Cell-mediated mutagenesis in cultured Chinese hamster cells by polycyclic hydrocarbons: mutagenicity and DNA reaction related to carcinogenicity in a series of compounds.

Three polycyclic hydrocarbons, benz(a)anthracene, 3-methylcholanthrene and 7,12-dimethylbenz(a)anthracene, have been studied in a cell-mediated mutagenesis system using BHK 21 cells to metabolize the hydrocarbons and V-79 cells as targets for detecting induced cytotoxicity and mutation. In large-scale experiments, the DNA of V-79 cells was analyzed by column chromatography to determine the nature and true extent of reaction of hydrocarbons with dexoyribonucleosides. Products with DNA formed by the two carcinogenic compounds were qualitatively very similar to those reported to occur in vivo and in primary cell cultures. Binding indices were calculated from the tritium content of DNA-hydrocarbon products, related to overall metabolism, for these two compounds together with benzo(a)pyrene and 7-methylbenz(a)anthracene using data from a previous study. These values reflected differences in carcinogenic potency between the compounds. Induced mutation frequencies were related to the extent of DNA reaction with each compound. At equivalent extents of DNA reaction with hydrocarbon products, levels of induced mutation were not significantly different.