title: Measurement of 'unscheduled' DNA synthesis in HeLa cells by liquid scintillation counting after carcinogen treatment.
abstract: HeLa cells, conditioned in an arginine-deficient medium to reduce DNA S-phase synthesis, were treated with one of four ultimate carcinogens (MNNG, BrMBA, N-acetoxy AAF and EMS) and one precarcinogen, AFB1. All treated cells preferentially incorporated [3H] thymidine as a result of DNA repair monitored by liquid scintillation counting of the extracted DNA. The cells showed some capacity to activate AFB1, but repair synthesis was much increased if a rat liver mixed function oxidase preparation was also present. At equimolar concentrations the various carcinogens stimulated different amounts of DNA repair; this variation was not proportional to the carcinogenic potency of the chemicals tested. Reasons for this are discussed as is the use of this technique as a screen for chemical carcinogens.
mesh_terms: D000099:Acetoxyacetylaminofluorene / Q000494:pharmacology; D000348:Aflatoxins / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001551:Benz(a)Anthracenes / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis*; D004260:DNA Repair; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D006367:HeLa Cells; D008099:Liver / Q000201:enzymology; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000378:metabolism; D051381:Rats; D013936:Thymidine / Q000378:metabolism
chemical_list: D000348:Aflatoxins; D001551:Benz(a)Anthracenes; D002273:Carcinogens; D008769:Methylnitronitrosoguanidine; D000099:Acetoxyacetylaminofluorene; D004247:DNA; D005020:Ethyl Methanesulfonate; D006899:Mixed Function Oxygenases; D013936:Thymidine