Overexpression of histone deacetylase 6 contributes to accelerated migration and invasion activity of hepatocellular carcinoma cells

Histone deacetylase 6 (HDAC6) is a cytoplasmic enzyme that regulates many important biological processes, including cell migration, viral infection and autophagy. The aim of this study was to investigate the significance of HDAC6 in the invasion and metastasis activities of hepatocellular carcinoma (HCC). Three HCC cell lines and two primary cultures of hepatocytes were used for biological experiments. Immunohistochemistry for HDAC6 protein was also examined in 70 resected primary HCCs. Knockdown of the HDAC6 gene in the HCC cell lines was carried out by treatment with siRNA, and their migration and invasion activities were examined by the scratch assay and Matrigel invasion assay, respectively. HDAC6 expression was greater in all of the HCC cell lines compared to the primary cultures of hepatocytes. Knockdown of HDAC6 markedly downregulated the migration and invasion activities of all HCC cell lines (P<0.05). Overexpression of HDAC6 protein to a level higher than that in the corresponding normal hepatocytes was observed in 14 (20%) of the 70 primary HCCs, and was significantly correlated with high clinical stage, number of tumors, vascular invasion and intrahepatic metastasis (P<0.05). These results suggest that overexpression of the HDAC6 protein is involved in the migration and invasion activities of HCC cells, and may be a good biomarker for prediction of intrahepatic metastasis.