Fig. 4

The miR-615-3p was regulated by circKIF20B to affect gefitinib IC50 value and cell proliferation. A MiR-615-3p was predicted as a target of circKIF20B in four databases. B The expression of miR-615-3p in serum exosomes of gefitinib-resistant and sensitive patients (n = 23/19), measured by qRT-PCR with U6 serving as an internal reference. C The expression of miR-615-3p in NSCLC tissues and matched normal tissues (n = 85). D The expression of miR-615-3p in the circKIF20B-KD group of PC9GR, the PC9GR transfected with LV3-NC served as control. E The expression of miR-615-3p in PC9GR circKIF20B-OE group, control was the cell transfected with GV689-NC. F The luciferase activity of HEK293T cell co-transfected with WT or MUT vectors and miR-615-3p mimics. G The expression of miR-615-3p was detected by qRT-PCR in PC9GR circKIF20B-OE cell lysates after pulldown with circKIF20B probe or oligo probe. The oligo probe group served as the control. H The gefitinib IC50 values of PC9GR co-transfected LV3-NC and inhibitors-NC, PC9GR circKIF20B-KD transfected inhibitors-NC, and PC9GR circKIF20B-KD transfected the inhibitors of miR-615-3p were detected using CCK-8 assay, respectively. I The gefitinib IC50 values of PC9GR co-transfected GV689-NC and mimics-NC, PC9GR circKIF20B-OE transfected mimics-NC, PC9GR circKIF20B-OE transfected the mimics of miR-615-3p were detected using CCK-8 assay, respectively. L The intracellular co-localization of circKIF20B and miR-615-3p in PC9, PC9GR, and Beas-2B cell lines by FISH. Nuclei were labeled with DAPI. J and M The cell cycle and apoptosis assays of PC9GR co-transfected with LV3-NC and inhibitor-NC, the circKIF20B-KD groups transfected with inhibitor-NC, and the circKIF20B-KD groups transfected with miR-615-3p inhibitors. K and N The cell cycle and apoptosis assays of PC9GR co-transfected with GV689-NC and mimic-NC, circKIF20B-OE groups transfected with mimics-NC, and the circKIF20B-OE groups transfected with miR-615-3p mimics. O and P The cell proliferation of the abovementioned groups was analyzed by EdU. Q and R The MEF2A, CDK4, and BAX protein expression of the abovementioned groups were analyzed using Western blotting