Objective  To investigate the effect of microRNA-27a (miR-27a) on the apoptosis of human lung adenocarcinoma cells A549 induced by lipopolysaccharide (LPS) by regulating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathway, and its mechanism is discussed preliminarily. Methods  The complementary binding sites of miR-27a and phosphatidylinositol-3 kinase catalytic subunit delta (PIK3CD) were analyzed by Starbase and verified by double luciferase. The A549 cells were divided into normal group, LPS group, LPS+miR-27a mimic negative control group, LPS+miR-27a mimic group, LPS+miR-27a mimic+PI3K activator group. In the LPS+miR-27a mimic negative control group, LPS+miR-27a mimic group and LPS+miR-27a mimic+PI3K activator group, the cells were transfected with miR-27a mimic negative control, miR-27a mimic and miR-27a mimic, respectively, and were cultured for 6 h. After that, the cells were cultured in complete medium for 24 h, and then, except for the normal group, the cells in the other groups were stimulated with 10 mg/L LPS for 24 h, and the PI3K activator 740 Y-P was added to the LPS+miR-27a mimic+PI3K activator group, and cells in normal group were cultured in complete medium for the same time. Real-time quantitative polymerase chain reaction was used to detect the expression level of miR-27a in cells; cell counting kit 8 was used to detect cell proliferation; Hoechst33342 staining and flow cytometry was used to detect apoptosis; autophagy of A549 cells was observed by transmission electron microscope; Western blot was used to detect the expression of PIK3CD, phosphorylated-AKT (p-AKT), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), cleaved caspase-3 and microtubule-associated protein 1 light chain 3 II (LC3II) protein. Results  There was a binding site between miR-27a and PIK3CD, which was verified by double luciferase. Compared with those in normal group, the expression level of miR-27a, proliferation rate and protein expression level of Bcl-2 in LPS group and LPS+miR-27a mimic negative control group were lower (P<0.05), the apoptosis rate, protein expression levels of PIK3CD, p-AKT, Bax, cleaved caspase-3, LC3Ⅱ were higher (P<0.05); compared with those in LPS group and LPS+miR-27a mimic negative control group, the expression level of miR-27a, proliferation rate and protein expression level of Bcl-2 in LPS+miR-27a mimic group were higher (P<0.05), the apoptosis rate, protein expression levels of PIK3CD, p-AKT, Bax, cleaved caspase-3, LC3Ⅱ were lower (P<0.05); compared with those in LPS+miR-27a mimic group, the expression level of miR-27a and proliferation rate in LPS+miR-27a mimic+PI3K activator group were lower (P<0.05), the apoptosis rate, protein expression levels of PIK3CD, p-AKT, cleaved caspase-3, LC3Ⅱ were higher (P<0.05). The number of cells in the normal group was more, the cells were closely arranged, the nucleus size was uniform, and the organelle structure was normal; in LPS group and LPS+miR-27a mimic negative control group, cells became round, nuclei pyknosis, formed clumps, and showed multiple round autophagic vesicles of different sizes; the number of nuclear pyknotic cells in LPS+miR-27a mimic group decreased, and the number of nuclear pyknotic cells in LPS+miR-27a mimic+PI3K activator group increased compared with LPS+miR-27a mimic group, a small number of circular autophagic vesicles were observed, but the number was different. Conclusion  Overexpression of miR-27a can inhibit PI3K/Akt pathway and reduce LPS induced apoptosis of human lung adenocarcinoma cells A549, which may be related to the reduction of autophagy.

Citation： ZHU Jinqi, CHEN Jianbo, YANG Hongzhong, GAO Xin. MiR-27a attenuates lipopolysaccharide-induced apoptosis of human lung adenocarcinoma cells A549 by regulating PI3K/AKT pathway mediated autophagy. Chinese Journal of Respiratory and Critical Care Medicine, 2022, 21(2): 118-125. doi: 10.7507/1671-6205.202109011 Copy