benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Leukemia-L5178

TWEAK, a recently identified member of the TNF family, is expressed on IFN-gamma-stimulated monocytes and induces cell death in certain tumor cell lines. In this study, we characterized the TWEAK-induced cell death in several tumor cell lines that exhibited distinct features. Although the TWEAK-induced cell death in Kym-1 cells was indirectly mediated by TNF-alpha and was inhibited by cycloheximide, the TWEAK-induced cell death in HSC3 cells or IFN-gamma-treated HT-29 cells was not inhibited by anti-TNF-alpha mAb or cycloheximide, suggesting a direct triggering of cell death via TWEAK receptor in the latter cell lines. The TWEAK-induced apoptosis in HSC3 cells and IFN-gamma-treated HT-29 cells was associated with caspase-8 and caspase-3 activation. Although a pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, inhibited the TWEAK-induced cell death in HSC3 cells, it rather sensitized HT-29 cells to TWEAK-induced cell death by necrosis. This necrosis was abrogated by lysosomal proteinase inhibitors, particularly a cathepsin B inhibitor, [L-3-trans-(propylcarbamoyl)oxirane-2-carbonyl]-L-isoleucyl-L-proline methyl ester. During the process of TWEAK-induced necrosis, cathepsin B was released from lysosome to cytosol. Although DR3 has been reported to be a receptor for TWEAK, all TWEAK-sensitive tumor cell lines used in this study did not express DR3 at either protein or mRNA level, but did bind CD8-TWEAK specifically. These results indicated that TWEAK could induce multiple pathways of cell death, including both caspase-dependent apoptosis and cathepsin B-dependent necrosis, in a cell type-specific manner via TWEAK receptor(s) distinct from DR3.

Topics: Amino Acid Chloromethyl Ketones; Animals; Antigens, CD; Apoptosis; Apoptosis Regulatory Proteins; Carrier Proteins; Caspase Inhibitors; Caspases; Cathepsin B; Cell Death; Cytokine TWEAK; Enzyme Activation; HT29 Cells; Humans; Interferon-gamma; Jurkat Cells; Leukemia L5178; Ligands; Mice; Necrosis; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Member 25; Receptors, Tumor Necrosis Factor, Type I; Signal Transduction; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha; Tumor Necrosis Factors; TWEAK Receptor