ABSTRACT
Objective: To investigate the expression of microRNA (miRNA, miR)-126 in esophageal carcinoma tissues and the effect of miR-126 on the proliferation and migration of esophageal cell line EC109. Methods: The expressions of miR-126 and sex determining region Y-box 2 (SOX2) mRNA in esophageal cancer tissues and their paracancerous tissues from 24 patients were detected by real-time fluorescence-based quantitative PCR. The expression of miR-126 in EC109 cells after transfection with miR-126 mimics or miR-negative control (NC) was detected by realtime fluorescence-based quantitative PCR. The abilities of cell proliferation and migration of EC109 cells transfected with miR-126 mimics were measured by MTT and Transwell assays, respectively. The dual luciferase reporter vectors containing 3'-untranslated region (3'-UTR) with miR-126 binding site of wild type or mutant SOX 2 gene were constructed by using Dual-Luciferase Reporter Assay System, then the relative activity of firefly luciferase was detected to confirm the binding site of miR-126 on SOX 2 gene. The expression levels of SOX2 mRNA and protein in EC109 cells transfected with miR-126 mimics were detected by real-time fluorescence-based quantitative PCR and Western blotting, respectively. The expression of SOX2 protein in esophageal cancer tissues and their paracancerous tissues was examined by immunohistochemistry. Results: The expression level of miR-126 in esophageal cancer tissues was lower than that in paracancerous tissues (P < 0.01), but the expression level of SOX2 mRNA was opposite (P < 0.05). The expression of miR-126 was negatively correlated with the expression of SOX2 (r =-0.837, P < 0.001). After transfection with miR-126 mimics, the expression level of miR-126 in EC109 cells was higher than that in miR-NC group (P < 0.01), but the abilities of cell proliferation and migration were opposite (P < 0.05, P < 0.01). miR-126 can directly target the SOX 2 3'-UTR through two predicted binding sites. The expression levels of SOX2 mRNA and protein in EC109 cells after transfection with miR-126 mimics were lower than those in miR-NC group (P < 0.01). The positive expression rate of SOX2 protein in esophageal cancer tissues was higher than that in paracancerous tissues (P < 0.01). Conclusion: The expression level of miR-126 is lower in esophageal carcinoma tissues, and miR-126 can inhibit the proliferation and migration of EC109 cells, in which SOX 2 may be one of the targeted genes.
