Effects of microRNA-182-5p on cell proliferation and invasion of esophageal squamous cell carcinoma and related molecular mechanisms

Abstract

Objective: To investigate the effects of microRNA-182-5p (miR-182-5p) on cell proliferation and invasion of esophageal squamous cell carcinoma (ESCC) and its related molecular mechanisms. Methods: Real-time quantitative polymerase chain reaction (RT-qPCR) was employed to detect the miR-182-5p expression in ESCC tissues and cells. MiR-182-5p inhibitor, miR-182-5p mimic and negative control (NC) were transfected into ESCC Eca109 and TE1 cells, and miR-182-5p expression after transfection was examined using RT-qPCR. Cell counting kit-8 (CCK-8) was utilized to investigate the cell proliferation and Transwell chamber was used to detect the cell invasion ability. Dual-luciferase reporter assay was used to detect the direct interaction of miR-182-5p and cell adhesion molecule 2 (CADM2), RT-qPCR was employed to detect CADM2 expression in ESCC tissues, the correlation between CADM2 and miR-182-5p was also examined. Finally, western blot was used to detect the protein expressions of CADM2, focal adhesion kinase (FAK), p-Akt and Akt after transfection. Results: The miR-182-5p level in ESCC tissues was (2.180±1.295), significantly higher than (0.890±0.284) in normal esophageal epithelial tissues (P<0.001). The survival ratio of ESCC patients with high miR-182-5p level was evidently lower than that of ESCC patients with low miR-182-5p level (P<0.05). MiR-182-5p expression was significantly associated with TNM staging and lymph node metastasis (P<0.05). The expressions of miR-182-5p in ESCC cells including EC9706, Eca109, TE1, KYSE450 and KYSE70 were (2.449±0.082), (2.965±0.088), (4.873±0.258), (1.338±0.045) and (1.999±0.082), respectively, obviously higher than (0.989±0.087) in normal esophageal epithelial cell Het-1A (all P<0.01). Besides, miR-182-5p inhibitor significantly downregulated the miR-182-5p expression in Eca109 and TE1, and suppressed cell proliferation and invasion ability. Conversely, miR-182-5p mimic significantly upregulated the miR-182-5p expression in Eca109 and TE1, and promoted cell proliferation and invasion ability. Dual-luciferase reporter assay revealed that co-transfection of CADM2-3'UTR-WT and miR-182-5p mimic significantly reduced the luciferase activities in Eca109 and TE1 cells (P<0.01), and CADM2 was the direct target of miR-182-5p. The expression of CADM2 in ESCC tissues was (0.190±0.143), markedly lower than (0.845±0.327) in normal esophageal epithelial tissues (P<0.001). The miR-182-5p level exhibited negative correlation with CADM2 level in ESCC tissues (r=-0.5004, P<0.001). In addition, CADM2 expression was closely correlated with TNM staging and lymph node metastasis (P<0.05). The survival ratio of ESCC patients with high CADM2 level was evidently higher than that of ESCC patients with low CADM2 level (P<0.05). MiR-182-5p inhibitor significantly upregulated the expression of CADM2 protein, but suppressed the protein expressions of FAK, p-Akt and Akt, whereas miR-182-5p mimic markedly downregulated the expression of CADM2 protein, but promoted the protein expressions of FAK, p-Akt and Akt. Conclusion: MiR-182-5p is implicated in the carcinogenesis and development of ESCC, and thus may be a potential molecular target for ESCC patients.