4.9. Apoptosis Inhibition Using Caspase Inhibitors

In order to determine whether TRAIL and/or xanthohumol—induced apoptosis is dependent on caspases, the following caspase inhibitors were used: caspase-3 inhibitor (z-DEVD-fmk), caspase-8 inhibitor (z-IETD-fmk), caspase-9 inhibitor (z-LEHD-fmk) and pancaspase inhibitor (z-VAD-fmk). The caspase inhibitors were obtained from R and D Systems [74]. The results of our earlier experiments (data not shown) confirmed that caspase inhibitors used alone did not reduce the viability of LNCaP cells (MTT assay) and did not induce apoptosis or necrosis of LNCaP cells (Apoptotest-FITC) [73]. LNCaP cells were incubated with 100 ng/mL TRAIL and/or 50 µM xantohumol and/or 20 µM caspase inhibitors for 24 h. Apoptotic cells were detected using flow cytometer LSR II with Apoptotest-FITC.