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

Objective 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.Methods 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.Results 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,P<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 P<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,P<0.001),whereas those in TAGLN-3'UTRMUT transfection cells were 1.019±0.056 and 1.008±0.021,respectively,showing no significantly statistical difference(P>0.05).Furthermore,miR-133b overexpression markedly downregulated TAGLN2,N-cadherin,Snail,Slug and Vimentin levels,and increased E-cadherin expression.Conclusion 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.