Overexpressed HDGF as an independent prognostic factor is involved in poor prognosis in Chinese patients with liver cancer

BACKGROUND: Hepatoma-derived growth factor (HDGF) is involved in the hepatocarcinogenesis. In this study, we investigated the HDGF expression in hepatocellular carcinoma (HCC) and its correlation with clinicopathologic features, including the survival of patients with HCC. Furthermore, we examined the biological processes regulated by HDGF during the development of using HepG2 cell line as a model system. METHODS: we used immunohistochemistry to compare HDGF protein expression in HCC and normal liver tissues and further analyze the HDGF protein expression in clinicopathologically characterized 137 HCC cases. We stably knocked down the endogenous expression level of HDGF in HepG2 cells with specific shRNA-expressing lentiviral vector. Following the successful establishment of stable cells, we examined in vitro cell growth by MTT assay, anchorage-independent growth by soft-agar colony formation assay and cell migration/invasion by transwell and boyden chamber assay. And in addition, we also investigated the in vivo tumor growth by xenograft transplantation of HepG2 cells into nude mice. RESULTS: Protein expression level of HDGF was markedly higher in HCC tissues than that in the normal liver tissues(P = 0.011). In addition, high expression of HDGF protein was positively correlated with T classification(p < 0.001), N classification (p < 0.001), and clinical stage (p < 0.001) of HCC patients. Patients with higher HDGF expression showed a significantly shorter overall survival time than did patients with low HDGF expression. Multivariate analysis suggested that HDGF expression might be an independent prognostic indicator(p < 0.001) for the survival of patients with HCC. HDGF-specific shRNA (shHDGF) successfully knocked down its endogenous expression in HepG2 cells. Compared to the parental and control shRNA-transfected (shCtrl) HepG2 cells, the shHDGF cells exhibited significantly reduced in vitro cell growth, anchorage-independent growth, cell migration and invasion (p < 0.05). In vivo, the xenograft transplants from shHDGF cells gave rise to much smaller tumors as compared to those from shCtrl cells. CONCLUSION: High HDGF expression is associated with poor overall survival in patients with HCC. Down-regulation of HDGF inhibits the growth, anchorage-independent growth, migration and invasion of HepG2 cells.