apoptosis via ATM/ATR, Chk1, Chk2, p53 and p73. Depending on the cellular background, O(6)MeG activates both the death receptor and the mitochondrial apoptotic pathway. The inter-individual expression of MGMT in human lymphocytes is highly variable. Given the key role of MGMT in cellular defense, determination of MGMT activity could be useful for assessing a patient's drug sensitivity. MGMT is expressed at highly variable amounts in human tumors. In gliomas, a correlation was found between MGMT activity, MGMT promoter methylation and response to O(6)AA. Although the human MGMT gene is inducible by glucocorticoids and genotoxins such as radiation and alkylating agents, the role of this induction in the protection against carcinogens and the development of chemotherapeutic alkylating drug resistance are still unclear. Modulation of MGMT expression in tumors and normal tissue is currently being investigated as a possible strategy for improving cancer therapy.
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Affiliation(s)
- Bernd Kaina
- Department of Toxicology, University of Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
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28
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Ollikainen M, Hannelius U, Lindgren CM, Abdel-Rahman WM, Kere J, Peltomäki P. Mechanisms of inactivation of MLH1 in hereditary nonpolyposis colorectal carcinoma: a novel approach. Oncogene 2007; 26:4541-9. [PMID: 17260015 DOI: 10.1038/sj.onc.1210236] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mutations in the DNA mismatch repair gene MLH1 are a major cause of hereditary nonpolyposis colorectal cancer (HNPCC). No mutant phenotype is observed before the wild-type (wt) allele is somatically inactivated in target tissue. We addressed the mechanisms of MLH1 inactivation in 25 colorectal (CRC) and 32 endometrial cancers (ECs) from MLH1 mutation carriers (Mut1, in-frame genomic deletion; Mut2, out-of-frame splice site mutation; Mut3, missense mutation). By a quantitative method, matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF), utilizing four intragenic single nucleotide polymorphisms and mutations, loss of heterozygosity (LOH) was present in 31/57 (54.4%) of tumors. The wt allele displayed LOH more often than the mutant allele (23/57 vs 8/57, P=0.006). For Mut1, LOH was more frequent in CRC than EC (10/11 vs 1/13, P<0.0001), whereas Mut2 and Mut3 displayed opposite LOH pattern. Moreover, although wt LOH predominated in CRC irrespective of the predisposing mutation, LOH often affected the mutant allele in EC from Mut2 and Mut3 carriers (6/19, 31.6%). MLH1 promoter methylation, which reflected a more widespread hypermethylation tendency, occurred in 4/55 (7.3%) of tumors and was inversely associated with LOH. In conclusion, the patterns of somatic events (LOH and promoter methylation) differ depending on the tissue and germline mutation, which may in part explain the differential tumor susceptibility of different organs in HNPCC. MALDI-TOF provides a novel approach for the detection and quantification of LOH.
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Affiliation(s)
- M Ollikainen
- Department of Medical Genetics, University of Helsinki, Helsinki, Finland.
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29
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Crinière E, Kaloshi G, Laigle-Donadey F, Lejeune J, Auger N, Benouaich-Amiel A, Everhard S, Mokhtari K, Polivka M, Delattre JY, Hoang-Xuan K, Thillet J, Sanson M. MGMT prognostic impact on glioblastoma is dependent on therapeutic modalities. J Neurooncol 2007; 83:173-9. [PMID: 17219056 DOI: 10.1007/s11060-006-9320-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Accepted: 12/14/2006] [Indexed: 01/08/2023]
Abstract
MGMT promoter methylation, which has been correlated with the response to alkylating agents, was investigated in a retrospective series of 219 glioblastomas (GBMs) treated with various modalities. MGMT methylation had no impact on survival for the whole group, but showed a significant advantage (17.1 months vs. 13.1) for patients treated with RT+ adjuvant chemotherapy (relative risk of death (RR) = 0.53; P = 0.041), particularly when patients received CT during the course of RT (MS = 19.9 months vs. 12.5 months; RR = 0.227, P = 0.001). This suggests that the prognostic impact of MGMT methylation is dependent on therapeutic modalities and schedules. MGMT methylation was not correlated with the main molecular alterations, such as 10q loss and p53 expression.
