Esophageal squamous cell carcinoma(ESCC)is one of the most lethal cancers worldwide.In this study,we aimed to investigate the underlying mechanisms of metastasis inhibition by miR-205 in ESCC.In microRNA(miRNA)array and quantitative RT-PCR analyses,we found that the expression level of miR-205 was significantly lower in patients with lymph node metastasis compared with that in patients without lymph node metastasis.After transfection of miR-205 mimics or inhibitors into ESCC cell lines,a significant negative correlation was observed between the expression level of miR-205 and Smad1.In luciferase reporter assays,we revealed that miR-205 inhibited the expression of SMAD1 by targeting the 30untranslated region(30-UTR)of SMAD1 mRNA in ESCC cells.Furthermore,our results showed that miR-205 suppressed the invasion and migration of ESCC cells,whereas Smad1 increased their invasion and migration.Taken together,our study demonstrates that miR-205 functions as a suppressor of tumor metastasis by regulating SMAD1expression through targeting the 30-UTR of SMAD1 mRNAin ESCC.Therefore,miR-205 may be a potential therapeutic target for miRNA-based therapy of ESCC.
