1
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Steinbuch KB, Bucardo M, Tor Y. Emissive Alkylated Guanine Analogs as Probes for Monitoring O 6-Alkylguanine-DNA-transferase Activity. ACS OMEGA 2024; 9:36778-36786. [PMID: 39220506 PMCID: PMC11360037 DOI: 10.1021/acsomega.4c05700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Revised: 07/22/2024] [Accepted: 08/13/2024] [Indexed: 09/04/2024]
Abstract
Human O 6-alkylguanine-DNA-transferase (hAGT) is a repair protein that provides protection from mutagenic events caused by O 6-alkylguanine lesions. As this stoichiometric activity is tissue-specific, indicative of tumor status, and correlated to chemotherapeutic success, tracking the activity of hAGT could prove to be informative for disease diagnosis and therapy. Herein, we explore two families of emissive O 6-methyl- and O 6-benzylguanine analogs based on our previously described th G N and tz G N , thieno- and isothiazolo-guanine surrogates, respectively, as potential reporters. We establish that O 6 -Bn th G N and O 6 -Bn tz G N provide a spectral window to optically monitor hAGT activity, can be used as substrates for the widely used SNAP-Tag delivery system, and are sufficiently bright to be visualized in mammalian cells using fluorescence microscopy.
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Affiliation(s)
| | | | - Yitzhak Tor
- Department of Chemistry and
Biochemistry, University of California San
Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, United States
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2
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Khalaj V, AghaAmiri S, Ghosh SC, Vargas SH, Momeny M, Azhdarinia A. A simple and rapid in vitro assay for identification of direct inhibitors of O 6-methylguanine-DNA methyltransferase. Biotechniques 2024; 76:343-351. [PMID: 39185783 DOI: 10.1080/07366205.2024.2352277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 04/26/2024] [Indexed: 08/27/2024] Open
Abstract
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that is overexpressed in certain tumors and is associated with resistance to the DNA alkylating agent temozolomide. MGMT inhibitors show potential in combating temozolomide resistance, but current assays for MGMT enzyme activity and inhibition, primarily oligonucleotide-based and fluorescent probe-based, are laborious and costly. The clinical relevance of temozolomide therapy calls for more convenient methodologies to study MGMT inhibition. Here, we extended the application of SNAP-Capture magnetic beads to develop a novel MGMT inhibition assay that demonstrated efficacy not only with known MGMT inhibitors, but also with the aldehyde dehydrogenase inhibitor, disulfiram. The assay uses standard fluorescence microscopy as a simple and reliable detection method, and is translationally applicable in drug discovery programs.
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Affiliation(s)
- Vahid Khalaj
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Solmaz AghaAmiri
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Sukhen C Ghosh
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Servando Hernandez Vargas
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Majid Momeny
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Ali Azhdarinia
- The Brown Foundation Institute of Molecular Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
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3
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Fang Q. The Versatile Attributes of MGMT: Its Repair Mechanism, Crosstalk with Other DNA Repair Pathways, and Its Role in Cancer. Cancers (Basel) 2024; 16:331. [PMID: 38254819 PMCID: PMC10814553 DOI: 10.3390/cancers16020331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
O6-methylguanine-DNA methyltransferase (MGMT or AGT) is a DNA repair protein with the capability to remove alkyl groups from O6-AlkylG adducts. Moreover, MGMT plays a crucial role in repairing DNA damage induced by methylating agents like temozolomide and chloroethylating agents such as carmustine, and thereby contributes to chemotherapeutic resistance when these agents are used. This review delves into the structural roles and repair mechanisms of MGMT, with emphasis on the potential structural and functional roles of the N-terminal domain of MGMT. It also explores the development of cancer therapeutic strategies that target MGMT. Finally, it discusses the intriguing crosstalk between MGMT and other DNA repair pathways.
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Affiliation(s)
- Qingming Fang
- Department of Biochemistry and Structural Biology, Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX 78229, USA
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4
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Tessmer I, Margison GP. The DNA Alkyltransferase Family of DNA Repair Proteins: Common Mechanisms, Diverse Functions. Int J Mol Sci 2023; 25:463. [PMID: 38203633 PMCID: PMC10779285 DOI: 10.3390/ijms25010463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/12/2024] Open
Abstract
DNA alkyltransferase and alkyltransferase-like family proteins are responsible for the repair of highly mutagenic and cytotoxic O6-alkylguanine and O4-alkylthymine bases in DNA. Their mechanism involves binding to the damaged DNA and flipping the base out of the DNA helix into the active site pocket in the protein. Alkyltransferases then directly and irreversibly transfer the alkyl group from the base to the active site cysteine residue. In contrast, alkyltransferase-like proteins recruit nucleotide excision repair components for O6-alkylguanine elimination. One or more of these proteins are found in all kingdoms of life, and where this has been determined, their overall DNA repair mechanism is strictly conserved between organisms. Nevertheless, between species, subtle as well as more extensive differences that affect target lesion preferences and/or introduce additional protein functions have evolved. Examining these differences and their functional consequences is intricately entwined with understanding the details of their DNA repair mechanism(s) and their biological roles. In this review, we will present and discuss various aspects of the current status of knowledge on this intriguing protein family.
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Affiliation(s)
- Ingrid Tessmer
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Geoffrey P. Margison
- School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK;
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5
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Stanfill SB, Hecht SS, Joerger AC, González PJ, Maia LB, Rivas MG, Moura JJG, Gupta AK, Le Brun NE, Crack JC, Hainaut P, Sparacino-Watkins C, Tyx RE, Pillai SD, Zaatari GS, Henley SJ, Blount BC, Watson CH, Kaina B, Mehrotra R. From cultivation to cancer: formation of N-nitrosamines and other carcinogens in smokeless tobacco and their mutagenic implications. Crit Rev Toxicol 2023; 53:658-701. [PMID: 38050998 DOI: 10.1080/10408444.2023.2264327] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 09/20/2023] [Indexed: 12/07/2023]
Abstract
Tobacco use is a major cause of preventable morbidity and mortality globally. Tobacco products, including smokeless tobacco (ST), generally contain tobacco-specific N-nitrosamines (TSNAs), such as N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-butanone (NNK), which are potent carcinogens that cause mutations in critical genes in human DNA. This review covers the series of biochemical and chemical transformations, related to TSNAs, leading from tobacco cultivation to cancer initiation. A key aim of this review is to provide a greater understanding of TSNAs: their precursors, the microbial and chemical mechanisms that contribute to their formation in ST, their mutagenicity leading to cancer due to ST use, and potential means of lowering TSNA levels in tobacco products. TSNAs are not present in harvested tobacco but can form due to nitrosating agents reacting with tobacco alkaloids present in tobacco during certain types of curing. TSNAs can also form during or following ST production when certain microorganisms perform nitrate metabolism, with dissimilatory nitrate reductases converting nitrate to nitrite that is then released into tobacco and reacts chemically with tobacco alkaloids. When ST usage occurs, TSNAs are absorbed and metabolized to reactive compounds that form DNA adducts leading to mutations in critical target genes, including the RAS oncogenes and the p53 tumor suppressor gene. DNA repair mechanisms remove most adducts induced by carcinogens, thus preventing many but not all mutations. Lastly, because TSNAs and other agents cause cancer, previously documented strategies for lowering their levels in ST products are discussed, including using tobacco with lower nornicotine levels, pasteurization and other means of eliminating microorganisms, omitting fermentation and fire-curing, refrigerating ST products, and including nitrite scavenging chemicals as ST ingredients.
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Affiliation(s)
- Stephen B Stanfill
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Andreas C Joerger
- Structural Genomics Consortium (SGC), Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Pablo J González
- Department of Physics, Universidad Nacional Litoral, and CONICET, Santa Fe, Argentina
| | - Luisa B Maia
- Department of Chemistry, LAQV, REQUIMTE, NOVA School of Science and Technology (FCT NOVA), Caparica, Portugal
| | - Maria G Rivas
- Department of Physics, Universidad Nacional Litoral, and CONICET, Santa Fe, Argentina
| | - José J G Moura
- Department of Chemistry, LAQV, REQUIMTE, NOVA School of Science and Technology (FCT NOVA), Caparica, Portugal
| | | | - Nick E Le Brun
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, UK
| | - Jason C Crack
- School of Chemistry, Centre for Molecular and Structural Biochemistry, University of East Anglia, Norwich, UK
| | - Pierre Hainaut
- Institute for Advanced Biosciences, Grenoble Alpes University, Grenoble, France
| | - Courtney Sparacino-Watkins
- University of Pittsburgh, School of Medicine, Division of Pulmonary Allergy and Critical Care Medicine, Vascular Medicine Institute, PA, USA
| | - Robert E Tyx
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Suresh D Pillai
- Department of Food Science & Technology, National Center for Electron Beam Research, Texas A&M University, College Station, TX, USA
| | - Ghazi S Zaatari
- Department of Pathology and Laboratory Medicine, American University of Beirut, Beirut, Lebanon
| | - S Jane Henley
- Division of Cancer Prevention and Control, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Benjamin C Blount
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Clifford H Watson
- Tobacco and Volatiles Branch, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center, Mainz, Germany
| | - Ravi Mehrotra
- Centre for Health, Innovation and Policy Foundation, Noida, India
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6
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Bai P, Fan T, Wang X, Zhao L, Zhong R, Sun G. Modulating MGMT expression through interfering with cell signaling pathways. Biochem Pharmacol 2023; 215:115726. [PMID: 37524206 DOI: 10.1016/j.bcp.2023.115726] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 07/28/2023] [Accepted: 07/28/2023] [Indexed: 08/02/2023]
Abstract
Guanine O6-alkylating agents are widely used as first-line chemotherapeutic drugs due to their ability to induce cytotoxic DNA damage. However, a major hurdle in their effectiveness is the emergence of chemoresistance, largely attributed to the DNA repair pathway mediated by O6-methylguanine-DNA methyltransferase (MGMT). MGMT plays an important role in removing the alkyl groups from lethal O6-alkylguanine (O6-AlkylG) adducts formed by chemotherapeutic alkylating agents. By doing so, MGMT enables tumor cells to evade apoptosis and develop drug resistance toward DNA alkylating agents. Although covalent inhibitors of MGMT, such as O6-benzylguanine (O6-BG) and O6-(4-bromothenyl)guanine (O6-4-BTG or lomeguatrib), have been explored in clinical settings, their utility is limited due to severe delayed hematological toxicity observed in most patients when combined with alkylating agents. Therefore, there is an urgent need to identify new targets and unravel the underlying molecular mechanisms and to develop alternative therapeutic strategies that can overcome MGMT-mediated tumor resistance. In this context, the regulation of MGMT expression via interfering the specific cell signaling pathways (e.g., Wnt/β-catenin, NF-κB, Hedgehog, PI3K/AKT/mTOR, JAK/STAT) emerges as a promising strategy for overcoming tumor resistance, and ultimately enhancing the efficacy of DNA alkylating agents in chemotherapy.
