Abstract A02: Neuroblastoma patient-derived orthotopic xenografts: Clinically relevant models for drug testing

Abstract Widespread metastasis is a major problem for the treatment of high-risk neuroblastoma. Relevant neuroblastoma animal models are hence needed to study and target high-risk metastatic neuroblastoma. We developed neuroblastoma patient-derived orthotopic xenografts (PDXs) using viably cryopreserved or fresh patient neuroblastoma fragments which were implanted orthotopically into immunodeficient NSG mice. Immunohistochemistry showed that PDXs retain neuroblastoma markers and a highly infiltrative growth pattern. Importantly, we found distant metastasis to lungs, liver and bone marrow. Single nucleotide polymorphism array analysis confirmed that PDXs maintain patient-specific chromosomal…

Extracellular matrix composition defines an ultra-high-risk group of neuroblastoma within the high-risk patient cohort

Background: Although survival for neuroblastoma patients has dramatically improved in recent years, a substantial number of children in the high-risk subgroup still die. Methods: We aimed to define a subgroup of ultra-high-risk patients from within the high-risk cohort. We used advanced morphometric approaches to quantify and characterise blood vessels, reticulin fibre networks, collagen type I bundles, elastic fibres and glycosaminoglycans in 102 high-risk neuroblastomas specimens. The Kaplan-Meier method was used to correlate the analysed elements with survival. Results: The organisation of blood vessels and reticulin fibres in neuroblastic tumours defined an ultra-high-risk patient subgr…

Patient-Derived Xenograft Models Reveal Intratumor Heterogeneity and Temporal Stability in Neuroblastoma.

Patient-derived xenografts (PDX) and the Avatar, a single PDX mirroring an individual patient, are emerging tools in preclinical cancer research. However, the consequences of intratumor heterogeneity for PDX modeling of biomarkers, target identification, and treatment decisions remain under-explored. In this study, we undertook serial passaging and comprehensive molecular analysis of neuroblastoma orthotopic PDXs, which revealed strong intrinsic genetic, transcriptional, and phenotypic stability for more than 2 years. The PDXs showed preserved neuroblastoma-associated gene signatures that correlated with poor clinical outcome in a large cohort of patients with neuroblastoma. Furthermore, we…

High levels of HIF-2α highlight an immature neural crest-like neuroblastoma cell cohort located in a perivascular niche

High HIF-2alpha protein levels in the sympathetic nervous system-derived childhood tumour neuroblastoma as well as immature phenotype correlate to unfavourable outcome. Here we show that a small subset of perivascularly located, strongly HIF-2alpha-positive tumour cells (MYCN amplified) lacks expression of differentiation markers, but expresses neural crest and early sympathetic progenitor marker genes such as Notch-1, HES-1, c-Kit, dHAND, and vimentin. HIF-2alpha- and CD68-positive tumour-associated macrophages were frequently found close to the immature and HIF-2alpha-positive neuroblastoma cells and as VEGF levels are high in the perivascular niche, we hypothesize that neuroblastoma neur…

snoRNPs Regulate Telomerase Activity in Neuroblastoma and Are Associated with Poor Prognosis

AbstractAmplification of the MYCN oncogene is strongly associated with poor prognosis in neuroblastoma (NB). In addition to MYCN amplification, many studies have focused on identifying patients with a poor prognosis based on gene expression profiling. The majority of prognostic signatures today are comprised of large gene lists limiting their clinical application. In addition, although of prognostic significance,most of these signatures fail to identify cellular processes that can explain their relation to prognosis. Here, we determined prognostically predictive genes in a data set containing 251 NBs. Gene Ontology analysis was performed on significant genes with a positive hazard ratio to …

Neuroblastoma patient-derived orthotopic xenografts reflect the microenvironmental hallmarks of aggressive patient tumours.

AbstractTreatment of high-risk childhood neuroblastoma is a clinical challenge which has been hampered by a lack of reliable neuroblastoma mouse models for preclinical drug testing. We have previously established invasive and metastasising patient-derived orthotopic xenografts (PDXs) from high-risk neuroblastomas that retained the genotypes and phenotypes of patient tumours. Given the important role of the tumour microenvironment in tumour progression, metastasis, and treatment responses, here we analysed the tumour microenvironment of five neuroblastoma PDXs in detail. The PDXs resembled their parent tumours and retained important stromal hallmarks of aggressive lesions including rich bloo…

From critters to cancers: bridging comparative and clinical research on oxygen sensing, HIF signaling, and adaptations towards hypoxia

The objective of this symposium at the First International Congress of Respiratory Biology (ICRB) was to enhance communication between comparative biologists and cancer researchers working on O(2) sensing via the HIF pathway. Representatives from both camps came together on August 13-16, 2006, in Bonn, Germany, to discuss molecular adaptations that occur after cells have been challenged by a reduced (hypoxia) or completely absent (anoxia) supply of oxygen. This brief "critters-to-cancer" survey discusses current projects and new directions aimed at improving understanding of hypoxic signaling and developing therapeutic interventions.

