title: Inhibition of 12-O-tetradecanoylphorbol-13-acetate-mediated epidermal ornithine decarboxylase induction and skin tumor promotion by new lipoxygenase inhibitors lacking protein kinase C inhibitory effects.
abstract: Both 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA861) and 3,4,2',4'-tetrahydroxychalcone inhibited 12-lipoxygenase of mouse epidermis. The IC50 of AA861 and 3,4,2',4'-tetrahydroxychalcone for epidermal 12-lipoxygenase were 1.9 and 0.2 microM, respectively. These agents showed very weak inhibitory actions on epidermal cyclooxygenase, with the potency of inhibition for cyclooxygenase less than 1/50 of that for lipoxygenase. Induction of epidermal ornithine decarboxylase by 12-O-tetradecanoylphorbol-13-acetate (TPA; 10 nmol/mouse) was potently inhibited by these agents in a dose-dependent manner (1-30 mumol/mouse). TPA (5 nmol/mouse)-induced skin tumor formation was also strongly suppressed by these agents (15 mumol/mouse). Both AA861 and 3,4,2',4'-tetrahydroxychalcone failed to inhibit partially purified epidermal protein kinase C activity. These results support the proposed involvement of lipoxygenase product(s) of arachidonic acid in TPA-induced skin tumor promotion.
mesh_terms: D000818:Animals; D016227:Benzoquinones; D002599:Chalcone / Q000031:analogs & derivatives / Q000494:pharmacology*; D047188:Chalcones; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D016859:Lipoxygenase Inhibitors; D009637:Masoprocol / Q000494:pharmacology; D051379:Mice; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D011427:Propiophenones / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011794:Quercetin / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology*; D012867:Skin / Q000201:enzymology*; D012878:Skin Neoplasms / Q000139:chemically induced*; D013755:Tetradecanoylphorbol Acetate
chemical_list: D016227:Benzoquinones; D047188:Chalcones; D016859:Lipoxygenase Inhibitors; D011427:Propiophenones; D011809:Quinones; C040918:butein; D002599:Chalcone; D009637:Masoprocol; C036837:2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone; D011794:Quercetin; D011493:Protein Kinase C; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate