Transformation of rat tracheal epithelial cells by benzo[a]pyrene and its metabolites.

Benzo[a]pyrene (B[a]P) and its 7,8-dihydrodiol form were metabolically activated to malignantly transform a non-tumorigenic rat tracheal epithelial cell line in culture. The proximal carcinogenic metabolite of B[a]P, diolepoxide I, was more efficient in transforming the epithelial cell line than the intermediate or parent compound, even at a 50- or 100-fold lower concentration, respectively. Inoculations of the transformed cell lines into immunosuppressed isogenic recipients produced differentiated carcinomas similar to those which occur in humans.