Characterization of aberrant splicing reveals CLK1 as a candidate oncogenic dependency in pediatric high-grade gliomas
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE273841 | GEO | 2024/08/20
REPOSITORIES: GEO
Similar Datasets
Project description:The outcome for children with high-grade gliomas (HGG) remains dismal, with a two-year survival rate of only 10-30%. Approximately half of pediatric HGGs are diffuse intrinsic pontine glioma (DIPG), a brainstem tumor that arises almost exclusively in children. Genome-wide analyses of copy number imbalances previously showed that platelet derived growth factor receptor alpha (PDGFRA) is the most frequent target of focal amplification in pediatric HGGs. To determine whether the PDGFRA is also targeted by more subtle mutations not detected by copy number analysis, we sequenced all PDGFRA coding exons from a cohort of pediatric HGGs. Somatic activating mutations were identified in 14.4% (13/90) of non-brainstem pediatric HGGs and 4.7% (2/43) of DIPGs, including missense mutations and in-frame deletions and insertions not previously described. 40% of tumors with mutation showed concurrent amplification, while 60% carried heterozygous mutations. Six different mutations impacting different domains all resulted in ligand-independent receptor activation that was blocked by small molecule inhibitors of PDGFR. Expression of mutants in p53-null primary mouse astrocytes conferred a proliferative advantage in vitro, and generated HGGs in vivo with complete penetrance when implanted into brain. The gene expression signatures reflected the spectrum of human diffuse HGGs. PDGFRA intragenic deletion of exons 8 and 9 were previously shown in adult HGG, but were not detected in 83 non-brainstem pediatric HGG and 57 DIPGs. Thus, a distinct spectrum of mutations confers constitutive receptor activation and oncogenic activity to PDGFR in childhood HGG. To better understand the consequence of PDGFRα mutation in pediatric gliomagenesis, retroviral constructs expressing wild-type PDGFRα or six selected PDGFRα mutants that affect different regions of the receptor were generated for functional studies. p53-null primary mouse astrocyte (PMA) cultures were chosen as a relevant cellular background to assess PDGFRα function.
2013-11-06 | E-GEOD-46190 | biostudies-arrayexpress
Project description:The outcome for children with high-grade gliomas (HGG) remains dismal, with a two-year survival rate of only 10-30%. Approximately half of pediatric HGGs are diffuse intrinsic pontine glioma (DIPG), a brainstem tumor that arises almost exclusively in children. Genome-wide analyses of copy number imbalances previously showed that platelet derived growth factor receptor alpha (PDGFRA) is the most frequent target of focal amplification in pediatric HGGs. To determine whether the PDGFRA is also targeted by more subtle mutations not detected by copy number analysis, we sequenced all PDGFRA coding exons from a cohort of pediatric HGGs. Somatic activating mutations were identified in 14.4% (13/90) of non-brainstem pediatric HGGs and 4.7% (2/43) of DIPGs, including missense mutations and in-frame deletions and insertions not previously described. 40% of tumors with mutation showed concurrent amplification, while 60% carried heterozygous mutations. Six different mutations impacting different domains all resulted in ligand-independent receptor activation that was blocked by small molecule inhibitors of PDGFR. Expression of mutants in p53-null primary mouse astrocytes conferred a proliferative advantage in vitro, and generated HGGs in vivo with complete penetrance when implanted into brain. The gene expression signatures reflected the spectrum of human diffuse HGGs. PDGFRA intragenic deletion of exons 8 and 9 were previously shown in adult HGG, but were not detected in 83 non-brainstem pediatric HGG and 57 DIPGs. Thus, a distinct spectrum of mutations confers constitutive receptor activation and oncogenic activity to PDGFR in childhood HGG.
