Mass spectrometric analysis of tobacco-specific nitrosamine-DNA adducts in smokers and nonsmokers (original) (raw)
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Tobacco-specific nitrosamine adducts: studies in laboratory animals and humans
Environmental Health Perspectives, 1993
This paper describes quantitation of human hemoglobin and DNA adducts of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). NNK and NNN are believed to be involved in cancers ofthe lung, esophagus, onl cavity, and pancreas in people who use tobacco products. The adduct dosimetry method employs GC-MS for quantitation of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) released by mild base hydrolysis of hemoglobin or acid hydrolysis of DNA as a biochemical marker of the pyridyloxobutylation metabolic activation pathway. Approximately 22% of smokers (n = 101) had elevated levels of HPB released from hemoglobin (range, 200-1600 fmole/g Hb). Adduct levels in snuff dippers ranged from 2001800 fmole/g Hb. HPB levels in nonsmokers were generally below the detection limit. Acid hydrolysis of lung and tracheal DNA obtained at autopsy and analysis for released HPB revealed levels ranging up to 50 fmole/mg DNA in smokers; the adduct was not detected in nonsmokers. These findings are consistent with data generated in studies of adduct formation by NNK in rats. The biological significance of the HPB-releasing DNA pyridylksobutylation pathway was compared to that of the DNA methylation pathway in the A/J mouse. These studies demonstrated that the persistence of O'-methylguanine in lung DNA is critical for tumorigenesis by NNK and that pyridylaobutylation enhances both peristence of O-methylguanine and tumorigenesis by acetoxymethylmethylnitrosamine. In the rat, the relative roles of methylation and pyridyloxobutylation in lung tumorigenesis by NNK are not as clearly defined. Although the biological significance of DNA methylation in NNK tumorigenesis is well characterized, dosimetry studies of tobacco-specific nitrosamines in humans should be carried out using biochemical markers of the pyridyloxobutylation pathway because of their specificity to tobacco products.
DNA and hemoglobin adducts as markers of metabolic activation of tobacco-specific carcinogens
Cancer research, 1992
Lung cancer is now the leading cause of excess mortality among smokers in the United States. The ability to identify smokers with the greatest risk of developing lung cancer would be an important step in reducing lung cancer mortality. Tobacco-specific nitrosamines such as 4-(methylnitrosamino)-l-(3-pyridyl)-l-butanone and /V'-nitrosonornicotine ' Presented at the
Metabolism of tobacco-specific N-nitrosamines by cultured human tissues
Proceedings of the National Academy of Sciences, 1983
N'-Nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are present in cigarette smoke and snuff'and are carcinogens in laboratory animals. In tobacco smokers, the buccal mucosa, trachea, esophagus, bronchi, and peripheral lung are exposed to smoke containing significant amounts of these N-nitrosamines. The results of 'the present study demonstrate that explants of these tissues as well as of the urinary bladder have the capacity to metabolize NNN and NNK by a-carbon hydroxylation. This metabolic pathway yields alkyldiazohydroxides, which are reactive and DNA-damaging electrophiles. The extent of a-carbon hydroxylation of NNN and NNK in human tissues was only 1/10th to 1/100th of that in animal tissues. Although the levels of a-carbon hydroxylation of NNN among different tissues of the same individual were similar, a 10-fold variation among individuals was observed. Reduction of the NNK carbonyl group was a major metabolic pathway observed with all human explants and may occur in the surface epithelia of the respiratory tract of smokers. These results provide further evidence that tobacco-specific N-nitrosamines could play a role in cancers related to the smoking and chewing of tobacco.
Biomarkers for human uptake and metabolic activation of tobacco-specific nitrosamines
Cancer research, 1994
Tobacco-specific nitrosamines are a group of carcinogens formed from nicotine and related tobacco alkaloids. Two of these compounds, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine, are believed to be involved as causative agents for cancers of the lung, oral cavity, esophagus, and pancreas associated with the use of tobacco products. The goal of the studies described here is to develop biomarkers which will allow us to understand the uptake, metabolic activation, and detoxification of these carcinogens in humans. Two metabolites of NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronide, have been identified and quantified in human urine. These metabolites allow assessment of NNK uptake in smokers, tobacco chewers, and people exposed to environmental tobacco smoke. NNK and N'-nitrosonornicotine form hemoglobin and DNA adducts upon metabolic activation by alpha-hydroxylation. These adducts release 4-hydroxy-1-(3-pyridyl)-1-butano...
PubMed, 1990
Hemoglobin adducts of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1(3-pyridyl)-1-butanone and N'-nitrosonornicotine were quantified in blood samples collected from snuff dippers, smokers, and nonsmokers. Mild base treatment of hemoglobin adducted by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone or N'-nitrosonornicotine releases 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB). HPB was enriched by solvent partitioning and derivatized to its pentafluorobenzoate. After purification by high performance liquid chromatography, HPB-pentafluorobenzoate was analyzed by capillary column gas chromatography with detection by negative ion chemical ionization mass spectrometry and selected ion monitoring. [4,4-D2]HPB was used as internal standard. The detection limit for HPB-pentafluorobenzoate was approximately 100 amol/injection or 5 fmol/g hemoglobin. Mean adduct levels (fmol HPB/g hemoglobin) were 517 +/- 538 (SD) in snuff dippers, 79.6 +/- 189 in smokers, and 29.3 +/- 25.9 in nonsmokers. Adduct levels in snuff dippers and in a subgroup of smokers were higher than would have been predicted solely based on estimates of exposure to tobacco-specific nitrosamines. The results of this study provide the first measurements of tobacco-specific nitrosamine hemoglobin adducts in humans and suggest new approaches to understanding the metabolic activation of 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine in humans.
