Fig. 3: Anti-OSMR antibody enhances sensitivity towards cisplatin.

a, b Cell viability was measured using CCK8 reagent in A2780 versus A2780-CisR cells, OVCAR8 versus OVCAR8-CisR cells were treated with different concentrations of cisplatin for 48 h. The IC₅₀ of cisplatin in both control and OSMR overexpressing cell lines were quantitated and presented below in the respective boxes. c, d Cell viability assay was measured using CCK8 reagent in A2780 and A2780-CisR and OVCAR8 vs. OVCAR8-CisR resistant cells treated with anti-OSMR B21 mAb (10 μg/mL) in combination with the indicated concentrations of cisplatin for 48 h. The IC₅₀ of B21 mAb in both control and OSMR overexpressing cell lines were quantitated and presented below in the respective boxes. e OVCAR8-CisR and A2780-CisR cells were grown in the presence and absence of B21 antibody or isotype control IgG (10 μg/mL each) with or without recombinant human rhOSM (100 ng/mL) for 15 days in 6-well plate. Colonies formed were stained using 0.5% of crystal violet and imaged. Colonies formed were lysed using 10% acetic acid and absorbance were quantitated at 560 nm (right panel). f Annexin V-FITC/PI based apoptosis assay was performed using flow cytometry in OVCAR8-CisR and A2780-CisR resistant cells that were treated with B21 antibody or isotype control IgG (10 μg/mL each) in combination with/without cisplatin and stimulated in the presence and absence of rhOSM (100 ng/mL) for 16 h. The representative quantitation histograms show percentage of cells that are viable and undergoing early or late apoptosis. g Western blot shows the expression of pro-apoptotic and anti-apoptotic proteins in OVCAR8-CisR cell lines that were treated with B21 anti-OSMR antibodies (10 µg/mL) in combination with cisplatin in the presence and absence of rhOSM (100 ng/mL) for 24 h. One-way ANOVA with Dunnett’s multiple comparison test was performed for significance. Data represent means ± SEM. ****P ≤ 0.0001, ***P ≤ 0.001, **P ≤ 0.01, *P ≤ 0.05, ns non-significant.