title: Restoration of TRAIL-induced apoptosis in a caspase-8-deficient neuroblastoma cell line by stable re-expression of caspase-8.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis in most tumor cells, a process sometimes potentiated by chemotherapeutic drugs or cycloheximide (CHX). Childhood neuroblastoma (NB) is a clinically and biologically heterogeneous neoplasm whose behavior can be explained by differential regulation of apoptosis. The non-invasive S-type NB cell lines are sensitive to TRAIL, whereas the invasive N-type NB cell lines are resistant. We have reported the silencing of caspase-8 expression in N-type cells as a possible mechanism of death receptor-mediated resistance to apoptosis in NB. The recently observed deregulation of caspase-10 in these cells prompted us to investigate the particular contribution of caspase-8 silencing in the resistance to TRAIL in N-type cells. Stable caspase-8 expression was therefore restored in the IGR-N91 cell line by retroviral infection. The IGR-N91-C8 cells became sensitive to TRAIL-mediated apoptosis, whereas the control vector-infected IGR-N91-M cells remained resistant. Interestingly, the apoptotic response to TRAIL was enhanced by co-treatment of SH-EP and IGR-N91-C8 cells with CHX or with sub-toxic concentration of doxorubicin (DOX) in a caspase-dependent manner, as cells could be protected from death by specific caspase-8 or pan-caspase inhibitors. CHX or DOX was shown to enhance TRAIL-induced caspase-8 activation and loss of mitochondrial transmembrane potential. In conclusion, restoration of active caspase-8 expression in caspase-8- and caspase-10-deficient IGR-N-91 cell line is necessary and sufficient to fully restore TRAIL-mediated cell death. Moreover, DOX and CHX were able to sensitize NB cell lines to TRAIL-induced apoptosis in a caspase-8-dependent manner by engaging death receptor and mitochondrial signaling pathways.
authors.affiliation: Onco-Hematology Research Unit, Department of Medical and Surgical Pediatrics, Centre Hospitalier Universitaire Vaudois, CH-1011 Lausanne, Switzerland.
authors.forename: Annick
authors.initials: A
authors.lastname: Mühlethaler-Mottet
authors.forename: Katia
authors.initials: K
authors.lastname: Balmas
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: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D053181:Caspase 8; D020169:Caspases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D045744:Cell Line, Tumor; D003513:Cycloheximide / Q000494:pharmacology; D004249:DNA Damage; D004789:Enzyme Activation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D009447:Neuroblastoma; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D003513:Cycloheximide; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases