title: Promotional effect of different phorbol esters on morphological transformation of hamster embryo cells.
abstract: Hamster embryo cells were sequentially exposed to benzo[a]pyrene (BaP) (3 days) and different phorbol esters (4 days). Compounds which have been shown to act as tumor promoters in mouse skin carcinogenesis, showed a promotion-like effect on the formation of morphologically transformed colonies, while non-promoting analogs did not enhance the transformation frequency. In experiments where the exposure sequence was reversed, i.e. 12-O-tetradecanoyl phorbol-13-acetate (TPA) in the first exposure period and BaP in the second period, no significant enhancement of the transformation frequency was observed. The exposure to a low concentration of BaP in the second exposure period following a higher concentration in the first period, resulted in a strong enhancement of the transformation frequency suggesting that BaP also acts as a promoter.
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene; D001580:Benzopyrenes / Q000008:administration & dosage / Q000494:pharmacology*; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002478:Cells, Cultured; D002999:Clone Cells; D006224:Cricetinae; D004622:Embryo, Mammalian; D008647:Mesocricetus; D010703:Phorbol Esters / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000008:administration & dosage
chemical_list: D001580:Benzopyrenes; D002273:Carcinogens; D010703:Phorbol Esters; D010704:Phorbols; D001564:Benzo(a)pyrene; D013755:Tetradecanoylphorbol Acetate