Involvement of prostaglandin E2 in ornithine decarboxylase induction by a tumor-promoting agent, 7-bromomethylbenz[a]anthracene, in mouse epidermis

A single topical application of 7-bromomethyl-benz[a]anthracene (BrMBA; 200 nmol) to mouse skin induced epidermal ornithine decarboxylase (OCD) activity. A topical application of indomethacin (1.2 μmol), a cyclooxygenase inhibitor, 10 min before BrMBA application markedly inhibited BrMBA-caused ODC induction. Concurrent application of prostaglandin E 2 (PGE 2 ; 0.1-1.5 μmol) reversed the inhibitory effect of indomethacin