Cells (5000 cells/well) were plated in 96-well plates in RPMI growth medium. After 24 h, cells were treated with increasing concentrations of carboplatin (Hospira Pty Ltd, 5–200 µM). Cell survival was assessed by MTT assay after 72 h as per manufacturer’s instructions (Sigma Aldrich). Absorbance was read at 595 nm on a microplate absorbance reader (Triad series multimode detector, Dynex technologies, Chantilly, VA, USA). GraphPad Prism (version 8.0.0) was used to calculate the IC50 of carboplatin in both OVCAR5 and OVCAR5 CBPR cells.
For proliferation assay, serial dilution of OVCAR5 parental and OVCAR5 CBPR cells was prepared and seeded at a density ranging from 5 × 102 to 1 × 105 per well in a 96-well plate and incubated overnight. Tetrazolium salt from the Cell Proliferation Kit I (MTT) (Roche Diagnostics, Risch-Rotkreuz, Switzerland) was then added to the wells at a final concentration of 0.5 mg/ml. The microplate was incubated for 4 h before 10 μl of solubilization solution was added into each well to aid complete solubilization of formazan crystals produced by metabolically active cells. Following an overnight incubation, the absorbance reading was taken at 595 nm on an iMark™ microplate absorbance reader (Bio-Rad Laboratories, Hercules, CA, USA).
For proliferation assay, serial dilution of OVCAR5 parental and OVCAR5 CBPR cells was prepared and seeded at a density ranging from 5 × 102 to 1 × 105 per well in a 96-well plate and incubated overnight. Tetrazolium salt from the Cell Proliferation Kit I (MTT) (Roche Diagnostics, Risch-Rotkreuz, Switzerland) was then added to the wells at a final concentration of 0.5 mg/ml. The microplate was incubated for 4 h before 10 μl of solubilization solution was added into each well to aid complete solubilization of formazan crystals produced by metabolically active cells. Following an overnight incubation, the absorbance reading was taken at 595 nm on an iMark™ microplate absorbance reader (Bio-Rad Laboratories, Hercules, CA, USA).