Fig. 3

Downregulation of circAKT3 facilitates cisplatin sensitivity of CDDP-resistant GC cells in vitro. a Illustration showing the siRNA targeting the back-splice junction (si-circ-1 and si-circ-2). b RT-qPCR results for circular and linear transcripts of AKT3 in SGC7901CDDP cells treated with or without siRNA (NC, negative control; si-NC, control oligonucleotides with scramble sequence; si-circ-1 and si-circ-2, oligonucleotides targeting the back-splice junction). c Relative cell viability of NC, si-NC- transfected or si-circ-1-transfected SGC7901CDDP cells in the presence of CDDP at the indicated concentrations for 48 h. d Colony-forming ability of the NC, si-NC-transfected and si-circ-1-transfected SGC7901CDDP cells in the absence (Vehicle) or presence of CDDP (6 μM) for 48 h. e The apoptotic rates of NC SGC7901CDDP cells and SGC7901CDDP cells transfected with si-NC or si-circ-1 in the absence (Vehicle) or presence CDDP (6 μM) for 48 h were visualized by flow cytometry. f Western blot analysis shows apoptotic proteins in NC SGC7901CDDP cells and SGC7901CDDP cells transfected with si-NC or si-circ-1 upon CDDP treatment (6 μM) for 48 h (GAPDH was used as the loading control). g Immunofluorescence staining of γH2AX foci in NC SGC7901CDDP cells and SGC7901CDDP cells transfected with si-NC or si-circ-1 at 2 h after CDDP treatment (6 μM). Scale bars, 10 μm. h Percentage of cells containing > 10 γH2AX foci in NC SGC7901CDDP cells and SGC7901CDDP cells transfected with si-NC or si-circ-1 at 0 to 8 h after CDDP treatment (6 μM) removal. i Western blot analysis of γH2AX and BRCA1 expression in NC SGC7901CDDP and BGC823CDDP cells and cells transfected with si-NC or si-circ-1 after CDDP treatment (6 μM) removal. The results are presented as the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001