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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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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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Harris CM, Zamperoni KE, Sernoskie SC, Chow NSM, Massey TE. Effects of in vivo treatment of mice with sulforaphane on repair of DNA pyridyloxylbutylation. Toxicology 2021; 454:152753. [PMID: 33741493 DOI: 10.1016/j.tox.2021.152753] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/08/2021] [Accepted: 03/12/2021] [Indexed: 01/08/2023]
Abstract
The phytochemical sulforaphane (SF) has gained interest for its apparent association with reduced cancer risk and other cytoprotective properties, at least some of which are attributed to activation of the transcription factor Nrf2. Repair of bulky DNA adducts is important for mitigating carcinogenesis from exogenous DNA damaging agents, but it is unknown whether in vivo treatment with SF affects adduct repair. At 12 h following a single oral dose of 100 mg/kg SF, an almost doubling in activity for repair of pyridyloxobutylated DNA was observed in CD-1 mouse liver nuclear extracts, but not in lung extracts. This change at 12 h in repair activity was preceded by the induction of Nrf2-regulated genes but not accompanied by changes in levels of the specific nucleotide excision repair (NER) proteins XPC, XPA, XPB and p53 or in binding of hepatic XPC, XPA and XPB to damaged DNA. SF also did not significantly alter histone deacetylase activity as measured by acetylated histone H3 levels, or stimulate formation of γ-H2A.X, a marker of DNA damage. A significant reduction in oxidative DNA damage, as measured by 8-OHdG (a biomarker of oxidative DNA damage), was observed only in DNA from the lungs of SF-treated mice 3 h post-dosing. These results suggest that the ability of SF to increase bulky adduct repair activity is organ-selective and is consistent with activation of the Nrf2 signaling pathway.
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Affiliation(s)
- Christopher M Harris
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Kristen E Zamperoni
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Samantha C Sernoskie
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Natalie S M Chow
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Thomas E Massey
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
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Doukas SG, Vageli DP, Lazopoulos G, Spandidos DA, Sasaki CT, Tsatsakis A. The Effect of NNK, A Tobacco Smoke Carcinogen, on the miRNA and Mismatch DNA Repair Expression Profiles in Lung and Head and Neck Squamous Cancer Cells. Cells 2020; 9:E1031. [PMID: 32326378 PMCID: PMC7226174 DOI: 10.3390/cells9041031] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/04/2020] [Accepted: 04/19/2020] [Indexed: 02/07/2023] Open
Abstract
Tobacco smoking is a common risk factor for lung cancer and head and neck cancer. Molecular changes such as deregulation of miRNA expression have been linked to tobacco smoking in both types of cancer. Dysfunction of the Mismatch DNA repair (MMR) mechanism has also been associated with a poor prognosis of these cancers, while a cross-talk between specific miRNAs and MMR genes has been previously proposed. We hypothesized that exposure of lung and head and neck squamous cancer cells (NCI and FaDu, respectively) to tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is capable of altering the expression of MSH2 and MLH1, key MMR components, by promoting specific miRNA deregulation. We found that either a low (1 μM) or high (2 μM) dose of NNK induced significant upregulation of "oncomirs" miR-21 and miR-155 and downregulation of "tumor suppressor" miR-422a, as well as the reduction of MMR protein and mRNA expression, in NCI and FaDu, compared to controls. Inhibition of miR-21 restored the NNK-induced reduced MSH2 phenotype in both NCI and FaDu, indicating that miR-21 might contribute to MSH2 regulation. Finally, NNK exposure increased NCI and FaDu survival, promoting cancer cell progression. We provide novel findings that deregulated miR-21, miR-155, and miR-422a and MMR gene expression patterns may be valuable biomarkers for lung and head and neck squamous cell cancer progression in smokers.
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Affiliation(s)
- Sotirios G. Doukas
- Department of Forensic Sciences and Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece; (S.G.D.); (A.T.)
