FIGURE 6.

Alternol induces generation of ROS, and alternol-induced sensitization of TRAIL was mediated by ROS. (A) Caki-1 cells were labeled with DCF-DA and incubated with 20 μM alternol for 6 h (left). Caki-1 cells were preexposed to NAC for 1 h, washed with PBS, labeled with DCF-DA, and treated with 20 μM alternol for 6 h (right). ROS generation was measured by a flow cytometer. (B) Caki-1 cells were preexposed to NAC for 1 h, washed with PBS, and treated with 20 μM alternol for 6 h. MDA levels and CAT activity were measured. (C,D,E,F) Caki-1 cells were treated as indicated for 24 h, and then total cellular lysates were subjected to western blot analysis with indicated antibodies. (G) Caki-1 cells were treated with NAC (15 mM), alternol (20 μM), and TRAIL (50 ng/ml) as indicated for 24 h. The apoptotic cells were analyzed by PI/annexin V staining assay. (H) After the treatment described above, the cell viabilities were analyzed by MTT assay. (I) After the treatment described above, caspase-3/-8 activities were assayed. Data are the mean ± SD of three independent experiments. **p < 0.01, compared with the untreated group.