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Transcription profiling of human pilocytic astrocytoma to develop molecular signatures

ABSTRACT: Pilocytic astrocytomas (PAs) are the most common glioma in children. While many PAs; are slow growing or clinically indolent, others exhibit more aggressive features with tumor; recurrence and death. In order to identify genetic signatures that might predict PA clinical; behavior, we performed gene expression profiling on 41 primary PAs arising sporadically and in; patients with neurofibromatosis type 1 (NF1). While no expression signature was found that; could discriminate clinically-aggressive or recurrent tumors from more indolent cases, PAs; arising in patients with NF1 did exhibit a unique gene expression pattern. In addition, we; identified a gene expression signature that stratified PAs by location (supratentorial versus; infratentorial). Experiment Overall Design: 41 pilocytic astrocytoma samples were analyzed.

ORGANISM(S): Homo sapiens

SUBMITTER: Sharma MK

PROVIDER: S-ECPF-GEOD-5675 | biostudies-other | 2007 Feb

REPOSITORIES: biostudies-other

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Transcription profiling of human pilocytic astrocytoma to develop molecular signatures

Project description:Pilocytic astrocytomas (PAs) are the most common glioma in children. While many PAs; are slow growing or clinically indolent, others exhibit more aggressive features with tumor; recurrence and death. In order to identify genetic signatures that might predict PA clinical; behavior, we performed gene expression profiling on 41 primary PAs arising sporadically and in; patients with neurofibromatosis type 1 (NF1). While no expression signature was found that; could discriminate clinically-aggressive or recurrent tumors from more indolent cases, PAs; arising in patients with NF1 did exhibit a unique gene expression pattern. In addition, we; identified a gene expression signature that stratified PAs by location (supratentorial versus; infratentorial). Experiment Overall Design: 41 pilocytic astrocytoma samples were analyzed.

2008-06-14 | E-GEOD-5675 | biostudies-arrayexpress

Human junior pilocytic astrocytoma

Project description:Microglia in the microenvironment of low-grade tumors have been shown to allow and support tumor growth, but the expression profile of these microglia are unknown. To examine the role of microglia in junior pilocytic astrocytomas, macrophages were flow sorted from cyroprotected surgical excisions of tumors and normal brain tissues. Upregulated markers of tumor-associated microglia were verified and compared to mouse tumor-associated microglia.

2020-07-03 | GSE65867 | GEO

Adult pilocytic astrocytoma in the molecular era: a comprehensive review.

Project description:Adult pilocytic astrocytoma (PA) is less prevalent than pediatric PA and is associated with a worse prognosis. In a literature review, we found that 88.3% of the molecular alterations in adult PA are associated with MAPK pathway dysregulation. The most common alterations are fusions of BRAF. Understanding of the mechanisms underlying this pathway has evolved substantially, heralding advancements in specific targeted therapy. Here, we review clinical and molecular features of adult PA, characteristics predicting aggressive behavior and approaches to standard and investigational therapies. We highlight epigenetic profiling and integrated diagnosis as an essential component of classifying PA.

| S-EPMC7962176 | biostudies-literature

Pilocytic astrocytoma

Project description:Pilocytic astrocytomas (PAs) are the most common glioma in children. While many PAs are slow growing or clinically indolent, others exhibit more aggressive features with tumor recurrence and death. In order to identify genetic signatures that might predict PA clinical behavior, we performed gene expression profiling on 41 primary PAs arising sporadically and in patients with neurofibromatosis type 1 (NF1). While no expression signature was found that could discriminate clinically-aggressive or recurrent tumors from more indolent cases, PAs arising in patients with NF1 did exhibit a unique gene expression pattern. In addition, we identified a gene expression signature that stratified PAs by location (supratentorial versus infratentorial). Keywords: Human, WHO grade I, Brain tumor, Pilocytic astrocytoma, NF1

2007-03-14 | GSE5675 | GEO

Molecular refinement of pilocytic astrocytoma in adult patients

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.

2024-01-01 | GSE244566 | GEO

MAPK pathway activation in pilocytic astrocytoma.

Project description:Pilocytic astrocytoma (PA) is the most common tumor of the pediatric central nervous system (CNS). A body of research over recent years has demonstrated a key role for mitogen-activated protein kinase (MAPK) pathway signaling in the development and behavior of PAs. Several mechanisms lead to activation of this pathway in PA, mostly in a mutually exclusive manner, with constitutive BRAF kinase activation subsequent to gene fusion being the most frequent. The high specificity of this fusion to PA when compared with other CNS tumors has diagnostic utility. In addition, the frequency of alteration of this key pathway provides an opportunity for molecularly targeted therapy in this tumor. Here, we review the current knowledge on mechanisms of MAPK activation in PA and some of the downstream consequences of this activation, which are now starting to be elucidated both in vitro and in vivo, as well as clinical considerations and possible future directions.

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Pilocytic astrocytoma demethylation and transcriptional landscapes link bZIP transcription factors to immune response.

