Fig. 5

CircKIF20B regulated gefitinib resistance and cell proliferation by MEF2A. A The PSMD11 and MEF2A were predicted as the downstream target of miR-615-3p from 5 databases. B The expression of MEF2A in serum exosomes of gefitinib-resistant and sensitive patients (n = 24/23) as measured by qRT-PCR, with β-actin serving as an internal reference. C The expression of MEF2A in the NSCLC tissues and matched normal tissues (n = 85). D MEF2A and miR-615-3p expression of the anti-Ago2 group was detected by qRT-PCR in the complex from PC9 lysates co-immunoprecipitation, with IgG group serving as the control. E The luciferase activity of HEK293T cell co-transfected with WT or MUT vectors and the mimics of miR-615-3p. F and H The RNA and protein expressions of MEF2A using qRT-PCR and Western blotting in the circKIF20B-KD and circKIF20B-OE groups, with the cells transfected with LV3-NC and GV689-NC serving as control. G and I The RNA and protein expressions of MEF2A in PC9GR transfected with miR-615-3p mimics or inhibitors were detected using qRT-PCR and Western blotting, the cells transfected with mimics-NC or inhibitor-NC serving as control. J The gefitinib IC50 values of PC9GR co-transfected LV3-NC and pEX3-NC, PC9GR circKIF20B-KD transfected pEX3-NC, PC9GR circKIF20B-KD transfected pEX3-MEF2A were detected by CCK-8 assay. K The IC50 values of gefitinib for PC9GR co-transfected GV689-NC and siRNA-NC, PC9GR circKIF20B-OE transfected siRNA-NC, circKIF20B-OE groups transfected siRNA1-MEF2A were detected using CCK-8 assay, respectively. L and N The cell cycle and apoptosis assays of PC9GR co-transfected with LV3-NC and pEX3-NC, the circKIF20B-KD groups transfected with pEX3-NC, and the circKIF20B-KD groups transfected with pEX3-MEF2A. M and O The cell cycle and apoptosis assays of PC9GR co-transfected with GV689-NC and siRNA-NC, the circKIF20B-OE groups transfected with siRNA-NC, and the circKIF20B-OE groups transfected with siRNA1-MEF2A. P and Q EdU analyzed the cell proliferation of the abovementioned groups. R and S The MEF2A, CDK4, and BAX protein expression of the abovementioned groups were analyzed by Western blotting