miR-1200 rescued the decreased CDDP resistance due to circ_0026359 depletion in CDDP-resistant gastric cancer cells. SGC-7901/CDDP cells were cotransfected with si-circ_0026359#1/si-NC and miR-1200 inhibitor/NC-inhibitor. (a) Expression levels of miR-1200 and POLD4 mRNA were examined by RT-qPCR. U6 and GAPDH were detected as control, respectively. (b) Protein levels of POLD4 were examined by western blot. α-Tubulin was detected as control. (c) MTT assay (1 μg/ml CDDP treated for 24, 36, and 48 hours), (d) IC50 analysis for CDDP, (e) cell colony formation assay (1 μg/ml CDDP treated for 48 hours), (f) caspase-3/7 assay (1 μg/ml CDDP treated for 48 hours), (g) DNA fragmentation assay (1 μg/ml CDDP treated for 48 hours), and (h) flow cytometry with Annexin V-FITC and PI staining (1 μg/ml CDDP treated for 48 hours) were performed, respectively, in SGC-7901/CDDP cells after cotransfection. ∗∗P < 0.01.