CircAKT3 inhibits glycolysis balance in lung cancer cells by regulating miR-516b-5p/STAT3 to inhibit cisplatin sensitivity

Objective Lung cancer was one of the most deadly cancers around the world. Circular RNA AKT3 (CircAKT3) was highly expressed in lung cancer and could inhibit cell proliferation, but there were few studies on the mechanism of specific regulation of drug resistance. Therefore, we aimed to provide new ideas and perspectives for the role of circAKT3 in the mechanism of tumor resistance. Methods The levels of circAKT3, miR-516b-5p and STAT3 in lung cancer tissues and cells were examined using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assays. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to examine the sensitivity of cells treated under different conditions to cisplatin (DDP). A glucose assay kit and lactate assay kit were used to assess glycolysis and lactate production of cells treated with different plasmids and 2-deoxy-glucose (2-DG). Western blot analysis was used to detect the expression level of the hypoxia-inducible factor (HIF-1 alpha) in A549 and H1299 cells. Starbase 3.0 predicted a targeted relationship between circAKT3 and miR-516b-5p, STAT3 and miR-516b-5p, and the relationship was proved by a dual-luciferase reporter assay. Knockdown of circAKT3 was used to study the effects of circAKT3 on tumor development in vivo. Results The levels of circAKT3 and STAT3 were upregulated, miR-516b-5p was downregulation in lung cancer tissues and cells. Functionally, circAKT3 knockdown improved cell sensitivity to DDP, and repressed glycolysis in lung cancer cells. Meanwhile, inhibition of HIF-1 alpha-dependent glycolysis attenuated the circAKT3-induced increase of chemo-resistance in A549 cells. Mechanistically, miR-516b-5p was found to possess some binding sites with circAKT3. Noticeably, the inhibitory action of circAKT3 knockdown on DDP resistance and glycolysis was overturned through inhibitor of miR-516b-5p in lung cancer cells. Furthermore, besides, circAKT3 knockdown suppressed lung tumor cell growth by the miR-516b-5p/STAT3 axis in vivo. Conclusions CircAKT3 inhibit cisplatin sensitivity of lung cancer cells at least partly through regulating miR-516b-5p/STAT3 axis-mediated glycolysis balance, providing a possible long noncoding RNA -targeted therapy for lung cancer.