Vegfr-1 Targeting Sirna Inhibition Of Proliferation Of Human Breast Cancer Cells In Vivo And In Vitro Study

Background & Objective Vascular endothelial growth factor(VEGF) and its receptors(VEGFR) play an important role in the development,infiltration and extension of the breast cancer cells.At present,we have discovered three kinds of VEGFR:VEGFR1(FLT-1,KDR),VEGFR2(FLK-1) and FLT-4.VEGFR1 plays the most important role in the cellular growth and differentiation and is connected with the proliferation of the endothelial cells and angiogenesis,the expression rates of VEGFR1 in breast cancer cells were 80%.In theory if we inhibit the expression of VEGFR1,the growth of tumor vessels will then be prevented,thereby the growth of tumor/the proliferation of cancer cells will be inhibited,and it become a way to treat tumor.In this study,we utilized chemically modified siRNA to knockdown VEGFR1 gene expression in vitro and in vivo,to investigate the feasibility and specificity of RNAi by chemically modified siRNA for gene therapy in breast cancer.Methods The siRNA targeted to VEGFR1 of both human and rat,and was transfected into MCF-7,SHZ-88cells and SK-BR-3 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 breast cancer cells proliferation.The changes of VEGFR1 gene expression in both siRNA treatment groups and control groups were measured by RT-PCR and Western blotting in vitro and in vivo.Results Experiments in vitro showed that siRNA directed against VEGFR1 gene effectively inhibited the proliferation of MCF-7 and SHZ-88 cells.The inhibitory rate were 50.1%and 49.8%. The siRNA directed against VEGFR-1 down-regulated the expression of VEGFR1 in both levels of mRNA and protein(p＜0.05),The siRNA groups 50 nmol/L,100 nmol/L and 200 nmol/L all have statistical significance(P＜0.05),50 nmol/L and 100 nmol/L have statistical significance with 200 nmol/L(P＜0.05),but 100 nmol/L has no statistical significance with 200 nmol/L(P＞0.05).VEGFR1 can inhibite the proliferation of breast cells in a certain density..In vivo,the growth of tumor was visibly suppressed.Furthermore,the expression of VEGFR1 has the same change In excised tumors as in cultured breast cancer cells.In contrast,there were no obvious changes in control groups.Conclusion RNAi mediated by chemically modified siRNA markedly decreased VEGFR1 gene expression and inhibited cellular proliferation.It may have the potential as a therapeutic modality to treat human breast cancer.VEGFR1 may be a new target for breast cancer treatment.