Figure 6
The HDAC1-3 inhibitor entinostat phenocopies the pan-HDAC inhibitor vorinostat. (a) Basal expression of HDAC1, 2, 3 and 6 in A549, H460 and 34LU cell lines was assessed by western blotting and quantified by densitometry relative to GAPDH. (b) Effect of different HDAC inhibitors on FLIP expression was determined by western blotting. The cells were treated for 24 h with 5 μM vorinostat, 50 nM panobinostat (pan-HDAC inhibitors), 5 μM entinostat (HDAC1-3-selective inhibitor) or 5 μM ACY-775 (HDAC6-selective inhibitor). (c) Western blot analysis of FLIP expression and PARP cleavage in H460, A549 and 34LU cell lines treated with combinations of entinostat and cisplatin for 48 h or entinostat and TRAIL for 24 h. (d) H460, A549 and 34LU cells were treated with entinostat or vorinostat in combination with cisplatin for 48 h or TRAIL for 24 h as indicated. Apoptosis was determined by sub-G1 analysis. Significance was assessed by two-way ANOVA. (e) A549 cells were either co-treated with entinostat and cisplatin for 48 h, or pre-treated with entinostat for 6 h, followed by TRAIL addition for a further 18 h. Cells were transfected with 20 nM procaspase-8-targeted siRNA (siCaspase-8) or control siRNA (SC) for 48 h before cisplatin/entinostat and TRAIL/entinostat treatment. Significance was determined using Student’s t-test: *P<0.05; **P<0.01; ***P<0.001
