The tumour promoter 12-O-tetradecanoylphorbol-13-acetate increases the activities of some peroxisome-associated enzymes in in vitro cell culture.

A study was conducted on the effects of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on peroxisomal enzyme activities in mouse embryo fibroblasts C3H/10T1/2 C18 cells and chemically transformed C3H/10T1/2 MCA16 cells. TPA is a potent tumour promoter and treatment with this compound of the two cell lines induced peroxisomal fatty acid beta-oxidation, carnitine acetyltransferase, palmitoyl-CoA hydrolase, and catalase activities after 240 h of treatment. Stimulation of the corresponding enzyme activities was dose-related and cycloheximide inhibited the TPA-induced enzyme activities, except that of carnitine acetyltransferase. The MCA16 cells appeared to be more sensitive than the C18 cells in inducing peroxisome-associated enzyme activities after TPA treatment. The activities of the microsomal marker, NADPH-cytochrome c reductase and the mitochondrial marker, glutamate dehydrogenase were not enhanced by TPA treatment. The results indicate that TPA has peroxisomal effects and may be classified as a peroxisome proliferator.