title: Nuclear FOXO3 predicts adverse clinical outcome and promotes tumor angiogenesis in neuroblastoma.
abstract: Neuroblastoma is the most frequent, extracranial solid tumor in children with still poor prognosis in stage IV disease. In this study, we analyzed FOXO3-phosphorylation and cellular localization in tumor biopsies and determined the function of this homeostasis regulator in vitro and in vivo. FOXO3-phosphorylation at threonine-32 (T32) and nuclear localization in biopsies significantly correlated with stage IV disease. DNA-damaging drugs induced nuclear accumulation of FOXO3, which was associated with elevated T32-phosphorylation in stage IV-derived neuroblastoma cells, thereby reflecting the in situ results. In contrast, hypoxic conditions repressed PKB-activity and caused dephosphorylation of FOXO3 in both, stroma-like SH-EP and high-stage-derived STA-NB15 cells. The activation of an ectopically-expressed FOXO3 in these cells reduced viability at normoxia, but promoted growth at hypoxic conditions and elevated VEGF-C-expression. In chorioallantoic membrane (CAM) assays STA-NB15 tumors with ectopic FOXO3 showed increased micro-vessel formation and, when xenografted into nude mice, a gene-dosage-dependent effect of FOXO3 in high-stage STA-NB15 cells became evident: low-level activation increased tumor-vascularization, whereas hyper-activation repressed tumor growth.The combined data suggest that, depending on the mode and intensity of activation, cellular FOXO3 acts as a homeostasis regulator promoting tumor growth at hypoxic conditions and tumor angiogenesis in high-stage neuroblastoma.
authors: Departments of Pediatrics II, Medical University Innsbruck, Innsbruck, Austria.
authors: Judith
authors: J
authors: Hagenbuchner
authors: Departments of Pediatrics II, Medical University Innsbruck, Innsbruck, Austria.|Pediatrics I, Medical University Innsbruck, Innsbruck, Austria.
authors: Martina
authors: M
authors: Rupp
authors: Pediatrics I, Medical University Innsbruck, Innsbruck, Austria.
authors: Christina
authors: C
authors: Salvador
authors: Pediatrics I, Medical University Innsbruck, Innsbruck, Austria.
authors: Bernhard
authors: B
authors: Meister
authors: Departments of Pediatrics II, Medical University Innsbruck, Innsbruck, Austria.
authors: Ursula
authors: U
authors: Kiechl-Kohlendorfer
authors: Pediatrics I, Medical University Innsbruck, Innsbruck, Austria.
authors: Thomas
authors: T
authors: Müller
authors: Tyrolean Cancer Research Institute, Innsbruck, Austria.
authors: Kathrin
authors: K
authors: Geiger
authors: Walter C. Mackenzie Centre, University of Alberta, Edmonton, Canada.
authors: Consolato
authors: C
authors: Sergi
authors: Departments of Pediatrics II, Medical University Innsbruck, Innsbruck, Austria.|Tyrolean Cancer Research Institute, Innsbruck, Austria.
authors: Petra
authors: P
authors: Obexer
authors: Pediatrics I, Medical University Innsbruck, Innsbruck, Austria.|Tyrolean Cancer Research Institute, Innsbruck, Austria.
authors: Michael J
authors: MJ
authors: Ausserlechner
mesh_terms: D000818:Animals; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D049109:Cell Proliferation; D002470:Cell Survival; D005260:Female; D000071316:Forkhead Box Protein O3 / Q000235:genetics* / Q000378:metabolism*; D018628:Gene Dosage; D006801:Humans; D051379:Mice; D009367:Neoplasm Staging; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000098:blood supply / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D010766:Phosphorylation; D011379:Prognosis; D016019:Survival Analysis; D013912:Threonine / Q000378:metabolism
chemical_list: C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D013912:Threonine
keywords: chemotherapy; chorioallantoic membrane (CAM); hypoxia