Suppression of acute hepatic injury by a synthetic prostacyclin agonist through hepatocyte growth factor expression

Abstract

Previous studies have demonstrated that mice disrupted with the cyclooxygenase-2 gene showed much more severe liver damage compared with wild-type mice after liver injury, and prostaglandins (PGs) such as PGE(1/2) and PGI(2) have decreased hepatic injury, but the mechanisms by which prostaglandins exhibit protective action on the liver have yet to be addressed. In the present study, we investigated the mechanism of the protective action of PGI(2) using the synthetic IP receptor agonist ONO-1301. In primary cultures of hepatocytes and nonparenchymal liver cells, ONO-1301 did not show protective action directly on hepatocytes, whereas it stimulated expression of hepatocyte growth factor (HGF) in nonparenchymal liver cells. In mice, peroral administration of ONO-1301 increased hepatic gene expression and protein levels of HGF. Injections of CCl4 induced acute liver injury in mice, but the onset of acute liver injury was strongly suppressed by administration of ONO-1301. The increases in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) by CCl4 were suppressed by 10 mg/kg ONO-1301 to 39.4 and 33.6%, respectively. When neutralizing antibody against HGF was administered with ONO-1301 and CCl4, the decreases by ONO-1301 in serum ALT and AST, apoptotic liver cells, and expansion of necrotic areas in liver tissue were strongly reversed by neutralization of endogenous HGF. These results indicate that ONO-1301 increases expression of HGF and that hepatoprotective action of ONO-1301 in CCl4-induced liver injury may be attributable to its activity to induce expression of HGF, at least in part. The potential for involvement of HGF-Met-mediated signaling in the hepatotrophic action of endogenous prostaglandins generated by injury-dependent cyclooxygenase-2 induction is considerable.

A Novel Long-Acting Prostacyclin Agonist (ONO-1301) With an Angiogenic Effect: Promoting Synthesis of Hepatocyte Growth Factor and Increasing Cyclic AMP Concentration via IP-Receptor Signaling

“…The inhibition constant (K i ) values for the IP receptor of cicaprost, iloprost, carbacyclin, iso carbacyclin, beraprost, and ONO-1301 in the previous study using Chinese hamster ovary cells was 10,11,110,15,16, and 47 nM, respectively (46). ONO-1301 might have an ability to stimulate EPI receptors and IP receptors and then induce desensitization.…”

“…The antibodies against HGF were prepared as described in our previous paper (11). Recombinant rat HGF was expressed in Chinese hamster ovary cells and purified from the culture supernatant, as described elsewhere (28,29).…”

Suppression of fibrogenic gene expression and liver fibrosis using a synthetic prostacyclin agonist

“…Because we previously showed that PGI 2 analogues induce the gene expression of HGF (22), we speculated that ONO-1301 might enhance expression of the HGF gene and exert biological action through the induction of HGF. The onset of acute liver injury was strongly suppressed in a mouse model by the administration of ONO-1301, while the suppression of acute liver injury by ONO-1301 was reversed by the neutralization of endogenous HGF (36). In the present study, the therapeutic action of ONO-1301 on liver fibrosis and the possible involvement of HGF in its action were examined.…”

“…By contrast, the administration of HGF and the expression of the HGF gene suppressed the development of liver fibrosis/cirrhosis (20,27,35). HGF treatment accelerated the resolution of fibrosis in experimental animal models, instrongly enhanced the expression of HGF and induced CREB-Ser133 phosphorylation, and that the biological activity of ONO-1301 that enhanced HGF expression was cancelled by a selective inhibition of PKA (36). Thus, ONO-1301 up-regulates the gene expression of HGF via an IP receptor-mediated signaling pathway.…”

“…ONO-1301 was obtained from ONO Pharmaceutical Co., Ltd. (Osaka, Japan). Recombinant rat HGF was expressed in Chinese hamster ovary cells and purified from the culture supernatant, essentially as described elsewhere (36). The purity of rat HGF exceeded 98% as determined by SDS-polyacrylamide gel electrophoresis and protein staining with Coomassie brilliant blue.…”