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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
| | - 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
| | - Guohui Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
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7
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Sun G, Bai P, Fan T, Zhao L, Zhong R, McElhinney RS, McMurry TBH, Donnelly DJ, McCormick JE, Kelly J, Margison GP. QSAR and Chemical Read-Across Analysis of 370 Potential MGMT Inactivators to Identify the Structural Features Influencing Inactivation Potency. Pharmaceutics 2023; 15:2170. [PMID: 37631385 PMCID: PMC10458236 DOI: 10.3390/pharmaceutics15082170] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/16/2023] [Accepted: 08/19/2023] [Indexed: 08/27/2023] Open
Abstract
O6-methylguanine-DNA methyltransferase (MGMT) constitutes an important cellular mechanism for repairing potentially cytotoxic DNA damage induced by guanine O6-alkylating agents and can render cells highly resistant to certain cancer chemotherapeutic drugs. A wide variety of potential MGMT inactivators have been designed and synthesized for the purpose of overcoming MGMT-mediated tumor resistance. We determined the inactivation potency of these compounds against human recombinant MGMT using [3H]-methylated-DNA-based MGMT inactivation assays and calculated the IC50 values. Using the results of 370 compounds, we performed quantitative structure-activity relationship (QSAR) modeling to identify the correlation between the chemical structure and MGMT-inactivating ability. Modeling was based on subdividing the sorted pIC50 values or on chemical structures or was random. A total of nine molecular descriptors were presented in the model equation, in which the mechanistic interpretation indicated that the status of nitrogen atoms, aliphatic primary amino groups, the presence of O-S at topological distance 3, the presence of Al-O-Ar/Ar-O-Ar/R..O..R/R-O-C=X, the ionization potential and hydrogen bond donors are the main factors responsible for inactivation ability. The final model was of high internal robustness, goodness of fit and prediction ability (R2pr = 0.7474, Q2Fn = 0.7375-0.7437, CCCpr = 0.8530). After the best splitting model was decided, we established the full model based on the entire set of compounds using the same descriptor combination. We also used a similarity-based read-across technique to further improve the external predictive ability of the model (R2pr = 0.7528, Q2Fn = 0.7387-0.7449, CCCpr = 0.8560). The prediction quality of 66 true external compounds was checked using the "Prediction Reliability Indicator" tool. In summary, we defined key structural features associated with MGMT inactivation, thus allowing for the design of MGMT inactivators that might improve clinical outcomes in cancer treatment.
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Affiliation(s)
- Guohui Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; (P.B.); (T.F.); (L.Z.); (R.Z.)
| | - Peiying Bai
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; (P.B.); (T.F.); (L.Z.); (R.Z.)
| | - Tengjiao Fan
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; (P.B.); (T.F.); (L.Z.); (R.Z.)
- Department of Medical Technology, Beijing Pharmaceutical University of Staff and Workers, Beijing 100079, China
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; (P.B.); (T.F.); (L.Z.); (R.Z.)
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental and Viral Oncology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; (P.B.); (T.F.); (L.Z.); (R.Z.)
| | - R. Stanley McElhinney
- Chemistry Department, Trinity College, D02 PN40 Dublin, Ireland; (T.B.H.M.); (D.J.D.)
| | - T. Brian H. McMurry
- Chemistry Department, Trinity College, D02 PN40 Dublin, Ireland; (T.B.H.M.); (D.J.D.)
| | - Dorothy J. Donnelly
- Chemistry Department, Trinity College, D02 PN40 Dublin, Ireland; (T.B.H.M.); (D.J.D.)
| | - Joan E. McCormick
- Chemistry Department, Trinity College, D02 PN40 Dublin, Ireland; (T.B.H.M.); (D.J.D.)
| | - Jane Kelly
- Carcinogenesis Department, Paterson Institute for Cancer Research, Manchester M20 9BX, UK;
| | - Geoffrey P. Margison
- Carcinogenesis Department, Paterson Institute for Cancer Research, Manchester M20 9BX, UK;
- Epidemiology and Public Health Group, School of Health Sciences, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PG, UK
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8
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Pei J, Su Z, Zeng X, Zhong Y, Zhang Y, Yang Y, Lu Q, Li J, Deng Y. Protocatechuic aldehyde acts synergistically with dacarbazine to augment DNA double-strand breaks and promote apoptosis in cutaneous melanoma cells. BMC Complement Med Ther 2023; 23:111. [PMID: 37024907 PMCID: PMC10077623 DOI: 10.1186/s12906-023-03933-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 03/22/2023] [Indexed: 04/08/2023] Open
Abstract
BACKGROUND Despite rapid developments in immunotherapy and targeted therapy, dacarbazine (DTIC)-based chemotherapy still has been placed at the first-line for advanced melanoma patients who are after failure of immunotherapy or targeted therapy. However, the limited response rate and survival benefit challenge the DTIC-based chemotherapy for advanced melanoma patients. METHODS Two melanoma cell lines, A375 and SK-MEL-28 were cultured with PA and DTIC over a range of concentrations for 72 h and the cell viabilities were detected by CCK8 assay. The Bliss model and ZIP model were used for calculating the synergistic effect of PA and DTIC. DNA double-strand breaks in the two cell lines were examined by the Comet assay, and cell apoptosis was analyzed by flow cytometry. The short hairpin RNA (shRNA)-mediated knockdown, Real-time polymerase chain reaction (RT-PCR) and Western blot were performed for molecular analysis. RESULTS In the present study, we report that Protocatechuic aldehyde (PA) synergistically enhances the cytotoxicity of DTIC to two melanoma cell lines, A375 and SK-MEL-28. The combination of PA and DTIC augments DNA double-strand breaks and increases cell apoptosis. Further mechanism study reveals that PA destabilizes MGMT protein (O-6-Methylguanine-DNA Methyltransferase) through the ubiquitin-proteasome process and directly repairs DTIC-induced genetic lesions. Knockdown of MGMT compromises the synergistic effect between PA and DTIC. CONCLUSION Our study demonstrates that the bioactive compound, Protocatechuic aldehyde, synergistically promotes the cytotoxicity of DTIC to melanoma cells through destabilization of MGMT protein. It could be a potential candidate for melanoma chemotherapy.
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Affiliation(s)
- Junxia Pei
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Zhou Su
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Pharmacy, Chengdu University, Chengdu, 610106, China
| | - Xin Zeng
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Pharmacy, Chengdu University, Chengdu, 610106, China
| | - Ya Zhong
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Yamei Zhang
- Key Laboratory of Clinical Genetics, Affiliated hospital of Chengdu University, Chengdu, 610106, China
| | - Yixi Yang
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Qiuxia Lu
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China
- School of Food and Biological Engineering, Chengdu University, Chengdu, 610106, China
| | - Jian Li
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China.
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China.
- School of Basic Medical Sciences, Chengdu University, Chengdu, 610106, China.
| | - Yu Deng
- Engineering Research Center of Sichuan-Tibet Traditional Medicinal Plant, Chengdu University, Chengdu, 610106, China.
- Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, 610106, China.
- School of Basic Medical Sciences, Chengdu University, Chengdu, 610106, China.
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9
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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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10
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Fahrer J, Christmann M. DNA Alkylation Damage by Nitrosamines and Relevant DNA Repair Pathways. Int J Mol Sci 2023; 24:ijms24054684. [PMID: 36902118 PMCID: PMC10003415 DOI: 10.3390/ijms24054684] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/17/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023] Open
Abstract
Nitrosamines occur widespread in food, drinking water, cosmetics, as well as tobacco smoke and can arise endogenously. More recently, nitrosamines have been detected as impurities in various drugs. This is of particular concern as nitrosamines are alkylating agents that are genotoxic and carcinogenic. We first summarize the current knowledge on the different sources and chemical nature of alkylating agents with a focus on relevant nitrosamines. Subsequently, we present the major DNA alkylation adducts induced by nitrosamines upon their metabolic activation by CYP450 monooxygenases. We then describe the DNA repair pathways engaged by the various DNA alkylation adducts, which include base excision repair, direct damage reversal by MGMT and ALKBH, as well as nucleotide excision repair. Their roles in the protection against the genotoxic and carcinogenic effects of nitrosamines are highlighted. Finally, we address DNA translesion synthesis as a DNA damage tolerance mechanism relevant to DNA alkylation adducts.
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Affiliation(s)
- Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, RPTU Kaiserslautern-Landau, Erwin-Schrödinger Strasse 52, D-67663 Kaiserslautern, Germany
- Correspondence: (J.F.); (M.C.); Tel.: +496312052974 (J.F.); Tel: +496131179066 (M.C.)
| | - Markus Christmann
- Department of Toxicology, University Medical Center Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
- Correspondence: (J.F.); (M.C.); Tel.: +496312052974 (J.F.); Tel: +496131179066 (M.C.)
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11
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Rahman MA, Engelsen AST, Sarowar S, Bindesbøll C, Birkeland E, Goplen D, Lotsberg ML, Knappskog S, Simonsen A, Chekenya M. Bortezomib abrogates temozolomide-induced autophagic flux through an ATG5 dependent pathway. Front Cell Dev Biol 2022; 10:1022191. [PMID: 36619857 PMCID: PMC9814514 DOI: 10.3389/fcell.2022.1022191] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction: Glioblastoma (GBM) is invariably resistant to temozolomide (TMZ) chemotherapy. Inhibiting the proteasomal pathway is an emerging strategy to accumulate damaged proteins and inhibit their lysosomal degradation. We hypothesized that pre-treatment of glioblastoma with bortezomib (BTZ) might sensitize glioblastoma to temozolomide by abolishing autophagy survival signals to augment DNA damage and apoptosis. Methods: P3 patient-derived glioblastoma cells, as well as the tumour cell lines U87, HF66, A172, and T98G were investigated for clonogenic survival after single or combined treatment with temozolomide and bortezomib in vitro. We investigated the requirement of functional autophagy machinery by utilizing pharmacological inhibitors or CRISPR-Cas9 knockout (KO) of autophagy-related genes -5 and -7 (ATG5 and ATG7) in glioblastoma cells and monitored changes in autophagic flux after temozolomide and/or bortezomib treatments. P3 wild-type and P3 ATG5-/- (ATG5 KO) cells were implanted orthotopically into NOD-SCID mice to assess the efficacy of bortezomib and temozolomide combination therapy with and without functional autophagy machinery. Results: The chemo-resistant glioblastoma cells increased autophagic flux during temozolomide treatment as indicated by increased degradation of long-lived proteins, diminished expression of autophagy markers LC3A/B-II and p62 (SQSTM1), increased co-localisation of LC3A/B-II with STX17, augmented and no induction of apoptosis. In contrast, bortezomib treatment abrogated autophagic flux indicated by the accumulation of LC3A/B-II and p62 (SQSTM1) positive autophagosomes that did not fuse with lysosomes and thus reduced the degradation of long-lived proteins. Bortezomib synergistically enhanced temozolomide efficacy by attenuating cell proliferation, increased DNA double-strand breaks, and apoptosis in an autophagy-dependent manner. Abolishing autophagy in ATG5 KOs reversed the bortezomib-induced toxicity, rescued glioblastoma cell death and reduced animal survival. Discussion: We conclude that bortezomib abrogates temozolomide induced autophagy flux through an ATG5 dependent pathway.
