Abstract: Objective To construct and identify the siRNA eukaryotic expression vector targeting gene CXC chemokine receptor-4 and study its role in invasion ability of bread cancer cells. Methods Two siRNAs were designed and synthesized according to the coding the cDNA sequence of CXCR4 gene and cloned into eukaryotic expression plasmid pGE-1-U6/kna.The constructed CXCR4-siRNA expression vector was transfected into MDA-MB-231 cells by liposome.Western blotting were used to evaluate the suppression of CXCR4 expression in different groups. The invasion and migration of MDA-MB-231 cells were evaluated by cell invasion assay in vitro. Results　Enzyme digestion and DNA sequencing confirmed that the CXCR4-siRNA expression vector was constructed successfully. After transfection,the CXCR4-siRNA obviously suppressed the expression of CXCR4 compared with control groups and the ability of cell migration was decreased markedly. Conclusions CXCR4-siRNA expression vector can effectively suppress CXCR4 expression in the breast cancer cell and decrease potential of cell invasion, which may provide a novel applicable strategy for gene therapy of breast cancer metastasis.

Key words: breast cancer, CXCR4 gene, siRNA, RNAi