| T2 |
470-1480 |
RESULTS |
denotes |
TRAIL alone or cisplatin alone caused minimal cytotoxicity. The combination of TRAIL and cisplatin synergistically enhanced apoptotic death, caspase-8 and caspase-3 activation, as well as poly(ADP-ribose) polymerase cleavage. However, the total cellular levels and the surface expression of TRAIL receptor proteins, such as death receptors 4 and 5 and decoy receptors 2 and 1, were not significantly changed by treatment with TRAIL and cisplatin. Interestingly, the level of the short form of Fas-associated death domain-like interleukin-1beta-converting enzyme-inhibitory protein (FLIP(S)) but not the long form of Fas-associated death domain-like interleukin-1beta-converting enzyme-inhibitory protein was reduced through cleavage. Benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone a caspase-3 inhibitor, blocked the cleavage of FLIP(S) and caspase-3 activation. Overexpression of FLIP(S) protected cells from apoptotic death and FLIP(S) cleavage during treatment with TRAIL in combination with cisplatin. |