Figure 3.

WTC-01 triggers caspase-9-dependent apoptosis in human NPC cells.(A) Time-dependent activation of pro- and anti-apoptotic proteins following WTC-01 treatment. NPC-TW01 and HONE-1 cells were treated with 0.45 μM of WTC-01 for the indicated times. The protein levels of apoptosis-related proteins were evaluated using Western blot analysis with β-actin as an internal control. (B) Kinetics of caspase-8 and -9 activation in NPC-TW01 and HONE-1 cells. Cells were treated with 0.45 μM of WTC-01 for different periods and caspase activity was analysed. Data represent means ± SD for three determinations. (C) Caspase inhibition affects the cytotoxicity of WTC-01 in NPC-TW01 cells. NPC-TW01 cells were pretreated with 100 μM of caspase-8 inhibitor (Z-IEHD-FMK-TFA) or caspase-9 inhibitor (Z-IETD-FMK), respectively, for 1 h followed by WTC-01(4.5 μM, at 10-fold the IC₅₀) for another 72 h. Cell viability was determined by MTT assay.