title: Arsenite-induced apoptosis of human neuroblastoma cells requires p53 but occurs independently of c-Jun.
abstract: Arsenite treatment of human SH-SY5Y neuroblastoma cells leads to an upregulation of caspase-3/7 activity and to the fragmentation of chromatin that is accompanied by elevated p53 and c-Jun levels. Expression of a truncated mutant of p53, p53DD, which interfered with the oligomerization of p53, suppressed the arsenite-induced upregulation of caspase-3/7 activity and the fragmentation of chromatin, indicating that p53 is required for arsenite-induced cell death. These data were corroborated by knockdown experiments of p53 following expression of a p53-specific short hairpin RNA. Likewise, expression of either p53DD or knockdown of p53 prevented caspase-3/7 activation and chromatin fragmentation induced by nutlin-3, a compound that prevents the interaction between p53 and the E3 ubiquitin ligase MDM2. Transcriptional upregulation of a chromatin-embedded p53-responsive reporter gene in either arsenite or nutlin-3 stimulated neuroblastoma cells revealed that the transcriptional activity of p53 was increased under these conditions. Expression of a c-Jun-specific short hairpin RNA failed to impair arsenite-induced caspase-3/7 activation and fragmentation of chromatin. Likewise, inhibition of c-Jun target gene expression by expression of a dominant-negative mutant of c-Jun did not interfere with arsenite-induced caspase-3/7 activation and chromatin fragmentation. However, this approach successfully reduced caspase-3/7 activity induced as a result of forced expression of a constitutively active mutant of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase (MEKK)-1. Together, these data show that the upregulation of p53 is causally linked with arsenite-induced cell death in neuroblastoma cells, whereas the upregulation of c-Jun is not part of this apoptotic signaling cascade.
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Keim
authors.forename: O G
authors.initials: OG
authors.lastname: Rössler
authors.forename: T L
authors.initials: TL
authors.lastname: Rothhaar
authors.forename: G
authors.initials: G
authors.lastname: Thiel
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D018053:Arsenites / Q000494:pharmacology*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D006801:Humans; D020287:In Situ Nick-End Labeling; D009447:Neuroblastoma / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D018053:Arsenites; D016755:Proto-Oncogene Proteins c-jun; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C015001:arsenite