Insulator dysfunction and oncogene activation in IDH mutant gliomas
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE70991 | GEO | 2015/12/23
SECONDARY ACCESSION(S): PRJNA290069
REPOSITORIES: GEO
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Project description:Gain-of-function IDH mutations define major clinical and prognostic classes of gliomas. Mutant IDH protein produces a novel onco-metabolite, 2-hydroxyglutarate (2-HG), that interferes with iron-dependent hydroxylase enzymes, including the TET family of 5'-methylcytosine hydroxylases. TET enzymes are critical for the dynamic regulation of DNA methylation. IDH mutant gliomas thus manifest a CpG island methylator phenotype (G-CIMP), though the functional significance of this altered epigenetic state remains unclear. Here we show that IDH1 mutant gliomas exhibit hyper-methylation at CTCF binding sites, leading to reduced binding of this methylation-sensitive insulator protein. Loss of CTCF binding is associated with a loss of insulation between topological domains and aberrant gene activation. We specifically demonstrate that loss of CTCF at a domain boundary permits a constitutive enhancer to aberrantly interact with the receptor tyrosine kinase gene PDGFRA, a prominent glioma oncogene. Treatment of IDH mutant gliomaspheres with demethylating agent partially restores insulator function and reduces PDGFRA expression. Conversely, CRISPR-mediated disruption of the CTCF binding sequence in IDH wildtype gliomaspheres induces PDGFRA expression and increases proliferation. Our study suggests that IDH mutations promote gliomagenesis by disrupting chromosomal topology and allowing aberrant regulatory interactions that induce oncogene expression. CTCF occupancy characterization and histone H3K27 acetylation profiling in IDH1 mutant and wild-type glioma patient specimens and culture models. ChIP-seq raw data is to be made available through dbGaP (controlled access) due to patient privacy concerns.
2015-12-23 | E-GEOD-70991 | biostudies-arrayexpress
Project description:<p>Metabolic lesions with pleiotropic effects on epigenetic regulation and other cellular processes are widely implicated in cancer, yet their oncogenic mechanisms remain poorly understood. Succinate dehydrogenase (SDH) deficiency causes a subset of gastrointestinal stromal tumors (GISTs) with DNA hyper-methylation. Here we associate this hyper-methylation with changes in chromosome topology that activate oncogenic programs. To investigate epigenetic alterations in this disease, we systematically mapped DNA methylation, CTCF insulators, enhancers and chromosome topology in KIT-mutant, PDGFRA-mutant and SDH-deficient GISTs. Although these respective subtypes share similar enhancer landscapes, we identified hundreds of putative insulators where DNA methylation replaced CTCF binding in SDH-deficient GISTs. We focused on disrupted insulators that partitions super-enhancers from FGF3, FGF4 and the KIT oncogene. Recurrent loss of this insulator alters locus topology in SDH-deficient GISTs, allowing aberrant physical interaction between enhancers and oncogenes. CRISPR-mediated excision of the corresponding CTCF motif in an SDH-intact model disrupted the boundary and up-regulated FGFs and KIT expression. Our findings reveal how a metabolic lesion destabilizes chromatin structure to facilitate the initiation and selection of epigenetic alterations that drive oncogenic programs in the absence of canonical mutations.</p>
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Project description:Epigenetic lesions that disrupt gene regulatory elements and expression are increasingly recognized as pervasive drivers of human cancers. However, we currently lack the in vitro and in vivo models required to functionally validate such lesions and their tumorigenic impact. Here we model aberrations that arise in Isocitrate Dehydrogenase mutant (IDHmut) lower-grade gliomas, which exhibit profound DNA hypermethylation. We initially focus on a CTCF insulator downstream of the PDGFRA oncogene that is recurrently disrupted in IDHmut gliomas. We demonstrate that disruption of the syntenic insulator in mouse oligodendrocyte-progenitor cells (OPCs) allows an OPC-specific enhancer to contact and induce PDGFRA, thereby increasing proliferation. In contrast, insulator disruption did not affect PDGFRA expression in neural progenitor cells (NPCs), which lack the enhancer. We also model a second recurrent epigenetic lesion in IDHmut gliomas, the methylation-dependent silencing of the CDKN2A tumor suppressor. We show that inactivation of CDKN2A/p19ARF by de novo promoter methylation or mutation drives OPC proliferation and synergizes with PDGFRA insulator loss. Finally, we use lentiviruses to coordinately inactivate the PDGFRA insulator and CDKN2A in mouse corpus callosum, resulting in low-grade gliomagenesis in vivo. Our study recapitulates recurrent epigenetic lesions in mouse models and demonstrates that combination of PDGFRA activation and CDKN2A silencing can transform OPCs in vitro and drive gliomagenesis in vivo.
