The role of interaction between hepatocyte growth factor and heparan sulfate proteoglycan in the progression of hepatocellular carcinoma

HGF-SF/c-Met is the most potent proliferative signaling pathway for hepatocytes and its aberrancies are very important to explain proliferative and metastatic characteristics of hepatocarcinogenesis. Additionally, it is known that Heparan Sulphate Proteoglycans (HSPGs) works as a co-receptor for HGF/SF and this interaction to modulate signaling. In particular carcinomas, heparin has been found to be increased HGF-induced cell invasion, cell motility and cell proliferation. Contradictorily, increased in HSPG expression has been reported to have negative effect on cell proliferation in HCC. We previously showed that heparin inhibits HGF-induced cell proliferation, cell invasion and cell motility and further microarray analysis was performed to determine molecular mechanism behind heparin induced HGF-SF/c-Met signaling in HCC. One of the gene that disregulate heparin and/or HGF-SF induction was Egr-1 in SKHep1. Therefore Egr-1 may contribute heparin and/or HGF-SF induced in biological consequences in HCC. First we investigated the dose dependent effects of heparin on HGF-SF induced invasion, motility and proliferation of SK-Hep1 cells with boyden chamber, invasion assay . Alteration in Egr-1 expression level and its transcriptional activity were determined by RT-PCR, and lucipherase reporter assay with pGL2-luc-B-Egr1 vector, respectively. In order to define molecular mechanisms of altered Egr-1 expression, phosphorylated and unphosphorylated forms of MAPK, levels were analyzed by western blotting. We showed that heparin inhibits HGF-induced cell invasion and also HGF- induced Egr-1 expression was found to be inhibited by heparin in SKHep1 cell line as a dose dependent manner. Moreover, it is found that heparin inhibits HGF-induced transcriptional activity of Egr-1 and HGF-induced p-MET, p-MAPK in a dose dependent manner while did not affect unphosphorylated ones.Our data concluded that heparin induced Egr-1 downregulation inhibits cell invasion and induced by HGF-SF in HCC cell lines. It may be a new aspect for the understanding molecular mechanism in HCC and good target to improve new drugs.