BACKGROUNDBreast cancer is one of the most common malignant female diseases worldwide. It is a significant threat to every woman's health. Vascular endothelial growth inhibitor (VEGI) is known to be abundant in endothelial cells. According to previous literature, overexpression of VEGI has been shown to inhibit tumor neovascularisation and progression in cellular and animal models, but there has been limited research on the significance of VEGI in the breast cancer.

METHODSIn our study, cell lines MDA-MB-231 were first constructed in which VEGI mediated by lentivirus over-expressed. The effects of VEGI over-expression on MDA-MB-231 cells were investigated both in vitro and in vivo. The expression of VEGI in the MDA-MB-231 cells after infection of lentivirus was analyzed using real-time PCR and Western blotting. The effect of the biological characteristics of MDA-MB-231 cells was assessed by growth, invasion, adhesion, and migration assay with subcutaneous tumor-bearing nude mice models. Then the growth curves of the subcutaneous tumors were studied. Expressions of VEGI, CD31 and CD34 in the tumors were analyzed by immunohistochemistry and apoptosis was detected by flow cytometry and immunohistochemistry.

RESULTSInfection of MDA-MB-231 cells within the lentivirus resulted in approximately a 1 000-fold increase in the expression of VEGI. As can be seen in the invasion, adhesion and migration assay, the over-expression of VEGI can inhibit the ability of MDA-MB-231 cells during migration, adhesion and invasion. The volume of the subcutaneous tumor in the over-expression group was distinctly and significantly less than that of the control groups. Immunohistochemistry analysis of the tumor biopsies clearly showed the expression of VEGI in the over-expression group increased while CD31 and CD34 decreased significantly. In vitro and in vivo, the early apoptosis rate and the apoptosis index were increased within the VEGI over-expression group as compared with the control group.

CONCLUSIONSTaken together, recombinant lentivirus that were successfully constructed, demonstrated up-regulated VEGI gene expression in breast cancer cells. Lentivirus-mediated over-expression of VEGI weakened the ability of the breast cancer cell migration, adhesion and invasion. Over-expression of VEGI diminished the tumorigenic capacity of breast cancer cells in vivo. Up-regulation of VEGI gene expression however inhibited breast cancer MDA-MB-231 cell in the early apoptosis.