Proteomic identification of RhoA as a potential biomarker for proliferation and metastasis in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world, and there is an urgent need to discover novel factors that can act as biomarkers for prognostic assessment and therapeutic targets of HCC. In this study, highly purified plasma membrane proteins from clinical tissue samples were obtained using a strategy combining sucrose density gradient centrifugation and subsequent phase partition. Using a two-dimensional gel electrophoresis and MALDI-Q-TOF MS/MS-based proteomics approach, we identified 13 plasma membrane-associated proteins that were differentially expressed in HCC and normal liver tissues. Of those, RhoA was one of the most significantly upregulated proteins in HCC, and its overexpression was confirmed using Western blotting. Immunohistochemistry suggested a link between RhoA expression and poor differentiation and clinicopathologic stage. Suppression of RhoA expression in HepG2 and Hep3B cells by RNA interference led to significant inhibition of cell growth, induction of apoptosis, and a decrease in migration. Our data suggest that RhoA may serve as a potential biomarker and an attractive therapeutic target for HCC.