Cancer Epidemiology Biomarkers & Prevention, 2010
Background: Smokers are exposed to significant doses of carcinogens, including tobacco-specific nitrosamines (TSNA). Previous studies have shown significant global differences in the levels of TSNAs in cigarette smoke because of the variation in tobacco blending and curing practices around the world. Methods: Mouth-level exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) measured in cigarette butts and urinary concentrations of its major metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1butanol (NNAL) were examined among 126 daily smokers in four countries over a 24-hour study period. Results: As mouth-level exposure of NNK increased, the urinary NNAL increased even after adjustment for other covariates (β = 0.46, P = 0.004). The relationship between mouth-level exposure to nicotine and its salivary metabolite, cotinine, was not statistically significant (β = 0.29, P = 0.057), likely because of the very limited range of differences in mouth-level nicotine exposure in this population. Conclusions: We have shown a direct association between the 24-hour mouth-level exposure of NNK resulting from cigarette smoking and the concentration of its primary metabolite, NNAL, in the urine of smokers. Internal dose concentrations of urinary NNAL are significantly lower in smokers in countries that have lower TSNA levels in cigarettes such as Canada and Australia in contrast to countries that have high levels of these carcinogens in cigarettes, such as the United States. Impact: Lowering the levels of NNK in the mainstream smoke of cigarettes through the use of specific tobacco types and known curing practices can significantly affect the exposure of smokers to this known carcinogen. Cancer Epidemiol Biomarkers Prev; 19(6); 1389-98. ©2010 AACR.
Tobacco-specific N-nitrosamines in tobacco and mainstream smoke of Indian cigarettes
Food and Chemical Toxicology, 1991
Different brands of Indian cigarettes were analysed, by gas chromatography-thermal energy analysis, for the presence of carcinogenic tobacco-specific N-nitrosamines (TSNA) in both tobacco and mainstream smoke. Preformed TSNA in cigarette tobacco ranged between 68 and 730 ng N-nitrosonornicotine (NNN)/cigarette, between 19 and 174ng 4-(N-nitrosomethylamino)-l-(3-pyridyl)-l-butanone (NNK)/cigarette and between 98 and 519ng N-nitrosoanabasine (NAB) together with N-nitrosoanatabine (NAT)/cigarette. The amounts of NNN, NNK and NAB/NAT in mainstream smoke were 11-156, 7-73 and 17-146 ng/cigarette, respectively.
Tobacco Control, 2011
Background Modification of tobacco curing methods and other changes in cigarette manufacturing techniques could substantially reduce the levels of tobacco-specific nitrosamines (TSNA), a group of potent carcinogens, in cigarette smoke. In 1999, two major US cigarette manufacturers stated their intent to move towards using tobaccos low in TSNA. There is no information available on current TSNA levels in tobacco of various cigarettes available in the US, particularly in the newer varieties introduced over the past decade. Methods Seventeen brands of cigarettes were purchased in April of 2010 from retail stores in Minnesota. TSNA levels were measured in the tobacco filler and smoke of these cigarettes. Results In all brands, the sum of two potent carcinogenic TSNA-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine-in cigarette filler averaged 2.54 (±1.05) mg/g tobacco. This value is virtually identical to the sum of these two carcinogens reported for the tobacco of a US filtered cigarette in 1979. TSNA levels in smoke positively correlated with those in tobacco filler of the same cigarettes. Conclusion We found no indication that any meaningful attempt was made to reduce or at least control TSNA levels in the new varieties of the popular brands Marlboro and Camel introduced over the last decade. In light of the recently granted regulatory authority to the FDA over tobacco products, regulation of TSNA levels in cigarette tobacco should be strongly considered to reduce the levels of these potent carcinogens in cigarette smoke.
Tobacco Control, 2012
Background Modification of tobacco curing methods and other changes in cigarette manufacturing techniques could substantially reduce the levels of tobacco-specific nitrosamines (TSNA), a group of potent carcinogens, in cigarette smoke. In 1999, two major US cigarette manufacturers stated their intent to move towards using tobaccos low in TSNA. There is no information available on current TSNA levels in tobacco of various cigarettes available in the US, particularly in the newer varieties introduced over the past decade. Methods Seventeen brands of cigarettes were purchased in April of 2010 from retail stores in Minnesota. TSNA levels were measured in the tobacco filler and smoke of these cigarettes. Results In all brands, the sum of two potent carcinogenic TSNA-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine-in cigarette filler averaged 2.54 (±1.05) mg/g tobacco. This value is virtually identical to the sum of these two carcinogens reported for the tobacco of a US filtered cigarette in 1979. TSNA levels in smoke positively correlated with those in tobacco filler of the same cigarettes. Conclusion We found no indication that any meaningful attempt was made to reduce or at least control TSNA levels in the new varieties of the popular brands Marlboro and Camel introduced over the last decade. In light of the recently granted regulatory authority to the FDA over tobacco products, regulation of TSNA levels in cigarette tobacco should be strongly considered to reduce the levels of these potent carcinogens in cigarette smoke.