Abstract: Objective  To investigate the expression of Nestin and its relationship with tamoxifen curative effect and prognosis of patients with breast cancer. Methods  A total of 82 patients with breast cancer who received tamoxifen therapy after radical mastectomy in Department of Breast Surgery of Enshi Tujia Miao Autonomous Prefecture Central Hospital of Hubei Province from March 2009 to March 2013 were collected. And the paired cancer tissues and adjacent normal tissues preserved in liquid nitrogen were also collected. Fluorescent quantitative real-time PCR (RT-PCR) and immunohistochemistry were used to detect the content of Nestin mRNA and the expression of Nestin in breast cancer tissues. The expression of Nestin in breast cancer tissues and its relationship with clinicopathologic features were analyzed. Breast cancer cell line MCF-7 was selected, small interfering RNA (siRNA) was used to silence Nestin in MCF-7 cells, and the influence on tamoxifen sensitivity was observed. The relationship of Nestin and epithelial-mesenchymal transition (EMT) was detected using Western blotting. Results  The results of RT-PCR indicated that the mRNA level of Nestin in breast cancer tissues was 3.87 times as high as that in paracancerous tissues (6.34±1.56 vs. 1.64±0.52, t=26.140, P＜0.001). Immunohistochemical staining suggested that the positive rate of Nestin in breast cancer tissues was 75.61% (62/82), which was significantly higher than that in paracancerous tissues ［24.39% (20/82)］, with a significant difference (χ2=43.024, P＜0.001). The expression of Nestin was related to lymphatic vessel infiltration (χ2=7.499, P=0.006) and lymph node metastasis (χ2=6.770, P=0.034), and it was not related to the age of patients (χ2=3.242, P=0.072), tumor size (χ2=2.358, P=0.308), histological grade (χ2=0.294, P=0.863), ductal infiltrating status (χ2=0.180, P=0.671) and triple negative breast cancer (χ2=0.142, P=0.706). The analysis of Cox risk ratio model showed that Nestin expression (HR=1.982, P<0.001; HR=1.537, P<0.001), lymphatic vessel invasion (HR=2.502, P<0.001; HR=1.715, P<0.001) and lymph node metastasis (HR=1.818, P<0.001; HR=1.446, P<0.001) were independent prognostic risk factors for progress-free survival and overall survival in breast cancer patients. After Nestin knockout in breast cancer cell line MCF-7, the IC50 value of MCF-7 to tamoxifen decreased from (48.05±2.22) μmol/L to (35.59±2.92) μmol/L, with a significant difference (t=6.489, P=0.003). Silencing Nestin significantly up-regulated E-cadherin (7.21±1.15 vs. 1.02±0.01, t=6.654, P=0.024) and down-regulated the mesenchyme index Vimentin (0.17±0.08 vs. 1.01±0.02, t=25.015, P＜0.001) in MCF-7 cells. Conclusion  Nestin is over-expressed in breast cancer, which is associated with reduced efficacy of tamoxifen. Nestin may be a new potential prognostic biomarker for breast cancer.

Key words: Breast neoplasms, Tamoxifen, Nestin, Biomarkers, tumor