Dissociation of 12-O-tetradecanoylphorbol-13-acetate and 3-methylcholanthrene-induced induction in ornithine decarboxylase and aryl hydrocarbon hydroxylase activities in C57BL/6 mouse dermal fibroblasts in culture.

The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) and 3-methyl-cholanthrene (MC) on ornithine decarboxylase (ODC) and aryl hydrocarbon hydroxylase (AHH) activities were studied in C57BL/6 mouse dermal fibroblasts in culture. TPA selectively induced ODC activity and MC selectively induced AHH activity in these cells. Acute (10 h) exposure of the cells to DL-alpha-difluoromethyl ornithine (DFMO) led to a marked inhibition of ODC activity without any significant effect on induced AHH activity. Chronic inhibition of ODC activity (4 days) resulted in a slight inhibition of basal AHH activity, but the inducibility of AHH was enhanced alpha-Naphtho-flavone, SKF 525 A and indomethacin exerted unequal effects on the enzyme activities. These results indicate that ODC and AHH induction processes are independent events with no causal link.