u-PA and c-met mRNA expression is co-ordinately enhanced while hepatocyte growth factor mRNA is down-regulated in human hepatocellular carcinoma

Hepatocyte growth factor/scatter factor (HGF/SF) is one of the most important humoral mediators of liver regeneration. It is potentially related to molecular mechanisms of hepatocarcinogenesis via a paracrine system involving its cellular receptor, c-met. In this study, the expression patterns of HGF and c-met were evidenced by multiplex RT-PCR in different specimens of human hepatic tissues (n = 71). A significant increase of c-met mRNA expression was detected in hepatitis (P = 0.001), cirrhosis (P = 0.006), and hepatocellular carcinoma (HCC) tissue (P = 0.003) compared with normal parenchyma and steatosis. HGF mRNA expression was significantly higher only in hepatitis (P = 0.01). Over-expression of c-met mRNA and under-expression of HGF mRNA were detected in the HCCs compared with the corresponding peri-tumoral tissues. Neither HGF nor c-met expression was related to age, sex, tumor size, grading, presence of pseudocapsula, and proliferative activity of the malignant hepatocytes. A significant inverse correlation was found between c-met mRNA expression level and survival (in months) of patients (P = 0.007), as previously shown for urokinase-type plasminogen activator (u-PA) mRNA (P = 0.027). In addition, c-met mRNA expression was strictly associated with u-PA mRNA level in HCC samples (P = 0.001). These data show that a loss of balance concerning HGF, c-met, and u-PA mRNA expression occurs during hepatocarcinogenesis. Particularly, up-regulation of c-met and u-PA mRNA transcription appears to be coordinately regulated, and their levels of expression are inversely correlated with survival; they must therefore play an important role in the development and progression of human HCC and may also be relevant prognostic markers.