Inhibition of the induction of ornithine decarboxylase activity by 12-O-tetradecanoylphorbol-13-acetate in mouse skin by sphingosine sulfate.

We investigated the effect of sphingosine sulfate on the induction of ODC (ornithine decarboxylase) activity by TPA (12-O-tetradecanoylphorbol-13-acetate) in mouse skin. When applied topically to the shaved skin of SENCAR mice at dosages of 10-40 mumol per animal, 30 min before the superficial application of 8.5 nmol of TPA, sphingosine sulfate dramatically inhibited the induction of ODC activity by the tumor promoter. Significant inhibition of TPA-induced ODC activity was observed at 4, 6 and 8 h after TPA treatment in separate studies. The results indicate that sphingosine sulfate is an effective inhibitor of ODC induction by TPA in mouse skin.