title: Modulation of tumor necrosis factor apoptosis-inducing ligand- induced NF-kappa B activation by inhibition of apical caspases.
abstract: Tumor necrosis factor (TNF) apoptosis-inducing ligand (TRAIL), a member of the TNF family, induces apoptosis in many transformed cells. We report TRAIL-induced NF-kappaB activation, concomitant with production of the pro-inflammatory cytokine Interleukin-8 in the relatively TRAIL-insensitive cell line, HEK293. In contrast, TRAIL-induced NF-kappaB activation occurred in HeLa cells only upon pretreatment with the caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-(OMe) fluoromethyl ketone (z-VAD.fmk), indicating that this was due to a caspase-sensitive component of TRAIL-induced NF-kappaB activation. NF-kappaB activation was mediated by the death receptors, TRAIL-R1 and -R2, but not by TRAIL-R3 or -R4 and was only observed in HeLa cells in the presence of z-VAD.fmk. Receptor-interacting protein, an obligatory component of TNF-alpha-induced NF-kappaB activation, was cleaved during TRAIL-induced apoptosis. We show that receptor-interacting protein is recruited to the native TRAIL death-inducing signaling complex (DISC) and that recruitment is enhanced in the presence of z-VAD.fmk, thus providing an explanation for the potentiation of TRAIL-induced NF-kappaB activation by z-VAD.fmk in TRAIL-sensitive cell lines. Examination of the TRAIL DISC in sensitive and resistant cells suggests that a high ratio of c-FLIP to caspase-8 may partially explain cellular resistance to TRAIL-induced apoptosis. Sensitivity to TRAIL-induced apoptosis was also modulated by inhibition or activation of NF-kappaB. Thus, in some contexts, modulation of NF-kappaB activation possibly at the level of apical caspase activation at the DISC may be a key determinant of sensitivity to TRAIL-induced apoptosis.
authors.affiliation: MRC Toxicology Unit, Hodgkin Building, University of Leicester, P. O. Box 138, Lancaster Road, Leicester LE1 9HN, United Kingdom.
authors.forename: N
authors.initials: N
authors.lastname: Harper
authors.forename: S N
authors.initials: SN
authors.lastname: Farrow
authors.forename: A
authors.initials: A
authors.lastname: Kaptein
authors.forename: G M
authors.initials: GM
authors.lastname: Cohen
authors.forename: M
authors.initials: M
authors.lastname: MacFarlane
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D020169:Caspases / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D051017:Apoptosis Regulatory Proteins; D061945:Caspase Inhibitors; D016209:Interleukin-8; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011506:Proteins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C506249:RIPK1 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D020169:Caspases