2023-07-25 | GSE225793 | GEO
Project description:Epigenetic lesions that disrupt gene regulatory elements and expression are increasingly recognized as pervasive drivers of human cancers. However, we currently lack the in vitro and in vivo models required to functionally validate such lesions and their tumorigenic impact. Here we model aberrations that arise in Isocitrate Dehydrogenase mutant (IDHmut) lower-grade gliomas, which exhibit profound DNA hypermethylation. We initially focus on a CTCF insulator downstream of the PDGFRA oncogene that is recurrently disrupted in IDHmut gliomas. We demonstrate that disruption of the syntenic insulator in mouse oligodendrocyte-progenitor cells (OPCs) allows an OPC-specific enhancer to contact and induce PDGFRA, thereby increasing proliferation. In contrast, insulator disruption did not affect PDGFRA expression in neural progenitor cells (NPCs), which lack the enhancer. We also model a second recurrent epigenetic lesion in IDHmut gliomas, the methylation-dependent silencing of the CDKN2A tumor suppressor. We show that inactivation of CDKN2A/p19ARF by de novo promoter methylation or mutation drives OPC proliferation and synergizes with PDGFRA insulator loss. Finally, we use lentiviruses to coordinately inactivate the PDGFRA insulator and CDKN2A in mouse corpus callosum, resulting in low-grade gliomagenesis in vivo. Our study recapitulates recurrent epigenetic lesions in mouse models and demonstrates that combination of PDGFRA activation and CDKN2A silencing can transform OPCs in vitro and drive gliomagenesis in vivo.
2023-07-25 | GSE225732 | GEO
Project description:Gliomas are immunologically cold tumors that can be broken into several categories based on either RNA expression profiles or methylation profiles, with isocitrate dehydrogenase (IDH) mutations defining a major segregration between types. IDH mutant gliomas often exhibit defects in the retinoic acid pathway. We treated mice harboring IDH mutant gliomas with all-trans retinoic acid, and found that this treatment cause reductions in tumor growth and a swith in immune profiles in the tumor microenvironment.
2024-04-19 | GSE172387 | GEO
Project description:Diffuse gliomas represent the most prevalent class of primary brain tumor. Despite significant recent advances in the understanding of glioblastoma (WHO IV), its most malignant subtype, lower-grade (WHO II and III) glioma variants remain comparatively understudied, especially in light of their notably variable clinical behavior. To examine the foundations of this heterogeneity, we performed multidimensional molecular profiling, including global transcriptional analysis, on 101 lower-grade diffuse astrocytic gliomas collected at our own institution, and validated our findings using publically available gene expression and copy number data from large independent patient cohorts. We found that IDH mutational status delineated molecularly and clinically distinct glioma subsets, with IDH mutant (IDH mt) tumors exhibiting TP53 mutations, PDGFRA overexpression, and prolonged survival, and IDH wild-type (IDH wt) tumors exhibiting EGFR amplification, PTEN loss, and unfavorable disease outcome. Furthermore, global expression profiling revealed three robust molecular subclasses within lower-grade diffuse astrocytic gliomas, two of which were predominantly IDH mt and one almost entirely IDH wt. IDH mt subclasses were distinguished from each other on the basis of TP53 mutations, DNA copy number abnormalities, and links to distinct stages of neurogenesis in the subventricular zone (SVZ). This latter finding implicates discrete pools of neuroglial progenitors as cells of origin for the different subclasses of IDH mt tumors. In summary, we have elucidated molecularly distinct subclasses of lower-grade diffuse astrocytic glioma that dictate clinical behavior and demonstrate fundamental associations with both IDH mutational status and neuroglial developmental stage. 80 tumor samples, one normal tissue sample (brain)
2012-02-24 | E-GEOD-35158 | biostudies-arrayexpress
Project description:Epigenetic aberrations are widespread in cancer, yet the underlying mechanisms and causality remain poorly understood. A subset of gastrointestinal stromal tumors (GISTs) lack canonical kinase mutations but instead have succinate dehydrogenase (SDH)-deficiency and global DNA hyper-methylation. Here we associate this hyper-methylation with changes in genome topology that activate oncogenic programs. To investigate epigenetic alterations systematically, we mapped DNA methylation, CTCF insulators, enhancers, and chromosome topology in KIT-mutant, PDGFRA-mutant, and SDH-deficient GISTs. Although these respective subtypes shared similar enhancer landscapes, we identified hundreds of putative insulators where DNA methylation replaced CTCF binding in SDH-deficient GISTs. We focused on a disrupted insulator that normally partitions a core GIST super-enhancer from the FGF4 oncogene. Recurrent loss of this insulator alters locus topology in SDH-deficient GISTs, allowing aberrant physical interaction between enhancer and oncogene. CRISPR-mediated excision of the corresponding CTCF motifs in an SDH-intact GIST model disrupted the boundary and strongly up-regulated FGF4 expression. We also identified a second recurrent insulator loss event near the KIT oncogene, which is also highly expressed across SDH-deficient GISTs. Finally, we established a patient-derived xenograft (PDX) from an SDH-deficient GIST that faithfully maintains the epigenetic state of the parental tumor, including hyper-methylation and insulator defects. This PDX model is highly sensitive to FGF receptor (FGFR) inhibitor, and more so to combined FGFR and KIT inhibition, validating the functional significance of the underlying epigenetic lesions. Our study reveals how epigenetic alterations can drive oncogenic programs in the absence of canonical kinase mutations, with implications for mechanistic targeting of aberrant pathways in cancers.
