title: Unscheduled DNA synthesis related to transformation grade of human urothelial cells.
abstract: Unscheduled DNA synthesis (UDS) was studied by quantitative autoradiography in human urothelial cells of three transformation grades (TGr I-III). Cells incubated in arginine-free medium supplemented with hydroxyurea showed dose-dependent UDS after administration of agents injurious to DNA, while the scheduled synthesis of DNA was nearly totally suppressed. UDS was demonstrated after treatment with the ultimate carcinogen N-methyl-N-nitroso-N'-nitroguanidine (CAS: 70-25-7) or with the procarcinogen 4-nitroquinoline-1-oxide (4-NQO; CAS: 56-57-5). In cultures treated with benzo[a]pyrene (CAS: 50-32-8), which requires a different activation system than that for 4-NQO, UDS was less pronounced. In 9 cell lines the average rates of UDS were inversely related to TGr. Two cell lines showed a different pattern.
mesh_terms: D015112:4-Nitroquinoline-1-oxide / Q000494:pharmacology; D001345:Autoradiography; D002273:Carcinogens / Q000494:pharmacology*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D004260:DNA Repair; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells; D006801:Humans; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D001743:Urinary Bladder / Q000166:cytology* / Q000187:drug effects
chemical_list: D002273:Carcinogens; D008769:Methylnitronitrosoguanidine; D015112:4-Nitroquinoline-1-oxide