Inhibition of Skin Tumor Promotion by Retinoic Acid and its Metabolite 5,6-Epoxyretinoic Acid

Ajit K. Verma, Thomas J. Slaga, Phillip W. Wertz, Gerald C. Mueller, R. K. Boutwell

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


The ability of 5,6-epoxyretinoic acid, a biologically active metabolite of retinoic acid, to inhibit both the induction of ornithine decarboxylase (ODC) activity and skin tumor promotion by 12-0-tetradecanoylphorbol-13-acetate (TPA) was evaluated. Application of 5,6-epoxyretinoic acid either concurrently with or 1 hr after each application of TPA to the initiated mouse skin inhibited the formation of skin tumors as effectively as did retinoic acid. 5,6-Dihydroretinoic acid, which is a poor substrate for epoxidation, also inhibited skin tumor promotion. 5,6-Epoxyretinoic acid, 5,6-dihydroretinoic acid, and retinoic acid were equally effective in inhibiting the induction of ODC activity by TPA. Insect juvenile hormones inhibited neither the induction of ODC activity nor skin tumor promotion by TPA. These results indicate that (a) epoxidation of retinoic acid at the 5,6-position is not a rate-limiting modification for the anti-promoting activity of retinoic acid and that (b) inhibition of the induction by TPA of mouse epidermal ODC activity may be a simple test for screening the potential prophylactic activities of new retinoids.

Original languageEnglish (US)
Pages (from-to)2367-2371
Number of pages5
JournalCancer Research
Issue number7
StatePublished - Jul 1 1980
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


Dive into the research topics of 'Inhibition of Skin Tumor Promotion by Retinoic Acid and its Metabolite 5,6-Epoxyretinoic Acid'. Together they form a unique fingerprint.

Cite this