TRAIL-induced apoptosis: between tumor therapy and immunopathology

The death ligand members of the tumor necrosis factor (TNF) family are potent inducers of apoptosis in a variety of cell types. In particular, TNF-related apoptosis-inducing ligand (TRAIL) has recently received much scientific and commercial attention because of its potent tumor cell-killing activity while leaving normal untransformed cells mostly unaffected. Furthermore, TRAIL strongly synergizes with conventional chemotherapeutic drugs in inducing tumor cell apoptosis, making it a most promising candidate for future cancer therapy. Increasing evidence indicates, however, that TRAIL may also induce or modulate apoptosis in primary cells. A particular concern is the potential side effect of TRAIL-based tumor therapies in the liver. In this review we summarize some of the recent findings on the role of TRAIL in tumor cell and hepatocyte apoptosis.