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Li Y, Hecht SS. Metabolism and DNA Adduct Formation of Tobacco-Specific N-Nitrosamines. Int J Mol Sci 2022; 23:5109. [PMID: 35563500 PMCID: PMC9104174 DOI: 10.3390/ijms23095109] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/29/2022] [Accepted: 04/30/2022] [Indexed: 01/06/2023] Open
Abstract
The tobacco-specific N-nitrosamines 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) always occur together and exclusively in tobacco products or in environments contaminated by tobacco smoke. They have been classified as "carcinogenic to humans" by the International Agency for Research on Cancer. In 1998, we published a review of the biochemistry, biology and carcinogenicity of tobacco-specific nitrosamines. Over the past 20 years, considerable progress has been made in our understanding of the mechanisms of metabolism and DNA adduct formation by these two important carcinogens, along with progress on their carcinogenicity and mutagenicity. In this review, we aim to provide an update on the carcinogenicity and mechanisms of the metabolism and DNA interactions of NNK and NNN.
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Affiliation(s)
- Yupeng Li
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA;
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA;
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Chemopreventive Role of Apigenin against the Synergistic Carcinogenesis of Human Papillomavirus and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone. Biomedicines 2020; 8:biomedicines8110472. [PMID: 33158065 PMCID: PMC7694184 DOI: 10.3390/biomedicines8110472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 10/26/2020] [Accepted: 10/31/2020] [Indexed: 12/15/2022] Open
Abstract
Tobacco smoke and human papillomavirus (HPV) are both crucial causes of cancer, and their cooperative carcinogenesis has drawn more attention in recent years. Apigenin (AP), a typical flavonoid abundantly found in flowers of plants, vegetables, and fruits, has been demonstrated to exert an anti-carcinogenic effect on various types of cancer. In this study, we investigated the capability of AP against malignant transformation and DNA damage of immortalized human esophageal epithelial (SHEE) cells induced by the synergism of HPV18 and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The results indicated that the enhancement of migration, invasion, and proliferation ability of SHEE cells induced by HPV and NNK could be effectively inhibited by AP. Moreover, the levels of pyridyloxybutylated (POB)-DNA adducts induced by NNK via P450-catalyzed metabolic activation could also be significantly suppressed by AP. Further analyses on the molecular mechanism revealed that AP inhibited the synergistic carcinogenesis of NNK and HPV on SHEE cells by reducing the expression of mutp53, CDK4, Cyclin D1, and p-Rb (Ser 780), increasing caspase-3 activity, thereby arresting the cell cycle at G1 phase and promoting apoptosis of SHEE cells. We hypothesize that the decrease in NNK-induced POB-DNA adduct levels is related to the deactivation of P450 by AP, which needs to be confirmed in future studies. This study highlights that AP may be employed as a promising chemopreventive agent against cancers in smokers with an HPV infection.
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Zhuang Z, Li J, Sun G, Cui X, Zhang N, Zhao L, Chan PKS, Zhong R. Synergistic Effect between Human Papillomavirus 18 and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone on Malignant Transformation of Immortalized SHEE Cells. Chem Res Toxicol 2019; 33:470-481. [PMID: 31874558 DOI: 10.1021/acs.chemrestox.9b00371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhuochen Zhuang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Jintao Li
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Guohui Sun
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Xin Cui
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Na Zhang
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Lijiao Zhao
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
| | - Paul K. S. Chan
- Departments of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
| | - Rugang Zhong
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Sciences and Bioengineering, Beijing University of Technology, Beijing 100124, China
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Khariwala SS, Ma B, Ruszczak C, Carmella SG, Lindgren B, Hatsukami DK, Hecht SS, Stepanov I. High Level of Tobacco Carcinogen-Derived DNA Damage in Oral Cells Is an Independent Predictor of Oral/Head and Neck Cancer Risk in Smokers. Cancer Prev Res (Phila) 2017; 10:507-513. [PMID: 28679497 PMCID: PMC5712492 DOI: 10.1158/1940-6207.capr-17-0140] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/06/2017] [Accepted: 06/30/2017] [Indexed: 02/07/2023]
Abstract