Project description:BackgroundPilocytic astrocytoma (PA) is the most common pediatric brain tumor. While genome and transcriptome landscapes are well studied, data of the complete methylome, tumor cell composition, and immune infiltration are scarce.MethodsWe generated whole genome bisulfite sequence (WGBS) data of 9 PAs and 16 control samples and integrated available 154 PA and 57 control methylation array data. RNA sequence data of 49 PAs and 11 control samples as well as gene expression arrays of 248 PAs and 28 controls were used to assess transcriptional activity.ResultsDNA-methylation patterns of partially methylated domains suggested high stability of the methylomes during tumorigenesis. Comparing tumor and control tissues of infra- and supratentorial location using methylation arrays revealed a site specific pattern. Analysis of WGBS data revealed 9381 significantly differentially methylated regions (DMRs) in PA versus control tissue. Enhancers and transcription factor (TF) motifs of five distinct TF families were found to be enriched in DMRs. Methylation together with gene expression data-based in silico tissue deconvolution analysis indicated a striking variation in the immune cell infiltration in PA. A TF network analysis showed a regulatory relation between basic leucine zipper (bZIP) transcription factors and genes involved in immune-related processes.ConclusionWe provide evidence for a link of focal methylation differences and differential gene expression to immune infiltration.

| S-EPMC7523467 | biostudies-literature

The clinical and molecular characteristics of progressive hypothalamic/optic pathway pilocytic astrocytoma.

Project description:BackgroundUnresectable hypothalamic/optic pathway pilocytic astrocytoma (PA) often progresses despite multiple therapies. Identifying clinical and molecular characteristics of progressive tumors may aid in prognostication and treatment.MethodsWe collected 72 unresectable, non-neurofibromatosis type 1-associated hypothalamic/optic pathway PA to identify clinical and biologic factors associated with tumor progression. Tumors that progressed after therapy, metastasized, or resulted in death were categorized into Cohort B; those that did not meet these criteria were categorized into Cohort A. DNA methylation and transcriptome analyses were performed on treatment-naïve tumors, and the findings were validated by immunohistochemistry (IHC).ResultsThe median follow-up of the entire cohort was 12.3 years. Cohort B was associated with male sex (M:F = 2.6:1), younger age at diagnosis (median 3.2 years vs 6.7 years, P = .005), and high incidence of KIAA1549-BRAF fusion (81.5% vs 38.5%, P = .0032). Cohort B demonstrated decreased CpG methylation and increased RNA expression in mitochondrial genes and genes downstream of E2F and NKX2.3. Transcriptome analysis identified transcription factor TBX3 and protein kinase PIM1 as common downstream targets of E2F and NKX2.3. IHC confirmed increased expression of TBX3 and PIM1 in Cohort B tumors. Gene enrichment analysis identified enrichment of MYC targets and MAPK, PI3K/AKT/mTOR, and p53 pathways, as well as pathways related to mitochondrial function.ConclusionsWe identified risk factors associated with progressive PA. Our results support the model in which the p53-PIM1-MYC axis and TBX3 act alongside MAPK and PI3K/AKT/mTOR pathways to promote tumor progression, highlighting potential new targets for combination therapy and refining disease prognostication.

| S-EPMC10076943 | biostudies-literature

The age of adult pilocytic astrocytoma cells.

Project description:Adult pilocytic astrocytomas (PAs) have been regarded as indistinguishable from pediatric PAs in terms of genome-wide expression and methylation patterns. It has been unclear whether adult PAs arise early in life and remain asymptomatic until adulthood, or whether they develop during adulthood. We sought to determine the age and origin of adult human PAs using two types of "marks" in the genomic DNA. First, we analyzed the DNA methylation patterns of adult and pediatric PAs to distinguish between PAs of different anatomic locations (n = 257 PA and control brain tissues). Second, we measured the concentration of nuclear bomb test-derived 14C in genomic DNA (n = 14 cases), which indicates the time point of the formation of human cell populations. Our data suggest that adult and pediatric PAs developing in the infratentorial brain are closely related and potentially develop from precursor cells early in life, whereas supratentorial PAs might show age and location-specific differences.

| S-EPMC8062266 | biostudies-literature

MicroRNA profiling in pediatric pilocytic astrocytoma reveals biologically relevant targets, including PBX3, NFIB, and METAP2.

Project description:Pilocytic astrocytoma (PA) is a World Health Organization grade I glioma that occurs most commonly in children and young adults. Specific genetic alterations have been described in PA, but the pathogenesis remains poorly understood. We studied microRNA (miRNA) alterations in a large cohort of patients with PA. A total of 43 PA, including 35 sporadic grade I PA, 4 neurofibromatosis-1 (NF1)-associated PA, and 4 PA with pilomyxoid features, as well as 5 nonneoplastic brain controls were examined. BRAF fusion status was assessed in most cases. RNA was examined using the Agilent Human miRNA Microarray V3 platform. Expression of miRNA subsets was validated using quantitative real-time PCR (qRT-PCR) with Taqman probes. Validation of predicted protein targets was performed on tissue microarrays with the use of immunohistochemistry. We identified a subset of miRNAs that were differentially expressed in pediatric PAs versus normal brain tissue: 13 miRNAs were underexpressed, and 20 miRNAs were overexpressed in tumors. Differences were validated by qRT-PCR in a subset, with mean fold change in tumor versus brain of -17 (miR-124), -15 (miR-129), and 19.8 (miR-21). Searching for predicted protein targets in Targetscan, we identified a number of known and putative oncogenes that were predicted targets of miRNA sets relatively underexpressed in PA. Predicted targets with increased expression at the mRNA and/or protein level in PA included PBX3, METAP2, and NFIB. A unique miRNA profile exists in PA, compared with brain tissue. These miRNAs and their targets may play a role in the pathogenesis of PA.

| S-EPMC3534421 | biostudies-literature

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