Cytotoxicity Evaluation of Anticancer Drugs

Cytotoxicity was determined using MTT and colony formation assays as previously described (2 (link),16 (link)). MTT assay was used to determine cytotoxicity of anticancer drugs. Briefly, cells were seeded in 96-well plate at 3000 cells/well and cultured for 24 hrs followed by treatment with anticancer drugs and cultured continuously for 72 hrs at 37°C. Then, MTT (5 mg/mL) was added to the culture and incubated for another 4 hrs. The culture medium was then aspirated followed by addition of DMSO and absorption was determined using a 96-well plate reader. For colony formation assay, 100–200 cells/well were seeded in 6-well plate and cultured for 24 hrs before IR treatment. The cells were then cultured for 10 days before fixation and staining with crystal violent (0.005% in 20% methanol). The colonies were counted manually. Both the fitted sigmoidal dose response curve and IC₅₀ were calculated using Graph Pad Prism Program.