Exposure to tobacco-specific nitrosamines (TSNA) and polycyclic aromatic hydrocarbons (PAH) is recognized to play an important role in the development of oral/head and neck squamous cell cancer (HNSCC). We recently reported higher levels of TSNA-associated DNA adducts in the oral cells of smokers with HNSCC as compared with cancer-free smokers. In this study, we further investigated the tobacco constituent exposures in the same smokers to better understand the potential causes for the elevated oral DNA damage in smokers with HNSCC. Subjects included cigarette smokers with HNSCC (cases, n = 30) and cancer-free smokers (controls, n = 35). At recruitment, tobacco/alcohol use questionnaires were completed, and urine and oral cell samples were obtained. Analysis of urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and N'-Nitrosonornicotine (NNN; TSNA biomarkers), 1-hydroxypyrene (1-HOP, a PAH), cotinine, 3'-hydroxycotinine, and the nicotine metabolite ratio (NMR) were performed. Cases and controls differed in mean age, male preponderance, and frequency of alcohol consumption (but not total alcoholic drinks). Univariate analysis revealed similar levels of NNN, 1-HOP, and cotinine between groups but, as reported previously, significantly higher DNA adduct formation in the cases. Multiple regression adjusting for potential confounders showed persistent significant difference in DNA adduct levels between cases and controls [ratio of geometric means, 20.0; 95% CI, 2.7-148.6). Our cohort of smokers with HNSCC demonstrates higher levels of TSNA-derived oral DNA damage in the setting of similar exposure to nicotine and tobacco carcinogens. Among smokers, DNA adduct formation may act as a predictor of eventual development of HNSCC that is independent of carcinogen exposure indicators. Cancer Prev Res; 10(9); 507-13. ©2017 AACRSee related editorial by Johnson and Bauman, p. 489.
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Affiliation(s)
- Samir S Khariwala
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, Minnesota.
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Bin Ma
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Chris Ruszczak
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Steven G Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Bruce Lindgren
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | | | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Environmental Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota
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Nilsson R. Use of rodent data for cancer risk assessment of smokeless tobacco in the regulatory context. Regul Toxicol Pharmacol 2017. [PMID: 28625913 DOI: 10.1016/j.yrtph.2017.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To support risk management decisions, information from different fields has been integrated in this presentation to provide a realistic quantitative cancer risk assessment of smokeless tobacco. Smoking among Swedish men is currently below 10%, while about 20% use a special smokeless tobacco (snus) as a substitute for cigarettes. Epidemiological data and molecular biomarkers demonstrate that rodent bioassays with tobacco specific nitrosamines (TSNA) overestimate cancer risk from snus by more than one order of magnitude. The underlying reasons are discussed. DNA damage constitutes a necessary, although not sufficient prerequisite for cancer initiation. Individuals who have not used tobacco exhibit DNA lesions identical with those induced by TSNA. No increase above this adduct background can be shown from snus, and extensive epidemiological studies in Sweden have failed to demonstrate elevated cancer risks even in long term users. A "bench mark" for acceptable risk of 1/10(6) derived from rodent data has been suggested when regulating snus. By relating similarly derived estimates for some food contaminants, the implementation even of a limit of 1/10(4) may be unrealistic. The management of smokeless tobacco products has rarely been based on a scientifically sound risk assessment, where attention is given to the outstandingly higher hazards associated with smoking.
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Affiliation(s)
- Robert Nilsson
- Vinča Institute of Nuclear Sciences, Laboratory for Physical Chemistry, University of Belgrade, Vinča, Serbia.
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Ma B, Ruszczak C, Jain V, Khariwala SS, Lindgren B, Hatsukami DK, Stepanov I. Optimized Liquid Chromatography Nanoelectrospray-High-Resolution Tandem Mass Spectrometry Method for the Analysis of 4-Hydroxy-1-(3-pyridyl)-1-butanone-Releasing DNA Adducts in Human Oral Cells. Chem Res Toxicol 2016; 29:1849-1856. [PMID: 27618873 PMCID: PMC5148665 DOI: 10.1021/acs.chemrestox.6b00254] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Metabolic activation of the carcinogenic tobacco-specific N-nitrosamines leads to the formation of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts. We recently developed a liquid chromatography (LC)-tandem mass spectrometry (MS/MS) method for the analysis of HPB-releasing DNA adducts in human oral cells. However, given the limited amounts of DNA that can be extracted from oral cells, higher sensitivity and selectivity are required for the reliable analysis of these adducts in future studies. We have developed a new sensitive LC-nanoelectrospray ionization-high-resolution MS/MS method for the analysis of HPB-releasing DNA adducts in oral cells. A new procedure was also developed for guanine analysis by LC-MS/MS. The detection limit of the developed assay is 5 amol, and the limit of quantitation is 0.35 fmol HPB on-column, starting with 50 pg of DNA. The method was tested by analyzing oral samples from 65 smokers, including 30 head and neck squamous cell carcinoma (HNSCC) patients and 35 cancer-free controls. In all smokers, the levels of HPB-releasing DNA adducts averaged 6.22 ± 16.18 pmol/mg DNA, with significant interindividual variation being consistent with previous reports. The median HPB-releasing DNA adduct level was 6.6 times greater for those with HNSCC than for smokers without HNSCC (p = 0.002). The developed highly sensitive and selective method is a valuable tool for future measurement of HPB-releasing DNA adducts in tobacco users, which can potentially provide critical insights for the identification of individuals at risk for cancer.