2013-11-06 | GSE46190 | GEO
Project description:Immune cell infiltration is a common feature of solid cancers, where T cells typically function as cytotoxic effectors to limit tumor growth, prompting therapies that activate this antineoplastic property (immune checkpoint inhibition; ICI). Unfortunately, ICI treatments have been largely ineffective for high-grade brain tumors (gliomas; HGGs). Leveraging several single-cell RNA sequencing datasets, we report greater CD8+ exhausted T cells in human pediatric low-grade gliomas (LGGs) relative to adult and pediatric HGGs. Using several preclinical mouse LGG models (Nf1-OPG mice), we showed that these PD1+/TIGIT+ CD8+ terminally exhausted T cells are restricted to the tumor tissue, where they express paracrine factors necessary for OPG growth. Importantly, ICI treatments with anti-PD1 and anti-TIGIT antibodies attenuate Nf1-OPG tumor proliferation through suppression of cytokine-mediated immune axis support, rather than by T cell-mediated cytotoxicity. Collectively, these findings establish a previously unrecognized function for CD8+ exhausted T cells as specialized regulators of LGG maintenance.
2024-10-23 | GSE244433 | GEO
Project description:Splicing alterations are very common in cancer and might affect disease initiation and progression. In several cancers, mutations in splicing factor genes are responsible for aberrant splicing. We show that certain aggressive cancers, such as pediatric T-cell acute lymphoblastic leukemia (T-ALL), have an alternative mechanism for aberrant splicing that involves post-translational regulation of the splicing machinery via deubiquitination. We initially demonstrated that T-ALL presents with extensive exon skipping events affecting proteasomal transcripts, cell cycle and epigenetic regulators. Performing an unbiased genetic screen study for RNA binding proteins, we showed that the serine/arginine-rich splicing factor (SRSF) proteins, controlling exon skipping are critical for T-ALL survival. In our effort to dissect mechanisms of aberrant regulation of SRSF proteins, we focused on the pro-oncogenic deubiquitinase ubiquitin-specific peptidase 7 (USP7) to show it regulates the levels of the SRSF proteins at the post-translational level via active deubiquitination. We further demonstrated that USP7 inhibitors can change the splicing landscape and block T-ALL growth. Our drug studies show that decrease of the levels of SRSF proteins splicing inhibitors sensitize cells to the clinically used splicing inhibitor H3B-8800. Driven by our molecular findings on aberrant splicing of proteasomal transcripts, we demonstrate that H3B-8800 could act synergistically with proteasome inhibitors, paving the way for new therapeutic schemes in pediatric leukemia. Collectively this study provides the proof-of-principle for regulation of splicing factors independently of mutations and via deubiquitination and suggests new therapeutic modalities and combinations in cancer.
| MSV000084383 | MassIVE
Project description:Background:Breast cancer is the second most frequent type of cancer affecting women. We are increasingly aware that changes in mRNA splicing are associated with various characteristics of cancer. The most deadly aspect of cancer is metastasis, the process by which cancer spreads from the primary tumor to distant organs. However, little is known specifically about the involvement of alternative splicing in the formation of macroscopic metastases. Our study investigates transcript isoform changes that characterize tumors of different abilities to form growing metastases. Results:To identify alternative splicing events (ASEs) that are associated with the fully metastatic phenotype in breast cancer, we used Affymetrix Exon Microarrays to profile mRNA isoform variations genome-wide in weakly metastatic (168FARN and 4T07) and highly metastatic (4T1) mammary carcinomas. Statistical analysis identified significant expression changes in 7606 out of 155,994 (4%) exons and in 1725 out of 189,460 (1%) intronic regions, which affect 2623 out of 16,654 (16%) genes. These changes correspond to putative alternative isoforms - several of which are novel - that are differentially expressed between tumors of varying metastatic phenotypes. Gene pathway analysis showed that 1224 of genes expressing alternative isoforms were involved in cell growth, cell interactions, cell proliferation, cell migration and cell death and have been previously linked to cancers and genetic disorders. We chose ten predicted splice variants for RT-PCR validation, eight of which were successfully confirmed (MED24, MFI2, SRRT, CD44, CLK1 and HNRNPH1). These include three novel intron retentions in CD44, a gene in which isoform variations have been previously associated with the metastasis of several cancers. Conclusions:Our findings reveal that various genes are differently spliced and/or expressed in association with the metastatic phenotype of tumor cells. Identification of metastasis-specific isoforms may contribute to the development of improved breast cancer stage identification and targeted therapies. Keywords: Seek pre-mRNA changes associated with the fully metastatic phenotype in breast cancer We used RNA tumor tissues derived from three murine mammary carcinoma cell lines (168FARN, 4T07 and 4T1); four biological replicates of 168FARN, four biological replicates of 4T07, and four biological replicates of 4T1 were hybridized independently at McGill university site.
