24, 25 Indeed, the Kaplan-Meier analysis shows that patients with HCC who had high p28GANK expression in general had worse prognosis than those with low expression. We believe that p28GANK is an attractive candidate gene for risk prognostication and therapy of HCC. However, our data is apparently at odds with a recent

report suggesting that the cumulative survival rate of patients with gankyrin-positive HCC was significantly higher than those patients with gankyrin-negative HCC.26 The discrepancy may be due to different backgrounds of specimens used, including the www.selleckchem.com/products/sorafenib.html proportion of hepatitis C virus and hepatitis B virus infection, sex of patients, and the classification/criteria of tumor-node-metastasis (TNM) staging. Recently, Ortiz and Tang reported that gankyrin messenger Fulvestrant supplier RNA and protein increased in human esophageal squamous cell carcinoma (ESCC) or colorectal cancer (CRC), and its overexpression is poor prognosis of ESCC or CRC due to its significant correlation with TNM stages and metastasis of these tumors, respectively.27, 28 Therefore, p28GANK overexpression may be involved in development of human digestive malignancies such as HCC, ESCC, and CRC. The effect of p28GANK on tumor invasion and metastasis was directly demonstrated in our in vitro and in vivo studies. In both subcutaneous

and orthotopic xenografts, overexpression of p28GANK generated larger primary tumors and more lung metastasis foci, and higher levels of vascularization and angiogenesis, indicating their more aggressive and metastatic properties. Moreover, down-regulation

of p28GANK led to severe suppression of tumor growth and lung metastasis of HCC in mice. To our knowledge, this is the first report that p28GANK expression is critical for HCC metastasis, in addition to tumor proliferation and growth. In this study, we found that TWIST1 is indeed involved in p28GANK-driven EMT. Moreover, p28GANK isothipendyl modulated HIF-1α hyperactivation and expression correlated with TWIST up-regulation and E-cadherin down-regulation. Thus, our data suggest a requirement for HIF-1α in p28GANK-driven EMT. We also observed a role of HIF-1α in p28GANK-regulated VEGF and MMP2 expression, consistent with previous reports that HIF-1α up-regulates VEGF, promoting angiogenesis and invasion of HCC.29–31 Taken together, this study clearly demonstrates a crucial role for p28GANK in induction of EMT and angiogenesis through regulation of HIF-1α, VEGF, and MMP2 expression. An increase in AKT signal is a key tumor survival mechanism, and promotes tumor metastatic processes including EMT, resistance to apoptosis, and angiogenesis.32–34 Previous studies have demonstrated that activated AKT plays a critical role in hematogenous intrahepatic metastasis in an orthotopic implantation model of HCC.35 Our group previously showed a protective role of p28GANK in HCC cells against endoplasmic reticulum stress-induced apoptosis, partially through enhancing AKT phosphorylation.