The effects of H3.3K27M mutation on developing mouse brain and cooperation with Trp53 on enhancing tumorigenesis in the genetic model of H3.3K27M [RNA-Seq]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE120882 | GEO | 2020/10/27
REPOSITORIES: GEO
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Project description:Diffuse intrinsic pontine gliomas (DIPG) are devastating pediatric brain tumors for which there is no effective therapy. A lack of pre-clinical genetic models has affected efforts to develop therapies targeted to DIPG. Over 60% of DIPG patients carry a mutation in the histone H3F3A gene (H3.3K27M) that is often accompanied by a mutation in the TP53 gene. Here we created a genetic model in which H3.3K27M is expressed under the mouse Fabp7 promoter. These mice have disrupted embryonic development and increased susceptibility to development of lymphomas. Crosses to Trp53 knockout mice further accelerated lymphomagenesis and led to brain tumour development. Some but not all tumours acquired additional oncogenic alterations. The brain tumours faithfully recapitulate the expression profiles of DIPG patients, and brain tumours and lymphomas share significant similarities in pathway alterations, pointing to a core H3.3K27M transcriptome. Overall, this mouse model provides key insights into how H3.3K27M mutations regulate DIPG at the cellular and tumour level.
2020-10-27 | GSE120883 | GEO
Project description:Diffuse intrinsic pontine gliomas (DIPG) are a deadly paediatric brain tumours, non-resectable due to brainstem localisation and diffusive growth. Patients with DIPG have a dismal prognosis of 9-12 months of survival with no effective therapy. Over 80% of DIPGs harbour a mutation in histone 3 (H3.3 or H3.1) resulting in a lysine to methionine substitution (H3K27M). H3K27M causes global epigenetic alterations (a loss of H3K27 trimethylation and an increase in H3K27 acetylation) resulting in aberrant gene expression. To date, no therapeutic strategy exists to suppress the levels of oncogenic H3K27M.
We show that pan-HDAC inhibitors (HDACi) lead to the temporary but significant reduction in the H3.33K27M protein (up to 80%) in multiple glioma cell lines expressing the H3.3K27M histone variant, without changes in the H3F3A mRNA expression. The H3.3K27M occupancy at the chromatin is greatly reduced upon HDACi (SB939) treatment, as shown by ChIPseq analysis. H3.3K27M loss is most striking at SB939-upregulated genes suggesting the role in repression of these genes. In addition, genes previously reported as H3K27M-dependent become downregulated in response to SB939 treatment. We discover that the SB939-mediated loss of H3.3K27M is partially blocked by a lysosomal inhibitor, chloroquine. Moreover, the loss of H3.3K27M is facilitated by co-occurrence of H2A.Z, as evidenced by the knock-down of H2A.Z histone isoforms. ChIPseq analysis confirms the occupancy of H3.3K27M and H2A.Z at the same SB939-inducible genes.
Altogether, we provide new insight into disease-specific mechanism of HDAC inhibition and demonstrate pharmacological modulation of the oncogenic H3.3K27M protein levels. These findings open a new possibility to directly target the H3.3K27M oncohistone, which may be exploited in future therapies.
2023-10-05 | MSV000093052 | MassIVE
Project description:Recent studies have identified a Lys 27-to-methionine (K27M) mutation at one allele of H3F3A, one of the two genes encoding histone H3 variant H3.3, in 60% of high-grade pediatric glioma cases. The median survival of this group of patients after diagnosis is ∼1 yr. Here we show that the levels of H3K27 di- and trimethylation (H3K27me2 and H3K27me3) are reduced globally in H3.3K27M patient samples due to the expression of the H3.3K27M mutant allele. Remarkably, we also observed that H3K27me3 and Ezh2 (the catalytic subunit of H3K27 methyltransferase) at chromatin are dramatically increased locally at hundreds of gene loci in H3.3K27M patient cells. Moreover, the gain of H3K27me3 and Ezh2 at gene promoters alters the expression of genes that are associated with various cancer pathways. These results indicate that H3.3K27M mutation reprograms epigenetic landscape and gene expression, which may drive tumorigenesis. We performed chromatin-immunoprecipitation of H3K27me3, H3K4me3, and EZH2 in SF7761 and NSC cell lines. And do RNA-seq in SF7761, SF8828 and NSC cell lines. SF7761 and SF8628 cell lines from patients harboring the histone H3.3 K27M mutation were obtained from Hashizume et al. (2012). NSCs (N7800-100) were purchased from Invitrogen and cultured and maintained in NSC medium (A10509-01, StemPro NSC SFM, Invitrogen).