2010-06-08 | E-GEOD-21994 | biostudies-arrayexpress
Project description:The synthesis and processing of mRNA, from transcription to translation initiation, often requires splicing of intragenic material. The final mRNA composition varies based upon proteins that modulate splice site selection. EWS-FLI1 is an Ewing sarcoma (ES) oncogene with an interactome that we demonstrate to have multiple partners in spliceosomal complexes. We evaluate EWS-FLI1 upon post-transcriptional gene regulation using both exon array and RNA-seq. Genes that potentially regulate oncogenesis including CLK1, CASP3, PPFIBP1, and TERT validate as alternatively spliced by EWS-FLI1. EWS-FLI1 also alters splicing by directly binding to known splicing factors including DDX5, hnRNPK, and PRPF6. Reduction of EWS-FLI1 produces an isoform of g-TERT that has increased telomerase activity compared to WT TERT. The small molecule YK-4-279 is an inhibitor of EWS-FLI1 oncogenic function that disrupts specific protein interactions including DDX5 and RNA helicase A (RHA) that alters RNA splicing ratios. As such, YK-4-279 validates the splicing mechanism of EWS-FLI1 showing alternatively spliced gene patterns that significantly overlap with EWS-FLI1 reduction and WT human mesenchymal stem cells. Exon array analysis of 75 ES patient samples show similar isoform expression patterns to cell line models expressing EWS-FLI1, supporting the clinical relevance of our findings. These experiments establish systemic alternative splicing as an oncogenic process modulated by EWS-FLI1. EWS-FLI1 modulation of mRNA splicing may provide insight into the contribution of splicing towards oncogenesis, and reciprocally, EWS-FLI1 interactions with splicing proteins may inform the splicing code. Alternative splicing of RNA allows a limited number of coding regions in the human genome to produce proteins with diverse functionality. Alternative splicing has also been implicated as an oncogenic process. Identifying aspects of cancer cells that differentiate them from non-cancer cells remains an ongoing challenge and our research suggests that alternatively spliced mRNA and subsequent protein isoforms will provide new anti-cancer targets. We determined that the key oncogene of Ewing sarcoma (ES), EWS-FLI1, regulates alternative splicing in multiple cell line models. These experiments establish oncogenic aspects of splicing which are specific to cancer cells and thereby illuminate potentially oncogenic splicing shifts as well as provide a useful stratification mechanism for ES patients. We analyzed three models of EWS-FLI1 using Affymetrix GeneChip Human Exon 1.0 ST microarray: (i) Ewing's sarcoma TC32 wild-type cells expressing EWS-FLI1, and TC32 cells where EWS-FLI1 was reduced with a lentiviral shRNA; (ii) A673i, which has a doxycycline-inducible shRNA to reduce EWS-FLI1 expression, and wild-type EWS-FLI1 to screen for alternative splicing as measured by exon-specific expression changes; and (iii) human mesenchymal stem cells (hMSC), a putative cell of origin of Ewing's sarcoma, exogenously expressing EWS-FLI1, and hMSC wild-type cells without EWS-FLI1. Three biological replicates were included for each condition. The Bioconductor package "oligo" in the R programming language was used for normalization and background correction. Analysis was carried out using only core probesets, as defined by the manufacturer.
