Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA309837 | ENA |
REPOSITORIES: ENA
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Project description:Paediatric low-grade gliomas (LGGs) account for about a third of all brain tumours in children. We conducted a detailed study of DNA methylation to improve our understanding of the biology of pilocytic and diffuse astrocytomas. Comparisons were performed between tumours and normal brain controls from matching location, and between pilocytic and diffuse astrocytomas. Pilocytic astrocytomas were found to have a distinctive signature involving 315 CpG sites, with the majority of the sites (312 CpG sites) hypomethylated in pilocytic astrocytomas. Additionally many of the sites were located within annotated enhancers. The distinct signature in pilocytic astrocytomas was not present in diffuse astrocytomas or in published profiles of other brain tumours and normal brain tissue. On further analysis of the 315 CpG sites, the AP-1 transcription factor complex was predicted to bind within 200bp of a subset of teh 315 differentially methylated CpG sites. We also observed up-regulation of the AP-1 factors, FOS and FOSL1 in pilocytic astrocytomas. Our findings highlight novel epigenetic differences between pilocytic and diffuse astrocytomas, in addition to well-described alterations involving BRAF, MYB and FGFR1.
2016-05-10 | GSE77241 | GEO
Project description:Copy number analysis of 21 paediatric low-grade astrocytomas identified a discrete copy number gain of 1.9Mb in chromosome band 7q34. The gain was present in 12/14 cerebellar pilocytic astrocytomas. Subsequent analysis of tumour cDNA indentified a novel gene fusion between KIAA1549 and BRAF in these tumours. Copy number analysis of 21 paediatric low-grade astrocytomas using the Affymetrix GeneChip Human Mapping 250K Nsp Array. This study comprised 14 pilocytic astrocytomas, 4 diffuse astrocytomas, one pilomyxoid astrocytoma, one pilomyxoid glioma and one pleomorphic xanthoastrocytoma. Tumours were compared to the mean of two normal male DNA controls.
2010-04-09 | E-GEOD-14960 | biostudies-arrayexpress
Project description:In this study, we screened a cohort of 57 paediatric brain tumours, with a wide range of pathologies to identify microRNA profiles We analysed the microRNA profiles in paediatric brain tumours as compared to normal adult brain. Our cohort included 14 pilocytic astrocytomas, 3 diffuse astrocytomas, 2 anaplastic astrocytomas, 5 glioblastomas, 14 ependymomas, 9 medulloblastomas, 5 atypical teratoid/rhabdoid tumours, 4 choroid plexus papillomas, 1 papillary glioneuronal, and 7 adult brain controls.
2015-12-10 | E-GEOD-42657 | biostudies-arrayexpress
Project description:In this study, we screened a cohort of 57 paediatric brain tumours, with a wide range of pathologies to identify gene expression profiles We analysed gene expression in paediatric brain tumours as compared to normal adult brain in order to understand the molecular profiles. Our cohort included 15 pilocytic astrocytomas, 3 diffuse astrocytomas, 2 anaplastic astrocytomas, 5 glioblastomas, 14 ependymomas, 9 medulloblastomas, 5 atypical teratoid/rhabdoid tumours, 4 choroid plexus papillomas, 8 adult brain and 8 foetal brain controls.
2013-07-29 | E-GEOD-42656 | biostudies-arrayexpress
Project description:Copy number analysis of 21 paediatric low-grade astrocytomas identified a discrete copy number gain of 1.9Mb in chromosome band 7q34. The gain was present in 12/14 cerebellar pilocytic astrocytomas. Subsequent analysis of tumour cDNA indentified a novel gene fusion between KIAA1549 and BRAF in these tumours.
