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

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.

15-Deoxy-Δ12,14-prostaglandin J2 Induces Apoptosis in Ha-ras-transformed Human Breast Epithelial Cells by Targeting IκB kinase–NF-κB Signaling

15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), an endogenous ligand for PPAR gamma, has differential effects on cancer cell proliferation and survival depending on the dose and the type of cells. In the present study, we have investigated the effects of 15d-PGJ(2) on apoptosis of the Ha-ras transformed human breast epithelial (MCF10A-ras) cells. When MCF10A-ras cells were treated with 15d-PGJ(2) (10 mu M) for 24 hours, they underwent apoptosis as evidenced by characteristic morphological features, an increased proportion of sub-G(0)/G(1) cell population, a typical pattern of annexin V/propidium iodide staining, perturbation of mitochondrial transmembrane potential (Delta psi(m)), and cleavage of caspase-3 and its substrate PARP. A pan-caspase inhibitor, Z-Val-Ala-Asp (OCH3)-fluoromethyl ketone attenuated cytotoxicity and proteolytic cleavage of caspase-3 induced by 15d-PGJ(2). The 15d-PGJ(2)-induced apoptosis was accompanied by enhanced intracellular accumulation of reactive oxygen species (ROS), which was abolished by the antioxidant N-acetyl-L-cysteine (NAC). 15d-PGJ(2) inhibited the DNA binding activity of NF-kappa B which was associated with inhibition of expression and catalytic activity of IKB kinase beta (IKK beta). 15d-PGJ(2)-mediated inhibition of IKK beta and nuclear translocation of phospho-p65 was blocked by NAC treatment. 9,10-Dihydro-PGJ(2), a non-electrophilic analogue of 15d-PGJ(2), failed to produce ROS, to inhibit NF-kappa B DNA binding, and to induce apoptosis, suggesting that the electrophilic apunsaturated carbonyl group of 15d-PGJ(2) is essential for its pro-apoptotic activity. 15d-PGJ(2)-induced inactivation of IKK(i was also attributable to its covalent thiol modification at the cysteine 179 residue of IKK beta. Based on these findings, we propose that 15d-PGJ(2) inactivates IKK beta-NF-kappa B signaling through oxidative or covalent modification of IKK beta, thereby inducing apoptosis in Ha-ras transformed human breast epithelial cells.