Figure 7

RAIDD has a critical role in initiating LBH589-induced apoptosis. (a) Inhibition assay of caspases. Cells were treated with 25 nM of LBH589 or 100 ng/ml of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) with indicated concentrations of caspase-inhibitors for 24 h. Results were evaluated by Annexin-V/PI staining. Experiments were performed in triplicate and results were expressed as the mean±s.d. (b and c) Effects of siRNA against caspase-2, caspase-9, RAIDD, PIDD and RIP. At 24 h after transfection, cells were incubated for 24 h with either vehicle or 50 nM of LBH589. Results were evaluated using Annexin-V/PI staining or the JC-1 dye and analyzed with flow cytometric analysis. Results were expressed as the mean±s.d. for three independent experiments and were also analyzed using Student’s t-test. ^*P<0.01 compared with si-control. (d) Western blotting. At 24 h after transfection, cells were incubated for 24 h with either vehicle or 50 nM of LBH589 and western blotting was performed.