Project description:Diffuse midline gliomas (DMGs), including diffuse intrinsic pontine gliomas (DIPGs), bearing lysine-to-methionine mutations in histone H3 at lysine 27 (H3K27M) are lethal childhood brain cancers. These tumors harbor a global reduction in the transcriptional repressive mark H3K27me3 accompanied by an increase in the transcriptional activation mark H3K27ac. We postulated that H3K27M mutations, in addition to altering H3K27 modifications, reprogram the master chromatin remodeling SWI/SNF complex. The SWI/SNF complex can exist in two main forms termed BAF and PBAF that play central roles in neurodevelopment and cancer. Moreover, BAF antagonizes PRC2, the main enzyme catalyzing H3K27me3. We demonstrate that H3K27M gliomas show increased protein levels of the SWI/SNF complex ATPase subunits SMARCA4 and SMARCA2 and the PBAF component PBRM1. Additionally, knockdown of mutant H3K27M lowered SMARCA4 protein levels. The proteolysis targeting chimera (PROTAC) AU-15330 that simultaneously targets SMARCA4, SMARCA2, and PBRM1 for degradation exhibits cytotoxicity in H3.3K27M but not H3 wild-type cells. AU-15330 lowered chromatin accessibility measured by ATAC-seq at non-promoter regions and reduced global H3K27ac levels. Integrated analysis of gene expression, proteomics, and chromatin accessibility in AU-15330-treated cells demonstrated reduction in levels of FOXO1, a key member of the forkhead family of transcription factors. Moreover, genetic or pharmacologic targeting of FOXO1 resulted in cell death in H3K27M cells. Overall, our results suggest that H3K27M upregulates SMARCA4 levels and combined targeting of SWI/SNF ATPases in H3.3K27M can serve as a potent therapeutic strategy for these deadly childhood brain tumors.
Project description:Diffuse midline gliomas (DMGs), including diffuse intrinsic pontine gliomas (DIPGs), bearing lysine-to-methionine mutations in histone H3 at lysine 27 (H3K27M) are lethal childhood brain cancers. These tumors harbor a global reduction in the transcriptional repressive mark H3K27me3 accompanied by an increase in the transcriptional activation mark H3K27ac. We postulated that H3K27M mutations, in addition to altering H3K27 modifications, reprogram the master chromatin remodeling SWI/SNF complex. The SWI/SNF complex can exist in two main forms termed BAF and PBAF that play central roles in neurodevelopment and cancer. Moreover, BAF antagonizes PRC2, the main enzyme catalyzing H3K27me3. We demonstrate that H3K27M gliomas show increased protein levels of the SWI/SNF complex ATPase subunits SMARCA4 and SMARCA2 and the PBAF component PBRM1. Additionally, knockdown of mutant H3K27M lowered SMARCA4 protein levels. The proteolysis targeting chimera (PROTAC) AU-15330 that simultaneously targets SMARCA4, SMARCA2, and PBRM1 for degradation exhibits cytotoxicity in H3.3K27M but not H3 wild-type cells. AU-15330 lowered chromatin accessibility measured by ATAC-seq at non-promoter regions and reduced global H3K27ac levels. Integrated analysis of gene expression, proteomics, and chromatin accessibility in AU-15330-treated cells demonstrated reduction in levels of FOXO1, a key member of the forkhead family of transcription factors. Moreover, genetic or pharmacologic targeting of FOXO1 resulted in cell death in H3K27M cells. Overall, our results suggest that H3K27M upregulates SMARCA4 levels and combined targeting of SWI/SNF ATPases in H3.3K27M can serve as a potent therapeutic strategy for these deadly childhood brain tumors.
