Figure 8

Involvement of death receptor pathway. (A), Expression of FADD and caspase-8 by Western blot analysis. LNCaP cells were transiently transfected with either control plasmid or plasmid expressing dominant negative FADD (DN-FADD) or caspase-8 siRNA along with plasmid (pCMV-LacZ) encoding β-galactosidase (β-Gal) enzyme. There was no difference in transfection efficiency among groups. Cell lysates were run on SDS-PAGE to measure the expression of FADD and caspase-8 by Western blot analysis. (B), Effects of dominant negative FADD on resveratrol and/or TRAIL-induced apoptosis. LNCaP cells were transiently transfected as described above. Cells were treated with resveratrol (0, 10 or 20 μM) in the presence or absence of TRAIL (50 nM) for 48 h, and apoptosis was measured. Data represent mean ± SD. * = Significantly different from respective control; # and $ = treatment groups were significantly different, P < 0.05. (C), Effects of caspase-8 siRNA on resveratrol and/or TRAIL-induced apoptosis. LNCaP cells were transiently transfected as described above. Cells were treated with resveratrol (0, 10 or 20 μM) in the presence or absence of TRAIL (50 nM) for 48 h. Apoptosis was measured by DAPI staining. Data represent mean ± SD. * = Significantly different from respective control; # and $ = treatment groups were significantly different, P < 0.05. (D), Effects of caspase-8 inhibitors on resveratrol and/or TRAIL-induced apoptosis. LNCaP cells were pretreated with either control peptide or caspase-8 inhibitor z-IETD-fmk (50 μM) for 4 h, followed by treatment with resveratrol (0, 10 or 20 μM) in the presence or absence of TRAIL (50 nM) for 48 h. Apoptosis was measured by DAPI staining. Data represent mean ± SD. * = Significantly different from respective control; # and $ = treatment groups were significantly different, P < 0.05.