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Affiliation(s)
- Mohummad Aminur Rahman
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway,Department of Oncology, Haukeland University Hospital, Bergen, Norway,*Correspondence: Mohummad Aminur Rahman,
| | - Agnete S. T. Engelsen
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway,Department of Clinical Medicine and Centre for Cancer Biomarkers, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Shahin Sarowar
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Christian Bindesbøll
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Even Birkeland
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Dorota Goplen
- Department of Oncology, Haukeland University Hospital, Bergen, Norway
| | - Maria L. Lotsberg
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway,Department of Clinical Medicine and Centre for Cancer Biomarkers, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Stian Knappskog
- Department of Oncology, Haukeland University Hospital, Bergen, Norway,Department of Clinical Science, Faculty of Medicine, University of Bergen, Bergen, Norway
| | - Anne Simonsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway,Centre for Cancer Cell Reprogramming, Faculty of Medicine, University of Oslo, Oslo, Norway,Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Martha Chekenya
- Department of Biomedicine, Faculty of Medicine, University of Bergen, Bergen, Norway
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12
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Ghodke PP, Matse JH, Dawson S, Guengerich FP. Nucleophilic Thiol Proteins Bind Covalently to Abasic Sites in DNA. Chem Res Toxicol 2022; 35:1805-1808. [PMID: 35482010 DOI: 10.1021/acs.chemrestox.2c00068] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the course of studies on the enhancement of 1,2-dibromoethane-induced DNA base pair mutations by O6-alkylguanine-DNA alkyltransferase (AGT, MGMT), we discovered the facile reaction of AGT with an abasic site in DNA, leading to covalent cross-linking. The binding of AGT differs from the mechanism reported for the protein HMCES; instead it appears to involve formation of a stable thioglycoside. Facile cross-linking was also observed with the protease papain, which like AGT has a low pKa cysteine, and the tripeptide glutathione.
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Affiliation(s)
- Pratibha P Ghodke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Johannes H Matse
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - Scott Dawson
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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13
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Zhang Y, Han L, Tian X, Peng C, Chen Y. Ligand‐Directed Caging Enables the Control of Endogenous DNA Alkyltransferase Activity with Light inside Live Cells. Angew Chem Int Ed Engl 2022; 61:e202115472. [DOI: 10.1002/anie.202115472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Indexed: 12/29/2022]
Affiliation(s)
- Yixin Zhang
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Lili Han
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- School of Physical Science and Technology ShanghaiTech University 100 Haike Road Shanghai 201210 China
| | - Xiaoxu Tian
- National Facility for Protein Science in Shanghai Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Science Shanghai 201210 China
| | - Chao Peng
- National Facility for Protein Science in Shanghai Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Science Shanghai 201210 China
| | - Yiyun Chen
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- School of Physical Science and Technology ShanghaiTech University 100 Haike Road Shanghai 201210 China
- School of Chemistry and Material Sciences Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences 1 Sub-lane Xiangshan Hangzhou 310024 China
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14
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Hill P, Zellmann F, Vukova T, Marini F, Kolmar S, Kaina B, Hofmann TG, Nikolova T. Dose response to methylating agents in the γH2AX, SCE and colony formation assays: Effect of MGMT and MPG overexpression. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 876-877:503462. [PMID: 35483785 DOI: 10.1016/j.mrgentox.2022.503462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/29/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Cells have developed diverse protective mechanisms that enable them to tolerate low doses of genotoxic compounds. DNA repair processes attenuate the mutagenic and carcinogenic effects of alkylating agents, and multiple studies indicate a key role of specific DNA repair factors and pathways in establishing non-linear dose response relationships. Using an overexpression approach, we investigated the impact of O6-methylguanine-DNA-methyltransferase (MGMT), which repairs O6-methylguanine (O6MeG) in a damage reversal reaction, and N-methylpurine-DNA glycosylase (MPG), which acts as an apical enzyme in the BER pathway, on the DNA damage response to the alkylating agents MNNG and MMS. Our data indicate a clear protective effect of MGMT against MNNG-induced nuclear γH2AX foci formation, sister chromatid exchanges (SCE) and cytotoxicity, as determined in the colony formation assay. MGMT protected with similar efficiency against MMS-induced cytotoxicity and γH2AX foci formation, but suppressed SCE induction only weakly, which indicates that recombination events induced by MMS result from other lesions than O6MeG. In contrast, overexpression of MPG had only a very mild protective effect on the cellular defense against MMS and MNNG. Collectively, our data indicate that overexpression of MGMT results in non-linear DNA damage responses to O6MeG inducers. In contrast, MPG overexpression has only minor impact on the DNA damage response to alkylating drugs, indicating that other downstream enzymes in the BER pathway are limiting.
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Affiliation(s)
- Philipp Hill
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Felix Zellmann
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Tsvetomira Vukova
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Federico Marini
- Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Sarah Kolmar
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Thomas G Hofmann
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Teodora Nikolova
- Institute of Toxicology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
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15
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Resolving the subtle details of human DNA alkyltransferase lesion search and repair mechanism by single-molecule studies. Proc Natl Acad Sci U S A 2022; 119:e2116218119. [PMID: 35259021 PMCID: PMC8931253 DOI: 10.1073/pnas.2116218119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
We directly visualize DNA translocation and lesion recognition by the O6-alkylguanine DNA alkyltransferase (AGT). Our data show bidirectional movement of AGT monomers and clusters on undamaged DNA that depended on Zn2+ occupancy of AGT. A role of cooperative AGT clusters in enhancing lesion search efficiencies by AGT has previously been proposed. Surprisingly, our data show no enhancement of DNA translocation speed by AGT cluster formation, suggesting that AGT clusters may serve a different role in AGT function. Our data support preferential cluster formation by AGT at alkyl lesions, suggesting a role of these clusters in stabilizing lesion-bound complexes. From our data, we derive a new model for the lesion search and repair mechanism of AGT. The O6-alkylguanine DNA alkyltransferase (AGT) is an important DNA repair protein. AGT repairs highly mutagenic and cytotoxic alkylguanine lesions that result from metabolic products but are also deliberately introduced during chemotherapy, making a better understanding of the working mechanism of AGT essential. To investigate lesion interactions by AGT, we present a protocol to insert a single alkylguanine lesion at a well-defined position in long DNA substrates for single-molecule fluorescence microscopy coupled with dual-trap optical tweezers. Our studies address the longstanding enigma in the field of how monomeric AGT complexes at alkyl lesions seen in crystal structures can be reconciled with AGT clusters on DNA at high protein concentrations that have been observed from atomic force microscopy (AFM) and biochemical studies. A role of AGT clusters in enhancing lesion search efficiencies by AGT has previously been proposed. Surprisingly, our data show no enhancement of DNA translocation speed by AGT cluster formation, suggesting that AGT clusters may serve a different role in AGT function. Interestingly, a possible role of these clusters is indicated by preferential cluster formation at alkyl lesions in our studies. From our data, we derive a model for the lesion search and repair mechanism of AGT.
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16
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Zhang Y, Han L, Tian X, Peng C, Chen Y. Ligand‐Directed Caging Enables the Control of Endogenous DNA Alkyltransferase Activity with Light inside Live Cells. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yixin Zhang
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Lili Han
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- School of Physical Science and Technology ShanghaiTech University 100 Haike Road Shanghai 201210 China
| | - Xiaoxu Tian
- National Facility for Protein Science in Shanghai Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Science Shanghai 201210 China
| | - Chao Peng
- National Facility for Protein Science in Shanghai Zhangjiang Lab Shanghai Advanced Research Institute Chinese Academy of Science Shanghai 201210 China
| | - Yiyun Chen
- State Key Laboratory of Bioorganic and Natural Products Chemistry Centre of Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry University of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- School of Physical Science and Technology ShanghaiTech University 100 Haike Road Shanghai 201210 China
- School of Chemistry and Material Sciences Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences 1 Sub-lane Xiangshan Hangzhou 310024 China
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17
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Svec RL, McKee SA, Berry MR, Kelly AM, Fan TM, Hergenrother PJ. Novel Imidazotetrazine Evades Known Resistance Mechanisms and Is Effective against Temozolomide-Resistant Brain Cancer in Cell Culture. ACS Chem Biol 2022; 17:299-313. [PMID: 35119837 DOI: 10.1021/acschembio.2c00022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glioblastoma (GBM) is the most lethal primary brain tumor. Currently, frontline treatment for primary GBM includes the DNA-methylating drug temozolomide (TMZ, of the imidazotetrazine class), while the optimal treatment for recurrent GBM remains under investigation. Despite its widespread use, a majority of GBM patients do not respond to TMZ therapy; expression of the O6-methylguanine DNA methyltransferase (MGMT) enzyme and loss of mismatch repair (MMR) function as the principal clinical modes of resistance to TMZ. Here, we describe a novel imidazotetrazine designed to evade resistance by MGMT while retaining suitable hydrolytic stability, allowing for effective prodrug activation and biodistribution. This dual-substituted compound, called CPZ, exhibits activity against cancer cells irrespective of MGMT expression and MMR status. CPZ has greater blood-brain barrier penetrance and comparable hematological toxicity relative to TMZ, while also matching its maximum tolerated dose in mice when dosed once-per-day over five days. The activity of CPZ is independent of the two principal mechanisms suppressing the effectiveness of TMZ, making it a promising new candidate for the treatment of GBM, especially those that are TMZ-resistant.
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Affiliation(s)
- Riley L. Svec
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sydney A. McKee
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Matthew R. Berry
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Aya M. Kelly
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Timothy M. Fan
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Paul J. Hergenrother
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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18
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Murawska GM, Vogel C, Jan M, Lu X, Schild M, Slabicki M, Zou C, Zhanybekova S, Manojkumar M, Petzold G, Kaiser P, Thomä N, Ebert B, Gillingham D. Repurposing the Damage Repair Protein Methyl Guanine Methyl Transferase as a Ligand Inducible Fusion Degron. ACS Chem Biol 2022; 17:24-31. [PMID: 34982531 DOI: 10.1021/acschembio.1c00771] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We successfully repurpose the DNA repair protein methylguanine methyltransferase (MGMT) as an inducible degron for protein fusions. MGMT is a suicide protein that removes alkyl groups from the O6 position of guanine (O6G) and is thereafter quickly degraded by the ubiquitin proteasome pathway (UPP). Starting with MGMT pseudosubstrates (benzylguanine and lomeguatrib), we first demonstrate that these lead to potent MGMT depletion while affecting little else in the proteome. We then show that fusion proteins of MGMT undergo rapid UPP-dependent degradation in response to pseudosubstrates. Mechanistic studies confirm the involvement of the UPP, while revealing that at least two E3 ligase classes can degrade MGMT depending on cell-line and expression type (native or ectopic). We also demonstrate the technique's versatility with two clinically relevant examples: degradation of KRASG12C and a chimeric antigen receptor.
