ABSTRACT
Objective To investigate the expression relationship between microRNA-206 and Bcl-2 and its clinical significance in patients with triple-negative breast cancer (TNBC). Methods Thirty- one patients with TNBC from April 2013 to August 2017 were selected. Tumor tissues and matched normal tissue were collected. The Bcl-2 level in tissue samples was detected by immunohistochemistry, and the microRNA-206 expression was detected using real-time fluorescence quantitative polymerase chain reaction (qRT-PCR). The correlation of Bcl-2 and microRNA-206 with the clinical pathological characteristic of patients was analyzed. The TNBC cell line (MDA-MB-231) was cultured and transfected with microRNA-206 mimics in order to up-regulate the microRNA-206 level. The expression changes of Bcl-2 after microRNA-206 up-regulation were estimated by qRT-PCR and Western blot. The proliferation change of MDA-MB-231 was measured by CCK-8 cell viability kit. Results The total Bcl-2 positive rate in TNBC tissues was significantly higher than that in normal tissues:64.52％(20/31) vs. 35.48％(11/31), and there was statistical difference (χ2=5.226, P=0.022). The relative level of microRNA-206 in tissues from TNBC patients with higher expression of Bcl-2 was significantly lower than that in tissues from TNBC patients with lower Bcl-2 level (0.645 ± 0.062 vs. 1.000 ± 0.181), and there was statistical difference (t=6.363, P=0.003). In TNBC patients, the Bcl-2 level in tumor tissues was related to lymphatic metastasis, TNM stage and tumor size (χ2=4.917, 8.791 and 6.091; P = 0.026, 0.003 and 0.013). The microRNA-206 was associated with lymphatic metastasis and tumor size (χ2 = 6.856 and 4.774, P = 0.008 and 0.028). After up-regulation of microRNA-206, the relative mRNA Bcl- 2 decreased to 0.641 ± 0.031, compared with non- transfection control (1.000 ± 0.164), and the difference was statistically significant (t=7.468, P=0.001). Also the protein of Bcl-2 was reduced. Up-regulated microRNA-206 restrained the proliferation of MDA-MB-231 cells. Conclusions MicroRNA-206 may regulate the level of Bcl-2 in TNBC. This regulation relationship is involved with the development of TNBC.