Small Interfering RNAs Directed Against VEGF Gene Inhibit The Proliferation Of Breast Cancer Cells In Vitro And In Vivo

Background & ObjectiveAngiogenesis, the formation of blood vessels, is a vital process in tumor growth, invasion and metastasis. Vascular endothelial growth factor (VEGF), which can especially promote endothelial cell division, proliferation, and migration, plays a critical role in tumor angiogenesis. Inhibiting the expression of VEGF by RNAi was efficiently applicable to the treatment of cancers as an antiangiogenic therapeutic. In this study, we utilized chemically modified siRNA to inhibit VEGF gene expression in vitro and in vivo, to investigate the feasibility and specificity of gene therapy for breast cancer.MethodsThe VEGF siRNA was transfected into MCF-7 cells and transplanted tumors in nude mice to induce RNAi by transfecting agent of cationic liposome Lipofectamine2000^TM. MTT assay was used to detect the inhibitory rate of MCF-7 cells proliferation, cells were observed in shape with an invert microscope and in apoptosis dyed by Hoechst33258 with a fluorescence microscope. The changes of VEGF, Bcl-2 and Bax gene expression in both siRNA treatment groups and control groups were measured by RT-PCR and Western Blotting in vitro and in vivo.ResultsExperiments in vitro showed that siRNA directed against VEGF effectively inhibited the proliferation of MCF-7 cells, the inhibitory rate was 52.5%. Apoptosis bodies were observed in stained cells by Hoechst 33258 under a fluorescence microscope seventy-two hours after siRNA being transfected. The siRNA directed against VEGF down-regulated the expression of VEGF in both levels of mRNA and protein (p＜0.01), Bcl-2 expression changed obviously and the ratio of Bcl-2 to Bax decreased; Experiment data in vivo showed that the growth of tumor was suppressed visibly and the expression of VEGF,Bcl-2 and Bax have the same changes in excised tumors as in cultured MCF-7 cells. In contrast, there were no obvious changes in control groups.ConclusionRNAi mediated by chemically modified siRNA efficiently decreases VEGF gene expression, inhibits cellular proliferation, induces cell apoptosis in vitro and in vivo and may be a potential and therapeutic modality to treat human cancers.