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Affiliation(s)
- Emmanuelle Crinière
- INSERM, U711, Biologie des Interactions Neurones & Glie, Université Pierre et Marie Curie, Faculté de Médecine, Paris, France
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30
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Sekiguchi M. Molecular devices for high fidelity of DNA replication and gene expression. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2006; 82:278-296. [PMID: 25792791 PMCID: PMC4338819 DOI: 10.2183/pjab.82.278] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 10/12/2006] [Indexed: 06/04/2023]
Abstract
Certain types of DNA lesions, produced through cellular metabolic processes and also by external environmental stresses, are responsible for the induction of mutations as well as of cancer. Most of these lesions can be eliminated by DNA repair enzymes, and cells carrying the remaining DNA lesions are subjected to apoptosis. The persistence of damaged bases in RNA can cause errors in gene expression, and the cells appear to possess a mechanism which can prevent damaged RNA molecules from entering the translation process. We have investigated these processes for high fidelity of DNA replication and gene expression, by using both biochemical and genetic means. We herein describe (1) the molecular mechanisms for accurate DNA synthesis, (2) mammalian proteins for sanitizing the DNA precursor pool, (3) error avoidance mechanisms for gene expression under oxidative stress, and (4) the roles of DNA repair and apoptosis in the prevention of cancer.
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Affiliation(s)
- Mutsuo Sekiguchi
- Fukuoka Dental College, 2–15–1 Tamura, Sawara-ku, Fukuoka 814–0193, Japan (e-mail: )
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31
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Sekiguchi M. A quest to understand molecular mechanisms for genetic stability. DNA Repair (Amst) 2006; 5:750-8. [PMID: 16621730 DOI: 10.1016/j.dnarep.2006.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2006] [Indexed: 11/26/2022]
Abstract
In the midst of the post-war turmoil in Japan, I fortunately followed a path to become a scientist. Sometime at an early stage of my career, I encountered the problem of the cellular response to DNA damage and had the chance to discover a DNA repair enzyme. This event greatly influenced the subsequent course of my research, and I extended my studies toward elucidating the molecular mechanisms of mutagenesis as well as of carcinogenesis. Through these studies I came to understand the importance of mechanisms for dealing with the actions of reactive oxygen species to the living systems. These recollections deal with these endeavors with emphasis on the early part of my scientific career.
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Affiliation(s)
- Mutsuo Sekiguchi
- Frontier Research Center, Fukuoka Dental College, Tamura, Sawara-ku, Fukuoka 814-0006, Japan.
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32
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Smith-Roe SL, Hegan DC, Glazer PM, Buermeyer AB. Mlh1-dependent suppression of specific mutations induced in vivo by the food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP). Mutat Res 2005; 594:101-12. [PMID: 16256150 DOI: 10.1016/j.mrfmmm.2005.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 08/17/2005] [Accepted: 08/20/2005] [Indexed: 12/01/2022]
Abstract
Disruption of the DNA mismatch repair (MMR) pathway results in elevated mutation rates, inappropriate survival of cells bearing DNA damage, and increased cancer risk. Relatively little is known about the potential impact of environmentally relevant carcinogens on cancer risk in individuals with MMR-deficiency. We determined the effect of MMR status (Mlh1+/+ versus Mlh1-/-) on mutagenesis induced by the cooked-meat mutagen, 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) within cII and supFG1 transgene reporters. Despite being a lymphomagen in mice, PhIP was not mutagenic in thymus. In colon, PhIP exposure induced 3-fold more mutations in Mlh1-deficient mice compared to their Mlh1+/+ littermates. Similar induction was seen in Mlh1-/- small intestine. Analysis of mutational spectra revealed that G/C to T/A transversions, the "signature PhIP mutation", were induced to similar levels regardless of Mlh1 status. In contrast, Mlh1-/- mice exhibited hypermutability to frameshifts, G/C to A/T transitions, and G/C to C/G transversions. Thus, both the level and types of mutation induced by PhIP are influenced by the activity of the MMR system. MMR may suppress PhIP-induced mutation through recognition and processing of specific mispairs (PhIP-G/T, PhIP-G/G, and PhIP-G/loop mispairs). In contrast, the PhIP-G/A mispair is unlikely to be a MMR substrate. In addition, the similar induction of both transversions and transitions in Mlh1-/- mice suggests that mutagenic bypass of PhIP-G is similarly efficient with dATP, dTTP, and dGTP, in contrast to previously published conclusions. Our data suggests that MMR-deficiency would increase the likelihood of PhIP-induced carcinogenic mutations. Further evaluation of the risk that consumption of heterocyclic amines may impart to MMR-deficient individuals therefore is warranted.
