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Multiple pathways of TWEAK-induced cell death
Masafumi Nakayama1, Kazumi Ishidoh, Nobuhiko Kayagaki
1Department of Immunology, Allergy Research Center, Division of Pathology, Central Laboratory of Medical Sciences, Juntendo University School of Medicine, Tokyo, Japan.
Abstract:
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.
Insights
Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) triggers distinct cell death pathways, including apoptosis and necrosis, depending on the cell type. TWEAK utilizes receptors other than DR3, indicating diverse mechanisms of action in cancer cells.
Area of Science:
- Immunology
- Cell Biology
- Cancer Research
Background:
- Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a cytokine involved in inflammation and cell death.
- TWEAK belongs to the TNF superfamily and is expressed on IFN-gamma-stimulated monocytes.
- Its role in inducing cell death in various tumor cell lines requires detailed characterization.
Purpose of the Study:
- To investigate the distinct mechanisms of TWEAK-induced cell death in different tumor cell lines.
- To identify the specific pathways and receptors involved in TWEAK-mediated apoptosis and necrosis.
- To elucidate the cell type-specific responses to TWEAK stimulation.
Main Methods:
- Characterization of TWEAK-induced cell death in Kym-1, HSC3, and IFN-gamma-treated HT-29 cells.
- Assessment of the roles of TNF-alpha, cycloheximide, and specific inhibitors (caspase and lysosomal proteinase inhibitors) in TWEAK-induced cell death.
- Analysis of TWEAK receptor expression (DR3) and binding (CD8-TWEAK) on sensitive tumor cell lines.
- Detection of caspase activation and cathepsin B release.
Main Results:
- TWEAK induced TNF-alpha-mediated cell death in Kym-1 cells, inhibited by cycloheximide.
- TWEAK triggered direct cell death in HSC3 and IFN-gamma-treated HT-29 cells, independent of TNF-alpha and cycloheximide.
- HSC3 cells underwent caspase-dependent apoptosis, while HT-29 cells exhibited cathepsin B-dependent necrosis.
- TWEAK-sensitive cells did not express DR3 but specifically bound CD8-TWEAK, suggesting alternative TWEAK receptors.
Conclusions:
- TWEAK induces multiple cell death pathways, including caspase-dependent apoptosis and cathepsin B-dependent necrosis.
- The mode of TWEAK-induced cell death is cell type-specific.
- TWEAK mediates its effects through receptors distinct from DR3.