Unknown,Transcriptomics,Genomics,Proteomics

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Expression data of endothelial cells from mouse hindbrain and genetic Wnt-medulloblastoma and Shh-medulloblastoma mouse models

ABSTRACT: The childhood brain tumour medulloblastoma includes four subtypes with very different prognoses. Here, we show that paracrine signals driven by mutant Beta-Catenin in WNT-medulloblastoma â an essentially curable form of the disease â induce an aberrant fenestrated vasculature that permits the accumulation of high levels of intra-tumoural chemotherapy and a robust therapeutic response. In contrast, SHH-medulloblastoma â a less curable disease subtype â contains an intact blood brain barrier, rendering this tumour impermeable and resistant to chemotherapy. Remarkably, the medulloblastoma-endothelial cell paracrine axis can be manipulated in vivo, altering chemotherapy permeability and clinical response. Thus, medulloblastoma genotype dictates tumour vessel phenotype, explaining in part the disparate prognoses among medulloblastoma subtypes and suggesting an approach to enhance the chemoresponsiveness of other brain tumours. We used microarrays to detail the global program of gene expression within endothelial cells from normal mouse hindbrain and genetic mouse models of different medulloblastoma subtypes to identify and verify up-regulated and down-regulated genes Endothelial cells were isolated from adult mouse hindbrain and genetic mouse models of Wnt and Shh-medulloblastoma using Cd-144 and Cd-105 antibodies based magnetic sorting. RNA was extracted and used for hybridization on Affymetrix microarrays. We sought to identify changes in endothelial gene expression patterns based on the surrounding microenvironment, so we purified endothelial cells from normal mouse brain or tumors from genetic mouse models. These include the Shh-medulloblastoma model (Ptch+/-; Ink4c -/-) and Wnt-medulloblastoma model (Blbp-Cre; mutant Ctnnb1+/-; p53-/-; mutant Pik3ca +/-)

ORGANISM(S): Mus musculus

SUBMITTER: David Finkelstein

PROVIDER: E-GEOD-73753 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Medulloblastoma (MB) is the most common malignant brain tumor. MB is a cerebellar tumor that occurs mostly in children between the ages of 3-7 years but also in adults. Human MBs are classified into four subgroups: Wingless (WNT), Sonic Hedgehog (SHH), Group 3 (G3) and G4, each of which with distinct molecular signatures. SHH MBs with MYCN amplification and TP53 mutations and G3 MBs characterized by C-MYC (MYC) overexpression in ~17% of cases from gene amplification with stem like properties, are the most aggressive and least curable with current therapeutic regimen. Using an orthotopic transplant approach, we found that enforced expression of MYCN in cerebellar granule neural progenitors (CGNPs) from 5-7 days old Trp53-null mice induced SHH MBs after transfer in the cortices or cerebella of naive recipient mice. In contrast, overexpression of MYC induced G3 MBs. Because MYCN and MYC bind to the same E-box DNA sequences, we hypothesized that the difference between MYC and MYCN-induced gene expression and tumor identity might be due to their interaction with different partners in CGNPs. In this study, we investigated the role of the Myc interacting zinc finger protein 1 (MIZ1). We found that MIZ1 binds with higher affinity to MYC than to MYCN and that MIZ1 and MYC co-occupy thousands of promoters in G3 MB. Remarkably, enforced expression of a MYC mutant (MYCV394D) that no longer binds to MIZ1 in Trp53-null CGNPs or expression of wild type MYC in CGNPs that lack functional Miz1 resulted in massive changes of the resulting tumorâ??s transcriptional program. Tumors differed from both SHH and G3 medulloblastoma and had a later time of onset compared to MYC-driven G3 medulloblastoma. Our data demonstrate that interaction of MYC with MIZ1 is required for the development of G3 medulloblastoma. ChIP-Seq experiments for Miz1, c-Myc and NMyc from murine medulloblastoma material. Either sorted tumor cells (Miz1 and c-Myc) or spheres from tumor cells (Miz1 and NMyc) were used. Input-samples were sequenced as controls. RNA-Seq from G3 medulloblastomas after restoration of Atoh1 expression.

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Expression data of endothelial cells from mouse hindbrain and genetic Wnt-medulloblastoma and Shh-medulloblastoma mouse models

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