Abstract B23: Neuroblastoma patient-derived orthotopic xenografts: Clinically relevant models for drug testing

Abstract Background: We previously established neuroblastoma patient-derived orthotopic xenografts (PDXs) by implanting patient neuroblastoma fragments into immunodeficient NSG mice. SNP array analysis confirmed that PDXs maintain patient-specific chromosomal aberrations 1p del, MYCN amp and 17q gain. Immunohistochemistry showed that PDXs retain neuroblastoma markers and a highly infiltrative growth pattern. Importantly, we found spontaneous distant metastasis to lungs, liver and bone marrow. In vitro cultures established from the PDXs express neuroblastoma markers and retain their tumorigenic and metastatic ability in vivo after orthotopic injection. Methods and Results: Given the importan…

Recruitment of HIF-1α and HIF-2α to common target genes is differentially regulated in neuroblastoma: HIF-2α promotes an aggressive phenotype

In neuroblastoma specimens, HIF-2alpha but not HIF-1alpha is strongly expressed in well-vascularized areas. In vitro, HIF-2alpha protein was stabilized at 5% O2 (resembling end capillary oxygen conditions) and, in contrast to the low HIF-1alpha activity at this oxygen level, actively transcribed genes like VEGF. Under hypoxia (1% O2), HIF-1alpha was transiently stabilized and primarily mediated acute responses, whereas HIF-2alpha protein gradually accumulated and governed prolonged hypoxic gene activation. Knockdown of HIF-2alpha reduced growth of neuroblastoma tumors in athymic mice. Furthermore, high HIF-2alpha protein levels were correlated with advanced clinical stage and high VEGF expr…

Individual patient risk stratification of high-risk neuroblastomas using a two-gene score suited for clinical use

Several gene expression-based prognostic signatures have been described in neuroblastoma, but none have successfully been applied in the clinic. Here we have developed a clinically applicable prognostic gene signature, both with regards to number of genes and analysis platform. Importantly, it does not require comparison between patients and is applicable amongst high-risk patients. The signature is based on a two-gene score (R-score) with prognostic power in high-stage tumours (stage 4 and/or MYCN-amplified diagnosed after 18 months of age). QPCR-based and array-based analyses of matched cDNAs confirmed cross platform (array-qPCR) transferability. We also defined a fixed cut-off value iden…

Prognostic value of SOX2 expression in neuroblastoma.

Neuroblastoma with MYCN amplification plus 11q deletion: immunohistochemical expression of angiogenic factors

Neuroblastoma (NB) is an extra-cranial solid neoplasm in childhood. Genetic markers as MYCN amplification (MNA) and deletion of 11q (11q ) are considered factors with an adverse prognosis. Usually, an inverse relationship between MNA and 11q is found. Approximately 13% of the MNA cases present with 11q . These cases show a dramatic decline in survival rates. Hypoxia-inducible factor-2a (HIF-2a) protein expression has been described as an indicator of poor outcome, has been correlated with an aggressive phenotype in NB, and serves as a marker for stem cell-like phenotypes. Additionally, HIF-2a positive cells strongly express vascular endothelial growth factor (VEGF) and, as such, could be in…

HIF-1α and HIF-2α Are Differentially Regulated In vivo in Neuroblastoma: High HIF-1α Correlates Negatively to Advanced Clinical Stage and Tumor Vascularization

Abstract Purpose: Hypoxia is considered to be a major driving force behind tumor angiogenesis. The stabilization and activation at hypoxia of the hypoxia-inducible factors HIF-1α and HIF-2α and the concomitant induction of expression of vascular endothelial growth factor (VEGF) and other proangiogenic factors provide a molecular frame for hypoxia-driven tumor angiogenesis. This study has investigated how HIF and VEGF protein levels relate to each other with regard to vascularization, tumor stage, and overall survival in neuroblastoma. Experimental Design: Tissue cores taken from tumor specimens representing 93 children with neuroblastoma were arranged on a microarray and stained for HIF-1α,…

HIF-1α induces MXI1 by alternate promoter usage in human neuroblastoma cells

Adaptation to low oxygen conditions is essential for maintaining homeostasis and viability in oxygen-consuming multi-cellular tissues, including solid tumors. Central in these processes are the hypoxia-inducible transcription factors, HIF-1 and HIF-2, controlling genes involved in e.g. glucose metabolism and neovascularization. Tumor hypoxia and HIF expression have also been associated with a dedifferentiated phenotype and increased aggressiveness. In this report we show that the MAX interactor-1 (MXI1) gene is directly regulated by HIF proteins in neuroblastoma and breast cancer cells. HIF-binding and transactivation were detected within MXI1 gene regulatory sequences in the vicinity of th…