towards improved death receptor targeted therapy for ... - TI Pharma

Chapter 3
Figure 2 (continued). (e) Expression and cleavage of caspase‐8, Bid, RIP1, caspase‐9, caspase‐3, PARP
in H460 cells after 3 h and 24 h incubation with 50 ng/ml TRAIL. (f) H460 cells were treated with
SP600125 (10 µM) or SB203580 (10 µM) with or without TRAIL for 3h and the phosphorylation status
of JNK and p38 were determined.
Effect of RIP1 on TRAIL‐induced caspases activation and p38 and JNK phosphorylation
Next, we further explored the role of RIP1 in mediating p38 and JNK signaling in NSCLC
cells. In H460 cells, RIP1 expression was reduced using a specific shRNA leading to an
increased amount of cell death after 24 h TRAIL treatment when compared to vector
control cells, revealing its contribution to prosurvival effects (Fig. 3a). JNK inhibition by
SP600125 further increased the amount of cell death in these cells. The decrease in TRAIL‐
induced cell death in H460 cells by SB203580‐mediated p38 inhibition was not observed in
H460‐shRIP1 cells. In agreement with stronger apoptosis activation in RIP1‐silenced cells
an increase in caspase‐8, ‐9, and ‐3 cleavages were detected (Fig. 3b). Unexpectedly,
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