Preliminary mechanism study of transient receptor potential cation channel subfamily V member 2 expression mediated by microRNA-202-5p regulating self-renewal of triple-negative breast cancer stem cells

Objective To investigate self-renewal ability of triple-negative breast cancer (TNBC) stem cells regulated by microRNA (miRNA, miR)-202-5p via transient receptor potential cation channel subfamily V member 2 (TRPV2). Methods The expression of miR-202-5p in stem cells was detected by real-time quantitative PCR (RT-qPCR). Expressions of TRPV2, estrogen-related-receptor β (ESRRB), SRY-like HMG box 2 (Sox2), octamer binding factor 4 (Oct4), stem cell markers CD133 and CD13 were detected by RT-qPCR and Western blotting. Further experiments were conducted to explore characterization of stem cells. SPSS 21.0 statistical software was used to analyze the data. When P<0.05, the difference was statistically significant. Results Expression of miR-202-5p was low in TNBC stem cells (1.00±0.17 vs. 0.58±0.20; t=2.771, P<0.05). After treatment with miR-202-5p mimic+ shTRPV2, CD133, CD13, Oct4, Sox2 and Esrrb mRNA (Esrrb [(1.10±0.09) vs. (0.39±0.04), t=22.800, P<0.05], Sox2 [(1.10±0.08) vs. (0.41±0.06), t=21.820, P<0.05], Oct4 [(1.00±0.09) vs. (0.43±0.07), t=15.810, P<0.05], CD133 [(1.01±0.09) vs. (0.41±0.07), t=6.640, P<0.05] and CD13 [(0.99±0.09) vs. (0.40±0.07), t=16.360, P<0.05] and protein expression decreased, and the ability of cell sphere-forming [(1.03±0.06) vs. (0.43±0.05), t=24.290, P<0.05], cloning [(65.00±4.76) vs. (28.44±3.88), t=18.830, P<0.05] and proliferation decreased significantly [(18.43±1.88) vs. (9.02±1.22), t=13.280, P<0.05]. While after miR-202-5p inhibitor treatment CD133, CD13, Oct4, Sox2 and Esrrb mRNA (Esrrb [(1.11±0.08) vs. (2.11±0.16), t=17.680, P<0.05], Sox2 [(1.09±0.06) vs. (2.15±0.10), t=28.740, P<0.05], Oct4 [(0.98±0.07) vs. (2.09±0.19), t=17.340, P<0.05], CD133 [(1.01±0.07) vs. (2.22±0.10), t=31.350, P<0.05] and CD13 [(0.94±0.05) vs. (2.32±0.11), t=36.120, P<0.05]) and protein expression increased, and the ability of cell sphere-forming [(1.47±0.09) vs. (1.83±0.10), t=8.460, P<0.05], cloning [(77.23±6.00) vs. (110.37±11.25), t=8.220, P<0.05] and proliferation [(20.42±2.04) vs. (30.68±2.82), t=9.320, P<0.05] increased significantly. Conclusion Up-regulation of miR-202-5p in TNBC cells inhibits the expression of the TRPV2 gene and the inhibits the ability of TNBC stem cells to self-renew. Key words: MicroRNA-202-5p; Transient receptor potential cation channel subfamily V member 2; Triple-negative breast cancer; Stem cells; Self-renewal ability