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Affiliation(s)
- Gosia M. Murawska
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Caspar Vogel
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Max Jan
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
| | - Xinyan Lu
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Matthias Schild
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Mikolaj Slabicki
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
| | - Charles Zou
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
| | - Saule Zhanybekova
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
| | - Manisha Manojkumar
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
| | - Georg Petzold
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Peter Kaiser
- Department of Biological Chemistry, University of California, Irvine, California 92697, United States
| | - Nicolas Thomä
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Benjamin Ebert
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
| | - Dennis Gillingham
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland
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19
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Kossenas K, Constantinou C. Epidemiology, Molecular Mechanisms, and Clinical Trials: an Update on Research on the Association Between Red Meat Consumption and Colorectal Cancer. Curr Nutr Rep 2021; 10:435-467. [PMID: 34665439 DOI: 10.1007/s13668-021-00377-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE OF THE REVIEW Colorectal cancer is the second most common cause of cancer death in the world. The aim of this review is to provide an update on recent epidemiological studies, the molecular mechanisms involved, and ongoing clinical trials investigating the relationship between red meat consumption and colorectal cancer. RECENT FINDINGS Evidence in the literature proposes an association between red meat consumption and development of colorectal cancer, and there is some insight with regard to the mechanisms involved. Twenty studies of the IARC report (1990-2015) showed that red meat is positively associated with colorectal cancer whereas 14 studies either supported no positive association or no statistically significant association between red meat consumption and risk for CRC. More recent epidemiological studies conducted from 2016 and onwards provided further evidence that adherence to diets low in red and/or processed meat reduces the risk of colorectal cancer. Evidence from recent studies supports that quantity, doneness, and preparation of red meat play a role in colorectal carcinogenesis. Red meat's degradation products allow for the creation of a pro-inflammatory colonic microenvironment, and the gut microbiome plays a role in colorectal carcinogenesis. Heme, hydrogen sulfide, lipid peroxidation, nitroso compounds, and the bacterium Fusobacterium Nucleatum (as well as possibly other bacteria such as Akkermansia muciniphila, Eubacterium cylindroides, Eubacterium eligens 1 and 2, and Eubacterium rectale 1 and 2) also partake in the process of colorectal carcinogenesis. Several clinical trials are underway investigating the effects of different diets and red meat substitution products on colorectal cancer incidence as well as the underlying molecular mechanisms involved in the process.
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Affiliation(s)
- Konstantinos Kossenas
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, P.O. Box 24005, 21 Ilia Papakyriakou, 2414 Engomi, CY-1700, Nicosia, Cyprus
| | - Constantina Constantinou
- Department of Basic and Clinical Sciences, University of Nicosia Medical School, P.O. Box 24005, 21 Ilia Papakyriakou, 2414 Engomi, CY-1700, Nicosia, Cyprus.
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20
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Kostka T, Empl MT, Seiwert N, Geisen SM, Hoffmann P, Adam J, Seeger B, Shay JW, Christmann M, Sturla SJ, Fahrer J, Steinberg P. Repair of O6-carboxymethylguanine adducts by O6-methylguanine-DNA methyltransferase in human colon epithelial cells. Carcinogenesis 2021; 42:1110-1118. [PMID: 34115837 DOI: 10.1093/carcin/bgab049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/23/2021] [Accepted: 06/09/2021] [Indexed: 11/13/2022] Open
Abstract
The protein O6-methylguanine-DNA methyltransferase (MGMT) is able to repair the mutagenic O6-methylguanine adduct back to guanine. In this context, it may protect against colorectal cancer (CRC) formation associated with N-nitroso compounds. Such compounds may be endogenously formed by nitrosylation of amino acids, which can give rise to mutagenic O6-methylguanine (O6-MeG) and O6-carboxymethylguanine (O6-CMG) adducts. It is well-established that O6-MeG is repaired by MGMT. However, up to now, whether O6-CMG is repaired by this enzyme remains unresolved. Therefore, the aim of the present study was to analyze the fate of both types of O6-guanine adducts in the presence and absence of MGMT activity. To this end, MGMT activity was efficiently blocked by its chemical inhibitor O6-benzylguanine in human colon epithelial cells (HCEC). Exposure of cells to azaserine (AZA) caused significantly higher levels of both O6-MeG and O6-CMG adducts in MGMT-inhibited cells, with O6-CMG as the more abundant DNA lesion. Interestingly, MGMT inhibition did not result in higher levels of AZA-induced DNA strand breaks in spite of elevated DNA adduct levels. In contrast, MGMT inhibition significantly increased DNA strand break formation after exposure to temozolomide (TMZ), a drug that exclusively generates O6-MeG adducts. In line with this finding, the viability of the cells was moderately reduced by TMZ upon MGMT inhibition, whereas no clear effect was observed in cells treated with AZA. In conclusion, our study clearly shows that O6-CMG is repaired by MGMT in HCEC, thereby suggesting that MGMT might play an important role as a tumor suppressor in diet-mediated CRC.
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Affiliation(s)
- Tina Kostka
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Institute of Food Science and Human Nutrition, Gottfried Wilhelm Leibniz University Hannover, 30167 Hannover, Germany
| | - Michael T Empl
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Nina Seiwert
- Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Susanne M Geisen
- Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
| | - Pascal Hoffmann
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Janine Adam
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
| | - Bettina Seeger
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Markus Christmann
- Department of Toxicology, University Medical Center Mainz, 55131 Mainz, Germany
| | - Shana J Sturla
- Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
| | - Jörg Fahrer
- Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Pablo Steinberg
- Institute for Food Toxicology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany.,Max Rubner-Institut, Federal Research Institute of Nutrition and Food, 76131 Karlsruhe, Germany
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21
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Tsao N, Schärer OD, Mosammaparast N. The complexity and regulation of repair of alkylation damage to nucleic acids. Crit Rev Biochem Mol Biol 2021; 56:125-136. [PMID: 33430640 DOI: 10.1080/10409238.2020.1869173] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
DNA damaging agents have been a cornerstone of cancer therapy for nearly a century. The discovery of many of these chemicals, particularly the alkylating agents, are deeply entwined with the development of poisonous materials originally intended for use in warfare. Over the last decades, their anti-proliferative effects have focused on the specific mechanisms by which they damage DNA, and the factors involved in the repair of such damage. Due to the variety of aberrant adducts created even for the simplest alkylating agents, numerous pathways of repair are engaged as a defense against this damage. More recent work has underscored the role of RNA damage in the cellular response to these agents, although the understanding of their role in relation to established DNA repair pathways is still in its infancy. In this review, we discuss the chemistry of alkylating agents, the numerous ways in which they damage nucleic acids, as well as the specific DNA and RNA repair pathways which are engaged to counter their effects.
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Affiliation(s)
- Ning Tsao
- Department of Pathology and Immunology, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA
| | - Orlando D Schärer
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea.,Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea
| | - Nima Mosammaparast
- Department of Pathology and Immunology, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA
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22
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Copp W, Wilds CJ. O 6 -Alkylguanine DNA Alkyltransferase Mediated Disassembly of a DNA Tetrahedron. Chemistry 2020; 26:14802-14806. [PMID: 32543755 DOI: 10.1002/chem.202002565] [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: 05/26/2020] [Indexed: 11/05/2022]
Abstract
Tetrahedron DNA structures were formed by the assembly of three-way junction (TWJ) oligonucleotides containing O6 -2'-deoxyguanosine-alkylene-O6 -2'-deoxyguanosine (butylene and heptylene linked) intrastrand cross-links (IaCLs) lacking a phosphodiester group between the 2'-deoxyribose residues. The DNA tetrahedra containing TWJs were shown to undergo an unhooking reaction by the human DNA repair protein O6 -alkylguanine DNA alkyltransferase (hAGT) resulting in structure disassembly. The unhooking reaction of hAGT towards the DNA tetrahedra was observed to be moderate to virtually complete depending on the protein equivalents. DNA tetrahedron structures have been explored as drug delivery platforms that release their payload in response to triggers, such as light, chemical agents or hybridization of release strands. The dismantling of DNA tetrahedron structures by a DNA repair protein contributes to the armamentarium of approaches for drug release employing DNA nanostructures.
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Affiliation(s)
- William Copp
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec, H4B 1R6, Canada
| | - Christopher J Wilds
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec, H4B 1R6, Canada
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Le DV, Jiang JH. Fluorescence determination of the activity of O 6-methylguanine-DNA methyltransferase based on the activation of restriction endonuclease and the use of graphene oxide. Mikrochim Acta 2020; 187:300. [PMID: 32347374 DOI: 10.1007/s00604-020-04280-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 04/13/2020] [Indexed: 12/27/2022]
Abstract
A fluorescence method is described for the determination of the activity of O6-methylguanine-DNA methyltransferase (MGMT). It is based on the activation of restriction endonuclease PvuII and the adsorbing a fluorophore-labelled DNA onto the surface of graphene oxide (GO). MGMT activity removes the methyl group from O6-methylguanine (O6MeG) in the fluorophore-labelled DNA to unblock the specific recognition site for further hydrolysis reaction of restriction endonuclease PvuII. The endonuclease catalytic reaction releases fluorophores (5-carboxyfluorescein) from fluorophore-labelled DNA, which can avoid fluorescence quenching by GO, creating an abundance of the fluorescence signal. The fluorescence increase in the assay is thus directly dependent on the MGMT activity. Under the optimal conditions with the emission wavelength of 519 nm (exitation at 494 nm), the activity of the MGMT can be determined in the range 0.5 to 35 ng mL-1 with a detection limit of 0.15 ng mL-1. This is extremely sensitive for the determination of MGMT. The short time of analysis (2 h) is superior to many reported strategies. The method can also be extended for the rapid and sensitive activity assay of other DNA repair enzymes by designing a proper substrate DNA. Conceivably, the technique represents a powerful tool for diagnosis and drug exploitation. Graphical abstract Schematic representation of the fluorescence method for MGMT activity assay.
