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.

Objective: To assess the pollution characteristics and risk assessment of carcinogenicity or non-carcinogenicity on heavy metals in PM_2.5 in Shenzhen. Methods: PM_2.5 samples were collected monthly from the year of 2014 to 2015, and analyzed by seasons. 12 heavy metal elements (Pb, Hg, Mn, Sb, Al, As, Be, Cd, Cr, Ni, Se, Tl) in PM_2.5 were detected by ICP-MS spectrometry. Health risk assessment was conducted using the recommended United States Environmental Protection Agency (USA EPA) model. Results: The median of PM_2.5 concentration was 45.10 μg/m³ in Longgang district of Shenzhen. The non-carcinogenecity risks of the metals in PM_2.5 existed in spring, autumn and winter (HQ>1). Three metal elements including As, Mn and Cd have higher HQ levels. The carcinogenecity risk levels in four seasons were winter, autumn, spring and summer, respectively. The carcinogenecity risks in four seasons were between 10^-6 to 10^-4. As, Cr and Cd have higher carcinogenicityrisks. Conclusion The heavy metals in PM_2.5 have both carcinogenecity risk and non-carcinogenecity risk to residents in Longgang district of Shenzhen, the occupational health management must be continuously strengthened, the further research and the measures for prevention and control should be considered.