Hepatitis C virus core protein potentiates proangiogenic activity of hepatocellular carcinoma cells

// Yu-Yun Shao 1, 3, 6 , Min-Shu Hsieh 2, 4 , Han-Yu Wang 3 , Yong-Shi Li 3 , Hang Lin 3 , Hung-Wei Hsu 3 , Chung-Yi Huang 3 , Chih-Hung Hsu 1, 3 and Ann-Lii Cheng 1, 3, 5, 6 1 Graduate Institute of Oncology, College of Medicine, National Taiwan University, Taipei City, Taiwan 2 Department of Pathology, Graduate Institute of Pathology, College of Medicine, National Taiwan University, Taipei City, Taiwan 3 Department of Oncology, National Taiwan University Hospital, Taipei City, Taiwan 4 Department of Pathology, National Taiwan University Hospital, Taipei City, Taiwan 5 Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan 6 National Taiwan University Cancer Center, Taipei City, Taiwan Correspondence to: Chih-Hung Hsu, email: chihhunghsu@ntu.edu.tw Keywords: angiogenesis, core protein, hepatitis C virus, hepatocellular carcinoma Received: July 04, 2017     Accepted: August 29, 2017     Published: September 30, 2017 ABSTRACT Increased angiogenic activity has been demonstrated in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC), but the mechanism was unclear. To study the role of HCV core protein, we used tube formation and Matrigel plug assays to assess the proangiogenic activity of an HCC cell line, HuH7, and 2 of its stable clones—HuH7-core-high and HuH7-core-low, with high and low HCV core protein expression, respectively. In both assays, HuH7-core-high and HuH7-core-low cells dose-dependently induced stronger angiogenesis than control cells. HuH7 cells with HCV core protein expression showed increased mRNA and protein expression of vascular endothelial growth factor (VEGF). VEGF inhibition by bevacizumab reduced the proangiogenic activity of HuH7-core-high cells. The promotor region of VEGF contains the binding site of activator protein-1 (AP-1). Compared with controls, HuH7-core-high cells had an increased AP-1 activity and nuclear localization of phospho-c-jun. AP-1 inhibition using either RNA knockdown or AP-1 inhibitors reduced the VEGF mRNA expression and the proangiogenic activity of HuH7-core-high cells. Among 131 tissue samples from HCC patients, HCV-related HCC revealed stronger VEGF expression than did hepatitis B virus-related HCC. In conclusion, increased VEGF expression through AP-1 activation is a crucial mechanism underlying the proangiogenic activity of the HCV core protein in HCC cells.