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Affiliation(s)
- Bin Ma
- Masonic Cancer Center, University of Minnesota
| | | | - Vipin Jain
- Masonic Cancer Center, University of Minnesota
| | - Samir S. Khariwala
- Masonic Cancer Center, University of Minnesota
- Department of Otolaryngology, Head and Neck Surgery, University of Minnesota
| | | | | | - Irina Stepanov
- Masonic Cancer Center, University of Minnesota
- Division of Environmental Health Sciences, University of Minnesota
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Liu S, Wang Y. Mass spectrometry for the assessment of the occurrence and biological consequences of DNA adducts. Chem Soc Rev 2015; 44:7829-54. [PMID: 26204249 PMCID: PMC4787602 DOI: 10.1039/c5cs00316d] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exogenous and endogenous sources of chemical species can react, directly or after metabolic activation, with DNA to yield DNA adducts. If not repaired, DNA adducts may compromise cellular functions by blocking DNA replication and/or inducing mutations. Unambiguous identification of the structures and accurate measurements of the levels of DNA adducts in cellular and tissue DNA constitute the first and important step towards understanding the biological consequences of these adducts. The advances in mass spectrometry (MS) instrumentation in the past 2-3 decades have rendered MS an important tool for structure elucidation, quantification, and revelation of the biological consequences of DNA adducts. In this review, we summarized the development of MS techniques on these fronts for DNA adduct analysis. We placed our emphasis of discussion on sample preparation, the combination of MS with gas chromatography- or liquid chromatography (LC)-based separation techniques for the quantitative measurement of DNA adducts, and the use of LC-MS along with molecular biology tools for understanding the human health consequences of DNA adducts. The applications of mass spectrometry-based DNA adduct analysis for predicting the therapeutic outcome of anti-cancer agents, for monitoring the human exposure to endogenous and environmental genotoxic agents, and for DNA repair studies were also discussed.
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Affiliation(s)
- Shuo Liu
- Environmental Toxicology Graduate Program, University of California, Riverside, California, USA
| | - Yinsheng Wang
- Environmental Toxicology Graduate Program, University of California, Riverside, California, USA and Department of Chemistry, University of California, Riverside, CA 92521-0403, USA.
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Deibel E, Klink D, Schmitz OJ. New derivatization strategies for the ultrasensitive analysis of non-aromatic analytes with APLI-TOF-MS. Anal Bioanal Chem 2015. [DOI: 10.1007/s00216-015-8908-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Stepanov I, Muzic J, Le CT, Sebero E, Villalta P, Ma B, Jensen J, Hatsukami D, Hecht SS. Analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in human exfoliated oral mucosa cells by liquid chromatography-electrospray ionization-tandem mass spectrometry. Chem Res Toxicol 2013; 26:37-45. [PMID: 23252610 PMCID: PMC3631465 DOI: 10.1021/tx300282k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Quantitation of DNA adducts could provide critical information on the relationship between exposure to tobacco smoke and cancer risk in smokers. In this study, we developed a robust and sensitive liquid chromatography-tandem mass spectrometry method for the analysis of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing DNA adducts in human oral cells, a noninvasive source of DNA for biomarker studies. Isolated DNA undergoes acid hydrolysis, after which samples are purified by solid-phase extraction and analyzed by LC-ESI-MS/MS. The developed method was applied to the analysis of samples obtained via collection with a commercial mouthwash from 30 smokers and 15 nonsmokers. In smokers, the levels of HPB-releasing DNA adducts averaged 12.0 pmol HPB/mg DNA (detected in 20 out of 28 samples with quantifiable DNA yield), and in nonsmokers, the levels of adducts averaged 0.23 pmol/mg DNA (detected in 3 out of 15 samples). For the 30 smoking subjects, matching buccal brushings were also analyzed, and HPB-releasing DNA adducts were detected in 24 out of 27 samples with quantifiable DNA yield, averaging 44.7 pmol HPB/mg DNA. The levels of adducts in buccal brushings correlated with those in mouthwash samples of smokers (R = 0.73, p < 0.0001). Potentially, the method can be applied in studies of individual susceptibility to tobacco-induced cancers in humans.