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Affiliation(s)
- Dinh-Vu Le
- Faculty of Chemical Engineering, Industrial University of Ho Chi Minh City, 12 Nguyen Van Bao St. Go Vap, Ho Chi Minh, 70000, Viet Nam.
| | - Jian-Hui Jiang
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, Hunan, China
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Sun X, Sun G, Huang Y, Hao Y, Tang X, Zhang N, Zhao L, Zhong R, Peng Y. 3-Bromopyruvate regulates the status of glycolysis and BCNU sensitivity in human hepatocellular carcinoma cells. Biochem Pharmacol 2020; 177:113988. [PMID: 32330495 DOI: 10.1016/j.bcp.2020.113988] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/17/2020] [Indexed: 12/19/2022]
Abstract
Chloroethylnitrosoureas (CENUs) are bifunctional antitumor alkylating agents, which exert their antitumor activity through inducing the formation of dG-dC interstrand crosslinks (ICLs) within DNA double strand. However, the complex process of tumor biology enables tumor cells to escape the killing triggered by CENUs, as for instance with the detoxifying activity of O6-methylguanine DNA methyltransferase (MGMT) to accomplish DNA damage repair. Considering the fact that most tumor cells highly depend on aerobic glycolysis to provide energy for survival even in the presence of oxygen (Warburg effect), inhibition of aerobic glycolysis may be an attractive strategy to overcome the resistance and improve the chemotherapeutic effects of CENUs. Especially, 3-bromopyruvate (3-BrPA), a small molecule alkylating agent, has been emerged as an effective glycolytic inhibitor (energy blocker) in cancer treatment. In view of its tumor specificity and inhibition on cellular multiple targets, it is likely to reduce the chemoresistance when chemotherapeutic drugs are combined with 3-BrPA. In this study, we investigated the effects of 3-BrPA on the chemosensitivity of two human hepatocellular carcinoma (HCC) cell lines to the cytotoxic effects of l,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and the underlying molecular mechanism. The sensitivity of SMMC-7721 and HepG2 cells to BCNU was significantly increased by 2 h pretreatment with micromolar dosage of 3-BrPA. Moreover, 3-BrPA decreased the cellular ATP and GSH levels, and extracellular lactate excreted by tumor cells, and the effects were more effective when 3-BrPA was combined with BCNU. Cellular hexokinase-II (HK-II) activity was also reduced after exposure to the treatment of 3-BrPA plus BCNU. Based on the above results, the effects of 3-BrPA on the formation of dG-dC ICLs induced by BCNU was investigated by stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The results indicated that BCNU produced higher levels of dG-dC ICLs in SMMC-7721 and HepG2 cells pretreated with 3-BrPA compared to that without 3-BrPA pretreatment. Notably, in MGMT-deficient HepG2 cells, the levels of dG-dC ICLs were significantly higher than MGMT-proficient SMMC-7721 cells. In general, these findings revealed that 3-BrPA, as an effective glycolytic inhibitor, may be considered as a potential clinical chemosensitizer to optimize the therapeutic index of CENUs.
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Affiliation(s)
- Xiaodong Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China
| | - Guohui Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Yaxin Huang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Yuxing Hao
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Xiaoyu Tang
- College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Na Zhang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, PR China.
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
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Mattossovich R, Merlo R, Miggiano R, Valenti A, Perugino G. O6-alkylguanine-DNA Alkyltransferases in Microbes Living on the Edge: From Stability to Applicability. Int J Mol Sci 2020; 21:E2878. [PMID: 32326075 PMCID: PMC7216122 DOI: 10.3390/ijms21082878] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/09/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023] Open
Abstract
The genome of living cells is continuously exposed to endogenous and exogenous attacks, and this is particularly amplified at high temperatures. Alkylating agents cause DNA damage, leading to mutations and cell death; for this reason, they also play a central role in chemotherapy treatments. A class of enzymes known as AGTs (alkylguanine-DNA-alkyltransferases) protects the DNA from mutations caused by alkylating agents, in particular in the recognition and repair of alkylated guanines in O6-position. The peculiar irreversible self-alkylation reaction of these enzymes triggered numerous studies, especially on the human homologue, in order to identify effective inhibitors in the fight against cancer. In modern biotechnology, engineered variants of AGTs are developed to be used as protein tags for the attachment of chemical ligands. In the last decade, research on AGTs from (hyper)thermophilic sources proved useful as a model system to clarify numerous phenomena, also common for mesophilic enzymes. This review traces recent progress in this class of thermozymes, emphasizing their usefulness in basic research and their consequent advantages for in vivo and in vitro biotechnological applications.
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Affiliation(s)
- Rosanna Mattossovich
- Institute of Bioscience and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy; (R.M.); (R.M.)
| | - Rosa Merlo
- Institute of Bioscience and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy; (R.M.); (R.M.)
| | - Riccardo Miggiano
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Via Bovio 6, 28100 Novara, Italy;
| | - Anna Valenti
- Institute of Bioscience and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy; (R.M.); (R.M.)
| | - Giuseppe Perugino
- Institute of Bioscience and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy; (R.M.); (R.M.)
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Alkyltransferase-like protein clusters scan DNA rapidly over long distances and recruit NER to alkyl-DNA lesions. Proc Natl Acad Sci U S A 2020; 117:9318-9328. [PMID: 32273391 DOI: 10.1073/pnas.1916860117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alkylation of guanine bases in DNA is detrimental to cells due to its high mutagenic and cytotoxic potential and is repaired by the alkyltransferase AGT. Additionally, alkyltransferase-like proteins (ATLs), which are structurally similar to AGTs, have been identified in many organisms. While ATLs are per se catalytically inactive, strong evidence has suggested that ATLs target alkyl lesions to the nucleotide excision repair system (NER). Using a combination of single-molecule and ensemble approaches, we show here recruitment of UvrA, the initiating enzyme of prokaryotic NER, to an alkyl lesion by ATL. We further characterize lesion recognition by ATL and directly visualize DNA lesion search by highly motile ATL and ATL-UvrA complexes on DNA at the molecular level. Based on the high similarity of ATLs and the DNA-interacting domain of AGTs, our results provide important insight in the lesion search mechanism, not only by ATL but also by AGT, thus opening opportunities for controlling the action of AGT for therapeutic benefit during chemotherapy.
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27
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Glycolytic inhibition by 3-bromopyruvate increases the cytotoxic effects of chloroethylnitrosoureas to human glioma cells and the DNA interstrand cross-links formation. Toxicology 2020; 435:152413. [PMID: 32109525 DOI: 10.1016/j.tox.2020.152413] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/19/2020] [Accepted: 02/25/2020] [Indexed: 12/19/2022]
Abstract
DNA interstrand cross-links (ICLs) are essential for the antitumor activity of chloroethylnitrosoureas (CENUs). Commonly, CENUs resistance is mainly considered to be associated with O6-methylguanine-DNA methyltransferase (MGMT) within tumors. Bypassing the MGMT-mediated resistance, to our knowledge, herein, we first utilized a novel glycolytic inhibitor, 3-bromopyruvate (3-BrPA), to increase the cytotoxic effects of l,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to human glioma cells based on the hypothesis that blocking energy metabolism renders tumor cells more sensitive to chemotherapy. We found 3-BrPA significantly increased the cell killing by BCNU in human glioma SF763 and SF126 cell lines. Significantly decreased levels of extracellular lactate, cellular ATP and glutathione (GSH) were observed after 3-BrPA treatment, and the effects were more remarkable with 3-BrPA in combination with BCNU. Considering that the role of ATP and GSH in drug efflux, DNA damage repair and drug inactivation, we determined the effect of 3-BrPA on the formation of dG-dC ICLs induced by BCNU using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As expected, the levels of lethal dG-dC ICLs induced by BCNU were obviously enhanced after 3-BrPA pretreatment. Based on these results, 3-BrPA and related glycolytic inhibitors may be promising to enhance the cell killing effect and reverse the clinical chemoresistance of CENUs and related antitumor agents.
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Seiwert N, Heylmann D, Hasselwander S, Fahrer J. Mechanism of colorectal carcinogenesis triggered by heme iron from red meat. Biochim Biophys Acta Rev Cancer 2019; 1873:188334. [PMID: 31783067 DOI: 10.1016/j.bbcan.2019.188334] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/25/2019] [Accepted: 11/25/2019] [Indexed: 02/07/2023]
Abstract
Colorectal cancer (CRC) is one of the major tumor entities worldwide, with an increasing incidence in younger people. CRC formation is causally linked to various genetic, life-style and dietary risk factors. Among the ladder, the consumption of red meat has emerged as important risk factor contributing to CRC. A large body of evidence shows that heme iron is the critical component of red meat, which promotes colorectal carcinogenesis. In this review, we describe the uptake and cellular fate of both heme and inorganic iron in intestinal epithelial cells. Next, an overview on the DNA damaging properties of heme iron is provided, highlighting the DNA adducts relevant for CRC etiology. Moreover, heme triggered mechanisms leading to colonic hyperproliferation are presented, which are intimately linked to changes in the intestinal microbiota induced by heme. A special focus was set on the impact of heme iron on innate and adaptive immune cells, which could be relevant in the context of CRC. Finally, we recapitulate in vivo studies providing evidence for the tumor-promoting potential of dietary heme iron. Altogether, heme iron affects numerous key pathways involved in the pathogenesis of CRC.
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Affiliation(s)
- Nina Seiwert
- Department of Toxicology, University Medical Center Mainz, 55131 Mainz, Germany; Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, 35392 Giessen, Germany; Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Daniel Heylmann
- Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, 35392 Giessen, Germany
| | | | - Jörg Fahrer
- Department of Toxicology, University Medical Center Mainz, 55131 Mainz, Germany; Rudolf Buchheim Institute of Pharmacology, Justus Liebig University Giessen, 35392 Giessen, Germany; Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany.
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Bortezomib administered prior to temozolomide depletes MGMT, chemosensitizes glioblastoma with unmethylated MGMT promoter and prolongs animal survival. Br J Cancer 2019; 121:545-555. [PMID: 31413318 PMCID: PMC6888814 DOI: 10.1038/s41416-019-0551-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 07/10/2019] [Accepted: 07/25/2019] [Indexed: 11/28/2022] Open
Abstract
Background Resistance to temozolomide (TMZ) is due in part to enhanced DNA repair mediated by high expression of O6-methyl guanine DNA methyltransferase (MGMT) that is often characterised by unmethylated promoter. Here, we investigated pre-treatment of glioblastoma (GBM) cells with the 26S-proteasome inhibitor bortezomib (BTZ) as a strategy to interfere with MGMT expression and thus sensitise them to TMZ. Methods Cell lines and patient GBM-derived cells were examined in vitro, and the latter also implanted orthotopically into NOD-SCID C.B.-Igh-1b/lcrTac-Prkdc mice to assess efficacy and tolerability of BTZ and TMZ combination therapy. MGMT promoter methylation was determined using pyrosequencing and PCR, protein signalling utilised western blotting while drug biodistribution was examined by LC-MS/MS. Statistical analysis utilised Analysis of variance and the Kaplan–Meier method. Results Pre-treatment with BTZ prior to temozolomide killed chemoresistant GBM cells with unmethylated MGMT promoter through MGMT mRNA and protein depletion in vitro without affecting methylation. Chymotryptic activity was abolished, processing of NFkB/p65 to activated forms was reduced and corresponded with low MGMT levels. BTZ crossed the blood–brain barrier, diminished proteasome activity and significantly prolonged animal survival. Conclusion BTZ chemosensitized resistant GBM cells, and the schedule may be amenable for temozolomide refractory patients with unmethylated MGMT promoter.
