Metabolism and formation of DNA adducts of benzo(a)pyrene in human diploid fibroblasts.

Cultured human diploid skin fibroblasts incubated with [G-3H]benzo(a)pyrene yielded about 10 times more H2O-=soluble benzo(a)pyrene metabolites and DNA adducts of stationary growth phase than did proliferating cultures. This increased formation could be blocked by alpha-naphthoflavone. Trichloropropenoxide and cyclohexenoxide, inhibitors of the epoxide hydratase, inhibited predominantly the formation of DNA adducts. Cultures from older individuals formed significantly more benzo(a)pyrene metabolites and DNA adducts, but control cultures from patients with either lung cancer or melanoma did not. The age influence was not apparent when the ratio of DNA adducts to H2O-soluble metabolites was determined for each individual cell line. However, the proportion of DNA-bound material in the cells from patients with lung cancer was significantly increased compared to cells from melanoma patients or healthy individuals.