Cytochrome P-450 Family 1 in Rat Embryo Cell Culture Immortalized by Rausher Leukemia Virus

We studied comparative expression and activity of cytochrome P450 family 1 (CYP1) isoforms in rat embryo cells, both primary and immortalized by Rausher leukemia virus (RLV). In RLV-infected embryonal cells compared with the initial ones the expression levels of CYP1A1 and 1B1 mRNAs and benzoa]pyrene (BP) hydroxylase activity were higher, regardless of their treatment with the CYP1 inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin. The sensitivity to BP and 7,12-dimethylbenzoa]anthracene was higher in the cells immortalized with RLV. The expression level of mRNAs of induction-mediating proteins aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator was the same in both cell cultures tested. Higher sensitivity of cells immortalized with RLV compared with the initial embryo cells to transforming effect of BP, which was described previously, is possibly associated with elevated expression of CYP1 isoforms.