- Department of Surgery, The Yale Larynx Laboratory, New Haven, CT 06510, USA;
| | - Dimitra P. Vageli
- Department of Surgery, The Yale Larynx Laboratory, New Haven, CT 06510, USA;
| | - George Lazopoulos
- Department of Cardiothoracic Surgery, Medical School, University of Crete, 71110 Heraklion, Greece;
| | - Demetrios A. Spandidos
- Laboratory of Clinical Virology, Medical School, University of Crete, 71110 Heraklion, Greece;
| | - Clarence T. Sasaki
- Department of Surgery, The Yale Larynx Laboratory, New Haven, CT 06510, USA;
| | - Aristidis Tsatsakis
- Department of Forensic Sciences and Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece; (S.G.D.); (A.T.)
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Leng J, Wang Y. Liquid Chromatography-Tandem Mass Spectrometry for the Quantification of Tobacco-Specific Nitrosamine-Induced DNA Adducts in Mammalian Cells. Anal Chem 2017; 89:9124-9130. [PMID: 28749651 PMCID: PMC5620023 DOI: 10.1021/acs.analchem.7b01857] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Quantification of DNA lesions constitutes one of the main tasks in toxicology and in assessing health risks accompanied by exposure to carcinogens. Tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) can undergo metabolic transformation to give a reactive intermediate that pyridyloxobutylates nucleobases and phosphate backbone of DNA. Here, we reported a highly sensitive method, relying on the use of nanoflow liquid chromatography-nanoelectrospray ionization-tandem mass spectrometry (nLC-nESI-MS/MS), for the simultaneous quantifications of O6-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxyguanosine (O6-POBdG) as well as O2- and O4-[4-(3-pyridyl)-4-oxobut-1-yl]-thymidine (O2-POBdT and O4-POBdT). By using this method, we measured the levels of the three DNA adducts with the use of 10 μg of DNA isolated from cultured mammalian cells exposed to a model pyridyloxobutylating agent, 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc). Our results demonstrated, for the first time, the formation of O4-POBdT in naked DNA and in genomic DNA of cultured mammalian cells exposed with NNKOAc. We also revealed that the levels of the three lesions increased with the dose of NNKOAc and that O2-POBdT and O4-POBdT could be subjected to repair by the nucleotide excision repair (NER) pathway. The method reported here will be useful for investigations about the involvement of other DNA repair pathways in the removal of these lesions and for human toxicological studies in the future.
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Affiliation(s)
- Jiapeng Leng
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
| | - Yinsheng Wang
- Corresponding Author. Tel.: (951) 827-2700. Fax: (951) 827-4713.
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Potential risk of esophageal squamous cell carcinoma due to nucleotide excision repair XPA and XPC gene variants and their interaction among themselves and with environmental factors. Tumour Biol 2016; 37:10193-207. [PMID: 26831662 DOI: 10.1007/s13277-016-4895-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/20/2016] [Indexed: 02/07/2023] Open
Abstract
The association of nucleotide excision repair (NER) gene polymorphisms with esophageal squamous cell carcinoma (ESCC) is inconclusive. The aim of the current study was to assess the association of repair gene xeroderma pigmentosum A (XPA) (rs-1800975) and xeroderma pigmentosum C (XPC) (rs-2228000) polymorphisms with ESCC risk as well as modifying effects of environmental factors. The genotyping was done in 450 confirmed ESCC cases and equal number of individually matched controls by the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) and direct sequencing methods. Conditional logistic regression models were used to assess the genotypic associations and interactions. A high ESCC risk was found in subjects who carried the homozygous minor allele of XPA (odds ratio (OR) = 3.57; 95 % confidence interval (CI) = 1.76-7.23), and the risk was higher when analysis was limited to participants who were ever smokers (OR = 4.22; 95 % CI = 2.01-8.88), lived in adobe houses (OR = 8.42; 95 % CI = 3.74-18.95), consumed large volumes of salt tea (OR = 7.42; 95 % CI = 3.30-16.69), or had a positive family history of cancer (FHC) (OR = 9.47; 95 % CI = 4.67-19.20). In case of XPC, a homozygous minor allele also showed strong association with ESCC risk (OR = 4.43; 95 % CI = 2.41-8.16). We again observed a very strong effect of the above environmental factors in elevating the risk of ESCC. Further, the variant genotypes of both genes in combination showed an increased risk towards ESCC (OR = 7.01; 95 % CI = 3.14-15.64) and such association was synergistically significant. Salt tea consumption showed an interaction with genotypes of XPA and XPC. However, an interaction with FHC was significant in the case of XPA genotype only. XPA and XPC genotypes are associated with an increased risk of ESCC, and such association was reasonably modulated by different exposures.
