Fig 2: QPRT is involved in miR-654-3p suppressed cisplatin resistance of IGROV-1/DDP cells. IGROV-1/DDP cells were transfected with si-NC, si-QPRT, miR-inhibitor and si-QPRT + miR-inhibitor. (A) Post-transfection, reverse transcription-quantitative PCR was used to detect the mRNA expression of QPRT. (B) Following transfection and cisplatin treatment, MTT assay was used to examine cell viability. (C) Following transfection and cisplatin treatment, DNA biosynthesis was detected by BrdU labelling, and BrdU-positive cells were counted and subjected to statistical analysis. (D) Hoechst 33258 staining was performed, and the percentage of apoptotic cells is expressed as the means ± SD of 3 independent experiments. (E) Cell migration was detected by wound-healing assay. (F) Western blotting was used to detect the protein expression levels of P-gp, Total caspase3, cleaved-caspase3, PI3K, p-PI3K, AKT, p-AKT and QPRT. **P<0.01 and ***P<0.001 vs. IGROV-1; #P<0.05 and ##P<0.01 vs. si-NC; &P<0.05 and &&P<0.01 vs. miR-inhibitor. QPRT, quinolinate phosphoribosyl transferase; IGROV-1/DDP, cisplatin-resistant IGROV-1 cells; miR, microRNA; si-NC, negative control small interfering RNA; si-QPRT, small interfering RNA targeting QPRT; P-gp, permeability glycoprotein.

Fig 3: ABCE1 activation reverses the promoting effects of miR-145 overexpression on K562/ADM cell sensitivity to ADM. (A) Relative protein expression of ABCE1 detected by western blot analysis. (B) Relative cell viability in each group detected by MTT assay. (C) Relative cell colonies in K562/ADM cells treated with 6 µmol/l ADM measured by colony formation assay. (D) Relative apoptosis of K562/ADM cells treated with 6 µmol/l ADM measured by flow cytometry. (E) Levels of MRP1 and P-gp of K562/ADM cells with 6 µmol/l ADM measured by western blot analysis. **P<0.01; n=3. Data in (A-D) were analyzed by one-way ANOVA, and data in (E) were analyzed by two-way ANOVA. Tukey's multiple comparisons test was used as a post hoc test. ADM, adriamycin; miR-145, microRNA-145; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MRP1, multidrug resistance protein 1; P-gp, P-glycoprotein.

Fig 4: Low expression of miR-145 reduces the sensitivity of K562 cells to ADM. (A) Relative miR-145 expression in K562 cells detected by RT-qPCR. (B) Relative viability of K562 cells treated with various concentrations of ADM measured by MTT assay. (C) Relative cell colonies of K562 cells treated with 0.6 µmol/l ADM measured by colony formation assay. (D) Relative cell apoptosis of K562 cells treated with 0.6 µmol/l ADM measured by flow cytometry. (E) Levels of MRP1 and P-gp of K562 cells treated with 0.6 µmol/l ADM measured by western blot analysis. (F) The morphology and apoptosis of K562 cells treated with 0.6 µmol/l ADM were observed under a fluorescence microscope. **P<0.01; n=3. Data in (A, C and D) were analyzed by one-way ANOVA, while data in (B and E) were analyzed by two-way ANOVA. Tukey's multiple comparisons test was used as a post hoc test. ADM, adriamycin; miR-145, microRNA-145; RT-qPCR, reverse transcription quantitative polymerase chain reaction; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MRP1, multidrug resistance protein 1; P-gp, P-glycoprotein; ANOVA, analysis of variance.

Fig 5: MiR-370 mediated the regulatory effect of circ_0003496 knockdown on OS/DXR cell proliferation, migration, invasion and DXR sensitivity. KHOS/DXR and MG63/DXR cells were transfected with si-NC, si-circ_0003496, si-circ_0003496+in-miR-NC or si-circ_0003496+in-miR-370, followed by the assessment of miR-370 expression by qRT-PCR (A), the IC50 value for DXR (B) and cell proliferation (C and D) by CCK-8 assay, cell migration (E) and invasion (F) by transwell assay, cell apoptosis by flow cytometry (G), the expression levels of MRP1, P-gp and LRP by Western blot (H). *P < 0.05.