The low-affinity neurotrophin receptor, p75, is upregulated in ganglioneuroblastoma/ganglioneuroma and reduces tumorigenicity of neuroblastoma cells in vitro and in vivo

Ziel dieser Studie war, die funktionelle Bedeutung des niedrig-affinen NGF-Rezeptors p75NTR in neuroblastischen Tumoren näher zu untersuchen. Mit der immunhistochemischen Methode eines Tissue Microarray wurden zunächst 93 primäre, unbehandelte neuroblastische Tumoren analysiert. Eingeschlossen waren hier-bei 72 Neuroblastome und 21 Ganglioneuroma/Ganglioneuroblastome. Wenig differen-zierte Neuroblastome waren fast ausschließlich p75NTR-negativ, wohingegen p75NTR in differenzierenden Neuroblastomen und den neuroblastischen Tumorzellen der Ganglio-neuroblastome und Ganglioneurome nachgewiesen werden konnte. Auf mRNA-Ebene konnten für eine unabhängige Kohorte mit 110 neuroblastischen Tumoren ähnliche Er-gebnisse gezeigt werden. In dieser zweiten Kohorte zeigte eine Kaplan-Meier-Analyse, dass hohe p75NTR mRNA-Expression mit ereignisfreiem Überleben korreliert. In acht etablierten Neuroblastom-Zelllinien wurde die p75NTR-Expression mittels Durch-flusszytometrie analysiert. In keiner der Zelllinien war p75NTR Expression nachweisbar. Stabil p75NTR transfizierte SY5Y-Zellen zeigten im MTT-Viabilitätsassay unabhängig von der Anwesenheit des p75NTR-Liganden NGF einen signifikant erniedrigten Anteil von vitalen Zellen nach 12 Tagen im Vergleich zu Kontrollen. Mittels BrdU-Assay und Anne-xin-V-Assay konnte in stabil p75NTR-exprimierenden Zellen sowohl eine verminderte Pro-liferationsrate als auch eine erhöhte Apoptoserate nachgewiesen werden. Um den Effekt von p75NTR auf neuroblastische Tumoren in vivo zu untersuchen, wurde ein Xenograft Maus-Modell benutzt. In allen Mäusen, denen die parentalen SY5Y-Zellen injiziert wurden, konnte Tumorwachstum beobachtet werden. In den Mäusen, die stabil p75NTR-exprimierende SY5Y-Zellen injiziert bekamen, konnte innerhalb von 180 Tagen kein Tumorwachstum erkannt werden. Diese Ergebnisse lassen den Schluss zu, dass p75NTR-Expression im Verlauf der Ent-wicklung von der Neuralleistenstammzelle zum Neuroblastom verloren geht, und dass die Re-Expression von p75NTR vor allem in primären neuroblastischen Tumorzellen mit dem Differenzierungsgrad zu einem benigneren Tumortyp korreliert. Funktionell führt die stabi-le Expression von p75NTR in Neuroblastomzellen zum Verlust der Tumorigenität im Xe-nograft-Maus-Modell. Die in anderen Tumoren beschriebene Funktion von p75NTR als Stammzellmarker kann anhand der vorliegenden Ergebnisse für das Neuroblastom nicht bestätigt werden.Neuroblastoma, the most common extracranial tumor of childhood, is derived from neural crest progenitor cells that fail to differentiate along their predefined route to sympathetic neurons or sympatho-adrenergic adrenal cells. Although expression of the high-affinity neurotrophin receptors, TrkA and TrkB, is of major importance in neuroblastoma, the significance of the expression of the low-affinity neurotrophin receptor, p75, is unclear. Here, we analyzed immunohistochemically expression of p75 on a tissue microarray of 93 primary neuroblastic tumors and assessed the functional consequences of p75 expression in neuroblastoma cell lines. We found the p75 receptor protein to be expressed in neuroblastic cells of ganglioneuromas/ganglioneuroblastomas as well as differentiating neuroblastomas, but not in poorly differentiated neuroblastomas. In an unrelated cohort of 110 neuroblastic tumors, p75 mRNA expression levels correlated with differentiation, and patients with tumors that expressed p75 at high levels had an increased event-free and overall survival. In addition, we did not detect p75 expression in 8 established neuroblastoma cell lines examined with FACS analysis. These cell lines exhibited an undifferentiated morphology, and were all derived from aggressive, high-stage neuroblastomas. Ectopic p75 expression in the SH-SY5Y neuroblastoma cell line significantly reduced proliferation, increased the fraction of apoptotic cells in vitro and resulted in a loss of tumorigenicity in nude mice. Taken together, our data suggest that expression of the p75 low-affinity neurotrophin receptor is correlated with a reduced level of tumorigenicity, and that induction of p75 expression may be an option to revert features of an aggressive tumor phenotype

The low-affinity neurotrophin receptor, p75, is upregulated in ganglioneuroblastoma/ganglioneuroma and reduces tumorigenicity of neuroblastoma cells in vivo

Neuroblastoma, the most common extracranial tumor of childhood, is derived from neural crest progenitor cells that fail to differentiate along their predefined route to sympathetic neurons or sympatho-adrenergic adrenal cells. Although expression of the high-affinity neurotrophin receptors, TrkA and TrkB, is of major importance in neuroblastoma, the significance of the expression of the low-affinity neurotrophin receptor, p75, is unclear. Here, we analyzed immunohistochemically expression of p75 on a tissue microarray of 93 primary neuroblastic tumors and assessed the functional consequences of p75 expression in neuroblastoma cell lines. We found the p75 receptor protein to be expressed in neuroblastic cells of ganglioneuromas/ganglioneuroblastomas as well as differentiating neuroblastomas, but not in poorly differentiated neuroblastomas. In an unrelated cohort of 110 neuroblastic tumors, p75 mRNA expression levels correlated with differentiation, and patients with tumors that expressed p75 at high levels had an increased event-free and overall survival. In addition, we did not detect p75 expression in 8 established neuroblastoma cell lines examined with FACS analysis. These cell lines exhibited an undifferentiated morphology, and were all derived from aggressive, high-stage neuroblastomas. Ectopic p75 expression in the SH-SY5Y neuroblastoma cell line significantly reduced proliferation, increased the fraction of apoptotic cells in vitro and resulted in a loss of tumorigenicity in nude mice. Taken together, our data suggest that expression of the p75 low-affinity neurotrophin receptor is correlated with a reduced level of tumorigenicity, and that induction of p75 expression may be an option to revert features of an aggressive tumor phenotype. (C) 2008 Wiley-Liss, Inc

Low incidence of symptomatic osteonecrosis after allogeneic HSCT in children with high-risk or relapsed ALL - results of the ALL-SCT 2003 trial

Osteonecrosis (ON) was prospectively assessed in 557 children and adolescents in the Berlin-Frankfurt-Münster Stem Cell Transplantation in children with acute lymphoblastic leukaemia 2003 trial. Median age at haematopoietic stem cell transplantation (HSCT) was 10·3 years (range 0·5-26). Cumulative incidence of symptomatic ON (sON) was 9% at 5 years (standard deviation 1%), median time from HSCT to diagnosis of sON was 12·4 months (range 1-126). Multivariate analysis identified age at HSCT [10-15 years vs. 15 years vs. <10 years: HR 5·46, P = 0·001], diagnosis of sON prior to HSCT and chronic graft-versus-host disease (yes versus no: HR 2·696, P = 0·015) as significant independent risk factors for the development of sON