STABLE EXPRESSION OF HUMAN CYTOCHROME-P450 2E1 IN V79 CHINESE-HAMSTERCELLS

A V79 Chinese hamster cell line was constructed for stable expression of human cytochrome P450 2E1 (CYP2E1) by integration of a SV40 Early p romoter recombinant CYP2E1 cDNA into the chromosomal DNA. The cDNA enc oded CYP2E1 was effectively expressed and enzymatically active, as sho wn by hydroxylation of chlorzoxazone and of p-nitrophenol, at rates of about 70 pmol x mg(-1) total protein X min(-1). CYP2E1 content and ac tivity was increased upon cultivation in the presence of ethanol indic ating a substrate mediated stabilization effect. A similar stabilizing effect was also observed for inhibitors of CYP2E1, e.g. imidazole, 4- methylpyrazole, and isoniazid. The feasibility of the newly establishe d cell line V79MZh2E1 for toxicological studies was shown by CYP2E1-me diated activation of N-nitrosodimethylamine and p-nitrophenol and a do se-dependent cytotoxic and mutagenic effect.