2015-03-31 | E-GEOD-65941 | biostudies-arrayexpress
Project description:Epigenetic alterations are recurrently observed in cancer and are the subject of active therapeutic investigations. Midline high-grade gliomas (HGGs) are deadly brain tumors characterized by lysine-to-methionine substitutions at position 27 in histone 3 (H3) variants (denoted H3K27M), which are core components of the nucleosome. H3K27M, the first event in midline HGG development, results in a drastic loss of the repressive histone mark H3K27 tri-methylation (H3K27me3), and a notable increase in H3K27 acetylation (H3K27ac), a mark associated with active chromatin and cellular identity. H3K27ac gain was suggested to promote tumorigenesis in H3K27M-HGGs, but how these opposing marks shape oncogenesis remains controversial. We therefore characterized the active regulatory chromatin states in H3.3K27M and H3K27 wild-type HGGs and in H3.3K27M CRISPR/Cas9 knockout tumor-derived cell lines, as an isogenic tumor model of the mutation. We show that H3.3K27M-HGGs have distinct promoter, enhancer, super-enhancer, and core transcription factor circuitries from wild-type HGGs. However, while removal of H3.3K27M restores gross H3K27ac levels to those of wild-type HGGs, we observe minimal disruption of H3K27ac deposition at these active transcriptional elements, suggesting that they are a function of the cell of origin and independent of direct H3K27M mutagenesis and active regulation. Using quantitative ChIP-seq, we show that in H3.3K27M-HGGs, H3K27ac is pervasively deposited across the genome, including at normally silent repeat elements, leading to their increased baseline expression. H3.3K27M cells respond to DNA demethylating agents and histone deacetylase inhibitors, which further increase repeat element expression, including that of specific endogenous retroviral (ERVs) families. Our findings decouple cell lineage programs from H3K27M-dependent pervasive deposition of H3K27 acetylation. De-repression of ERVs may enhance the triggering of innate immune pathways, representing a therapeutic vulnerability in H3.3K27M HGGs.
2019-05-13 | GSE117446 | GEO
Project description:Epigenetic alterations are recurrently observed in cancer and are the subject of active therapeutic investigations. Midline high-grade gliomas (HGGs) are deadly brain tumors characterized by lysine-to-methionine substitutions at position 27 in histone 3 (H3) variants (denoted H3K27M), which are core components of the nucleosome. H3K27M, the first event in midline HGG development, results in a drastic loss of the repressive histone mark H3K27 tri-methylation (H3K27me3), and a notable increase in H3K27 acetylation (H3K27ac), a mark associated with active chromatin and cellular identity. H3K27ac gain was suggested to promote tumorigenesis in H3K27M-HGGs, but how these opposing marks shape oncogenesis remains controversial. We therefore characterized the active regulatory chromatin states in H3.3K27M and H3K27 wild-type HGGs and in H3.3K27M CRISPR/Cas9 knockout tumor-derived cell lines, as an isogenic tumor model of the mutation. We show that H3.3K27M-HGGs have distinct promoter, enhancer, super-enhancer, and core transcription factor circuitries from wild-type HGGs. However, while removal of H3.3K27M restores gross H3K27ac levels to those of wild-type HGGs, we observe minimal disruption of H3K27ac deposition at these active transcriptional elements, suggesting that they are a function of the cell of origin and independent of direct H3K27M mutagenesis and active regulation. Using quantitative ChIP-seq, we show that in H3.3K27M-HGGs, H3K27ac is pervasively deposited across the genome, including at normally silent repeat elements, leading to their increased baseline expression. H3.3K27M cells respond to DNA demethylating agents and histone deacetylase inhibitors, which further increase repeat element expression, including that of specific endogenous retroviral (ERVs) families. Our findings decouple cell lineage programs from H3K27M-dependent pervasive deposition of H3K27 acetylation. De-repression of ERVs may enhance the triggering of innate immune pathways, representing a therapeutic vulnerability in H3.3K27M HGGs.
