Id-1 promotes angiogenesis in hepatocellular carcinoma through HIF-1α-mediated VEGF upregulation

Session - Tumor Biology 14: Tumor Angiogenesis and the Microenvironment 2: no. 1860BACKGROUND: Hepatocellular carcinoma (HCC) is a highly vascularized tumor associated with poor prognosis. Angiogenesis plays a critical role in rapid growth and metastasis of HCC. Vascular endothelial growth factor (VEGF) is one of the most important angiogenic factors in HCC. A better understanding of the regulatory mechanisms of VEGF expression in HCC may reveal novel targets for treatment of this cancer. Recently, Id-1 (inhibitor of differentiation/DNA synthesis) has been suggested to play a role in cancer angiogenesis but the molecular mechanism remains unknown. Given the central role of VEGF in cancer angiogenesis, we performed a study to elucidate whether overexpression of Id-1 promotes angiogenesis in HCC by interacting with VEGF. METHODOLOGY: In this study, we examined the expression of Id-1 and its relationship with expression of VEGF in HCC by performing immunohistochemistry on HCC tissue microarray. The role of Id-1 in regulating angiogenesis in HCC was evaluated in vitro by ectopic Id-1 transfection, and the effect of inhibition of Id-1 expression on angiogenesis and tumor growth of HCC was studied in vitro and in vivo. RESULTS: Id-1over-expression correlated with HCC metastasis (p<0.001), and its expression significantly correlated with VEGF expression (p