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Xue J, Yang S, Seng S. Mechanisms of Cancer Induction by Tobacco-Specific NNK and NNN. Cancers (Basel) 2014; 6:1138-56. [PMID: 24830349 PMCID: PMC4074821 DOI: 10.3390/cancers6021138] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/13/2014] [Accepted: 04/28/2014] [Indexed: 11/17/2022] Open
Abstract
Tobacco use is a major public health problem worldwide. Tobacco-related cancers cause millions of deaths annually. Although several tobacco agents play a role in the development of tumors, the potent effects of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) are unique. Metabolically activated NNK and NNN induce deleterious mutations in oncogenes and tumor suppression genes by forming DNA adducts, which could be considered as tumor initiation. Meanwhile, the binding of NNK and NNN to the nicotinic acetylcholine receptor promotes tumor growth by enhancing and deregulating cell proliferation, survival, migration, and invasion, thereby creating a microenvironment for tumor growth. These two unique aspects of NNK and NNN synergistically induce cancers in tobacco-exposed individuals. This review will discuss various types of tobacco products and tobacco-related cancers, as well as the molecular mechanisms by which nitrosamines, such as NNK and NNN, induce cancer.
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Affiliation(s)
- Jiaping Xue
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA.
| | - Suping Yang
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | - Seyha Seng
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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Wang XY, Jensen-Taubman SM, Keefe KM, Yang D, Linnoila RI. Achaete-scute complex homolog-1 promotes DNA repair in the lung carcinogenesis through matrix metalloproteinase-7 and O(6)-methylguanine-DNA methyltransferase. PLoS One 2012; 7:e52832. [PMID: 23300791 PMCID: PMC3530493 DOI: 10.1371/journal.pone.0052832] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 11/21/2012] [Indexed: 11/19/2022] Open
Abstract
Lung cancer is the leading cause of cancer-related deaths in the world. Achaete-scute complex homolog-1 (Ascl1) is a member of the basic helix-loop-helix (bHLH) transcription factor family that has multiple functions in the normal and neoplastic lung such as the regulation of neuroendocrine differentiation, prevention of apoptosis and promotion of tumor-initiating cells. We now show that Ascl1 directly regulates matrix metalloproteinase-7 (MMP-7) and O(6)-methylguanine-DNA methyltransferase (MGMT). Loss- and gain-of-function experiments in human bronchial epithelial and lung carcinoma cell lines revealed that Ascl1, MMP-7 and MGMT are able to protect cells from the tobacco-specific nitrosamine NNK-induced DNA damage and the alkylating agent cisplatin-induced apoptosis. We also examined the role of Ascl1 in NNK-induced lung tumorigenesis in vivo. Using transgenic mice which constitutively expressed human Ascl1 in airway lining cells, we found that there was a delay in lung tumorigenesis. We conclude that Ascl1 potentially enhances DNA repair through activation of MMP-7 and MGMT which may impact lung carcinogenesis and chemoresistance. The study has uncovered a novel and unexpected function of Ascl1 which will contribute to better understanding of lung carcinogenesis and the broad implications of transcription factors in tobacco-related carcinogenesis.
