Fig. 1.

Reovirus increases the susceptibility of human ovarian cancer cells to TRAIL-induced apoptosis in a caspase 8-dependent manner. (A) The ovarian cancer cell lines PA-1, SKOV-3 and OVCAR3 were infected with reovirus (MOI 10) in the presence or absence of IETD-fmk (20 μM). Twenty four (OVCAR3 and PA-1) or 8 (SKOV3) h later the cells were treated with TRAIL (20 ng/ml) and apoptosis was determined after a further 18-24 h. Apoptosis was significantly (P < 0.001,***) enhanced in PA-1 and SKOV-3 and OVCAR3 cells treated with reovirus and TRAIL compared to cells treated with TRAIL or reovirus alone. Apoptosis was also significantly (P < 0.001,***) enhanced in OVCAR3 cells treated with reovirus and TRAIL compared to OVCAR3 cells treated with TRAIL and reovirus in the presence of IETD-fmk. (B) OVCAR3 cells were treated with TRAIL (20 ng/ml) for 1 h prior to being infected with reovirus (MOI 10). Apoptosis was determined after a further 35 h. Apoptosis was significantly (P < 0.001,***) enhanced in cells treated with reovirus and TRAIL compared to cells treated with TRAIL or reovirus alone. The graphs (A and B) show the percentage of cells with apoptotic nuclear morphology from at least 3 independent experiments for OVCAR3 and PA-1 cells and 2 independent experiments for SKOV-3 cells. Error bars represent standard errors of the mean. The effect of reovirus and TRAIL on apoptosis in OVCAR3 cells was found to be synergistic as determined by a 2×2 factorial ANOVA both when reovirus was added before TRAIL (C, see above for details) and when TRAIL was added before reovirus (D, see above for details)