Project description:Genome wide DNA methylation profiling of 79 histologically diagnosed pilocytic astrocytoma (PA) in adults, of which we were able to upload 71 samples. The methylation profiling indicates that many of the histologically diagnosed PA do not show a concordant methylation classification.
Project description:Pilocytic astrocytomas (PA) are the most common brain tumor in pediatric patients and can cause significant morbidity, including chronic neurological deficiencies. They are characterized by activating alterations in the mitogen-activated protein kinase (MAPK) pathway, but little else is known about their development. To further define their molecular development, we analysed the global DNA methylation profiles of 61 PAs and 6 normal cerebellum samples and integrated this data with transcriptome profiling. These data revealed two subgroups of PA that separate according to tumor location (infratentorial versus supratentorial), and identified key neural developmental genes that are differentially methylated between the two groups. Significant expression differences were identified for the majority of differentially methylated genes, and these were unexpectedly associated with a strong positive correlation between methylation and expression. We also identified a large number of differentially methylated/expressed genes between cerebellar PAs and normal cerebellum, which included additional developmental genes. Total RNA from 49 PA tumour samples and 9 normal cerebellum samples (from commercial sources) were hybridised to the Affymetrix HG U133 Plus 2.0 microarrays.
Project description:Pilocytic astrocytomas (PA) are the most common brain tumor in pediatric patients and can cause significant morbidity, including chronic neurological deficiencies. They are characterized by activating alterations in the mitogen-activated protein kinase (MAPK) pathway, but little else is known about their development. To further define their molecular development, we analysed the global DNA methylation profiles of 61 PAs and 6 normal cerebellum samples and integrated this data with transcriptome profiling. These data revealed two subgroups of PA that separate according to tumor location (infratentorial versus supratentorial), and identified key neural developmental genes that are differentially methylated between the two groups. Significant expression differences were identified for the majority of differentially methylated genes, and these were unexpectedly associated with a strong positive correlation between methylation and expression. We also identified a large number of differentially methylated/expressed genes between cerebellar PAs and normal cerebellum, which included additional developmental genes.
Project description:Pilocytic astrocytomas (PA) are the most common brain tumor in pediatric patients and can cause significant morbidity, including chronic neurological deficiencies. They are characterized by activating alterations in the mitogen-activated protein kinase (MAPK) pathway, but little else is known about their development. To map the global DNA methylation profiles of these tumors, we analysed 61 PAs and 6 normal cerebellum samples using Illumina's Infinium HumanMethylation450 BeadChips. These data revealed two subgroups of PA that separate according to tumor location (infratentorial versus supratentorial), and identified key neural developmental genes that are differentially methylated between the two groups. Integration with transcriptome microarray data highlighted significant expression differences, which were unexpectedly associated with a strong positive correlation between methylation and expression. Differentially methylated probes were often identified within the gene body and/or regions up- or downstream of the gene, rather than at the transcription start site. We also identified a large number of differentially methylated genes between cerebellar PAs and normal cerebellum, which included additional developmental genes. Bisulphite converted DNA from 61 PA tumours (fresh frozen) and 6 normal cerebellum (from commerical sources) were hybridised to the Illumina Infinium HumanMethylation450 BeadChips.
Project description:Pilocytic astrocytomas (PA) are the most common brain tumor in pediatric patients and can cause significant morbidity, including chronic neurological deficiencies. They are characterized by activating alterations in the mitogen-activated protein kinase (MAPK) pathway, but little else is known about their development. To map the global DNA methylation profiles of these tumors, we analysed 61 PAs and 6 normal cerebellum samples using Illumina's Infinium HumanMethylation450 BeadChips. These data revealed two subgroups of PA that separate according to tumor location (infratentorial versus supratentorial), and identified key neural developmental genes that are differentially methylated between the two groups. Integration with transcriptome microarray data highlighted significant expression differences, which were unexpectedly associated with a strong positive correlation between methylation and expression. Differentially methylated probes were often identified within the gene body and/or regions up- or downstream of the gene, rather than at the transcription start site. We also identified a large number of differentially methylated genes between cerebellar PAs and normal cerebellum, which included additional developmental genes.
Project description:Genome-wide DNA methylation profiling of 30 low-grade neuroepithelial tumors with FGFR1 alterations including rosette-forming glioneuronal tumor, pilocytic astrocytoma, dysembryoplastic neuroepithelial tumor, and extraventricular neurocytoma. The Illumina Infinium EPIC 850k Human DNA Methylation Beadchip was used to obtain DNA methylation profiles across approximately 850,000 CpG sites of genomic DNA extracted from formalin-fixed, paraffin-embedded tumor tissue of 30 low-grade neuroepithelial tumors with FGFR1 alterations including kinase domain tandem duplication, in-frame fusion with TACC1, and hotspot missense mutation within the intracellular tyrosine kinase domain.
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.
Project description:<p>Neurofibromatosis type 1 (NF1) inherited cancer predisposition syndrome is one of the most common autosomal dominant tumor predisposition syndromes in which affected individuals develop brain tumors. These low-grade glial neoplasms (pilocytic astrocytomas) typically arise in children younger than 7 years of age and are hypothesized to result from a combination of germline and acquired somatic NF1 tumor suppressor gene mutations. In this study, whole genome sequence analysis was performed on three NF1-associated pilocytic astrocytoma tumors (NF1-PA) and matched normal blood samples to establish the genomic landscape of NF1-PA. These data support the existence of multiple distinct mechanisms (mutation, LOH, and methylation) underlying somatic NF1 inactivation in NF1-PA tumors.</p>