Abstract: To develop well defined in vitro cell system to test cytotoxicity of a number of model toxins, genetically engineered V79 Chinese hamster fibroblasts expressing isoenzymes of cytochrome P4501A1 XEM2 cells and V79 cells (parental), which lack cytochrome P450 enzyme activities, were used as controls. The cytotoxic effect of trans 7,8 dihydrbenzo(a)pyrene (BP-7,8-diol) on the parental cells V79 and V79 derived XEM2 cells were evaluated by two methods for cell viability. The data obtained expressed that BP-7,8-diol ranging from 1.0 μmol·L^-1 to 5.0 μmol·L^-1 in concentrations incubated for 24 h showed a strong cytotoxic effect in XEM2 cells (expressing rat cytochrome P4501A1) in a concentration dependent manner. Time dependent decrease for survival of XEM2 cells was also observed at 2.5 μmol·L^-1 concentration. Likewise, BP-7,8-diol did not alter the survival of the parental cells V79 under the same condition. This study also showed that α naphthoflavone (αNF), a well known inhibitor of cytochrome P4501A1 might alter BP-7,8-diol induced cytotoxicity in the XEM2 cells. Our results suggested that cytochrome P4501A1 is responsible for BP-7,8-diol induced cytotoxicity.

Key words: V79 cell line, XEM2 cell line, BP-7,8-diol, Cytotoxicity P4501A1