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Du H, Wang P, Li L, Wang Y. Repair and translesion synthesis of O6-alkylguanine DNA lesions in human cells. J Biol Chem 2019; 294:11144-11153. [PMID: 31167778 PMCID: PMC6643039 DOI: 10.1074/jbc.ra119.009054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/31/2019] [Indexed: 12/15/2022] Open
Abstract
O6-alkyl-2'-deoxyguanosine (O6-alkyl-dG) lesions are among the most mutagenic and prevalent alkylated DNA lesions that are associated with cancer initiation and progression. In this study, using a shuttle vector-based strand-specific PCR-competitive replication and adduct bypass assay in conjunction with tandem MS for product identification, we systematically assessed the repair and replicative bypass of a series of O6-alkyl-dG lesions, with the alkyl group being a Me, Et, nPr, iPr, nBu, iBu, or sBu, in several human cell lines. We found that the extent of replication-blocking effects of these lesions is influenced by the size of the alkyl groups situated on the O6 position of the guanine base. We also noted involvement of distinct DNA repair pathways and translesion synthesis polymerases (Pols) in ameliorating the replication blockage effects elicited by the straight- and branched-chain O6-alkyl-dG lesions. We observed that O6-methylguanine DNA methyltransferase is effective in removing the smaller alkyl groups from the O6 position of guanine, whereas repair of the branched-chain lesions relied on nucleotide excision repair. Moreover, these lesions were highly mutagenic during cellular replication and exclusively directed G→A mutations; Pol η and Pol ζ participated in error-prone bypass of the straight-chain lesions, whereas Pol κ preferentially incorporated the correct dCMP opposite the branched-chain lesions. Together, these results uncover key cellular proteins involved in repair and translesion synthesis of O6-alkyl-dG lesions and provide a better understanding of the roles of these types of lesions in the etiology of human cancer.
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Affiliation(s)
- Hua Du
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Lin Li
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, California 92521-0403
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31
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Steinberg P. Red Meat-Derived Nitroso Compounds, Lipid Peroxidation Products and Colorectal Cancer. Foods 2019; 8:foods8070252. [PMID: 31336781 PMCID: PMC6678524 DOI: 10.3390/foods8070252] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 12/30/2022] Open
Abstract
About 20 years ago, the research group of Sheila Anne Bingham in Cambridge, UK, showed for the first time that volunteers consuming large amounts of red meat excrete high amounts of nitroso compounds via feces. In the meantime, it has been demonstrated that heme leads to the enhanced formation of nitroso compounds in the gastrointestinal tract and that the main nitroso compounds formed in the gastrointestinal tract are S-nitrosothiols and the nitrosyl heme. Moreover, it has been postulated that these endogenously formed nitroso compounds may alkylate guanine at the O6-position, resulting in the formation of the promutagenic DNA lesions O6-methylguanine and O6-carboxymethylguanine, which, if not repaired (in time), could lead to gene mutations and, subsequently to the development of colorectal cancer. Alternatively, it has been postulated that heme iron could contribute to colorectal carcinogenesis by inducing lipid peroxidation. In the present review, the evidence supporting the above-mentioned hypotheses will be presented.
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Affiliation(s)
- Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131 Karlsruhe, Germany.
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Brickner JR, Townley BA, Mosammaparast N. Intersections between transcription-coupled repair and alkylation damage reversal. DNA Repair (Amst) 2019; 81:102663. [PMID: 31326362 DOI: 10.1016/j.dnarep.2019.102663] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The response to DNA damage intersects with many other physiological processes in the cell, such as DNA replication, chromatin remodeling, and the cell cycle. Certain damaging lesions, such as UV-induced pyrimidine dimers, also strongly block RNA polymerases, necessitating the coordination of the repair mechanism with remodeling of the elongating transcriptional machinery, in a process called transcription-coupled nucleotide excision repair (TC-NER). This pathway is typically not thought to be engaged with smaller lesions such as base alkylation. However, recent work has uncovered the potential for shared molecular components between the cellular response to alkylation and UV damage. Here, we review our current understanding of the alkylation damage response and its impacts on RNA biogenesis. We give particular attention to the Activating Signal Cointegrator Complex (ASCC), which plays important roles in the transcriptional response during UV damage as well as alkylation damage reversal, and intersects with trichothiodystrophy, an inherited disease associated with TC-NER.
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Affiliation(s)
- Joshua R Brickner
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Brittany A Townley
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Nima Mosammaparast
- Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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Serpe M, Forenza C, Adamo A, Russo N, Perugino G, Ciaramella M, Valenti A. The DNA Alkylguanine DNA Alkyltransferase-2 (AGT-2) Of Caenorhabditis Elegans Is Involved In Meiosis And Early Development Under Physiological Conditions. Sci Rep 2019; 9:6889. [PMID: 31053748 PMCID: PMC6499797 DOI: 10.1038/s41598-019-43394-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
DNA alkylguanine DNA alkyltransferases (AGTs) are evolutionary conserved proteins that repair alkylation damage in DNA, counteracting the effects of agents inducing such lesions. Over the last years AGTs have raised considerable interest for both the peculiarity of their molecular mechanism and their relevance in cancer biology. AGT knock out mice show increased tumour incidence in response to alkylating agents, and over-expression of the human AGT protein in cancer cells is frequently associated with resistance to alkylating chemotherapy. While all data available point to a function of AGT proteins in the cell response to alkylation lesions, we report for the first time that one of the two AGT paralogs of the model organism C. elegans, called AGT-2, also plays unexpected roles in meiosis and early development under physiological conditions. Our data suggest a role for AGT-2 in conversion of homologous recombination intermediates into post-strand exchange products in meiosis, and show that agt-2 gene down-regulation, or treatment of animals with an AGT inhibitor results in increased number of germ cells that are incompatible with producing viable offspring and are eliminated by apoptosis. These results suggest possible functions for AGTs in cell processes distinct from repair of alkylating damage.
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Affiliation(s)
- Mario Serpe
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Chiara Forenza
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Adele Adamo
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Noemi Russo
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Giuseppe Perugino
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Maria Ciaramella
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy
| | - Anna Valenti
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, Naples, 80131, Italy.
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Gupta D, Heinen CD. The mismatch repair-dependent DNA damage response: Mechanisms and implications. DNA Repair (Amst) 2019; 78:60-69. [PMID: 30959407 DOI: 10.1016/j.dnarep.2019.03.009] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/25/2019] [Accepted: 03/16/2019] [Indexed: 12/22/2022]
Abstract
An important role for the DNA mismatch repair (MMR) pathway in maintaining genomic stability is embodied in its conservation through evolution and the link between loss of MMR function and tumorigenesis. The latter is evident as inheritance of mutations within the major MMR genes give rise to the cancer predisposition condition, Lynch syndrome. Nonetheless, how MMR loss contributes to tumorigenesis is not completely understood. In addition to preventing the accumulation of mutations, MMR also directs cellular responses, such as cell cycle checkpoint or apoptosis activation, to different forms of DNA damage. Understanding this MMR-dependent DNA damage response may provide insight into the full tumor suppressing capabilities of the MMR pathway. Here, we delve into the proposed mechanisms for the MMR-dependent response to DNA damaging agents. We discuss how these pre-clinical findings extend to the clinical treatment of cancers, emphasizing MMR status as a crucial variable in selection of chemotherapeutic regimens. Also, we discuss how loss of the MMR-dependent damage response could promote tumorigenesis via the establishment of a survival advantage to endogenous levels of stress in MMR-deficient cells.
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Affiliation(s)
- Dipika Gupta
- Center for Molecular Oncology, UConn Health, Farmington, CT 06030, USA
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Yamashita S, Yokogami K, Matsumoto F, Saito K, Mizuguchi A, Ohta H, Takeshima H. MGMT promoter methylation in patients with glioblastoma: is methylation-sensitive high-resolution melting superior to methylation-sensitive polymerase chain reaction assay? J Neurosurg 2019; 130:780-788. [PMID: 29726772 DOI: 10.3171/2017.11.jns171710] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/10/2017] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The methylation status of the O6-methylguanine-DNA methyltransferase (MGMT) gene promoter is a prognostic factor in adults with glioblastoma (GBM); it also yields information that is useful for clinical decision-making in elderly GBM patients. While pyrosequencing is the gold standard for the evaluation of the methylation status of MGMT, methylation-sensitive polymerase chain reaction (MS-PCR) assay continues to be used widely. Although MS-PCR results exhibited a good correlation with the prognosis of patients with GBM treated under the Stupp protocol, interpretation of the bands is based on subjective judgment, and the assay cannot be used to analyze heterogeneously methylated samples. We assessed whether methylation-sensitive high-resolution melting (MS-HRM) is an alternative to MS-PCR. METHODS The authors prepared 3 primer sets that covered CpG 72–89 for MS-HRM analysis to determine the methylation levels of 6 human glioma cell lines. The results were validated by bisulfite sequencing of cloned alleles. The authors also subjected surgical samples from 75 GBM patients treated with temozolomide (TMZ) to MS-HRM to assess the MGMT methylation status and compared the findings with MS-PCR results using receiver operating characteristic (ROC), univariate, and multivariate analyses. RESULTS There was a strong correlation between the methylation levels of the 6 glioma cell lines evaluated by MSHRM and by bisulfite sequencing; with primers 1 and 2, the correlation was significant (r = 0.959 and r = 0.960, respectively, p < 0.01). Based on log-rank analysis, MS-HRM was significantly better than MS-PCR for predicting progressionfree survival (PFS) and overall survival (OS) based on the methylation status of the MGMT promoter (PFS predicted by MS-HRM and MS-PCR = 0.00023 and 0.0035, respectively; OS = 0.00019 and 0.00028, respectively). ROC analysis showed that the area under the curve was larger with MS-HRM than with MS-PCR (PFS: 0.723 vs 0.635; OS: 0.716 vs 0.695). Based on multivariate Cox regression analysis, MS-HRM was significantly better than MS-PCR for predicting the treatment outcome (MS-HRM vs MS-PCR: PFS, p = 0.001 vs 0.207; OS, p = 0.013 vs 0.135). CONCLUSIONS The authors’ findings show that MS-HRM is superior to MS-PCR for the detection of MGMT promoter methylation. They suggest MS-HRM as an alternative to MS-PCR for assessing the prognosis of patients with GBM.
