Up-Regulation of MicroRNA-133a Inhibits the MEK/ERK Signaling Pathway to Promote Cell Apoptosis and Enhance Radio-Sensitivity by Targeting EGFR in Esophageal Cancer In Vivo and In Vitro

This study aims to explore how microRNA-133a (miR-133a) affects cell apoptosis and radio-sensitivity by targeting EGFR via regulating MEK/ERK pathway in esophageal cancer (EC). A total of 358 EC patients were selected and assigned into the resistant and sensitive groups. Human EC KYSE 150 cell line was assigned into the blank, negative control (NC), miR-133a mimic, miR-133a inhibitors, si-EGFR, miR-133a inhibitors + si-EGFR groups after transfection. MiR-133a and EGFR mRNA expressions were detected by qRT-PCR and EGFR, MEK/ERK pathway-related protein expressions were detected by Western blotting. The radio-sensitivity and cell apoptosis were testified by clone formation and flow cytometry. MiR-133a was up-regulated but EGFR was down-regulated in the sensitive group than in the resistant group. Compared with the blank and NC groups, the miR-133a mimic and si-EGFR groups exhibited increased cell apoptosis rate but decreased EGFR, p-MEK1/2, and p-ERK1/2 protein expressions; while opposite trend was observed in the miR-133a inhibitors group. Compared with the miR-133a inhibitors group, the miR-133a inhibitors + si-EGFR group presented reduced cell survival rate, EGFR, p-MEK1/2, and p-ERK1/2 protein expressions but increased cell apoptosis rate. These results indicated that miR-133a could inhibit the MEK/ERK pathway to promote cell apoptosis and enhance radio-sensitivity by targeting EGFR in EC. J. Cell. Biochem. 118: 2625–2634, 2017. © 2017 Wiley Periodicals, Inc.