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Affiliation(s)
- Xiao-Yang Wang
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sandra M. Jensen-Taubman
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kathleen M. Keefe
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Danlei Yang
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - R. Ilona Linnoila
- Cell and Cancer Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
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Christmann M, Kaina B. O(6)-methylguanine-DNA methyltransferase (MGMT): impact on cancer risk in response to tobacco smoke. Mutat Res 2012; 736:64-74. [PMID: 21708177 DOI: 10.1016/j.mrfmmm.2011.06.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 05/23/2011] [Accepted: 06/08/2011] [Indexed: 05/31/2023]
Abstract
Tobacco, smoked, snuffed and chewed, contains powerful mutagens and carcinogens. At least three of them, N-dimethylnitrosamine, N'-nitrosonornicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, attack DNA at the O(6)-position of guanine. The resulting O(6)-alkylguanine adducts are repaired by the suicide enzyme O(6)-methylguanine-DNA methyltransferase (MGMT), which is known to protect against the mutagenic, genotoxic and carcinogenic effects of monofunctional alkylating agents. While in rat liver MGMT was shown to be subject to regulation by genotoxic stress leading to adaptive changes in its activity, in humans evidence of adaptive modulation of MGMT levels is still lacking. Several polymorphisms are known, which are suspected to impact on the risk of developing cancer. In this review we focus on three questions: (a) Has tobacco consumption by smoking or chewing an impact on MGMT expression and MGMT promoter methylation in normal and tumor tissue? (b) Is there an association between MGMT polymorphisms and cancer risk and is this risk related to smoking? (c) Does MGMT protect against tobacco-associated cancer? There are several lines of evidence for an increase of MGMT activity in the normal tissue of smokers compared to non-smokers. Furthermore, in tumors developed in smokers a tendency towards an increase of MGMT expression was found. The data points to the possibility that agents in tobacco smoke are able to trigger upregulation of MGMT in normal and tumor tissue. For MGMT promoter methylation data is conflicting. There is some evidence for an association between MGMT polymorphisms and smoking-induced cancer risk. The key question whether or not MGMT protects against tobacco smoke-induced cancer is difficult to answer since prospective studies on smokers versus non-smokers are lacking and appropriate animal studies with MGMT transgenic mice exposed to the complex mixture of tobacco smoke have not been performed, which indicates the need for further explorations.
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Affiliation(s)
- Markus Christmann
- Institute of Toxicology, University Medical Center Mainz, Mainz, Germany.
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Hang B. Formation and repair of tobacco carcinogen-derived bulky DNA adducts. J Nucleic Acids 2010; 2010:709521. [PMID: 21234336 PMCID: PMC3017938 DOI: 10.4061/2010/709521] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 07/16/2010] [Accepted: 09/17/2010] [Indexed: 01/08/2023] Open
Abstract
DNA adducts play a central role in chemical carcinogenesis. The analysis of formation and repair of smoking-related DNA adducts remains particularly challenging as both smokers and nonsmokers exposed to smoke are repetitively under attack from complex mixtures of carcinogens such as polycyclic aromatic hydrocarbons and N-nitrosamines. The bulky DNA adducts, which usually have complex structure, are particularly important because of their biological relevance. Several known cellular DNA repair pathways have been known to operate in human cells on specific types of bulky DNA adducts, for example, nucleotide excision repair, base excision repair, and direct reversal involving O6-alkylguanine DNA alkyltransferase or AlkB homologs. Understanding the mechanisms of adduct formation and repair processes is critical for the assessment of cancer risk resulting from exposure to cigarette smoke, and ultimately for developing strategies of cancer prevention. This paper highlights the recent progress made in the areas concerning formation and repair of bulky DNA adducts in the context of tobacco carcinogen-associated genotoxic and carcinogenic effects.
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Affiliation(s)
- Bo Hang
- Life Sciences Division, Department of Cancer and DNA Damage Responses, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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11
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An unprecedented nucleic acid capture mechanism for excision of DNA damage. Nature 2010; 468:406-11. [PMID: 20927102 DOI: 10.1038/nature09428] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 08/17/2010] [Indexed: 01/22/2023]
Abstract
DNA glycosylases that remove alkylated and deaminated purine nucleobases are essential DNA repair enzymes that protect the genome, and at the same time confound cancer alkylation therapy, by excising cytotoxic N3-methyladenine bases formed by DNA-targeting anticancer compounds. The basis for glycosylase specificity towards N3- and N7-alkylpurines is believed to result from intrinsic instability of the modified bases and not from direct enzyme functional group chemistry. Here we present crystal structures of the recently discovered Bacillus cereus AlkD glycosylase in complex with DNAs containing alkylated, mismatched and abasic nucleotides. Unlike other glycosylases, AlkD captures the extrahelical lesion in a solvent-exposed orientation, providing an illustration for how hydrolysis of N3- and N7-alkylated bases may be facilitated by increased lifetime out of the DNA helix. The structures and supporting biochemical analysis of base flipping and catalysis reveal how the HEAT repeats of AlkD distort the DNA backbone to detect non-Watson-Crick base pairs without duplex intercalation.
