Fascaplysin sensitizes cells to TRAIL-induced apoptosis through upregulating DR5 expression

This study investigated the molecular mechanism of anti-tumor effect of fascaplysin, a nitrogenous red pigment firstly isolated from a marine sponge. Microarray analysis show that the TNF and TNF receptor superfamily in human umbilical vein endothelial cells (HUVEC) and human hepatocarcinoma cells (BEL-7402) were significantly regulated by fascaplysin. Western Blot results reveal that fascaplysin increased the expression of cleaved caspase-9, active caspase-3, and decreased the level of procaspase-8 and Bid. Flow cytometry and cytotoxicity tests indicate that fascaplysin sensitized cells to tumor necrosis-related apoptosisinducing ligand-(TRAIL) induced apoptosis, which was markedly blocked by TRAIL R2/Fc chimera, a dominant negative form of TRAIL receptor DR5. Therefore, our results demonstrate that fascaplysin promotes apoptosis through the activation of TRAIL signaling pathway by upregulating DR5 expression.