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Kraus A, McKeague M, Seiwert N, Nagel G, Geisen SM, Ziegler N, Trantakis IA, Kaina B, Thomas AD, Sturla SJ, Fahrer J. Immunological and mass spectrometry-based approaches to determine thresholds of the mutagenic DNA adduct O6-methylguanine in vivo. Arch Toxicol 2018; 93:559-572. [DOI: 10.1007/s00204-018-2355-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 11/08/2018] [Indexed: 10/27/2022]
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Hsu SH, Chen SH, Kuo CC, Chang JY. Ubiquitin-conjugating enzyme E2 B regulates the ubiquitination of O 6-methylguanine-DNA methyltransferase and BCNU sensitivity in human nasopharyngeal carcinoma cells. Biochem Pharmacol 2018; 158:327-338. [PMID: 30449727 DOI: 10.1016/j.bcp.2018.10.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 10/25/2018] [Indexed: 02/06/2023]
Abstract
O6-Methylguanine-DNA methyltransferase (MGMT) is a DNA repair enzyme that removes the alkyl groups from the O6 position of guanine and is then degraded via ubiquitin-mediated degradation. Previous studies indicated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) facilitates the ubiquitination and degradation of MGMT in several types of cancer cells. However, the underlying mechanism of MGMT ubiquitination remains unclear. In this study, we demonstrated for the first time that ubiquitin-conjugating enzyme E2 B (UBE2B) is a novel regulator of MGMT ubiquitination mediated by BCNU in nasopharyngeal carcinoma (NPC) cells. The E3 ubiquitin ligase RAD18, a partner of UBE2B, is also involved in BCNU-mediated MGMT ubiquitination. Overexpression/knockdown of UBE2B enhanced/reduced BCNU-mediated MGMT ubiquitination. Surprisingly, UBE2B knockdown significantly increased BCNU cytotoxicity in NPC cells. Therefore, loss of UBE2B seems to disrupt ubiquitin-mediated degradation of alkylated MGMT. We found that UBE2B knockdown reduced MGMT activity, suggesting that loss of UBE2B leads to the accumulation of deactivated MGMT and suppresses MGMT protein turnover in BCNU-treated cells. These findings indicate that UBE2B modulates sensitivity to BCNU in NPC cells by regulating MGMT ubiquitination.
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Affiliation(s)
- Shih-Han Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan
| | - Shang-Hung Chen
- National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ching-Chuan Kuo
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Jang-Yang Chang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan; Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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The specific role of O 6-methylguanine-DNA methyltransferase inhibitors in cancer chemotherapy. Future Med Chem 2018; 10:1971-1996. [PMID: 30001630 DOI: 10.4155/fmc-2018-0069] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The DNA repair protein, O6-methylguanine DNA methyltransferase (MGMT), can confer resistance to guanine O6-alkylating agents. Therefore, inhibition of resistant MGMT protein is a practical approach to increase the anticancer effects of such alkylating agents. Numerous small molecule inhibitors were synthesized and exhibited potential MGMT inhibitory activities. Although they were nontoxic alone, they also inhibited MGMT in normal tissues, thereby enhancing the side effects of chemotherapy. Therefore, strategies for tumor-specific MGMT inhibition have been proposed, including local drug delivery and tumor-activated prodrugs. Over-expression of MGMT in hematopoietic stem cells to protect bone marrow from the toxic effects of chemotherapy is also a feasible selection. The future prospects and challenges of MGMT inhibitors in cancer chemotherapy were also discussed.
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Soll JM, Brickner JR, Mudge MC, Mosammaparast N. RNA ligase-like domain in activating signal cointegrator 1 complex subunit 1 (ASCC1) regulates ASCC complex function during alkylation damage. J Biol Chem 2018; 293:13524-13533. [PMID: 29997253 DOI: 10.1074/jbc.ra117.000114] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 07/03/2018] [Indexed: 02/05/2023] Open
Abstract
Multiple DNA damage response (DDR) pathways have evolved to sense the presence of damage and recruit the proper repair factors. We recently reported a signaling pathway induced upon alkylation damage to recruit the AlkB homolog 3, α-ketoglutarate-dependent dioxygenase (ALKBH3)-activating signal cointegrator 1 complex subunit 3 (ASCC3) dealkylase-helicase repair complex. As in other DDR pathways, the recruitment of these repair factors is mediated through a ubiquitin-dependent mechanism. However, the machinery that coordinates the proper assembly of this repair complex and controls its recruitment is still poorly defined. Here, we demonstrate that the ASCC1 accessory subunit is important for the regulation of ASCC complex function. ASCC1 interacts with the ASCC complex through the ASCC3 helicase subunit. We find that ASCC1 is present at nuclear speckle foci prior to damage, but leaves the foci in response to alkylation. Strikingly, ASCC1 loss significantly increases ASCC3 foci formation during alkylation damage, yet most of these foci lack ASCC2. These results suggest that ASCC1 coordinates the proper recruitment of the ASCC complex during alkylation, a function that appears to depend on a putative RNA-binding motif near the ASCC1 C terminus. Consistent with its role in alkylation damage signaling and repair, ASCC1 knockout through a CRISPR/Cas9 approach results in alkylation damage sensitivity in a manner epistatic with ASCC3. Together, our results identify a critical regulator of the ALKBH3-ASCC alkylation damage signaling pathway and suggest a potential role for RNA-interacting domains in the alkylation damage response.
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Affiliation(s)
- Jennifer M Soll
- From the Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Joshua R Brickner
- From the Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Miranda C Mudge
- From the Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University in St. Louis, St. Louis, Missouri 63110
| | - Nima Mosammaparast
- From the Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University in St. Louis, St. Louis, Missouri 63110
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Rossi F, Morrone C, Massarotti A, Ferraris DM, Valenti A, Perugino G, Miggiano R. Crystal structure of a thermophilic O6-alkylguanine-DNA alkyltransferase-derived self-labeling protein-tag in covalent complex with a fluorescent probe. Biochem Biophys Res Commun 2018; 500:698-703. [DOI: 10.1016/j.bbrc.2018.04.139] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 04/17/2018] [Indexed: 02/07/2023]
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Mostofa A, Punganuru SR, Madala HR, Srivenugopal KS. S-phase Specific Downregulation of Human O 6-Methylguanine DNA Methyltransferase (MGMT) and its Serendipitous Interactions with PCNA and p21 cip1 Proteins in Glioma Cells. Neoplasia 2018; 20:305-323. [PMID: 29510343 PMCID: PMC5909491 DOI: 10.1016/j.neo.2018.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/17/2018] [Accepted: 01/21/2018] [Indexed: 01/28/2023] Open
Abstract
Whether the antimutagenic DNA repair protein MGMT works solo in human cells and if it has other cellular functions is not known. Here, we show that human MGMT associates with PCNA and in turn, with the cell cycle inhibitor, p21cip1 in glioblastoma and other cancer cell lines. MGMT protein was shown to harbor a nearly perfect PCNA-Interacting Protein (PIP box) motif. Isogenic p53-null H1299 cells were engineered to express the p21 protein by two different procedures. Reciprocal immunoprecipitation/western blotting, Far-western blotting, and confocal microscopy confirmed the specific association of MGMT with PCNA and the ability of p21 to strongly disrupt the MGMT-PCNA complexes in tumor cells. Alkylation DNA damage resulted in a greater colocalization of MGMT and PCNA proteins, particularly in HCT116 cells deficient in p21 expression. p21 expression in isogenic cell lines directly correlated with markedly higher levels of MGMT mRNA, protein, activity and greater resistance to alkylating agents. In other experiments, four glioblastoma cell lines synchronized at the G1/S phase using either double thymidine or thymidine-mimosine blocks and subsequent cycling consistently showed a loss of MGMT protein at mid- to late S-phase, irrespective of the cell line, suggesting such a downregulation is fundamental to cell cycle control. MGMT protein was also specifically degraded in extracts from S-phase cells and evidence strongly suggested the involvement of PCNA-dependent CRL4Cdt2 ubiquitin-ligase in the reaction. Overall, these data provide the first evidence for non-repair functions of MGMT in cell cycle and highlight the involvement of PCNA in MGMT downregulation, with p21 attenuating the process.
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Affiliation(s)
- Agm Mostofa
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1406 S. Coulter Drive, Amarillo, TX 79106, USA
| | - Surendra R Punganuru
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1406 S. Coulter Drive, Amarillo, TX 79106, USA
| | - Hanumantha Rao Madala
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1406 S. Coulter Drive, Amarillo, TX 79106, USA
| | - Kalkunte S Srivenugopal
- Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1406 S. Coulter Drive, Amarillo, TX 79106, USA.
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Germline variants in IL4, MGMT and AKT1 are associated with prostate cancer-specific mortality: An analysis of 12,082 prostate cancer cases. Prostate Cancer Prostatic Dis 2018; 21:228-237. [PMID: 29298992 PMCID: PMC6026113 DOI: 10.1038/s41391-017-0029-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 11/09/2017] [Accepted: 11/20/2017] [Indexed: 02/08/2023]
Abstract
Background Prostate cancer (PCa) is a leading cause of mortality and genetic factors can influence tumour aggressiveness. Several germline variants have been associated with PCa-specific mortality (PCSM), but further replication evidence is needed. Methods Twenty-two previously identified PCSM-associated genetic variants were genotyped in seven PCa cohorts (12,082 patients; 1544 PCa deaths). For each cohort, Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals for risk of PCSM associated with each variant. Data were then combined using a meta-analysis approach. Results Fifteen SNPs were associated with PCSM in at least one of the seven cohorts. In the meta-analysis, after adjustment for clinicopathological factors, variants in the MGMT (rs2308327; HR 0.90; p-value = 3.5 × 10−2) and IL4 (rs2070874; HR 1.22; p-value = 1.1 × 10−3) genes were confirmed to be associated with risk of PCSM. In analyses limited to men diagnosed with local or regional stage disease, a variant in AKT1, rs2494750, was also confirmed to be associated with PCSM risk (HR 0.81; p-value = 3.6 × 10−2). Conclusions This meta-analysis confirms the association of three genetic variants with risk of PCSM, providing further evidence that genetic background plays a role in PCa-specific survival. While these variants alone are not sufficient as prognostic biomarkers, these results may provide insights into the biological pathways modulating tumour aggressiveness.
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Gutierrez R, Thompson Y, R. O’Connor T. DNA direct repair pathways in cancer. AIMS MEDICAL SCIENCE 2018. [DOI: 10.3934/medsci.2018.3.284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Aasland D, Reich TR, Tomicic MT, Switzeny OJ, Kaina B, Christmann M. Repair gene O 6 -methylguanine-DNA methyltransferase is controlled by SP1 and up-regulated by glucocorticoids, but not by temozolomide and radiation. J Neurochem 2018; 144:139-151. [PMID: 29164620 DOI: 10.1111/jnc.14262] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/05/2017] [Accepted: 11/14/2017] [Indexed: 12/27/2022]
Abstract
Therapy of malignant glioma relies on treatment with the O6 -methylating agent temozolomide (TMZ) concomitant with ionizing radiation followed by adjuvant TMZ. For the treatment of recurrences, DNA chloroethylating drugs are also used. The main killing lesion induced by these drugs is O6 -alkylguanine. Since this damage is repaired by O6 -methylguanine-DNA methyltransferase (MGMT), the repair enzyme represents a most important factor of drug resistance, limiting the therapy of malignant high-grade gliomas. Although MGMT has been shown to be transcriptionally up-regulated in rodents following genotoxic stress, it is still unclear whether human MGMT is subject to up-regulation. Here, we addressed the question whether MGMT in glioma cells is enhanced following alkylating drugs or ionizing radiation, using promoter assays. We also checked the response of glioma cell lines to dexamethasone. In a series of experiments, we found no evidence that the human MGMT promoter is significantly up-regulated following treatment with TMZ, the chloroethylating agent nimustine or radiation. It was activated, however, by dexamethasone. Using deletion constructs, we further show that the basal level of MGMT is mainly determined by the transcription factor SP1. The high amount of SP1 sites in the MGMT promoter likely prevents transcriptional up-regulation following genotoxic stress by neutralizing inducible signals. The regulation of MGMT by miRNAs plays only a minor role, as shown by DICER knockdown experiments. Since high dose dexamethasone concomitant with temozolomide is frequently used in glioblastoma therapy, induction of the MGMT gene through glucocorticoids in MGMT promoter unmethylated cases might cause further elevation of drug resistance, while radiation and alkylating drugs seem not to induce MGMT at transcriptional level.
