MicroRNA-520c-3p Functions as a Novel Tumor Suppressor in Lung Adenocarcinoma.

Lung cancer is a malignancy with one of the highest incidence rates, and it is the leading cause of cancer-related death. To gain further insights into the underlying mechanisms of tumor growth and metastasis, we investigated the role and expression of microRNAs in lung adenocarcinoma (LUAD). We discovered a significantly lower expression level of microRNA-520c-3p (miR-520c-3p) in LUAD tissues than in nontumor tissues. miR-520c-3p is known to regulate multiple biological functions and cellular behaviors. In this study, we show that AKT1 and AKT2 are key direct targets of miR-520c-3p, which are required for its biological roles in LUAD. Mechanistically, downregulation of miR-520c-3p in LUAD is due to DNA methylation of the miR-520c-3p promoter region. Conversely, the activity of the transcription factor Yin Yang 1 (YY1) results in the upregulation of miR-520c-3p. Taken together, our results reveal methylation/YY1/miR-520c-3p/AKT1/AKT2 as a molecular axis with a potent biological function and highlight miR-520c-3p as a novel potent tumor suppressor in LUAD.