MiR-92a targets PTEN/PI3K/Akt pathway to inhibit autophagy in non-small cell lung cancer cells

Abstract

Objective To investigate the effect of miR-92a on autophagy in non-small cell lung cancer cells (NSCLC) and its possible mechanism. Methods The paired NSCLC tissues and paracancerous tissues were collected from 53 NSCLC patients treated in the Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine from January 2016 to December 2018. The expression levels of miR-92a and PTEN, p-PI3K, p-Akt and LC3-Ⅱ in the paired tissues were detected by RT-PCR and immunohistochemical assay. MiR-92a-mimics, miR-92a-NC and miR-92a-inhibitor were respectively transfected into A549 cells. After 48 h, acridine orange staining was used to detect autophagy. Dual luciferase reporter assay was employed to verify the targeting relationship between miR-92a and PTEN, and Western blotting was performed to detect the expression of PTEN, p-PI3K, p-Akt and LC3-Ⅱ in each transfected cells. Results The mRNA expression of miR-92a was significantly higher in the NSCLC tissues than the normal lung tissues (P 0.05). However, for the patients with lymph node metastasis, at TNM Ⅲ~Ⅳ stage and lower differentiation, the expression levels of miR-92a in the cancer tissue was significantly higher when compared with those without metastasis, at TNM Ⅰ~Ⅱ stage and higher differentiation (P < 0.01). While opposite phenomena were observe when concerning of the expression of PTEN and LC3-Ⅱ (P < 0.01). Pyridine orange staining showed that the intracellular fluorescence was the weakest in the A549 cells transfected with miR-92a-mimics, while strongest in those with miR-92a-inhibitor. Among the 3 groups of cells with transfection, the expression of p-Akt and p-PI3K protein was the highest, and that of LC3-Ⅱ was the lowest in the miR-92a-mimics group (all P < 0.05). And opposite results were seen in the miR-92a-inhibitor group (all P < 0.05). Conclusion MiR-92a targets and inhibits PTEN expression, activates PI3K/Akt signaling pathway, and thus suppresses cell autophagy in NSCLC cells.

Keywords

• non-small cell lung cancer
• mir-92a
• pten
• pi3k/akt signaling pathway
• autophagy