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Affiliation(s)
- Dorthe Aasland
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
| | - Thomas R Reich
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
| | - Maja T Tomicic
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
| | - Olivier J Switzeny
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
| | - Bernd Kaina
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
| | - Markus Christmann
- Department of Toxicology, University Medical Center Mainz, Mainz, Germany
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Miggiano R, Valenti A, Rossi F, Rizzi M, Perugino G, Ciaramella M. Every OGT Is Illuminated … by Fluorescent and Synchrotron Lights. Int J Mol Sci 2017; 18:ijms18122613. [PMID: 29206193 PMCID: PMC5751216 DOI: 10.3390/ijms18122613] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 12/23/2022] Open
Abstract
O6-DNA-alkyl-guanine-DNA-alkyl-transferases (OGTs) are evolutionarily conserved, unique proteins that repair alkylation lesions in DNA in a single step reaction. Alkylating agents are environmental pollutants as well as by-products of cellular reactions, but are also very effective chemotherapeutic drugs. OGTs are major players in counteracting the effects of such agents, thus their action in turn affects genome integrity, survival of organisms under challenging conditions and response to chemotherapy. Numerous studies on OGTs from eukaryotes, bacteria and archaea have been reported, highlighting amazing features that make OGTs unique proteins in their reaction mechanism as well as post-reaction fate. This review reports recent functional and structural data on two prokaryotic OGTs, from the pathogenic bacterium Mycobacterium tuberculosis and the hyperthermophilic archaeon Sulfolobus solfataricus, respectively. These studies provided insight in the role of OGTs in the biology of these microorganisms, but also important hints useful to understand the general properties of this class of proteins.
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Affiliation(s)
- Riccardo Miggiano
- DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Via Bovio 6, 28100 Novara, Italy.
| | - Anna Valenti
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy.
| | - Franca Rossi
- DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Via Bovio 6, 28100 Novara, Italy.
| | - Menico Rizzi
- DSF-Dipartimento di Scienze del Farmaco, University of Piemonte Orientale, Via Bovio 6, 28100 Novara, Italy.
| | - Giuseppe Perugino
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy.
| | - Maria Ciaramella
- Institute of Biosciences and BioResources, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples, Italy.
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Baran K, Yang M, Dillon CP, Samson LL, Green DR. The proline rich domain of p53 is dispensable for MGMT-dependent DNA repair and cell survival following alkylation damage. Cell Death Differ 2017; 24:1925-1936. [PMID: 28753207 DOI: 10.1038/cdd.2017.116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 05/01/2017] [Accepted: 05/16/2017] [Indexed: 01/20/2023] Open
Abstract
In addition to promoting cell death and senescence, p53 also has important cellular survival functions. A mutant p53, lacking a proline-rich domain (p53ΔP), that is deficient in controlling both cell death and cell cycle arrest, was employed to determine the biological means by which p53 mediates survival upon DNA damage. While p53ΔP and p53-/- cells were equally resistant to many DNA damaging agents, p53ΔP cells showed an exquisite resistance to high doses of the alkylating agent Diazald (N-Methyl-N-(p-tolylsulfonyl)nitrosamide), as compared to cells completely deficient for p53 function. We determined that p53ΔP was capable of transcribing the repair gene, MGMT (O6-methylguanine-DNA methyltransferase) after irradiation or alkylation damage, resulting in DNA repair and cell survival. Consistent with these observations, p53ΔP mice show enhanced survival after IR relative to p53-/- mice. Suppression or deletion of MGMT expression in p53ΔP cells inhibited DNA repair and survival after alkylation damage, whereas MGMT overexpression in p53-deficient cells facilitated DNA repair and conferred survival advantage. This study shows that when cell death and cell cycle arrest pathways are inhibited, p53 can still mediate MGMT-dependent repair, to promote cell survival upon DNA damage.
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Affiliation(s)
- Katherine Baran
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
| | - Mao Yang
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
| | - Christopher P Dillon
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
| | - Leona L Samson
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
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Nikolova T, Roos WP, Krämer OH, Strik HM, Kaina B. Chloroethylating nitrosoureas in cancer therapy: DNA damage, repair and cell death signaling. Biochim Biophys Acta Rev Cancer 2017; 1868:29-39. [PMID: 28143714 DOI: 10.1016/j.bbcan.2017.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/25/2017] [Accepted: 01/26/2017] [Indexed: 01/20/2023]
Abstract
Chloroethylating nitrosoureas (CNU), such as lomustine, nimustine, semustine, carmustine and fotemustine are used for the treatment of malignant gliomas, brain metastases of different origin, melanomas and Hodgkin disease. They alkylate the DNA bases and give rise to the formation of monoadducts and subsequently interstrand crosslinks (ICL). ICL are critical cytotoxic DNA lesions that link the DNA strands covalently and block DNA replication and transcription. As a result, S phase progression is inhibited and cells are triggered to undergo apoptosis and necrosis, which both contribute to the effectiveness of CNU-based cancer therapy. However, tumor cells resist chemotherapy through the repair of CNU-induced DNA damage. The suicide enzyme O6-methylguanine-DNA methyltransferase (MGMT) removes the precursor DNA lesion O6-chloroethylguanine prior to its conversion into ICL. In cells lacking MGMT, the formed ICL evoke complex enzymatic networks to accomplish their removal. Here we discuss the mechanism of ICL repair as a survival strategy of healthy and cancer cells and DNA damage signaling as a mechanism contributing to CNU-induced cell death. We also discuss therapeutic implications and strategies based on sequential and simultaneous treatment with CNU and the methylating drug temozolomide.
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Affiliation(s)
- Teodora Nikolova
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
| | - Wynand P Roos
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
| | - Oliver H Krämer
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
| | - Herwig M Strik
- Department of Neurology, University Medical Center, Baldinger Strasse, 35033 Marburg, Germany
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
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Peterson LA. Context Matters: Contribution of Specific DNA Adducts to the Genotoxic Properties of the Tobacco-Specific Nitrosamine NNK. Chem Res Toxicol 2017; 30:420-433. [PMID: 28092943 PMCID: PMC5473167 DOI: 10.1021/acs.chemrestox.6b00386] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent pulmonary carcinogen in laboratory animals. It is classified as a Group 1 human carcinogen by the International Agency for Cancer Research. NNK is bioactivated upon cytochrome P450 catalyzed hydroxylation of the carbon atoms adjacent to the nitrosamino group to both methylating and pyridyloxobutylating agents. Both pathways generate a spectrum of DNA damage that contributes to the overall mutagenic and toxic properties of this compound. NNK is also reduced to form 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), which is also carcinogenic. Like NNK, NNAL requires metabolic activation to DNA alkylating agents. Methyl hydroxylation of NNAL generates pyridylhydroxybutyl DNA adducts, and methylene hydroxylation leads to DNA methyl adducts. The consequence of this complex metabolism is that NNK generates a vast spectrum of DNA damage, any form of which can contribute to the overall carcinogenic properties of this potent pulmonary carcinogen. This Perspective reviews the chemistry and genotoxic properties of the collection of DNA adducts formed from NNK. In addition, it provides evidence that multiple adducts contribute to the overall carcinogenic properties of this chemical. The adduct that contributes to the genotoxic effects of NNK depends on the context, such as the relative amounts of each DNA alkylating pathway occurring in the model system, the levels and genetic variants of key repair enzymes, and the gene targeted for mutation.
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Affiliation(s)
- Lisa A Peterson
- Masonic Cancer Center and Division of Environmental Health Sciences, University of Minnesota , Minneapolis, Minnesota 55455, United States
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Regulation of DNA Alkylation Damage Repair: Lessons and Therapeutic Opportunities. Trends Biochem Sci 2016; 42:206-218. [PMID: 27816326 DOI: 10.1016/j.tibs.2016.10.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/03/2016] [Accepted: 10/11/2016] [Indexed: 12/15/2022]
Abstract
Alkylation chemotherapy is one of the most widely used systemic therapies for cancer. While somewhat effective, clinical responses and toxicities of these agents are highly variable. A major contributing factor for this variability is the numerous distinct lesions that are created upon alkylation damage. These adducts activate multiple repair pathways. There is mounting evidence that the individual pathways function cooperatively, suggesting that coordinated regulation of alkylation repair is critical to prevent toxicity. Furthermore, some alkylating agents produce adducts that overlap with newly discovered methylation marks, making it difficult to distinguish between bona fide damaged bases and so-called 'epigenetic' adducts. Here, we discuss new efforts aimed at deciphering the mechanisms that regulate these repair pathways, emphasizing their implications for cancer chemotherapy.
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Interdomain interactions rearrangements control the reaction steps of a thermostable DNA alkyltransferase. Biochim Biophys Acta Gen Subj 2016; 1861:86-96. [PMID: 27777086 DOI: 10.1016/j.bbagen.2016.10.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/07/2016] [Accepted: 10/20/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Alkylated DNA-protein alkyltransferases (AGTs) are conserved proteins that repair alkylation damage in DNA by using a single-step mechanism leading to irreversible alkylation of the catalytic cysteine in the active site. Trans-alkylation induces inactivation and destabilization of the protein, both in vitro and in vivo, likely triggering conformational changes. A complete picture of structural rearrangements occurring during the reaction cycle is missing, despite considerable interest raised by the peculiarity of AGT reaction, and the contribution of a functional AGT in limiting the efficacy of chemotherapy with alkylating drugs. METHODS As a model for AGTs we have used a thermostable ortholog from the archaeon Sulfolobus solfataricus (SsOGT), performing biochemical, structural, molecular dynamics and in silico analysis of ligand-free, DNA-bound and mutated versions of the protein. RESULTS Conformational changes occurring during lesion recognition and after the reaction, allowed us to identify a novel interaction network contributing to SsOGT stability, which is perturbed when a bulky adduct between the catalytic cysteine and the alkyl group is formed, a mandatory step toward the permanent protein alkylation. CONCLUSIONS Our data highlighted conformational changes and perturbation of intramolecular interaction occurring during lesion recognition and catalysis, confirming our previous hypothesis that coordination between the N- and C-terminal domains of SsOGT is important for protein activity and stability. GENERAL SIGNIFICANCE A general model of structural rearrangements occurring during the reaction cycle of AGTs is proposed. If confirmed, this model might be a starting point to design strategies to modulate AGT activity in therapeutic settings.
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