FIGURE 3.

Upregulation of DR5 is essential for alternol-induced sensitization of TRAIL. (A) Caki-1 cells were transfected with DR5 siRNA, DR4 siRNA, or scramble siRNA. After 24 h, cells were treated with 20 μM alternol for an additional 24 h, and total cellular extracts were subjected to western blot assay using indicated antibodies. (B) Caki-1 cells were transfected with DR5 siRNA, DR4 siRNA, or scramble siRNA for 24 h, then cells were treated with alternol (20 μM), TRAIL (50 ng/ml), or combination for another 24 h, and then cellular lysates were subjected to western blot with indicated antibodies. (C) Cells were treated as described as above, and then, cells were stained with PI/annexin V and quantitatively analyzed the cell apoptotic rate. (D) After the same treatment described above, cell viability was measured using the MTT assay. (E) After the same treatment described above, caspase-3/-8 activities were assayed. Data are the mean ± SD of three independent experiments. **p < 0.01, compared with the combined treatment group after transfection of DR5 siRNA.