Figure 6. Caspase-2 cleavage is important for apigenin/paclitaxel-induced apoptosis.

A, HeLa cells were transfected with flag-caspase2 or RNAi-caspase2. Forty-eight hours after transfection, cells were treated with apigenin (15 µM), paclitaxel (4 nM) or both of them for 24 hours. The mitochondrial fraction was separated from cytosolic fraction. The protein levels of AIF, Endo G and cytochrome c in both fractions were measured. β-actin and COX-IV were probed as the cytosolic and mitochondrial control respectively. Cytosolic and mitochondrial fractions were displayed as C and M respectively. B, Cells were treated as same as described in A. Protein levels of PARP, cleaved PARP, procaspase-2 and procaspase-3 were determined by Western blot analysis. C, Flag-caspase2 or RNAi-caspase2 was transfected to HeLa cells, and 48 hours after tranfection, cells were treated with apigenin (15 µM), paclitaxel (4 nM) or both of them for 24 hours. Cell vitality was measured with a cytotoxicity detection kit from Promega. The experiment was independently repeated for three times and data were shown as mean±S.D. *p<0.05 compared with empty-plasmid transfected group.