2019-05-13 | GSE129136 | GEO
Project description:Epigenetic alterations are recurrently observed in cancer and are the subject of active therapeutic investigations. Midline high-grade gliomas (HGGs) are deadly brain tumors characterized by lysine-to-methionine substitutions at position 27 in histone 3 (H3) variants (denoted H3K27M), which are core components of the nucleosome. H3K27M, the first event in midline HGG development, results in a drastic loss of the repressive histone mark H3K27 tri-methylation (H3K27me3), and a notable increase in H3K27 acetylation (H3K27ac), a mark associated with active chromatin and cellular identity. H3K27ac gain was suggested to promote tumorigenesis in H3K27M-HGGs, but how these opposing marks shape oncogenesis remains controversial. We therefore characterized the active regulatory chromatin states in H3.3K27M and H3K27 wild-type HGGs and in H3.3K27M CRISPR/Cas9 knockout tumor-derived cell lines, as an isogenic tumor model of the mutation. We show that H3.3K27M-HGGs have distinct promoter, enhancer, super-enhancer, and core transcription factor circuitries from wild-type HGGs. However, while removal of H3.3K27M restores gross H3K27ac levels to those of wild-type HGGs, we observe minimal disruption of H3K27ac deposition at these active transcriptional elements, suggesting that they are a function of the cell of origin and independent of direct H3K27M mutagenesis and active regulation. Using quantitative ChIP-seq, we show that in H3.3K27M-HGGs, H3K27ac is pervasively deposited across the genome, including at normally silent repeat elements, leading to their increased baseline expression. H3.3K27M cells respond to DNA demethylating agents and histone deacetylase inhibitors, which further increase repeat element expression, including that of specific endogenous retroviral (ERVs) families. Our findings decouple cell lineage programs from H3K27M-dependent pervasive deposition of H3K27 acetylation. De-repression of ERVs may enhance the triggering of innate immune pathways, representing a therapeutic vulnerability in H3.3K27M HGGs.
2019-05-13 | GSE129135 | GEO
Project description:Epigenetic alterations are recurrently observed in cancer and are the subject of active therapeutic investigations. Midline high-grade gliomas (HGGs) are deadly brain tumors characterized by lysine-to-methionine substitutions at position 27 in histone 3 (H3) variants (denoted H3K27M), which are core components of the nucleosome. H3K27M, the first event in midline HGG development, results in a drastic loss of the repressive histone mark H3K27 tri-methylation (H3K27me3), and a notable increase in H3K27 acetylation (H3K27ac), a mark associated with active chromatin and cellular identity. H3K27ac gain was suggested to promote tumorigenesis in H3K27M-HGGs, but how these opposing marks shape oncogenesis remains controversial. We therefore characterized the active regulatory chromatin states in H3.3K27M and H3K27 wild-type HGGs and in H3.3K27M CRISPR/Cas9 knockout tumor-derived cell lines, as an isogenic tumor model of the mutation. We show that H3.3K27M-HGGs have distinct promoter, enhancer, super-enhancer, and core transcription factor circuitries from wild-type HGGs. However, while removal of H3.3K27M restores gross H3K27ac levels to those of wild-type HGGs, we observe minimal disruption of H3K27ac deposition at these active transcriptional elements, suggesting that they are a function of the cell of origin and independent of direct H3K27M mutagenesis and active regulation. Using quantitative ChIP-seq, we show that in H3.3K27M-HGGs, H3K27ac is pervasively deposited across the genome, including at normally silent repeat elements, leading to their increased baseline expression. H3.3K27M cells respond to DNA demethylating agents and histone deacetylase inhibitors, which further increase repeat element expression, including that of specific endogenous retroviral (ERVs) families. Our findings decouple cell lineage programs from H3K27M-dependent pervasive deposition of H3K27 acetylation. De-repression of ERVs may enhance the triggering of innate immune pathways, representing a therapeutic vulnerability in H3.3K27M HGGs.
2019-05-13 | GSE128744 | GEO