MicroRNA-182 promotes tumor cell growth by targeting transcription elongation factor A-like 7 in endometrial carcinoma.

BACKGROUND/AIMS Endometrial carcinoma (EC) is the most common gynecological malignancy among women worldwide. Despite its prevalence, the molecular mechanisms underlying endometrial carcinogenesis are poorly understood. The purpose of this study was to examine the role of microRNA-182 and its target gene transcription elongation factor A-like 7 (TCEAL7) in EC. METHODS The expression of miR-182 in human normal endometrial epithelial cells (NEEC) and in three human endometrial carcinoma cell lines (HEC-1B, RL95-2 and AN3CA) was measured by qRT-PCR, and the mRNA and protein expression of TCEAL7 were assessed in the same three endometrial carcinoma cell lines and NEEC by qRT-PCR and western blotting, respectively. Subsequently, the target of miR-182 was predicted by bioinformatics and confirmed using a luciferase assay. Cell proliferation and colony formation of RL95-2 cells were examined by MTT assay and crystal violet staining, respectively. The expression of NFκB-p65, c-Myc and cyclin D1 proteins was determined by Western blot analysis. RESULTS MiR-182 was significantly upregulated and TCEAL7 was downregulated in EC cell lines compared to NEEC. We showed that MiR-182 binds directly to a conserved 8 bp sequence in the 3'-UTR of TCEAL7, and inhibition of miR-182 upregulated TCEAL7 mRNA and protein expression to levels comparable to those induced by lentiviral-mediated overexpression of TCEAL7. MiR-182 inhibition decreased cell proliferation and colony formation ability, downregulated the expression of the pro-proliferative genes c-Myc and cyclin D1, and inhibited NFκB activation, and these effects were mimicked by TCEAL7 overexpression. CONCLUSIONS miR-182 acts as an oncogenic miRNA in EC, promoting cell proliferation by targeting the tumor suppressor gene TCEAL7 and modulating the activity of its downstream effectors c-Myc, cyclin D1 and NFκB.