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12
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Peterson LA. Formation, repair, and genotoxic properties of bulky DNA adducts formed from tobacco-specific nitrosamines. J Nucleic Acids 2010; 2010. [PMID: 20871819 PMCID: PMC2943119 DOI: 10.4061/2010/284935] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 07/08/2010] [Indexed: 12/24/2022] Open
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N′-nitrosonornicotine (NNN) are tobacco-specific nitrosamines present in tobacco products and smoke. Both compounds are carcinogenic in laboratory animals, generating tumors at sites comparable to those observed in smokers. These Group 1 human carcinogens are metabolized to reactive intermediates that alkylate DNA. This paper focuses on the DNA pyridyloxobutylation pathway which is common to both compounds. This DNA route generates 7-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxyguanosine, O2-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxycytosine, O2-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxythymidine, and O6-[4-(3-pyridyl)-4-oxobut-1-yl]-2′-deoxyguanosine as well as unstable adducts which dealkylate to release 4-hydroxy-1-{3-pyridyl)-1-butanone or depyriminidate/depurinate to generate abasic sites. There are multiple repair pathways responsible for protecting against the genotoxic effects of these adducts, including adduct reversal as well as base and nucleotide excision repair pathways. Data indicate that several DNA adducts contribute to the overall mutagenic properties of pyridyloxobutylating agents. Which adducts contribute to the carcinogenic properties of this pathway are likely to depend on the biochemistry of the target tissue.
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Affiliation(s)
- Lisa A Peterson
- Division of Environmental Health Sciences, Masonic Cancer Center, Mayo Mail Code 806, 420 Delaware St SE, Minneapolis, MN 55455, USA
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Li L, Perdigao J, Pegg AE, Lao Y, Hecht SS, Lindgren BR, Reardon JT, Sancar A, Wattenberg EV, Peterson LA. The influence of repair pathways on the cytotoxicity and mutagenicity induced by the pyridyloxobutylation pathway of tobacco-specific nitrosamines. Chem Res Toxicol 2009; 22:1464-72. [PMID: 19601657 PMCID: PMC2787827 DOI: 10.1021/tx9001572] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tobacco-specific nitrosamines, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine, are considered to be human carcinogens. Both compounds are metabolized to pyridyloxobutylating intermediates that react with DNA to form adducts such as 7-[4-(3-pyridyl)-4-oxobut-1-yl]guanine, O(2)-[4-(3-pyridyl)-4-oxobut-1-yl]cytosine, O(2)-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxythymidine (O(2)-pobdT), O(6)-[4-(3-pyridyl)-4-oxobut-1-yl]-2'-deoxyguanosine (O(6)-pobdG), and 4-hydroxy-1-(3-pyridyl)-1-butanone-releasing adducts. The role of specific DNA adducts in the overall genotoxic activity of the pyridyloxobutylation pathway is not known. One adduct, O(6)-pobdG, is mutagenic. To characterize the mutagenic and cytotoxic properties of pyridyloxobutyl DNA adducts, the impact of DNA repair pathways on the cytotoxic and mutagenic properties of the model pyridyloxobutylating agent, 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc), was investigated in Chinese hamster ovary cell lines proficient or deficient in O(6)-alkylguanine DNA alkyltransferase (AGT), deficient in both AGT and base excision repair (BER), or deficient in both AGT and nucleotide excision repair (NER). The repair of the four pyridyloxobutyl DNA adducts was determined in the same cell lines via sensitive LC-MS/MS methods. NNKOAc was more cytotoxic in the cell lines lacking AGT, BER, and NER repair pathways. It also induced more mutations in the hprt gene in the BER- and NER-deficient cell lines. However, AGT expression did not influence NNKOAc's mutagenicity despite efficient repair of O(6)-pobdG. Analysis of the hprt mutational spectra indicated that NNKOAc primarily caused point mutations at AT base pairs. GC to AT transition mutations were a minor contributor to the overall mutation spectrum, providing a rationale for the observation that AGT does not protect against the overall mutagenic properties of NNKOAc in this model system. The only adduct affected by the absence of effective NER was O(2)-pobdT. Slower repair of O(2)-pobdT in NER-deficient cells was associated with increased AT to TA transversion mutations, supporting the hypothesis that these mutations are caused by O(2)-pobdT. Together, these data support a hypothesis that the pyridyloxobutylation pathway generates multiple mutagenic and toxic adducts.
