Expression of microRNA-145 on the targeted regulation of SOX11 and its effect on proliferation and apoptosis of breast cancer cells

GUO Hui; ZHANG Bin; HU Limin

doi:10.3969/j.issn.1009-0460.2018.03.002

Abstract：Objective To explore the effect of microRNA-145 (miR-145) on the target regulation of sex determining region Y-box 11 (SOX11) and the effect on the proliferation and apoptosis of breast cancer cells. Methods Real-time fluorescence quantitative PCR (QPCR) was used to detect the expression level of miR-145 in normal mammary epithelial cells (HBL-100) and breast cancer MDA-MB-231 cells. MDA-MB-231 cells in growth phase were transfected with miR-145 mimics (overexpression group) or negative control plasmid NC (negative control group) by liposome method, and the cells without transfection were used as blank control group. QPCR was used to detect the miR-145 level of each group at 48 h after transfection. CCK-8 and Annexin V-FITC/PI were used to detect the proliferative rate and apoptosis rate of each group. QPCR and Western blotting were used to detect mRNA and protein levels of SOX11 at 48 h after transfection. The targeting regulatory relationship between miR-145 and SOX11 was verified by the luciferase report test. Results The level of miR-145 in HBL-100 cells was 1.047±0.026, higher than 0.218±0.019 of MDA-MB-231 cells (P＜0.05). The levels of miR-145 in blank control group, negative control group and overexpression group were 1.022±0.034, 0.987± 0.028 and 3.408±0.097, and the miR-145 level in overexpression group was higher than those in the other two groups (P＜0.05). The proliferative rates of the overexpression group were lower than those in the blank control group and the negative control group at 48 and 72 h after transfection (P＜0.05). As for the blank control group, negative control group and overexpression group, apoptotic rates were (6.12±0.79)％, (7.12±0.82)％ and (26.11土1.95)％, SOX11 mRNA levels were 1.066±0.074, 1.105±0.Q91 and 0.126±0.023, and SOX11 protein levels were 0.524±0.048, 0.492±0.056 and 0.173±0.038. Compared with other groups, there were higher apoptotic rate and lower mRNA and protein levels of SOX 11 in overexpression group (P＜0.05 ). Luciferase activity assay showed that miR-145 inhibited the luciferase activity of wild-type SOX 11 3' UTR reporter vector, but had no effect on the luciferase activity of mutant SOX 11 3' UTR. Conclusion The decreased expression of miRNA-145 in breast cancer cells may regulate the proliferation and apoptosis of breast cancer cells and bind with SOX 11 3' UTR, possibly becoming a new target for breast cancer therapy.