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Affiliation(s)
- Stephanie L Smith-Roe
- Department of Environmental and Molecular Toxicology, Oregon State University, 1007 ALS Bldg., Corvallis, OR 97331, USA
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Hidaka M, Takagi Y, Takano TY, Sekiguchi M. PCNA-MutSalpha-mediated binding of MutLalpha to replicative DNA with mismatched bases to induce apoptosis in human cells. Nucleic Acids Res 2005; 33:5703-12. [PMID: 16204460 PMCID: PMC1243802 DOI: 10.1093/nar/gki878] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Modified bases, such as O6-methylguanines, are produced in cells exposed to alkylating agents and cause apoptosis. In human cells treated with N-methyl-N-nitrosourea, we detected a protein complex composed of MutSα, MutLα and PCNA on damaged DNA by immunoprecipitation method using chromatin extracts, in which protein–protein interactions were stabilized by chemical crosslinking. Time course experiments revealed that MutSα, consisting of MSH2 and MSH6 proteins, and PCNA bind to DNA to form an initial complex, and MutLα, composed of MLH1 and PMS2, binds to the complex when the DNA is damaged. This sequential mode of binding was further confirmed by the findings that the association of PCNA–MutSα complex on chromatin was observed even in the cells that lack MLH1, whereas in the absence of MSH2 no association of MutLα with the chromatin was achieved. Moreover, reduction in the PCNA content by small-interfering RNA or inhibition of DNA replication by aphidicolin, an inhibitor of DNA polymerase, significantly reduced the levels of the PCNA–MutSα–MutLα complex and also suppressed an increase in the caspase-3 activity, a hallmark for the induction of apoptosis. These observations imply that the induction of apoptosis is coupled with the progression of DNA replication through the action of PCNA.
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Affiliation(s)
- Masumi Hidaka
- Department of Molecular Biology, Biomolecular Engineering Research Institute, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan.
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Abstract
The observation that mutations in tumor suppressor genes can have haploinsufficient, as well as gain of function and dominant negative, phenotypes has caused a reevaluation of the 'two-hit' model of tumor suppressor inactivation. Here we examine the history of haploinsufficiency and tumor suppressors in order to understand the origin of the 'two-hit' dogma. The two-hit model of tumor suppressor gene inactivation was derived from mathematical modeling of cancer incidence. Subsequent interpretations implied that tumor suppressors were recessive, requiring mutations in both alleles. This model has provided a useful conceptual framework for three decades of research on the genetics and biology of tumor suppressor genes. Recently it has become clear that mutations in tumor suppressor genes are not always completely recessive. Haploinsufficiency occurs when one allele is insufficient to confer the full functionality produced from two wild-type alleles. Haploinsufficiency, however, is not an absolute property. It can be partial or complete and can vary depending on tissue type, other epistatic interactions, and environmental factors. In addition to simple quantitative differences (one allele versus two alleles), gene mutations can have qualitative differences, creating gain of function or dominant negative effects that can be difficult to distinguish from dosage-dependence. Like mutations in many other genes, tumor suppressor gene mutations can be haploinsufficient, dominant negative or gain of function in addition to recessive. Thus, under certain circumstances, one hit may be sufficient for inactivation. In addition, the phenotypic penetrance of these mutations can vary depending on the nature of the mutation itself, the genetic background, the tissue type, environmental factors and other variables. Incorporating these new findings into existing models of the clonal evolution will be a challenge for the future.
