Figure 1.

PI-103 sensitized CRC Cell Lines to ABT-737-induced apoptosis. (A) Cells were exposed to DMSO or the indicated concentration of PI-103 and the indicated concentration of ABT-737 for 3 days. Cells were fixed and stained with SRB, and the absorbance relative to untreated (UnT) cells was determined relative to DMSO or PI-103 only-treated cells as appropriate for individual concentration response curves. (B-D) Cells were treated with the indicated combinations of 4 µMABT-737 (A and B) or 8 µMABT-737 (C) and 2 µMPI-103 for 24 hours. (A) The level of cleaved caspase 3, full-length PARP, cleaved PARP, and β-tubulin was assessed by Western blot analysis. Results are representative of three independent experiments. (B) Cells were stained with allophycocyanin (APC)-conjugated annexin V and 7AAD, and the percentage of annexin V-positive/7AAD-negative cells was determined by flow cytometry. (C) Cells were fixed and stained for conformationally changed BAK, and the percentage of positive cells was determined by immunofluorescence. All graphs represent the means of three independent experiments carried out in triplicate (A) or duplicate (C and D) ± SEM. *P < .05 according to two-tailed unpaired t test.