KDR 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),VEGFR2(FLK-1,KDR) and FLT-4.FLK-I(KDR) plays the most important role in the cellular growth and differentiation and is connected with the proliferation of the endothelial cells and angiogenesis.In this study,we utilized chemically modified siRNA to inhibit KDR gene expression in vitro and in vivo,to investigate the feasibility and specificity of gene therapy for breast cancer.Methods In vitro,the KDRsiRNA was transfected into MCF-7 cells to induce RNAi by using cationic liposome Lipofectamine2000^TM as transfecting agent.MTT assay was used to detect the inhibitory rate of MCF-7 cells proliferation.The changes of KDR mRNA expression in both siRNA treatment groups and control groups were measured by reverse transcription-polymerase chain reaction(RT-PCR).In vivo,the siRNA was transfected into transplanted tumor in nude mice by using cationic polymer nanoparticle "In vivo jetPEI^TM"as transfecting agent.Tumor growth was observed.The expressions of KDR mRNA and protein were measured by RT-PCR and immunohistochemical technology.Results Experiments in vitro showed that siRNA directed against KDR gene effectively inhibited the proliferation of MCF-7 cells.The inhibitory rate was 43.7%.The expression of KDR mRNA was downregulated(p＜0.05).In vivo,the growth of tumor was visibly suppressed.Furthermore,RT-PCR and immunohistochemical results indicated that KDR mRNA and protein expression were reduced in excised tumors(p＜0.05).In contrast,there were no obvious changes in control groups.Conclusion RNAi mediated by chemically modified siRNA markedly decreased KDR gene expression and inhibited cellular proliferation.It may have the potential as a therapeutic modality to treat human breast cancer.Also KDR may be a new target for breast cancer treatment.