15-Deoxy-Delta12,14-prostaglandin J2 inhibits angiotensin II-induced fibronectin expression via hepatocyte growth factor induction in human peritoneal mesothelial cells

15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) is an endogenous peroxisome proliferator-activated receptor gamma (PPARgamma) agonist that suppresses progressive matrix deposition; however, little is known about the effects of 15d-PGJ(2) on human peritoneal mesothelial cells (HPMCs). We investigated the following: (i) the expression of PPARgamma; (ii) the effect of 15d-PGJ(2) on angiotensin II (Ang II)-induced fibronectin (FN) expression and secretion; (iii) the effect of 15d-PGJ(2) (with or without Ang II and with or without the specific PPARgamma antagonist GW9662) and pioglitazone, a synthetic PPARgamma agonist, on hepatocyte growth factor (HGF) expression and secretion; (iv) the effect of HGF on Ang II-induced FN expression and secretion; (v) the expression of c-Met (a specific HGF receptor) and its phospho-signal; and (vi) the involvement of HGF in the effect produced by 15d-PGJ(2) using selective c-Met inhibitor PHA-665752. The presence of PPARgamma was detected by western blot analysis. 15d-PGJ(2) inhibited Ang II-induced FN expression and increased HGF expression, even in the presence of Ang II. This effect of HGF expression was completely prevented by co-treatment with GW9662. Additionally, upregulation of HGF secretion induced by 15d-PGJ(2) and HGF production induced by pioglitazone was revealed. We demonstrated the presence of c-Met, and presented evidence that HGF inhibits Ang II-induced FN expression and activates phosphorylation of c-Met, which is blocked by PHA-665752; 15d-PGJ(2) also activated c-Met phosphorylation. Furthermore, PHA-665752 attenuates the inhibitory effects of 15d-PGJ(2) on FN secretion. These findings suggest that 15d-PGJ(2) has a novel and potent antifibrotic effect in HPMC and this action is likely mediated by HGF.