Abstract
The prevalence of covalent modifications to DNA (carcinogen-DNA adducts) in 42 human urinary bladder biopsy samples was investigated by 32P-postlabeling methods, with enhancement by both nuclease P1 treatment and 1-butanol extraction. Total mean carcinogen-DNA adduct levels and the mean levels of several specific adducts were significantly elevated in DNA samples of 13 current smokers, as opposed to 9 never smokers or 20 ex-smokers (5 years abstinence). There was no significant difference between the latter two groups. Several DNA adducts enhanced by nuclease P1 treatment were chromatographically similar to putative hydrocarbon DNA adducts reported earlier for placenta and lung DNA samples obtained from cigarette smokers. Putative aromatic amine adducts were detected by 1-butanol extraction that were not present when the samples were treated with nuclease P1. One of these displayed chromatographic behavior identical to the predominant adduct induced by the human urinary bladder carcinogen, 4-aminobiphenyl, which is present in cigarette smoke. This adduct comigrated in several thin-layer chromatographic systems with a synthetic N-(deoxyguanosin-8-yl)-4-amino[2,2'-3H]biphenyl-3',5'-bisphosphate marker. Moreover, when this adduct was eluted from the thin-layer chromatograms of several individuals and injected onto an HPLC system, the 32P from the human bladder DNA samples coeluted in the same fraction as the tritiated synthetic N-(deoxyguanosin-8-yl)-4-aminobiphenyl marker. These data reinforce an association between cigarette smoking and DNA damage and suggest a molecular basis for the initiation of human urinary bladder cancer by cigarette smoke.