[MicroRNA-133b suppresses cell proliferation and invasion of esophageal squamous cell carcinoma via downregulating TAGLN2 expression].

To investigate the expression of microRNA-133b (miR-133b) in esophageal squamous cell carcinoma (ESCC), and explore its effect and the underlying molecular mechanisms on cell proliferation and invasion. Real-time quantitative PCR (qPCR) was used to examine miR-133b expression in 63 ESCC tissues and paired adjacent non-cancerous tissues, several ESCC cells (Eca109, EC9706, EC1, TE1, KYSE70) and normal esophageal epithelial cell Het-1A. MiR-133b mimic, inhibitor and negative control (NC) were transfected into TE1 cells. The effect of miR-133b on cell proliferation and invasion were determined by CCK-8 and Transwell assays, respectively. Subsequently, the target gene of miR-133b was predicted by online tools TargetScan and miRDB, which was verified by dual luciferase reporter assays. Finally, Western blot was utilized to detect the effects of miR-133b overexpression on expression of target gene TAGLN2 as well as EMT-related proteins E-cadherin, N-cadherin, Snail, Slug and Vimentin. Relative levels of miR-133b in ESCC tissues (0.295±0.040) were significantly lower than those in adjacent non-cancerous tissues (1.002±0.011, <0.001). The expression of miR-133b was tightly associated with clinical staging, lymph node metastasis and prognosis. Moreover, relative levels of miR-133b in ESCC cells Eca109, EC9706, EC1, TE1 and KYSE70 (0.679±0.031, 0.391±0.008, 0.236±0.016, 0.031±0.005 and 0.099±0.020) were evidently lower than that in normal esophageal epithelial cell Het-1A (1.005±0.016, all <0.001). In TE1 cells, miR-133b mimic significantly increased the level of miR-133b to 6.199±0.627, and suppressed cell proliferation and invasion, whereas miR-133b inhibitor obviously decreased its expression to 0.182±0.023, and promoted cell proliferation and invasion. Most notably, the relative luciferase activities of miR-133b-mimic group (0.320±0.018) in TE1 cells transfected with TAGLN-3'UTR-WT were markedly lower than that in NC group (1.010±0.036, <0.001), whereas those in TAGLN-3'UTR-MUT transfection cells were 1.019±0.056 and 1.008±0.021, respectively, showing no significantly statistical difference (>0.05). Furthermore, miR-133b overexpression markedly downregulated TAGLN2, N-cadherin, Snail, Slug and Vimentin levels, and increased E-cadherin expression. MiR-133b plays an important role in the proliferation and invasion of ESCC cells by regulating TAGLN2 expression, and it may be a potential therapeutic target for ESCC patients.