Abstract: Objective To explore the influence of RNA interference targeting Rab5a on invasion of breast cancer cells MCF-7.Method Four miRNA interference vectors targeting Rab5a were designed,constructed and transfected into breast cancer cell line MCF-7 each other.RT-PCR and Western blot were applied to selecte the most efficient group of miRNA interference suppression,then transwell assay were applied to analyse the cell invasiveness.Results RT-PCR analysis showed that cells MCF-7 transfected with Rab5a-miRNA-2 vector had the strongest inhibition of Rab5a gene,with the inhibition rate (50.01±2.69)%.Western blot analysis showed that cells transfected with Rab5a-miRNA-2 vector had the strongest inhibition of Rab5a protein,with the inhibition rate (68.49±3.70)%.Then we used Rab5a-miRNA-2 group for transwell assay.Transwell assay showed that the number of cells passing the membranes was 67.8±12.03 at 48h since transfecting,and was significantly different from the negative controls and blank controls(P＜0.01).Conclusion Rab5a silenced by miRNA expression vector can inhibit the invasiveness of breast cancer cells MCF-7.