title: Drug-mediated sensitization to TRAIL-induced apoptosis in caspase-8-complemented neuroblastoma cells proceeds via activation of intrinsic and extrinsic pathways and caspase-dependent cleavage of XIAP, Bcl-xL and RIP.
abstract: Neuroblastoma (NB) is a childhood neoplasm which heterogeneous behavior can be explained by differential regulation of apoptosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces rapid apoptosis in most tumor cells and thus represents a promising anticancer agent. We have reported silencing of caspase-8 expression in highly malignant NB cells as a possible mechanism of resistance to TRAIL-induced apoptosis. To explore the particular contribution of caspase-8 in such resistance, retroviral-mediated stable caspase-8 expression was induced in the IGR-N91 cells. As a result, sensitivity to TRAIL was fully restored in the caspase-8-complemented cells. TRAIL-induced cell death could be further enhanced by cotreatment of IGR-N91-C8 and SH-EP cells with cycloheximide or subtoxic concentrations of chemotherapeutic drugs in a caspase-dependent manner. Sensitization to TRAIL involved enhanced death receptor DR5 expression, activation of Bid and the complete caspases cascade. Interestingly, combined treatments also enhanced the cleavage-mediated inactivation of antiapoptotic molecules, XIAP, Bcl-x(L) and RIP. Our results show that restoration of active caspase-8 expression in a caspase-8-deficient NB cell line is necessary and sufficient to fully restore TRAIL sensitivity. Moreover, the synergistic effect of drugs and TRAIL results from activation of the caspase cascade via a mitochondrial pathway-mediated amplification loop and from the inactivation of apoptosis inhibitors.
authors.affiliation: Pediatric Oncology Research, Pediatric Department CHUV, CH-1011 Lausanne, Switzerland.
authors.forename: Annick
authors.initials: A
authors.lastname: Mühlethaler-Mottet
authors.forename: Katia Balmas
authors.initials: KB
authors.lastname: Bourloud
authors.forename: Katya
authors.initials: K
authors.lastname: Auderset
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Joseph
authors.forename: Nicole
authors.initials: N
authors.lastname: Gross
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects; D009447:Neuroblastoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein; D051020:bcl-X Protein
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D008562:Membrane Glycoproteins; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D051020:bcl-X Protein; D003513:Cycloheximide; C506249:RIPK1 protein, human; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases