Insufficient radiofrequency ablation promotes human hepatoma SMMC7721 cell proliferation by stimulating vascular endothelial growth factor overexpression

The aims of the current study were to investigate the influence of insufficient radiofrequency ablation (RFA) on the cell proliferation of the human hepatocellular carcinoma (HCC) cells, SMMC7721, and to elucidate the underlying mechanism. SMMC7721 cells were subjected to a 47°C treatment regimen to simulate insufficient RFA, in the presence or absence of KN93 [a specific inhibitor of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII)], PD98059 [a specific inhibitor of extracellular signal-regulated kinase (ERK)], or axitinib (a specific inhibitor of vascular endothelial growth factor (VEGF) receptor]. Cell proliferation was determined using a thiazolyl terazolium assay (MTT). The levels of CaMKII, phospho-CaMKII, ERK, phospho-ERK and VEGF were observed by western blot analysis. The results demonstrated that the 47°C treatment regimen: i) Triggered upregulation of VEGF expression in the SMMC7721 cells, which was reduced by CaMKII or ERK inhibition; ii) induced ERK activation was prevented by KN93; and iii) promoted SMMC7721 cell proliferation, which was greatly inhibited by axitinib, KN93 and PD98059. In conclusion, the results indicated that insufficient RFA promotes SMMC7721 cell proliferation by activating CaMKII/ERK-dependent VEGF overexpression.