Figure 3

HDACIs and TRAIL induce caspases-dependent apoptosis. A SH-EP cells were uninduced (no) or induced for 48 h by TRAIL (25 ng/ml) and M2 (125 ng/ml) (T) and NaB (1 mM), SAHA (2.5 μM) or TSA (0.5 μM), without caspases inhibitors, or with zIETD-fmk, zDEVD-fmk, zLEHD-fmk, zVDVAD-fmk or zVAD-fmk. Mean values of three representative experiments are shown. B Caspases cleavage is increased by simultaneous treatments with TRAIL and HDACIs. SH-EP cells were untreated (no) or treated with TRAIL (25 ng/ml) and M2 (125 ng/ml) (T) and/or NaB (1 mM), SAHA (2.5 μM) or TSA (0.5 μM) for 16 h. Whole cell extracts were analysed by immunoblotting for the cleavage of caspases-8, -2, -9, -3 and -7, and Bid. β-actin was used as loading control. Percentage of apoptotic cells (sub-G1 population) as analysed by the PI staining method after 16 h of treatments are indicated. C Caspase-3-like activities were induced by TRAIL/HDACIs co-treatments. Hydrolysis of DEVD-pNA was measured in SH-EP cells unstimulated (no) or treated with TRAIL (T) and/or NaB, SAHA or TSA for 16 h as in Fig. 3b. The caspase-3-like activities of stimulated cells, relative to unstimulated cells are indicated. The caspase-3/-7 inhibitor DEVD-fmk was used as control to inhibit hydrolysis of DEVD-pNA.