The transcription factor c-Jun regulates Smad4 expression by upregulating pre-miR-183 expression to promote invasion and metastasis of esophageal squamous cell carcinomas.

Abstract

MiR-183 is a tumor onco-miR and has been shown by our previous studies to be overexpressed in esophageal squamous cell carcinomas (ESCCs). In this study, we sought to determine the possible mechanisms of miR-183 in ESCC. In our study, cell migration and invasion, real-time PCR, Western blot, and chromatin immunoprecipitation (ChIP) assays were used to explore the mechanism of miR-183 in three ESCC cell lines. We found several potential transcription factors, including c-Jun, by bioinformatics methods. Using a ChIP assay, we identified that c-Jun binds to the promoter region of pre-miR-183 and that upregulated c-Jun expression is related to increased expression of miR-183. We found that downregulation of miR-183 significantly reduced the cell invasiveness and migration of ESCC cells, whereas upregulation of miR-183 via a mimic increased the cell migration and invasion of ESCC cells. We further discovered one direct miR-183 target gene, Smad4, which has been implicated in invasion and metastasis. Furthermore, miR-183 promoted epithelial-mesenchymal transition (EMT), which is involved in the invasion and migration of ESCC cells. Dysregulation of miR-183 has an important role in tumor growth and invasion because miR-183 targets Smad4. Therefore, suppression of miR-183 may provide a potential approach for treatment.