TY - JOUR
T1 - DNA adducts of the tobacco carcinogens 2-amino-9 H -pyrido[2,3- b ]indole and 4-aminobiphenyl are formed at environmental exposure levels and persist in human hepatocytes
AU - Nauwelaërs, Gwendoline
AU - Bellamri, Medjda
AU - Fessard, Valérie
AU - Turesky, Robert J.
AU - Langouët, Sophie
PY - 2013/9/16
Y1 - 2013/9/16
N2 - Aromatic amines and structurally related heterocyclic aromatic amines (HAAs) are produced during the combustion of tobacco or during the high-temperature cooking of meat. Exposure to some of these chemicals may contribute to the etiology of several common types of human cancers. 2-Amino-9H-pyrido[2,3-b]indole (AαC) is the most abundant HAA formed in mainstream tobacco smoke: it arises in amounts that are 25-100 times greater than the levels of the arylamine, 4-aminobiphenyl (4-ABP), a human carcinogen. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a prevalent HAA formed in cooked meats. AαC and MeIQx are rodent carcinogens; however, their carcinogenic potency in humans is unknown. A preliminary assessment of the carcinogenic potential of these HAAs in humans was conducted by examining the capacity of primary human hepatocytes to form DNA adducts of AαC and MeIQx, in comparison to 4-ABP, followed by the kinetics of DNA adduct removal by cellular enzyme repair systems. The principal DNA adducts formed were N-(deoxyguanosin-8-yl) (dG-C8) adducts. Comparable levels of DNA adducts were formed with AαC and 4-ABP, whereas adduct formation was ∼5-fold lower for MeIQx. dG-C8-AαC and dG-C8-4-ABP were formed at comparable levels in a concentration-dependent manner in human hepatocytes treated with procarcinogens over a 10,000-fold concentration range (1 nM-10 μM). Pretreatment of hepatocytes with furafylline, a selective inhibitor of cytochrome P450 1A2, resulted in a strong diminution of DNA adducts signifying that P450 1A2 is a major P450 isoform involved in bioactivation of these procarcinogens. The kinetics of adduct removal varied for each hepatocyte donor. Approximately half of the DNA adducts were removed within 24 h of treatment; however, the remaining lesions persisted over 5 days. The high levels of AαC present in tobacco smoke and its propensity to form persistent DNA adducts in human hepatocytes suggest that AαC can contribute to DNA damage and the risk of hepatocellular cancer in smokers.
AB - Aromatic amines and structurally related heterocyclic aromatic amines (HAAs) are produced during the combustion of tobacco or during the high-temperature cooking of meat. Exposure to some of these chemicals may contribute to the etiology of several common types of human cancers. 2-Amino-9H-pyrido[2,3-b]indole (AαC) is the most abundant HAA formed in mainstream tobacco smoke: it arises in amounts that are 25-100 times greater than the levels of the arylamine, 4-aminobiphenyl (4-ABP), a human carcinogen. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a prevalent HAA formed in cooked meats. AαC and MeIQx are rodent carcinogens; however, their carcinogenic potency in humans is unknown. A preliminary assessment of the carcinogenic potential of these HAAs in humans was conducted by examining the capacity of primary human hepatocytes to form DNA adducts of AαC and MeIQx, in comparison to 4-ABP, followed by the kinetics of DNA adduct removal by cellular enzyme repair systems. The principal DNA adducts formed were N-(deoxyguanosin-8-yl) (dG-C8) adducts. Comparable levels of DNA adducts were formed with AαC and 4-ABP, whereas adduct formation was ∼5-fold lower for MeIQx. dG-C8-AαC and dG-C8-4-ABP were formed at comparable levels in a concentration-dependent manner in human hepatocytes treated with procarcinogens over a 10,000-fold concentration range (1 nM-10 μM). Pretreatment of hepatocytes with furafylline, a selective inhibitor of cytochrome P450 1A2, resulted in a strong diminution of DNA adducts signifying that P450 1A2 is a major P450 isoform involved in bioactivation of these procarcinogens. The kinetics of adduct removal varied for each hepatocyte donor. Approximately half of the DNA adducts were removed within 24 h of treatment; however, the remaining lesions persisted over 5 days. The high levels of AαC present in tobacco smoke and its propensity to form persistent DNA adducts in human hepatocytes suggest that AαC can contribute to DNA damage and the risk of hepatocellular cancer in smokers.
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U2 - 10.1021/tx4002226
DO - 10.1021/tx4002226
M3 - Article
C2 - 23898916
AN - SCOPUS:84884227087
SN - 0893-228X
VL - 26
SP - 1367
EP - 1377
JO - Chemical research in toxicology
JF - Chemical research in toxicology
IS - 9
ER -