Objective      To determine the effect of short hairpin RNA-mediated silencing of Sox2 (sex determination region of Y chromosome-related HMG-box 2) on the invasion

proliferation and apoptosis in human breast cancer cells (MDA-MB-231) and on the expression of β-catenin and transcriptional intermediary factor 1γ (TIF1γ).       Methods      Constructed shRNA recombinant vector of targeted Sox2 gene was transfected into MDA-MB-231 cells. The cells transfected with plasmid pMafic7.1-shRNA-NC and those without served as negative and blank control. The protein expression of Sox2 in the 3 groups of cells was detect by Western blotting. The cell apoptosis was measured by flow cytometry. Transwell assay was used to detect the cellular invasiveness and metastasis. Cell vitality and proliferation were tested by MTS assay. The expression and distribution of β-catenin and TIF1γ protein were detected by Western blotting and immunohistochemical staining

respectively.       Results      Recombinant vector of pMafic7.1-shRNA-Sox2 was constructed successfully. When compared with negative and blank control cells

the transfected cells had obviously reduced level of Sox2 protein (P0.01)

significantly enhanced apoptotic rate (P0.05)

and remarkably reduced invasion

vitality and proliferation capacities (P0.05). The expression level of β-catenin  was significantly decreased in the transfected cells (0.15±0.04) than the negative (0.74±0.10) and blank control cells (0.79±0.07

both P0.05). So was that of TIF1γ (0.11±0.01 vs 0.64±0.07 and 0.74±0.05

both P0.05).       Conclusion      Targeted silencing of Sox2 enhances the apoptosis

and inhibits the proliferation and invasion in breast cancer cells

which may be related in the inhibition of Wnt/β-catenin signal pathway and TIF1γ.