2009-04-16 | GSE14960 | GEO
Project description:DNA methylation profiling of 26 individual isomorphic diffuse gliomas using Illumina HumanMethylation450 BeadChips or Illumina Infinium HumanMethylation850 BeadChips. Abstract: The “isomorphic subtype of diffuse astrocytoma” was identified histologically in 2004 as a supratentorial, highly differentiated glioma with low cellularity, low proliferation and focal diffuse brain infiltration. Patients typically had seizures since childhood and all were operated on as adults. To define the position of these lesions among brain tumours, we histologically, molecularly and clinically analysed 26 histologically prototypical isomorphic diffuse gliomas. Immunohistochemically, they were GFAP-positive, MAP2-, OLIG2- and CD34-negative, nuclear ATRX-expression was retained and proliferation was low. All 24 cases sequenced were IDH-wildtype. In cluster analyses of DNA-methylation data, isomorphic diffuse gliomas formed a group clearly distinct from other glial/glio-neuronal brain tumours and normal hemispheric tissue, most closely related to paediatric MYB/MYBL1-altered diffuse astrocytomas and angiocentric gliomas. Half of the isomorphic diffuse gliomas had copy number alterations of MYBL1 or MYB (13/25, 52%). Gene fusions of MYBL1 or MYB with various gene partners were identified in 11/22 (50%) and were associated with an increased RNA-expression of the respective MYB-family gene. Integrating copy number alterations and available RNA sequencing data, 20/26 (77%) of isomorphic diffuse gliomas demonstrated MYBL1 (54%) or MYB (23%) alterations. Clinically, 89% of patients were seizure-free after surgery and all had a good outcome. In summary, we here define a distinct benign tumour class belonging to the family of MYB/MYBL1-altered gliomas. Isomorphic diffuse glioma occurs both in children and adults, has a concise morphology, frequent MYBL1- and MYB-alterations and a specific DNA-methylation profile. As an exclusively histological diagnosis may be very challenging and as paediatric MYB/MYBL1-altered diffuse astrocytomas may have the same gene fusions, we consider DNA-methylation profiling very helpful for their identification.
2019-09-26 | GSE136361 | GEO
Project description:Array-based comparative genomic hybridisation analysis at 1Mb resolution of 44 pilocytic astrocytomas
| PRJNA106777 | ENA
Project description:Expression Analysis of Juvenile Pilocytic Astrocytomas by Oligonucleotide Microarray Reveals Two Potential Subgroups
| PRJNA110813 | ENA
Project description:Astrocytomas are heterogeneous intracranial glial neoplasms ranging from the highly aggressive malignant glioblastoma multiforme (GBM) to the indolent, low-grade pilocytic astrocytoma. We have investigated whether DNA microarrays can identify gene expression differences between high-grade and low-grade glial tumors. We compared the transcriptional profile of 45 astrocytic tumors including 21 GBMs and 19 pilocytic astrocytomas using oligonucleotide-based microarrays. Of the approximately 6800 genes that were analyzed, a set of 360 genes provided a molecular signature that distinguished between GBMs and pilocytic astrocytomas. Many transcripts that were increased in GBM were not previously associated with gliomas and were found to encode proteins with properties that suggest their involvement in cell proliferation or cell migration. Microarray-based data for a subset of genes was validated using real-time quantitative reverse transcription-PCR. Immunohistochemical analysis also localized the protein products of specific genes of interest to the neoplastic cells of high-grade astrocytomas. Our study has identified a large number of novel genes with distinct expression patterns in high-grade and low-grade gliomas.
2015-06-25 | GSE70231 | GEO
Project description:Pilocytic astrocytomas (PAs), WHO Grade I, are one of the most frequently occurring childhood brain tumors. We have used microarray comparative genomic hybridization (aCGH) at 1Mb resolution to study copy number changes in a series of PAs (n=44). Single hybridization per case. 44 pilocytic astrocytomas WHO grade I were analyzed. Target (tumor) labelled with Cy5 and reference with Cy3. Mixture of 20 normal male or female genomic DNA was used in sex-mismatched hybridization.
2008-04-28 | E-GEOD-11263 | biostudies-arrayexpress