title: Involvement of protein kinase C in the regulation of ornithine decarboxylase mRNA by phorbol esters in rat hepatoma cells.
abstract: The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates a rapid increase in ornithine decarboxylase (EC 4.1.1.17; ODC) activity in target cells. Here we demonstrate that this process involves a rapid accumulation of ODC mRNA, which is maximal 3 h after treatment (three- to eightfold greater than control cells) and decays to control levels within 18 h. Stimulation of ODC mRNA by TPA is blocked by phorbol dibutyrate down-regulation of protein kinase C (PKC). ODC mRNA was also induced by the PKC activators, phospholipase C and 1-oleoyl-2-acetyl-rac-glycerol, and blocked by kinase inhibitors (trifluoroperazine, H7, and palmitoyl-L-carnitine), consistent with a requirement for PKC activation in the induction mechanism. However, the non-PKC-specific protein kinase inhibitor HA1004 also suppressed expression of ODC mRNA in response to TPA, under conditions where it did not inhibit PKC, suggesting that additional kinases may be involved in the intracellular signalling process. The stability of the ODC mRNA (control value = 6.2 +/- 1.6 h) is not significantly changed by either TPA (5.7 +/- 0.8 h) or by cycloheximide (6.0 h). These results are inconsistent with any contribution from altered mRNA half-life towards the accumulation of ODC mRNA following treatment with phorbol ester tumor promoters.
authors.affiliation: University of Texas M.D. Anderson Cancer Center, Department of Carcinogenesis, Smithville 78957.
authors.forename: A P
authors.initials: AP
authors.lastname: Butler
authors.forename: P K
authors.initials: PK
authors.lastname: Mar
authors.forename: F F
authors.initials: FF
authors.lastname: McDonald
authors.forename: R L
authors.initials: RL
authors.lastname: Ramsay
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D004075:Diglycerides / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D007546:Isoquinolines / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009955:Ornithine Decarboxylase / Q000235:genetics*; D010172:Palmitoylcarnitine / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D007546:Isoquinolines; D010703:Phorbol Esters; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D010172:Palmitoylcarnitine; D015240:Phorbol 12,13-Dibutyrate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D010738:Type C Phospholipases; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate