[MiR-527 targeting Bcl-2 inhibits migration and promotes apoptosis in bladder urothelial cell carcinoma]

Objective: To investigate the expression of miR-527 in bladder urothelial cell carcinoma tissues (UCC) and cell lines, and to explore the mechanism by which miR-527 inhibits bladder cancer cell migration and promotes apoptosis through targeting Bcl-2. Methods: The expression of miR-527 in bladder UCC was analyzed using The Cancer Genome Atlas database. The expression of miR-527 in bladder UCC cell lines was verified by real-time quantitative reverse transcription polymerase chain reaction. The relationship between miR-527 and its target gene Bcl-2 was validated using a dual-luciferase reporter assay. miR-527 inhibitor and miR-527 mimic were constructed for cell transfection. Cell migration and apoptosis were assessed using wound healing assay and flow cytometry. Protein expression was detected by Western blot. In vivo tumorigenesis and the expressions of Bcl-2 and Ki-67 were evaluated using a nude mouse cell-derived xenograft model and immunohistochemistry. Results: Analysis of The Cancer Genome Atlas database revealed that miR-527 expression was significantly higher in bladder cancer tissues than in normal bladder tissues, whereas Bcl-2 protein expression was significantly lower. Dual-luciferase reporter assay confirmed that miR-527 directly targeted Bcl-2. Inhibition of miR-527 significantly upregulated Bcl-2 mRNA and protein levels (both P＜0.01), enhanced cell migration, and reduced apoptosis [migration rate: (100.00±0.00)% in the miR-527 inhibitor group vs. (47.74 ± 2.18)% in the T24 control group; apoptosis rate: (2.68±1.28)% vs. (11.82±5.19)%; both P＜0.05]. Overexpression of miR-527 produced opposite effects [migration rate: (45.22±3.66)% in the miR-527 overexpression group vs. (100.00±0.00)% in the UMUC-3 control group; apoptosis rate: (11.74±0.64)% vs. (3.81±0.75)%; both P＜0.05]. In animal experiments, overexpression of miR-527 significantly inhibited tumor growth and reduced the expressions of Bcl-2 and Ki-67 in tumor tissues, whereas inhibition of miR-527 promoted tumor growth, increased tumor cellular atypia, and enhanced the expressions of Bcl-2 and Ki-67. Conclusions: miR-527, as a tumor-associated gene, is highly expressed in bladder cancer tissues. Overexpression of miR-527 inhibits the growth and migration of bladder cancer cells and induces apoptosis by negatively regulating the Bcl-2.