Caspase-3 and -9 blocking peptides block Bcl-2-ASO–induced apoptosis in HS-Sultan cells.

HS-Sultan cells were cultured for 72 hours with or without 5 μg/mL Bcl-2-ASO, with 2 μM of each caspase inhibitory peptide, or control peptide (CP, or FA-FMK). Nonspecific toxicity of the control peptide (CP) was around 5%. VAD indicates pancaspase inhibitor. The toxicity of the blocking peptides was 2% to 5% above that of untreated, control cells (not shown). Apoptosis was determined by annexin V. Bars are ± SD of at least 3 experiments. ASO indicates Bcl-2-ASO; ASO+1, Bcl-2-ASO plus caspase-1 blocking peptide; ASO+2, Bcl-2-ASO plus caspase-2 blocking peptide, etc. For additional experimental details, see “Materials and methods.”