title: Linking of N-Myc to death receptor machinery in neuroblastoma cells.
abstract: The oncogene MYCN is amplified in aggressive neuroblastomas in which caspase-8, an essential component of death receptor pathways, is frequently inactivated, suggesting a critical role of death receptor-mediated apoptosis in suppression of N-Myc oncogenic activity. Elevated levels of N-Myc sensitize neuroblastoma cells to apoptosis induced by various death ligands. Using tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as a model, we define the mechanism underlying the sensitization effect. In neuroblastoma cells with increased expression of N-Myc, TRAIL triggers high levels of caspase-8 activation and Bid cleavage, leading to release of cytochrome c and Smac/DIABLO from mitochondria. However, the apoptotic process requires Smac/DIABLO, but not cytochrome c-mediated caspase-9 activation. N-Myc sensitizes neuroblastoma cells to TRAIL by up-regulating TRAIL receptor-2/DR5/KILLER and Bid. Moreover, DR5 mRNA is increased after N-Myc overexpression, and the human DR5 promoter contains two noncanonical E-boxes critical for the transcriptional activation by N-Myc. These findings establish a mechanistic link between N-Myc and death receptor machinery, which may serve as a checkpoint to guard the cell from N-Myc-initiated tumorigenesis.
authors.affiliation: Department of Biochemistry and Cancer Biology, Medical College of Ohio, Toledo, Ohio 43614, USA.
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Cui
authors.forename: Tai
authors.initials: T
authors.lastname: Li
authors.forename: Han-Fei
authors.initials: HF
authors.lastname: Ding
mesh_terms: D017209:Apoptosis / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D016259:Genes, myc; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000502:physiology; D009447:Neuroblastoma / Q000235:genetics*; D010957:Plasmids; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000502:physiology
chemical_list: D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C412403:DIABLO protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D016271:Proto-Oncogene Proteins c-myc; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases