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Berlin Brandenburg

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  • 1
    In: Neuro-Oncology, 2014, Vol. 16(suppl3), pp.iii28-iii28
    Description: BACKGROUND: Tumor recurrence is the main cause of death for children with medulloblastoma, the most common malignant childhood brain tumor. The MYCN oncogene is a poor prognosis marker and is amplified in the molecularly defined SHH and Group 4 subgroups but rarely in WNT and Group 3 subgroups of human medulloblastoma. Recent findings on childhood brain tumor relapse mechanisms suggest spatiotemporal differences within these four subgroups. SOX9 is a transcription factor that is important for glial fate determination in the brain but has also been found to promote tumor metastasization. We previously showed how expression of SOX9 correlates well with human SHH tumors but only few scattered SOX9-positive cells are found in SHH-independent Group 3 and Group 4 human medulloblastoma. METHODS: In order to study recurrence processes experimentally, we used a previously described transgenic Tet-OFF (Glt1-tTA) inducible model of MYCN-driven SHH-independent medulloblastoma (GTML mouse). To recreate metastatic recurrence we further used a Tet-ON (SOX9-rtTA) model that drives MYCN expression from the SOX9 promoter upon doxycycline treatment. RESULTS: By crossing the GTML Tet-OFF model with a Tet-ON transgene we managed to study rare SOX9-positive tumor cells after SOX9-negative tumor cells were first depleted using doxycycline. SOX9-positive GTML cells were tumorigenic and reinitiated distant recurrences over time. The SOX9-positive cells further showed an increased resistance to MYCN-targeted therapies. Relapses showed similar histopathology but presented generally higher levels SOX9 as compared to primary GTML tumors. A similar correlation was found in Group 3 and Group 4 medulloblastoma patients where isolated metastases had consistently higher SOX9 levels as compared to corresponding primary tumors. Finally, we overexpressed SOX9 in normal cerebellar stem cells transduced with mutationally stabilized MYCN-T58A and injected them back into the cerebellum of adult mice. Surprisingly, SOX9-positive MYCN-T58A brain tumors migrated and developed in the forebrain in contrast to the cerebellar stem cells transduced with MYCN-T58A only. CONCLUSIONS: Our findings suggest that increased levels of SOX9 drives migration in MYCN-driven medulloblastoma. Rare SOX9-positive tumor cells show an increased therapy resistance and are alone capable of reinitiating childhood brain tumors. Further characterization of SOX9-positive cells in Group 3 and Group 4 tumors could help us understand what drives metastatic medulloblastoma relapse and could lead to new therapies directed against these particularly serious cell types. SECONDARY CATEGORY: Tumor Biology.
    Keywords: Medicine;
    ISSN: 1522-8517
    E-ISSN: 1523-5866
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  • 2
    In: Nature, 2014
    Description: Medulloblastoma is a highly malignant paediatric brain tumour currently treated with a combination of surgery, radiation and chemotherapy, posing a considerable burden of toxicity to the developing child. Genomics has illuminated the extensive intertumoral heterogeneity of medulloblastoma, identifying four distinct molecular subgroups. Group 3 and group 4 subgroup medulloblastomas account for most paediatric cases; yet, oncogenic drivers for these subtypes remain largely unidentified. Here we describe a series of prevalent, highly disparate genomic structural variants, restricted to groups 3 and 4, resulting in specific and mutually exclusive activation of the growth factor independent 1 family proto-oncogenes, GFI1 and GFI1B. Somatic structural variants juxtapose GFI1 or GFI1B coding sequences proximal to active enhancer elements, including super-enhancers, instigating oncogenic activity. Our results, supported by evidence from mouse models, identify GFI1 and GFI1B as prominent medulloblastoma oncogenes and implicate 'enhancer hijacking' as an efficient mechanism driving oncogene activation in a childhood cancer.
    Keywords: Medulloblastoma – Research ; Medulloblastoma – Health Aspects ; DNA Sequencing – Analysis ; Growth Factor Receptors – Analysis;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 3
    Language: English
    In: Journal of Neuro-Oncology, 2014, Vol.118(2), pp.225-238
    Description: Primary brain tumors cumulatively represent the most common solid tumors of childhood and are the leading cause of cancer related death in this age group. Traditionally, molecular findings and histological analyses from biopsies of resected tumor tissue have been used for diagnosis and classification of these diseases. However, there is a dearth of useful biomarkers that have been validated and clinically implemented for pediatric brain tumors. Notably, diseases of the central nervous system (CNS) can be assayed through analysis of cerebrospinal fluid (CSF) and as such, CSF represents an appropriate medium to obtain liquid biopsies that can be informative for diagnosis, disease classification and risk stratification. Proteomic profiling of pediatric CNS malignancies has identified putative protein markers of disease, yet few effective biomarkers have been clinically validated or implemented. Advances in protein quantification techniques have made it possible to conduct such investigations rapidly and accurately through proteome-wide analyses. This review summarizes the current literature on proteomics in pediatric neuro-oncology and discusses the implications for clinical applications of proteomics research. We also outline strategies for translating effective CSF proteomic studies into clinical applications to optimize the care of this patient population.
    Keywords: Proteomics ; Cerebrospinal fluid (CSF) ; Pediatric ; Neuro-oncolgy ; Biomarker
    ISSN: 0167-594X
    E-ISSN: 1573-7373
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  • 4
    Language: English
    In: Journal of Neuro-Oncology, 2012, Vol.109(2), pp.415-423
    Description: Little is known about frequency, association with clinical characteristics, and prognostic impact of DNA copy number alterations (CNA) on survival in central primitive neuroectodermal tumors (CNS-PNET) and tumors of the pineal region. Searches of MEDLINE, Pubmed, and EMBASE—after the original description of comparative genomic hybridization in 1992 and July 2010—identified 15 case series of patients with CNS-PNET and tumors of the pineal region whose tumors were investigated for genome-wide CNA. One additional case study was identified from contact with experts. Individual patient data were extracted from publications or obtained from investigators, and CNAs were converted to a digitized format suitable for data mining and subgroup identification. Summary profiles for genomic imbalances were generated from case-specific data. Overall survival (OS) was estimated using the Kaplan–Meier method, and by univariable and multivariable Cox regression models. In their overall CNA profiles, low grade tumors of the pineal region clearly diverged from CNS-PNET and pineoblastoma. At a median follow-up of 89 months, 7-year OS rates of CNS-PNET, pineoblastoma, and low grade tumors of the pineal region were 22.9 ± 6, 0 ± 0, and 87.5 ± 12 %, respectively. Multivariable analysis revealed that histology (CNS-PNET), age (≤2.5 years), and possibly recurrent CNAs were associated with unfavorable OS. DNA copy number profiling suggests a close relationship between CNS-PNET and pineoblastoma. Low grade tumors of the pineal region differed from CNS-PNET and pineoblastoma. Due to their high biological and clinical variability, a coordinated prospective validation in future studies is necessary to establish robust risk factors.
    Keywords: Chromosomal imbalances ; Prognostic markers ; Comparative genomic hybridization ; Brain tumor
    ISSN: 0167-594X
    E-ISSN: 1573-7373
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