FIG. 7.

Effector caspase-3 expression in NDV-induced apoptosis of tumor cells. DF1 and various human tumor cells were either mock infected or infected with rLaSota V.F., rBC, or rBC-Edit strains of NDV at an MOI of 0.01. Culture supernatants were assayed by ELISA for caspase-3 production at 48 h postinfection. (A) The relative fluorescence units over mock-infected controls are shown for DF1 and a few representative human tumor cells for caspase-3. (B) Kinetics of caspase-3 production in HuTu80 cells. (C) Caspase-3 production in SH-SY5Y neuroblastoma cells. Results represent mean values + SEM from two independent experiments. Broad-spectrum caspase inhibitor does not prevent replication of NDV in human tumor cells. HuTu80 cells were pretreated for 1 h with 100 μM Z-VAD-FMK prior to infection with rLaSota V.F., rBC, or rBC-Edit (MOI = 1) virus or mock infection. Virus content in the supernatant of infected cells was assayed by a plaque assay in DF1 cells at the indicated time points postinfection (D). Virus titers in control cells with dimethyl sulfoxide treatment were not significantly different (P > 0.05). Results represent mean values + SEM from two independent experiments.