title: Phenylarsine oxide interferes with the death inducing signaling complex and inhibits tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induced apoptosis.
abstract: The mechanism by which tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces death is the subject of intense scrutiny due to its preferential targeting of transformed cells for deletion. Based on recent findings that the TRAIL-dependent death inducing signaling complex (DISC) forms and signals at the plasma membrane without being internalized, we investigated the possibility that agents that prevent endocytosis may stabilize the surface bound DISC and thereby enhance TRAIL-dependent signaling. We utilized phenylarsine oxide (PAO), a trivalent arsenical that has been reported to inhibit endocytosis and to induce mitochondrial permeability transition. Therefore PAO could, by two separate and independent activities, enhance TRAIL-induced killing. Paradoxically, we found that rather than synergizing with TRAIL, PAO was an effective inhibitor of TRAIL-induced killing. Recruitment of FADD and caspase-8 to the TRAIL-dependent DISC was diminished in a concentration-dependent manner in cells exposed to PAO. The effects of PAO could not be reversed by washing cells under non-reducing conditions, suggesting covalent linkage of PAO with its cellular target(s); however, 2,3-dimercaptoethanol effectively overcame the inhibitory action of PAO and restored sensitivity to TRAIL-induced apoptosis. PAO inhibited formation of the TRAIL-dependent DISC and therefore prevented all subsequent apoptotic events.
authors.affiliation: Medical Research Council Toxicology Unit, University of Leicester, Hodgkin Building, PO Box 138, Leicester LE1 9HN, UK.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Sun
authors.forename: Ana
authors.initials: A
authors.lastname: Canda-Sánchez
authors.forename: Ganesh R
authors.initials: GR
authors.lastname: Manjeri
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Cohen
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pinkoski
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001152:Arsenicals / Q000494:pharmacology*; D002051:Burkitt Lymphoma / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D045744:Cell Line, Tumor; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000187:drug effects / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D001152:Arsenicals; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha; C029341:oxophenylarsine; D020169:Caspases