title: Measurement of the response of HELA cells towards the radiomimetic activity of 12-O-tetradecanoylphorbol-13-acetate.
abstract: The sensitivity of HeLa cells in the G2 phase of the cell cycle towards the radiomimetic activity of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) (Kinzel et al. (1980) Science, 210, 429-431) has been utilized to establish dose response relationships. This was accomplished by analysis of mitotic curves and determination of cells not affected, a measurement known to be dose dependent in the case of very low X-ray doses. Half maximal activity was exerted by TPA at approximately 5 X 10(-9) M concentration. Mechanistically, however, TPA seems to exert its activity through a route different from that of X-rays or other radiomimetic drugs for 2 reasons: (1) the cellular response does not increase proportionally with dose; (2) cells recover from G2 blockage even in the presence of TPA. Therefore it appears as if the tumor promoter acts indirectly by triggering an exhaustable cellular activity which leads to the radiomimetic response.
mesh_terms: D000096:Acetone / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects* / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D006367:HeLa Cells; D006801:Humans; D007399:Interphase / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects; D010704:Phorbols / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D010704:Phorbols; D000096:Acetone; D013755:Tetradecanoylphorbol Acetate