Downregulation of long noncoding RNA TUG1 inhibits proliferation and induces apoptosis through the TUG1/miR-142/ZEB2 axis in bladder cancer cells

BACKGROUND: Bladder cancer is a common serious disease around the world. Long noncoding RNAs (lncRNAs) have been demonstrated to participate in the development and progression of various cancers, including bladder cancer. The aim of this study was to investigate the effects of lncRNA taurine upregulated gene 1 (TUG1) on proliferation and apoptosis in bladder cancer cell lines and the underlying mechanism. METHODS: The levels of TUG1 were detected by quantitative real time polymerase chain reaction (qRT-PCR) in bladder cancer tissues and cells. The mRNA and protein levels of zinc finger E-box binding homeobox 2 (ZEB2) were measured by qRT-PCR and Western blot analysis, respectively. The functional targets of TUG1 were predicted by online softwares and confirmed by luciferase reporter assay. The effects of TUG1 on cell proliferation and apoptosis were examined by MTT and apoptosis assay, respectively. The expression levels of β-catenin, cyclinD1, and c-Myc in T24 cells were determined by Western blot analysis. RESULTS: The levels of TUG1 and ZEB2 were significantly increased in bladder cancer tissues and cells. Knockdown of either TUG1 or ZEB2 inhibited proliferation and induced apoptosis in bladder cancer cells. Interestingly, ZEB2 overexpression reversed the effects of TUG1 knockdown on cell proliferation and apoptosis. Moreover, ZEB2 was verified as a direct target of miR-142 and miR-142 could specially bind to TUG1. In addition, downregulation of TUG1 inhibited the Wnt/β-catenin pathway by regulating ZEB2 expression in bladder cancer cells. CONCLUSION: Downregulation of TUG1 expression inhibited proliferation and induced apoptosis in bladder cancer cells by targeting ZEB2 mediated by miR-142 through the inactivation of Wnt/β-catenin pathway.