In-vitro cytotoxicity assay

Cells were seeded at a density of 10⁵ cells per well of a 96 well flat bottom plate and treated with increasing concentrations of Ara-C (0.1–80μM), Dnr (0.0025–1μM) or ATO (0.1–6μM). The plates were incubated for 48hrs in 5% CO₂ at 37°C. Ten μl of MTT reagent was added to the wells, and the cell viability was measured at standard wavelength 570nm and reference wavelength 630nm using EL800 reader with KC junior software (Biotek Winooski, VT, USA). All the experiments were performed in triplicates. The combinatorial index (CI) was calculated using Compusyn software (ComboSyn, Inc., Paramus, NJ). CI = 1 indicates additive effect, CI<1 indicates synergism and CI > 1 indicates antagonism in drug combinations.