Downregulation of MicroRNA-135b-5p Inhibits Esophageal Cancer Cell Progression via Targeting GNG7

Abstract

Objective: MicroRNAs (miRNAs) have emerged as the critical modulators of the tumorigenesis and tumor progression. Guanine nucleotide binding (G) protein gamma 7 (GNG7) has been shown to be closely associated with the occurrence of tumors. We aimed to investigate the effects of microRNA-135b-5p (miR-135b-5p) mediated GNG7 knockdown on the biological behavior of esophageal carcinoma (EC) cells. Material and Methods: The expression of miR-135b-5p and GNG7 in 33 cases of EC clinical tissues and EC cell lines, including TE-1, ECA109 and EC9706, were examined by PCR and western blotting assays to select the optimum cell line for subsequent experiments. After ECA109 cells were transfected with miR-135b-5p mimics or inhibitor, siRNA GNG7 and NC plasmids, the cell viability, migration invasion, proliferation and apoptosis of ECA109 cells were evaluated by MTT, wound healing, Transwell, colony formation and flow cytometry assays, respectively. The expression of relevant molecules (p53 and VEGF-A) was determined by western blot analysis. Results: The results indicated that the levels of miR-135b-5p were upregulated while GNG7 were downregulated in EC tissues in comparison with the corresponding normal tissues, and miR-135b-5p mimics and knockdown of GNG7 sharply increased cell viability, migration, invasion and colony formation of ECA109 cells, and inhibited cell apoptosis. The luciferase reporter assay identified that miR-135b-5p decreased the level of GNG7 via binding to the 3′-UTR of GNG7 gene. In addition, p53 expression were decreased and VEGFA expression was up-regulated in ECA109 cells after transfected with miR-135b-5p mimics and GNG7 siRNA. However, inhibition of miR-135b-5p suppressed biological behavior abilities and promoted apoptosis of ECA109 cells that was promoted by miR-135b-5p mimics and siRNA GNG7. Conclusions: In conclusion, miR-135b-5p is identified as a potential tumor-promoting miRNA likely through the regulation of GNG7 expression, which could be developed as a new therapeutic target for EC.