Curcumin induces expression of 15-hydroxyprostaglandin dehydrogenase in gastric mucosal cells and mouse stomach in vivo: AP-1 as a potential target

Abstract

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes the conversion of oncogenic prostaglandin E-2 to non-tumerigenic 15-keto prostaglandin E-2. In the present study, we found that curcumin, a yellow coloring agent present in the rhizome of Curcuma Tonga Linn (Zingiberaceae), induced expression of 15-PGDH at the both transcriptional and translational levels in normal rat gastric mucosal cells. By using deletion constructs of 15-PGDH promoter, we were able to demonstrate that activator protein-1 (AP-1) is the principal transcription factor responsible for regulating curcumin-induced 15-PGDH expression. Curcumin enhanced the expression of c-jun and cFos that are functional subunits of AP-1, in the nuclear fraction of cells. Silencing of c-jun suppressed curcumin-induced expression of 15-PGDH. Moreover, the chromatin immunoprecipitation assay revealed curcumin-induced binding of c-Jun to the AP-1 consensus sequence present in the 15-PGDH promoter. Curaimin increased phosphorylation of ERK1/2 and JNK. and pharmacologic inhibition of these kinases abrogated the curcumin-induced phosphorylation of clun and 15-PGDH expression. In contrast, tetrahydrocurcumin which lacks the alpha,beta-unsaturated carbonyl group failed to induce 15-PGDH expression, suggesting that the electrophilic carbonyl group of curcumin is essential for its induction of 15-PGDH expression. Curcumin restored the expression of 15-PGDH which is down-regulated by Helicobater pylori through suppression of DNA methyltransferase 1. In addition, oral administration of curcumin increased the expression of 15-PGDH and its regulators such as p-ERK1/2, p-JNK and c-Jun in the mouse stomach. Taken together, these findings suggest that curcumin-induced upregulation of 15-PGDH may contribute to chemopreventive effects of this phytochemical on inflammation-associated gastric carcinogenesis. (C) 2020 Elsevier Inc. All rights reserved.