Fig. 4.

Ring-DIMs increase the activity of the initiator caspase-8 in AD and AI prostate cancer cells. Activity of caspase-8 was measured by cleavage of the fluorogenic substrate Ac-IETD-AFC in response to a 24 h treatment of LNCaP cells (a) and PC-3 cells (b) with increasing concentrations (15–30 μM) of 4,4′-dibromoDIM (□), 7,7′-dibromoDIM (■), 4,4′-dichloroDIM (△), 7,7′-dichloroDIM (▲) or DIM (●). Inhibition of LNCaP cell death (c) and caspase-3 activity (d) after a 24 h exposure to 10 μM 4,4′-dibromoDIM in combination with 10 μM of the membrane permeable caspase-8 inhibitor z-IETD-fmk. (e) Cleavage of Bid after a 24 h exposure of LNCaP cells to 10 μM 4,4′-dibromoDIM or 20 μM 7,7′-dichloroDIM or DIM. In A, B, C and D, data are represented as mean ± SEM (n=3–5); *p<0.05