Gelsolin-like Actin-capping Protein (CapG) Overexpression in the Cytoplasm of Human Hepatocellular Carcinoma, Associated with Cellular Invasion, Migration and Tumor Prognosis

BACKGROUND/AIM: Human hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Patients with metastatic HCC (mHCC) show poor prognosis and high mortality. In previous reports, gelsolin-like actin-capping protein (CapG) has been demonstrated to regulate cancer invasion and metastasis in various human cancers. In this study, the expression of CapG was verified in normal and/or HCCs' specimens and HCC cell lines. Moreover, the bio-activity of CapG was also investigated. MATERIALS AND METHODS: The expression of CapG was examined in HCC's tissue-array by immunohistochemical (IHC) staining. The mRNA and protein of CapG in three HCC cell lines were determined using real-time RT-PCR and western blot. Moreover, a trans-well migration model and a matrigel-trans-well invasion assay were used to address the bio-activity of CapG in HCC cell lines. RESULTS: CapG was detected in the cytoplasm of normal liver tissue and HCC specimens. Importantly, CapG expression was elevated in the HCC specimens compared to normal cases and was significantly overexpressed in mHCC cases compared to normal cases. Moreover, patients with highly expressed CapG showed greater mortality in HCC cases. In addition, the RNA and protein levels of CapG among three HCC cell lines showed a positive association with cellular migration and invasive ability. CapG knockdown with shRNA in HCC cells also verified this finding. CONCLUSION: In the present study, it is demonstrated that CapG is expressed in the cytoplasm and could be used as a prognostic or diagnostic biomarker for mHCC in clinical specimens. Moreover, CapG might contribute to tumor motility and cancer-associated mortality.