Objective   To construct short hairpin RNA (shRNA) eukaryotic expression vectors targeting peroxiredoxinⅠ(PrxⅠ) gene and investigate the effect of down-regulating PrxⅠ expression on the biological functions of breast carcinoma MCF-7 cells.    Methods   The eukaryotic expression vectors targeting PrxⅠ gene were constructed and then transfected into MCF-7 cells. Transfection efficiency was evaluated by flow cytometry. The mRNA and protein expressions of PrxⅠ in MCF-7 cells were detected by RT-PCR and Western blotting. The proliferation of MCF-7 cells was determined by MTT assay. The cell cycle and apoptosis were evaluated by flow cytometry.    Results   The eukaryotic expression vectors pGPU6-HK（negative control）

pGPU6-Prx1

pGPU6-Prx2

pGPU6-Prx3 and pGPU6-Prx4 were successfully constructed and then transfected into MCF-7 cells respectively. Transfection efficiency was about 80％. The expression of PrxⅠ in MCF-7 cells transfected with 4 Prx vectors were inhibited significantly at both mRNA and protein levels

especially in the cells with pGPU6-Prx3

whose inhibitory rates were 82.6％ and 80.5％ respectively at mRNA and protein levels. When pGPU6-Prx3 group was compared with untransfected group and the group transfected with pGPU6-HK

the cell proliferation was markedly delayed (P0.05)

the cell apoptosis rate was significantly increased

and the cells were arrested in G1 phase and S phase were significantly decreased (P0.05).    Conclusion   Eukaryotic expression vectors of shRNA PrxⅠis successfully constructed

and specifically down-regulate the PrxⅠ expression at mRNA and protein levels. Transfection of pGPU6-Prx3 vector significantly inhibits cell proliferation

induces cell apoptosis

and regulates cell phase redistribution in MCF-7 cells.