Vascular endothelial growth factor: Evidence for autocrine signaling in hepatocellular carcinoma cell lines affecting invasion.

Abstract

Vascular endothelial growth factor (VEGF) is a well-known pivotal regulator of tumor angiogenesis. Apart from endothelial cells, it is also expressed in nonendothelial cells, including tumor cells themselves. Hence the aim of this study was to investigate the autocrine effects of VEGF in hepatocellular carcinoma (HCC) -derived cell lines. Two hepatocellular carcinoma cell lines (Hep3B and HepG2) were screened for expression of VEGF by quantitative real-time polymerase chain reaction (PCR) and its receptors VEGF-R1, VEGF-R2, and neuropilin-1 expression by reverse transcriptase-PCR, respectively. Furthermore, VEGF transcript was silenced by siRNA and the effects on cell migration, viability, and proliferation were determined by the wound healing assay, MTT assay, and propidium iodide staining, respectively. Both Hep3B and HepG2 cell lines expressed VEGF and all the three receptors at high levels. VEGF siRNA inhibited VEGF expression significantly in both Hep3B and HepG2 cell lines. Silencing of VEGF showed decreased migration in the Hep3B cell line. In both cell lines tested, there was decreased cell viability but no effect on cellular proliferation. Our data indicates that autocrine signaling of VEGF through its receptors exists in HCC cell lines, which has important implications for tumor invasion, metastasis, and for designing interventional strategies.