Project description:Purpose: More than 90% of children with diffuse intrinsic pontine glioma (DIPG) die within 2 years of diagnosis. There is a dire need to identify therapeutic targets, however lack of patient material for research has limited progress. We evaluated a large cohort of diffuse intrinsic pontine gliomas (DIPGs) to identify recurrent genomic abnormalities and gene expression signatures underlying DIPG. Patients and Methods: We used single nucleotide polymorphism arrays to evaluate genomic copy number imbalances in 43 DIPGs from 40 patients and in 8 low-grade exophytic brainstem gliomas. Gene expression arrays were used to evaluate expression signatures from 27 DIPGs, 6 low-grade exophytic brainstem gliomas and 66 low-grade gliomas arising outside the brainstem. Results: Frequencies of specific large-scale and focal imbalances varied significantly between DIPGs and pediatric glioblastomas outside the brainstem. Focal amplifications of genes within the receptor tyrosine kinase-Ras-PI3-kinase signaling pathway were found in 47% of DIPG, with PDGFRA and MET showing the highest frequency. 30% of DIPG contained focal amplifications of cell-cycle regulatory genes controlling RB phosphorylation, and 21% had concurrent amplification of genes from both pathways. Some tumors showed heterogeneity in amplification patterns. DIPGs showed distinct gene expression signatures relating to developmental processes compared to pediatric glioblastomas arising outside the brainstem, while expression signatures of low-grade exophytic brainstem gliomas were similar to low-grade gliomas outside the brainstem. Copy number analaysis: 43 DIPG samples, 8 Low Grade Gliomas using SNP6.0. Available matched normals are also profiled with SNP6.0. Expression analysis: 29 DIPG samples, 6 Low grade samples Please contact Suzanne Baker at Suzanne.Baker@stjude.org for CEL files and genotype calls.
Project description:We have used Illumina Infinium HumanMethylation450 BeadChip array profiling to profile paediatric high grade gliomas and diffuse intrinsic pontine gliomas. The 450K methylation array is being used to separate brain tumour samples on the basis of their methylation profiles which represent the cell of origin the time and place in which tumours arise. Methylation arrays provide data for an integrated molecular diagnosis of brain tumours and define specific molecular subgroups and subtypes of high grade gliomas carrying distinct driver mutations and patterns of somatic alterations. These data form part of an integrated meta-analysis of high grade gliomas in children combining DNA copy number, methylation and high throughput sequencing datasets.
Project description:Purpose: More than 90% of children with diffuse intrinsic pontine glioma (DIPG) die within 2 years of diagnosis. There is a dire need to identify therapeutic targets, however lack of patient material for research has limited progress. We evaluated a large cohort of diffuse intrinsic pontine gliomas (DIPGs) to identify recurrent genomic abnormalities and gene expression signatures underlying DIPG. Patients and Methods: We used single nucleotide polymorphism arrays to evaluate genomic copy number imbalances in 43 DIPGs from 40 patients and in 8 low-grade exophytic brainstem gliomas. Gene expression arrays were used to evaluate expression signatures from 27 DIPGs, 6 low-grade exophytic brainstem gliomas and 66 low-grade gliomas arising outside the brainstem. Results: Frequencies of specific large-scale and focal imbalances varied significantly between DIPGs and pediatric glioblastomas outside the brainstem. Focal amplifications of genes within the receptor tyrosine kinase-Ras-PI3-kinase signaling pathway were found in 47% of DIPG, with PDGFRA and MET showing the highest frequency. 30% of DIPG contained focal amplifications of cell-cycle regulatory genes controlling RB phosphorylation, and 21% had concurrent amplification of genes from both pathways. Some tumors showed heterogeneity in amplification patterns. DIPGs showed distinct gene expression signatures relating to developmental processes compared to pediatric glioblastomas arising outside the brainstem, while expression signatures of low-grade exophytic brainstem gliomas were similar to low-grade gliomas outside the brainstem.
Project description:This phase I trial studies the side effects and best dose of pembrolizumab and to see how well it works in treating younger patients with high-grade gliomas (brain tumors that are generally expected to be fast growing and aggressive), diffuse intrinsic pontine gliomas (brain stem tumors), brain tumors with a high number of genetic mutations, ependymoma or medulloblastoma that have come back (recurrent), progressed, or have not responded to previous treatment (refractory). Immunotherapy with monoclonal antibodies, such as pembrolizumab, may induce changes in the body’s immune system, and may interfere with the ability of tumor cells to grow and spread.
Project description:Diffuse midline glioma (DMG) identifies gliomas originating in the thalami, brainstem, cerebellum and spine. Within this entity, tumours that infiltrate the pons, called diffuse intrinsic pontine gliomas (DIPGs), have a rapid onset and devastating neurological symptoms. Radiotherapy is the only intervention that is able to modify the disease course, albeit not in a curative way. In recent years, liquid biopsies have represented the next step in clinical diagnostics due to their easily accessible nature. The purpose of this study is to profile circulating miRNA expression to disclose a potential prognostic signature with clinical impact.