A comparative investigation of DNA adducts, DNA strand breaks and gene mutations induced by benzo[a]pyrene and (+/-)-anti-benzo[a]pyrene-7,8-diol 9,10-oxide in cultured human cells.

Genotoxic effects of benzo[a]pyrene (BP) and its reactive metabolites (+/-)-anti-benzo[a]pyrene-7,8-diol 9,10-oxide ((+/-)-anti-BPDE) were comparatively investigated in vitro with the permanent human fibroblast cell line MRC5CV1. Induced DNA adducts were measured by 32P-postlabeling, DNA strand breakage was determined by the comet assay and the HPRT gene mutation test was used to detect cytotoxicity and mutagenicity. Treatment of MRC5CV1 cells with S9 mix-activated BP or with (+/-)-anti-BPDE resulted in a concentration-dependent increase in DNA adducts and strand breaks. Genotoxic effects of BP and (+/-)-anti-BPDE were detected by 32P-postlabeling and the comet assay with similar sensitivity. However, under the same experimental conditions, a clear induction of gene mutations was only found after (+/-)-anti-BPDE treatment. The relationship between the induction of primary DNA alterations like DNA strand breaks and DNA adducts and the induction of gene mutations is discussed.