Use of repair endonucleases for characterization of DNA damage induced by N-heterocyclic aromatic hydrocarbons.

Several repair endonucleases were used to characterize and quantify various types of DNA damage induced by 7H-dibenzo[c,g]carbazole (DBC) and its methyl derivative, N-methyldibenzo[c,g]carbazole (MeDBC). Differences in the DNA damage profile induced by these two derivatives were found to be related to their chemical structure and dependent on the way of their metabolic activation. Different ways of activation gave rise to different numbers of single strand breaks and DNA modifications or, at least, to different ratios of common modifications. DBC induced the highest level of breaks in human hepatal cell line Hep G2, while MeDBC induced most of the breaks in V79 cell line with stable expression of human cytochrome P4501A1. Our results support the idea of two different pathways of biotransformation of DBC and MeDBC.