WST-8 cell viability assay

Reduction of WST-8 by cellular dehydrogenases produce formazan, whose signal is directly proportional to the number of viable cells. Both reduced cell proliferation and cell loss due to drug toxicity diminish the WST-8 signal. We seeded 1 × 10⁴ cells per well in a 96-well plate and incubated overnight. Cells were then treated for 24 hours with various concentrations of etoposide (0.02, 0.05, 0.1, 0.2, 0.37, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50 μM). Cell viability was measured using a colorimetric cell viability kit (WST-8) from PromoKine, Germany. In short, after the treatment with etoposide, 10% WST-8 reagent was added to the cells. After 1-4 hours incubation in dark at room temperature, absorbance was measured at 450 nm using Spectramax iD3 (Molecular Devices, USA) spectrometer. Absorbance from the DMSO-treated cells (vehicle control) was considered as 100% cell viability and used to calculate percentage cell viability after etoposide treatment.