2019-10-16 | GSE107447 | GEO
Project description:Recent single-cell transcriptomic studies report that IDH-mutant gliomas share a common hierarchy of cellular phenotypes, independent of genetic subtype. However, the genetic differences between IDH-mutant glioma subtypes are prognostic, predictive of response to chemotherapy, and correlate with distinct tumor microenvironments. To reconcile these findings, we profiled 22 human IDH-mutant gliomas via single-cell assay for transposase-accessible chromatin (scATAC-seq). We determined the cell-type specific differences in transcription-factor expression and associated regulatory grammars between IDH-mutant glioma subtypes. We find that while IDH-mutant gliomas do share a common distribution of cell types, there are significant differences in the expression and targeting of transcription factors that regulate glial identity and cytokine elaboration. We knocked out the chromatin-remodeler ATRX, which suffers loss-of-function alterations in most IDH-mutant astrocytomas, in an IDH-mutant immunocompetent intracranial murine model. We find that both human ATRX-mutant gliomas and murine ATRX-knockout gliomas are more heavily infiltrated by immunosuppressive monocytic-lineage cells derived from circulation than ATRX-intact gliomas, in an IDH-mutant background. ATRX knockout in murine glioma recapitulates gene expression and open-chromatin signatures that are specific to human ATRX-mutant astrocytomas, including drivers of astrocytic lineage and immune-cell chemotaxis. ATRX knockout in murine glioma recapitulates gene expression and open chromatin signatures that are specific to human ATRX-mutant astrocytomas, including drivers of astrocytic lineage and immune-cell chemotaxis. Through single-cell cleavage under targets and tagmentation assays and meta-analysis of public data, we show that ATRX loss leads to a global depletion in CCCTC-binding factor association with DNA, gene dysregulation along associated chromatin loops, and protection from therapy-induced senescence.
2021-10-20 | GSE155430 | GEO
Project description:Catalytic activity of the ISWI family of remodelers is critical for nucleosomal organization and transcription factor binding, including the insulator protein CTCF. To define which subcomplex mediates these diverse functions we phenotyped a panel of isogenic mouse stem cell lines each lacking one of six ISWI accessory subunits. Individual deletions of either CERF, RSF1, ACF, WICH or NoRC subcomplexes only moderately affect the chromatin landscape, while removal of the NURF-specific subunit BPTF leads to drastic reduction in chromatin accessibility and Snf2h ATPase localization around CTCF sites. While this reduces distances to the adjacent nucleosomes it only modestly impacts CTCF binding itself. In absence of accessibility, the insulator function of CTCF is nevertheless impaired resulting in lower occupancy of cohesin and cohesin-loading factors, and reduced insulation at these sites, highlighting the need of NURF-mediated remodeling for open chromatin and proper CTCF function. Our comprehensive analysis reveals a specific role for NURF in mediating Snf2h localization and chromatin opening at bound CTCF sites showing that local accessibility is critical for cohesin binding and insulator function.
2024-03-13 | PXD042945 | Pride
Project description:Diffuse gliomas represent the most prevalent class of primary brain tumor. Despite significant recent advances in the understanding of glioblastoma (WHO IV), its most malignant subtype, lower-grade (WHO II and III) glioma variants remain comparatively understudied, especially in light of their notably variable clinical behavior. To examine the foundations of this heterogeneity, we performed multidimensional molecular profiling, including global transcriptional analysis, on 101 lower-grade diffuse astrocytic gliomas collected at our own institution, and validated our findings using publically available gene expression and copy number data from large independent patient cohorts. We found that IDH mutational status delineated molecularly and clinically distinct glioma subsets, with IDH mutant (IDH mt) tumors exhibiting TP53 mutations, PDGFRA overexpression, and prolonged survival, and IDH wild-type (IDH wt) tumors exhibiting EGFR amplification, PTEN loss, and unfavorable disease outcome. Furthermore, global expression profiling revealed three robust molecular subclasses within lower-grade diffuse astrocytic gliomas, two of which were predominantly IDH mt and one almost entirely IDH wt. IDH mt subclasses were distinguished from each other on the basis of TP53 mutations, DNA copy number abnormalities, and links to distinct stages of neurogenesis in the subventricular zone (SVZ). This latter finding implicates discrete pools of neuroglial progenitors as cells of origin for the different subclasses of IDH mt tumors. In summary, we have elucidated molecularly distinct subclasses of lower-grade diffuse astrocytic glioma that dictate clinical behavior and demonstrate fundamental associations with both IDH mutational status and neuroglial developmental stage.
2012-02-24 | GSE35158 | GEO