OBJECTIVETo evaluate the mechanism of increased invasion and migration of hepatocellular carcinoma (HCC) cells induced by vascular endothelial growth factor receptor-1 (VEGFR-1) activation.

METHODSVascular endothelial growth factor-B (VEGF-B) was used to induce and stimulate hepatocellular carcinoma cell line MHCC97-H. Morphologic changes of MHCC97-H were investigated. The expression of E-cadherin and alpha-catenin (two epithelial markers) and Vimentin and N-cadherin (two mesenchymal markers) was detected by reverse transcriptase polymerase chain reaction (RT- PCR), western blotting, and immunofluorescence staining. Cell invasion and migration test was performed.

RESULTSTreatment of MHCC97-H cells with VEGF-B led to morphologic changes characteristic of epithelial to mesenchymal transition (EMT), including loss of polarity, increased intercellular separation, and the presence of pseudopodia. Expression of the epithelial adhesion molecules, including E-cadherin and alpha-catenin, was decreased after VEGF-B treatment. Conversely, an increase in the expression of the mesenchymal cell markers, including N-cadherin and vimentin, was observed after VEGF-B treatment (P less than 0.05). VEGF-B-treated cells exhibited a change in E-cadherin from an organized, membrane-bound structure to a disorganized state in which it was noted to be dispersed throughout the cytoplasm. Pretreatment with VEGFR-1 blocking antibody 18F1 inhibited the change in localization of E-cadherin induced by VEGF-B treatment. The ability of invasion and migration of MHCC97-H was enhanced by VEGF-B reatment (P less alpha 0.05).

CONCLUSIONIncreased invasion and migration of HCC cells induced by VEGFR-1 activation was mediated by epithelial to mesenchymal transition.