MicroRNA-183 Acts as a Tumor Suppressor in Human Non-Small Cell Lung Cancer by Down-Regulating MTA1.

Backgrounds/aims: MicroRNAs (miRs) often contribute to the progression of non-small cell lung cancer (NSCLC) via regulation of mRNAs that are involved in lung homeostasis. We conducted a study aimed at exploring the roles of miR-183 in the proliferation, epithelial-mesenchymal transition (EMT), invasion and migration of human NSCLC cells via targeting MTA1.

Methods: NSCLC and adjacent normal tissues were collected from 194 patients with NSCLC. Positive expression of MTA1 protein was detected by immunohistochemistry. The highest levels of expression of miR-183 were detected using RT-qPCR in SPC-A-1 cells, which were selected and assigned to the following groups: blank, negative control (NC), miR-183 mimic, miR-183 inhibitor, siRNA-MTA1, and miR-183 inhibitor + siRNA-MTA1. The expression of miR-183 and the mRNA and protein expression of MTA1, E-cadherin, Vimentin, Snail, PCNA, Bax and Bcl-2 in tissues and transfected cells were measured using RT-qPCR and western blot analysis. Cell proliferation, apoptosis, migration and invasion were evaluated by CCK-8, flow cytometry, scratch tests and Transwell assays. Tumor xenografts were conducted in nude mice to determine tumor growth.

Results: SPC-A-1 cells with the highest levels of miR-183 expression were selected. Compared with adjacent normal tissues, the expression of miR-183 and the mRNA and protein expression of E-cadherin and Bax were decreased in NSCLC tissues, while mRNA and protein expression of MTA1, Vimentin, snail, PCNA and Bcl-2 were increased. MiR-183 was over-expressed in the miR-183 mimic group and under-expressed in the miR-183 inhibitor and miR-183 inhibitor + siRNA-MTA1 groups. In the miR-183 mimic and siRNA-MTA1 groups, the mRNA and protein expression of E-cadherin and Bax, as well as cell apoptosis, were enhanced, while the expression levels of MTA1, Vimentin, snail, PCNA and Bcl-2 mRNA and protein, cell proliferation, migration, invasion and tumor growth were reduced relative to the blank and NC groups. The miR-183 inhibitor group exhibited an opposite trend.

Conclusion: Our study indicates that miR-183 down-regulates MTA1 to inhibit the proliferation, EMT, migration and invasion of human NSCLC cells.