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Affiliation(s)
- Irina Stepanov
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
- Division of Environmental Health Sciences, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - John Muzic
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Chap T. Le
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Erin Sebero
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Peter Villalta
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Bin Ma
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Joni Jensen
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Dorothy Hatsukami
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware Street SE, Minneapolis, Minnesota 55455
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Kandiah M, Urban PL. Advances in ultrasensitive mass spectrometry of organic molecules. Chem Soc Rev 2013; 42:5299-322. [DOI: 10.1039/c3cs35389c] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Phillips DH, Venitt S. DNA and protein adducts in human tissues resulting from exposure to tobacco smoke. Int J Cancer 2012; 131:2733-53. [PMID: 22961407 DOI: 10.1002/ijc.27827] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 09/03/2012] [Indexed: 12/15/2022]
Abstract
Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.
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Affiliation(s)
- David H Phillips
- Analytical and Environmental Sciences Division, MRC-HPA Centre for Environment and Health, King's College London, London, United Kingdom.
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Böhm F, Schmid D, Denzinger S, Wieland WF, Richter E. DNA adducts of ortho-toluidine in human bladder. Biomarkers 2010; 16:120-8. [PMID: 21117897 DOI: 10.3109/1354750x.2010.534556] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND 4-Aminobiphenyl (4-ABP) and o-toluidine are known human bladder carcinogens, but only 4-ABP-releasing DNA adducts are known. METHODS Determination of 4-ABP and o-toluidine-releasing DNA adducts in epithelial and submucosal bladder tissues of sudden death victims (SDV: n=46), and bladder tumours (n=12) by gas chromatography/mass spectrometry. RESULTS Above background, 4 and 11 of 12 tumour samples contained adducts of 4-ABP (0.057 ± 0.125 fmol/µg DNA) and o-toluidine (8.72 ± 4.49 fmol/µg DNA), respectively. Lower adduct levels were present in both epithelial and submucosal bladder tissues of SDV (4-ABP: 0.011 ± 0.022 and 0.019 ± 0.047 fmol/µg DNA; o-toluidine: 0.24 ± 0.63 and 0.27 ± 0.70 fmol/µg DNA). CONCLUSION Detection of o-toluidine-releasing DNA adducts support the carcinogenicity of o-toluidine in the human bladder.
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Affiliation(s)
- Francine Böhm
- Walther Straub Institute, Department of Toxicology, Ludwig-Maximilians-University, Nussbaumstrasse 26, D-80336 Munich, Germany
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Schütte-Borkovec K, Heppel CW, Heling AK, Richter E. Analysis of myosmine, cotinine and nicotine in human toenail, plasma and saliva. Biomarkers 2009; 14:278-84. [PMID: 19476410 DOI: 10.1080/13547500902898164] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Myosmine is a minor tobacco alkaloid with widespread occurrence in the human diet. Myosmine is genotoxic in human cells and is readily nitrosated and peroxidated yielding reactive intermediates with carcinogenic potential. For biomonitoring of short-term and long-term exposure, analytical methods were established for determination of myosmine together with nicotine and cotinine in plasma, saliva and toenail by gas chromatography-mass spectrometry (GC/MS). Validation of the method with samples of 14 smokers and 10 non-smokers showed smoking-dependent differences of myosmine in toenails (66 +/- 56 vs 21 +/- 15 ng g(-1), p <0.01) as well as saliva (2.54 +/- 2.68 vs 0.73 +/- 0.65 ng ml(-1), p <0.01). However, these differences were much smaller than those with nicotine (1971 +/- 818 vs 132 +/- 82 ng g(-1), p <0.0001) and cotinine (1237 +/- 818 vs <35 ng g(-1)) in toenail and those of cotinine (97.43 +/- 84.54 vs 1.85 +/- 4.50 ng ml(-1), p <0.0001) in saliva. These results were confirmed in plasma samples from 84 patients undergoing gastro-oesophageal endoscopy. Differences between 25 smokers and 59 non-smokers are again much lower for myosmine (0.30 +/- 0.35 vs 0.16 +/- 0.18 ng ml(-1), p <0.05) than for cotinine (54.67 +/- 29.63 vs 0.61 +/- 1.82 ng ml(-1), p <0.0001). In conclusion, sources other than tobacco contribute considerably to the human body burden of myosmine.
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