Abstract: Background and purpose: Breast cancer is one of the most common malignant diseases in women and its malignant proliferation is the major cause of death. To investigate the effects of N-myc downstream regulated gene 2 (NDRG2) on proliferation of breast cancer cells by using two parallel cell lines (MCF-7 and LM-MCF-7) with different metastatic abilities. Methods: The expression level of NDRG2 in breast cancer cells was detected by Western blot. The effects of overexpressing (or down-regulating) NDRG2 on proliferation of breast cancer cells were investigated by flow cytometry. The expression and location of β-catenin were detected by Western blot and immunofluorescence respectively. NDRG2 blocking the transcription activity of β-catenin was investigated via co-transfecting MCF-7 cells with NDRG2 siRNA and pCMV-Tcfδ (lacking the portion responsible for the protein binding to DNA). Results: The expression level of NDRG2 was negatively related to the proliferation ability of breast cancer cells. Over-expressing NDRG2 (or down-regulating) via transfecting LM-MCF-7 (or MCF-7) cells with pCMV-NDRG2 (or NDRG2 siRNA) could inhibit (or promote) cell proliferation. Interestingly, the results of Western blot, immunofluorescence and flow cytometry revealed that down-regulation of NDRG2 resulted from the down-regulation of β-catenin and blocking its nuclear translocation, which led to losing control of the proliferation of breast cancer cells. Conclusion: NDRG2 inhibit the proliferation of breast cancer cells via down-regulating the expression of β-catenin and blocking its nuclear translocation, which is significant for exploring the molecular mechanism of proliferation of breast cancer cells.

Key words: Breast neoplasms, N-myc downstream regulated gene 2, β-catenin, Cell proliferation