MiR-205 inhibits the invasion and migration of esophageal squamous cell carcinoma by modulating SMAD1 expression

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 3′ untranslated region (3′-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 SMAD1 expression through targeting the 3′-UTR of SMAD1 mRNA in ESCC. Therefore, miR-205 may be a potential therapeutic target for miRNA-based therapy of ESCC.