15-hydroxyeicosatrienoic acid (15-HETrE) suppresses epidermal hyperproliferation via the modulation of nuclear transcription factor (AP-1) and apoptosis.

The purpose of this study was to ascertain whether the antiproliferative effect of 15-hydroxyeicosatrienoic acid (15-HETrE), a monohydroxy fatty acid generated from dihomo-gamma-linolenic acid, in an experimentally induced guinea pig hyperproliferative model involves alterations in nuclear transcription factor (AP-1) and apoptosis. The topical application of docosahexaenoic acid (DHA) to normal guinea pig skin elicited a severe hyperplasia which was accompanied by the suppression of AP-1 expression in a time-dependent manner. Since apoptosis is pivotal in tissue turnover, the expression of two apoptotic proteins (Bcl-2 and caspase-3) after DHA and 15-HETrE treatment was explored. DHA-induced hyperproliferation enhanced the expression of Bcl-2 (an antiapoptotic protein) but inhibited the expression of caspase-3 (an apoptotic protein). 15-HETrE, on the other hand, reversed the DHA-induced epidermal hyperplasia, and upregulated epidermal AP-1 expression. These events paralleled the suppression of Bcl-2 and the elevation of caspase-3. Taken together, these results suggest that the antiproliferative effect of 15-HETrE may, at least in part, be via the modulation of AP-1 and apoptosis.