Figure 1. Effects of ABT-737 in cancer cell lines under normoxic and hypoxic conditions.

(A) H146, H82 SCLC, and HCT116 CRC cells were incubated in normoxia or hypoxia (1% O₂) for 18 hours, after which they were exposed to a range of ABT-737 concentrations under continuous normoxia or hypoxia for 72 hours prior to determination of IC₅₀ values using the resazurin assay. (B) H146 SCLC and H82 SCLC cells were preincubated for 18 hours in normoxia or hypoxia (1% O₂) before treatment with ABT-737 at 89.1 nM and 12.2 μM, respectively, for the indicated times. Control cells were exposed to an equivalent concentration of drug diluent (DMSO) in normoxia or hypoxia at selected time points. HCT116 CRC cancer cells were preincubated for 18 hours in normoxia or hypoxia and treated with the indicated ABT-737 concentrations or DMSO vehicle with maintained hypoxia or normoxia and assessed 24 hours later. The percentage of cells undergoing apoptosis was determined by DAPI staining and counting at least 100 cells per field in duplicate. Data are mean ± SEM of 3 independent experiments. *P < 0.05, **P < 0.01; (Student’s 2-tailed t test).