Figure 1

Interactive effects of Smac/DIABLO with TRAIL on cell viability and apoptosis. (A), MCF-7 cells were pretreated with either Smac/DIABLO control peptide (25 μM) or Smac/DIABLO N7 peptide (25 μM) for 12 h, followed by treatment with TRAIL (75 nM) for 36 h. Cell viability and apoptosis were measured by XTT assay and DAPI staining, respectively. Data represent mean ± SE. * = significantly different from the respective control at P < 0.05. (B), MCF-7 cells were transiently transfected with plasmids expressing Smac/DIABLO full length, Smac Δ55 or neo for 24 h, and treated with TRAIL (75 nM) for 36 h. Cell viability was measured by XTT assay. Data represent mean ± SE. * = significantly different from the respective control at P < 0.05. Smac C = Smac control peptide, Smac P = Smac N7 peptide. (C), MDA-MB-453 cells were pretreated with various doses of either Smac/DIABLO control peptide (0–100 μM) or Smac/DIABLO N-7 peptide (0–100 μM) for 12 h, followed by treatment with TRAIL (75 nM) for 36 h. Cell viability was measured by XTT assay. Data represent mean ± SE. *, # = significantly different from the respective control at P < 0.05. (D), MDA-MB-468 cells were pretreated with various doses of either Smac/DIABLO control peptide (0–100 μM) or Smac/DIABLO N-7 peptide (0–100 μM) for 12 h, followed by treatment with TRAIL (75 nM) for 36 h. Cell viability was measured by XTT assay. Data represent mean ± SE. *, # = significantly different from the respective control at P < 0.05.