12-deoxyphorbolphenylacetate-20-acetate and 12-deoxyphorbolphenylacetate

Recent reports have claimed that activation of protein kinase C (PKC)-beta is sufficient for both differentiation and apoptosis in promyeloid HL60 cells. Phorbol esters which differentially activate PKC isoenzymes in vitro were used to induce differentiation and apoptosis in U937 cells; TPA and Dopp activate all U937 PKC isoenzymes, except PKC-zeta and Doppa activate only PKC-beta l. At concentrations of Doppa below 50 nM, only PKC-beta l was activated by 2 min and apoptosis was induced, but there was no differentiation of cells towards monocytes. TPA (1-25 nM) and Dopp (5-100 nM) activated PKC-alpha, -beta l and-gamma within 2 min and induced differentiation, but only increased apoptosis at the highest concentrations used. Thus, initial activation of PKC-beta l is insufficient for differentiation of U937 cells, but may lead to the induction of apoptosis.

Topics: Apoptosis; Enzyme Activation; Humans; Isoenzymes; Phorbol Esters; Protein Kinase C; Subcellular Fractions; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured

The phorbol ester, 12-deoxyphorbol-13-O-phenylacetate-20-acetate (DOPPA) has been shown to activate specifically the protein kinase C (PKC)-beta 1 isozyme in vitro (1). We have investigated the potential of DOPPA as a PKC-beta 1/2 isozyme-specific agonist in intact cells, employing U937 cells, which express beta 1/2, epsilon and zeta PKC and in Swiss 3T3 cells which lack PKC-beta 1/2 but express alpha, delta, epsilon and zeta PKC. Immunoblot analysis with isozyme-specific antibodies indicated that DOPPA can mediate the subcellular redistribution and down-modulation of all endogenous PKC isozymes (except PKC-zeta) in both U937 and Swiss 3T3 cells. Prolonged treatment (> 6 h) of cultures in down-modulation studies is complicated by the metabolism of DOPPA to 12-deoxyphorbol-13-phenylacetate (DOPP), a compound which activates all PKC isozymes tested in vitro (Ryves, W. J., et al. (1991) FEBS Lett., 288, 5-9). Nevertheless, because DOPPA induced rapid and dose-dependent phosphorylation of p80 in cells which do not express PCK-beta, p80 phosphorylation in Swiss 3T3 cells indicates that DOPPA can activate a non-beta PKC in vivo. The data suggest that DOPPA cannot be used as a PKC-beta-selective agonist in intact cell studies.

Topics: 3T3 Cells; Animals; Enzyme Activation; Humans; Isoenzymes; Mice; Phorbol Esters; Phosphorylation; Protein Kinase C; Proteins; Tumor Cells, Cultured

The pro-inflammatory tigliane esters 12-deoxyphorbolphenylacetate (12-DOPPA) and 12-deoxyphorbolphenylacetate-20-acetate (12-DOPPAA) at a dose of 0.1 microgram induced erythema in the mouse ear. Observations of ear redness were made both two and four hours after application. Indomethacin was only partly successful as an antagonist since 10% inhibition of 12-DOPPA and no inhibition of 12-DOPPAA induced erythema was produced four hours after application. The free radical scavengers, phenol, thioanisole and sodium benzoate all produced less than 30% inhibition of 12-DOPPA induced erythema and less than 15% inhibition of 12-DOPPAA, whereas aminopyrine produced 70% and 25% inhibition of 12-DOPPA and 12-DOPPAA respectively. The fact that free radical scavengers (with the exception of aminopyrine) and indomethacin, failed to markedly change the mouse ear reaction to 12-deoxyphorbol esters, indicated that this erythema is not entirely mediated via cyclooxygenase products. Mepyramine and cyproheptadine also failed to inhibit the erythema, whereas hydrocortisone produced a 55% inhibition of the 12-DOPPA and a 20% inhibition of the 12-DOPPAA reaction. The membrane stabilising agents trifluoperazine, promethazine, imipramine and desmethylimipramine were the most successful compounds used in inhibiting both 12-DOPPA and 12-DOPPAA induced erythema. In addition propranolol, which inhibits stimulus activation of phospholipase A2, produced 70% and 55% inhibition of the reaction of mice ears to 12-DOPPA and 12-DOPPAA.

Topics: Animals; Erythema; Female; Histamine H1 Antagonists; Hydrocortisone; Indomethacin; Irritants; Mice; Phorbol Esters

Topics: Animals; Female; Gastric Acid; Gastric Mucosa; Histamine Antagonists; In Vitro Techniques; Male; Phorbol Esters; Phorbols; Rats; Tetradecanoylphorbol Acetate