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Affiliation(s)
- Li Li
- Division of Environmental Health Sciences and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Brown PJ, Massey TE. In vivo treatment with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces organ-specific alterations in in vitro repair of DNA pyridyloxobutylation. Mutat Res 2009; 663:15-21. [PMID: 19152800 DOI: 10.1016/j.mrfmmm.2008.12.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 12/18/2008] [Accepted: 12/19/2008] [Indexed: 05/27/2023]
Abstract
To investigate the mechanisms responsible for inter-organ differences in susceptibility to 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK)-induced carcinogenesis, the objectives were to compare DNA repair activities of extracts from mouse lung and liver towards NNK-induced pyridyloxobutyl (POB) damage to plasmid DNA, and to determine if and the mechanism by which in vivo NNK treatment of mice alters DNA repair. Repair activity of POB adducts was three times greater in mouse liver than in mouse lung (P<0.05). Repair activities of lung extracts from mice 4 or 24 h post-NNK treatment were 30-45% those of control (P<0.05). Conversely, POB adduct repair was 2-3 times higher in liver extracts from NNK treated mice than in controls (4 h, 24 h, P<0.05). NNK treatment also decreased incision of POB adducts by 92% (4 h, P<0.05) in lung and increased incision by 169% (24 h, P<0.05) in liver. NNK decreased immunoreactive levels of the incision protein RPA in lung (P<0.05) 4 h post-treatment but increased immunoreactive lung RPA and XPB after 24 h (P<0.05). In liver, levels of immunoreactive proteins, XPA, XPB and ERCC1 were increased after NNK treatment (24 h, P<0.05). Binding of XPA and XPB from liver extracts to POB adducts increased following NNK treatment, while binding of XPA and XPB from lung decreased (4 h, 24 h). These results suggest that lower incision activity of nucleotide excision repair and NNK-mediated alterations in levels and activities of key incision proteins contribute to the relative susceptibility of mouse lung to NNK-induced carcinogenesis.
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Affiliation(s)
- Pamela J Brown
- Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario, Canada
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Clague J, Shao L, Lin J, Chang S, Zhu Y, Wang W, Wood CG, Wu X. Sensitivity to NNKOAc is associated with renal cancer risk. Carcinogenesis 2009; 30:706-10. [PMID: 19237609 DOI: 10.1093/carcin/bgp045] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cigarette smoking has been investigated as a major risk factor for renal cell carcinoma (RCC). 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is one of the most abundant carcinogenic N-nitrosamines present in cigarette smoke. However, the association between repair capacity of NNK-induced DNA damage and RCC risk remains unknown. We used the comet assay to assess whether sensitivity to a NNK precursor 4-[(acetoxymethyl) nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) induced DNA damage, which partly reflects host sensitivity to NNK, was associated with increased risk of RCC in a population-based case-control study. The study included 95 RCC cases and 188 matched controls. Epidemiologic data were collected via in-person interview. Baseline and NNK-induced DNA damage in peripheral blood lymphocytes were measured using the comet assay and quantified by the Olive tail moment. The NNKOAc-induced median Olive tail moments were significantly higher in cases than in controls (2.27 versus 1.76, P = 0.002). Using the 75th percentile Olive tail moments of the controls as the cutoff point, we found that higher levels of NNKOAc-induced DNA damage were associated with a significantly increased risk of RCC [odds ratio, 2.06; 95% confidence interval, 1.17-3.61]. In quartile analysis, there was a dose-response association between NNKOAc-induced damage and risk of RCC (P for trend, 0.006). Our data strongly suggest that higher levels of NNKOAc-induced damage are associated with higher risks of RCC. Future studies with larger sample sizes are warranted to further investigate whether repair of NNKOAc-induced damage, as quantified by the comet assay, could be used as a predictive marker for RCC risk.
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Affiliation(s)
- Jessica Clague
- Department of Epidemiology, University of Texas M. D. Anderson Cancer Center, 1155 Pressler, unit 1340, Houston, TX 77030, USA
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Havla J, Hill C, Abdel-Rahman S, Richter E. Evaluation of the mutagenic effects of myosmine in human lymphocytes using the HPRT gene mutation assay. Food Chem Toxicol 2009; 47:237-41. [DOI: 10.1016/j.fct.2008.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/31/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
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