title: Mechanism of the stimulatory effect of phorbol 12-myristate 13-acetate on cellular production of plasminogen activator.
abstract: The human Bowes melanoma cell line secretes a plasminogen activator identical to the extrinsic tissue plasminogen activator (EPA) and different from the urokinase-like plasminogen activators mostly found in human tumor lines. In the continuous presence of 100 ng/ml of phorbol 12-myristate 13-acetate (PMA) the 24-hr production of EPA was increased 5.3-fold (average). Preincubation of the cultures for a limited time period (optimally 3 to 6 hr) also resulted in an increase of the subsequent 24-hr production. EPA produced in the presence of PMA was serologically indistinguishable from that produced spontaneously and its molecular weight as defined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and fibrin-agar zymography was the same as that of spontaneously produced EPA. Treatment of the cells with actinomycin D inhibited PMA-induced EPA production. Also, RNA extracted from PMA-treated cells became enriched in mRNA for EPA. It is concluded that PMA acts by enhancing the transcription of the EPA gene. Cell-associated EPA levels were increased, even when tested as early as 3 hr after initiation of the PMA treatment, thus failing to support the view that increased EPA synthesis occurred as a result of depletion of the cellular pool.
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008545:Melanoma; D010704:Phorbols / Q000494:pharmacology*; D010960:Plasminogen Activators / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D010704:Phorbols; D012333:RNA, Messenger; D010960:Plasminogen Activators; D013755:Tetradecanoylphorbol Acetate