Identification of Gem as a new candidate prognostic marker in hepatocellular carcinoma

GTP binding protein overexpressed in skeletal muscle (Gem) is a Ras-related protein whose expression is induced in several cell types upon activation by extracellular stimuli. To investigate the potential roles of Gem in hepatocellular carcinoma (HCC), expression of Gem was examined in human HCC samples. Western blot analysis showed that compared with primary human hepatocytes and adjacent noncancerous tissue, significant down-regulation of Gem was found in HCC cells and tumor tissues. In addition, immunohistochemical analysis of Gem expression was investigated in 108 specimens of HCC tissues. Clinicopathological data were collected to analyze the association with Gem expression. Expression of Gem was significantly negatively correlated with histological grade (P=0.001), tumor size (P=0.020), and vascular invasion (P=0.005), and Gem was also negatively correlated with proliferation marker Ki-67 (P<0.01). More importantly, the Kaplan-Meier survival curves analysis revealed that low expression of Gem was associated with poor prognosis in HCC patients. Univariate analysis showed that Gem expression was associated with poor prognosis (P=0.006). Multivariate analysis indicated that Gem expression was an independent prognostic marker for HCC (P=0.007). Finally, serum starvation and release experiments showed that Gem expression was negatively related with cell proliferation. In the conclusion, our results suggested that down regulation of Gem expression was involved in the pathogenesis of hepatocellular carcinoma, and it might be a favorable independent prognostic parameter for HCC.