miR-92 has been reported to be upregulated in several human cancers. Until now, its expression pattern and biological roles in human bladder cancer still remains unexplored. The present study aims to clarify its expression, function, and potential molecular mechanisms in bladder cancer. Using real-time PCR, we found that miR-92 was upregulated in bladder cancer tissues compared with normal bladder tissues. We transfected miR-92 mimic and inhibitor in T24 and 5637 bladder cancer cells separately. We found that miR-92 mimic promoted T24 proliferation and invasion, with increased expression of cyclin D1, c-myc, and MMP7 at both mRNA and protein levels. Further investigation found that miR-92 could also promote epithelial-mesenchymal transition by downregulating E-cadherin protein and upregulating vimentin. In addition, miR-92 mimic also promoted activation of Wnt signaling. Meanwhile, miR-92 inhibitor displayed the opposite effects in 5637 cell line. By use of bioinformatic prediction software and luciferase reporter assay, we discovered that GSK3β acted as a direct target of miR-92. Additionally, GSK3β siRNA abrogated the effects of miR-92 mimic on cyclin D1 and MMP7. Moreover, we observed a negative correlation between GSK3β and miR-92 in bladder cancer tissues. In conclusion, our study demonstrated that upregulation of miR-92 is closely related with malignant progression of bladder cancer and miR-92 promotes proliferation, invasion, and Wnt/c-myc/MMP7 signaling by targeting GSK3β.
Keywords: Bladder cancer; GSK3β; Invasion; Proliferation; miR-92.