FIGURE 4.

MSI2 promotes gastric cancer (GC) cell resistance to cisplatin in vitro. (A) The SGC‐R and BGC‐R cells were transfected with si‐NC or si‐MSI2 treated with cisplatin (DDP) at different concentrations for 24 h, and the cell viability was then determined using the MTS assay. (B) SGC‐R and BGC‐R cells were treated with MSI2 inhibitor, FK228 (.125 μg/ml) and different concentrations of DDP for 24 h, and the cell viability was then measured using the MTS assay. DMSO: solvent control of FK228. (C) PI/Annexin V staining and flow cytometry in chemoresistant cells following si‐NC or si‐MSI2 transfection and treatment with or without DDP (8 μg/ml) for 24 h. (D) Resistant cells were treated with DDP (8 μg/ml), FK228 (.125 μg/ml) or DDP plus FK228 for 24 h. The apoptosis was measured by flow cytometry, and the number of apoptosis cells was quantified. (E) Apoptotic cells among MSI2 knocked‐down SGC‐R and BGC‐R cells treated with DDP (8 μg/ml) for 24 h were measured using anti‐cleaved‐PARP1 and cleaved‐caspase 3 through western blotting. (F) The caspase 3 and PARP1‐cleaved activities of resistant cells treated with DDP (8 μg/ml), FK228 (.125 μg/ml) or their combination for 24 h were analysed through western blotting. (G) The SGC7901 and BGC823 cells with ectopic overexpression of MSI2 were treated with different concentrations of DDP for 24 h, and the resultant cell viability was determined using the MTS assay. (H) Apoptosis of sensitive cells with or without MSI2 overexpression in the presence or absence of DDP treatment (1 μg/ml, 24 h) was evaluated through flow cytometry and then quantified. (I) Western blotting was performed to detect cleaved‐caspase 3 and cleaved‐PARP1 in sensitive cells with MSI2 overexpression following DDP treatment (1 μg/ml, 24 h). (J) Stable SGC7901 cells overexpressing LNC942 were transfected with MSI2 siRNAs and treated with different concentrations of DDP for 24 h, following which the cell viability was measured using the MTS assay. (K) Cell viability of stable SGC7901 cells overexpressing LNC942 treated with FK228 (.125 μg/ml) and different concentrations of DDP for 24 h was measured using the MTS assay. (L and N) SGC7901 cells that were stably overexpressing LNC942 were transfected with MSI2 siRNAs for 48 h and then treated with DDP (1 μg/ml) for 24 h, after which the apoptotic cells were analysed through flow cytometry (L) and western blotting (N). (M and O) SGC7901 cells stably overexpressing LNC942 were co‐treated with FK228 (.125 μg/ml) and DDP (1 μg/ml) for 24 h. Apoptotic cells were analysed by flow cytometry (M) and western blotting (O). Data in (A‐D), (G), (H), (J‐M) are represented as mean ± SD of the three independent experiments; the p value was determined using a two‐tailed unpaired Student's t test. ns, p > .05; *p < .05; **p < .01; ***p < .001