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Affiliation(s)
- Shannon R Payne
- Fred Hutchinson Cancer Research Center, Seattle, WA 90109, USA
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35
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Sanada M, Takagi Y, Ito R, Sekiguchi M. Killing and mutagenic actions of dacarbazine, a chemotherapeutic alkylating agent, on human and mouse cells: effects of Mgmt and Mlh1 mutations. DNA Repair (Amst) 2004; 3:413-20. [PMID: 15010317 DOI: 10.1016/j.dnarep.2003.12.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 12/26/2003] [Accepted: 12/26/2003] [Indexed: 11/19/2022]
Abstract
Among various types of drugs designed for use in cancer chemotherapy, some have the potential for alkylation. After metabolic activation, these chemicals attack DNA and alkylate their bases, thereby preventing multiplication of rapidly growing tumor cells. Some of alkylated bases cause mutations, leading to untoward induction of tumors. To search for the rationale to separate lethal and mutagenic effects of alkylation drugs, we investigated actions of dacarbazine, a monofunctional triazene, on mouse and human cell lines defective in the Mgmt and/or the Mlh1 gene, the former encoding a DNA repair methyltransferase and the latter a protein involved in mismatch repair and induction of apoptosis. Mgmt-deficient cells are hypersensitive to the killing action of dacarbazine. On the other hand, cells defective in both Mgmt and Mlh1 genes are as resistant to the drug as are wild-type cells, in terms of survival, but do have many mutations after dacarbazine treatment. Thus, the killing and mutagenic actions of dacabazine can be dissociated by manipulating actions of these gene products.
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Affiliation(s)
- Masayuki Sanada
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Tamura, Fukuoka 814-0193, Japan.
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36
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Meyers M, Hwang A, Wagner MW, Boothman DA. Role of DNA mismatch repair in apoptotic responses to therapeutic agents. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2004; 44:249-264. [PMID: 15468331 DOI: 10.1002/em.20056] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Deficiencies in DNA mismatch repair (MMR) have been found in both hereditary cancer (i.e., hereditary nonpolyposis colorectal cancer) and sporadic cancers of various tissues. In addition to its primary roles in the correction of DNA replication errors and suppression of recombination, research in the last 10 years has shown that MMR is involved in many other processes, such as interaction with other DNA repair pathways, cell cycle checkpoint regulation, and apoptosis. Indeed, a cell's MMR status can influence its response to a wide variety of chemotherapeutic agents, such as temozolomide (and many other methylating agents), 6-thioguanine, cisplatin, ionizing radiation, etoposide, and 5-fluorouracil. For this reason, identification of a tumor's MMR deficiency (as indicated by the presence of microsatellite instability) is being utilized more and more as a prognostic indicator in the clinic. Here, we describe the basic mechanisms of MMR and apoptosis and investigate the literature examining the influence of MMR status on the apoptotic response following treatment with various therapeutic agents. Furthermore, using isogenic MMR-deficient (HCT116) and MMR-proficient (HCT116 3-6) cells, we demonstrate that there is no enhanced apoptosis in MMR-proficient cells following treatment with 5-fluoro-2'-deoxyuridine. In fact, apoptosis accounts for only a small portion of the induced cell death response.
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Affiliation(s)
- Mark Meyers
- Department of Radiation Oncology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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