2014-09-20 | E-GEOD-61586 | biostudies-arrayexpress
Project description:Diffuse intrinsic pontine gliomas (DIPG) are paediatric malignant gliomas developing in the brainstem, where resection is unattainable, leaving palliative radiotherapy as the major standard of care. Patients with DIPG have dismal prognosis of 9-12 months of survival and currently there is no effective therapy. Over 80% of DIPGs harbour a mutation in histone 3 (H3.3 or H3.1) resulting in a lysine to methionine substitution (H3K27M). H3K27M causes global epigenetic alterations (a loss of H3K27 trimethylation and an increase H3K27 acetylation) resulting in aberrant gene expression. To date, no therapeutic strategy exists to suppress the levels of oncogenic H3K27M. We show that pan-HDAC inhibitors (HDACi) lead to the temporary but significant reduction in the H3.3K27M protein (up to 80%) in multiple glioma cell lines expressing the H3.3K27M histone variant, without changes in the H3F3A mRNA expression. The H3.3K27M occupancy at the chromatin is greatly reduced upon HDACi (SB939) treatment, as shown by ChIPseq analysis. H3.3K27M loss is most striking at SB939-upregulated genes suggesting re-expression of repressed genes. Certain H3K27M-dependent genes become downregulated in response to SB939 treatment. We discover that the SB939-mediated loss of H3.3K27M is partially blocked by a lysosomal inhibitor chloroquine. Moreover, the loss of H3.3K27M is facilitated by co-occurrence of H2A.Z, as evidenced by the knock-down of H2A.Z histone isoforms. ChIPseq analysis confirms the occupancy of H3.3K27M and H2A.Z at the same SB939-inducible genes. Altogether, we provide new insight into disease-specific mechanism of HDAC inhibition and demonstrate pharmacological modulation of the oncogenic H3.3K27M protein levels. These findings open a new possibility to directly target the H3.3K27M oncohistone, which may be exploited in future therapies.
2024-05-01 | GSE232283 | GEO
Project description:Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive brain tumour that is located in the pons and primarily affects children. Whole-exome sequencing studies have identified recurrent driver mutations in H3F3A and HIST1H3B, leading to the expression of histone H3 in which lysine 27 is substituted with methionine (H3K27M) in nearly 80% of DIPGs. H3K27M inhibits Polycomb Repressive Complex 2 (PRC2) activity by binding to its catalytic subunit EZH2 and although DIPGs with H3K27M mutation show global loss of H3 with trimethylated lysine 27 (H3K27me3), several genomic loci are still H3K27me3 positive. Here, we describe a new mouse DIPG model in which H3K27M potentiates tumourigenesis. Using this model and primary patient-derived DIPG cell lines, we show that H3K27M expressing tumours require PRC2 for proliferation. Furthermore, we demonstrate that small molecule EZH2 inhibitors abolish in vitro and in vivo tumour cell growth through a mechanism involving induction of the tumour suppressor protein p16INK4A. In agreement with this, we show that tumour cells with inactivated p16INK4A function do not respond to EZH2 inhibitors. By analysing genome-wide H3K27me3 enrichment profile in mouse DIPG model, we highlight distinct features of the loci that lose or retain H3K27me3 in H3K27M expressing cells. Taken together these results show that residual PRC2 activity is required for the proliferation of H3K27M positive DIPGs, and we propose a therapeutic strategy for these tumours using EZH2 inhibitors and expression of p16INK4A as a marker for stratifying potential responding tumours.
2017-08-31 | GSE71387 | GEO
Project description:Recent studies have identified a Lys 27-to-methionine (K27M) mutation at one allele of H3F3A, one of the two genes encoding histone H3 variant H3.3, in 60% of high-grade pediatric glioma cases. The median survival of this group of patients after diagnosis is ∼1 yr. Here we show that the levels of H3K27 di- and trimethylation (H3K27me2 and H3K27me3) are reduced globally in H3.3K27M patient samples due to the expression of the H3.3K27M mutant allele. Remarkably, we also observed that H3K27me3 and Ezh2 (the catalytic subunit of H3K27 methyltransferase) at chromatin are dramatically increased locally at hundreds of gene loci in H3.3K27M patient cells. Moreover, the gain of H3K27me3 and Ezh2 at gene promoters alters the expression of genes that are associated with various cancer pathways. These results indicate that H3.3K27M mutation reprograms epigenetic landscape and gene expression, which may drive tumorigenesis.
2014-09-20 | GSE61586 | GEO
Project description:Expression of histone H3.3K27M mutant proteins in diffuse intrinsic pontine glioma (DIPG) results in a global reduction of tri-methylation of H3K27 (H3K27me3), and paradoxically, H3K27me3 peaks remain at hundreds of genomic loci, a dichotomous change that lacks mechanistic insights. Here we show that the PRC2 complex is sequestered at poised enhancers, but not at active promoters with high levels of H3.3K27M proteins, thereby contributing to the global reduction of H3K27me3. Moreover, the levels of H3.3K27M proteins are low at the retained H3K27me3 peaks and consequently having minimal effects on the PRC2 activity at these loci. H3K27me3-mediated silencing at specific tumor suppressor genes, including Wilms Tumor 1, promotes proliferation of DIPG cells. These results support a model in which the PRC2 complex is redistributed to poised enhancers in H3.3K27M mutant cells and supports the proliferation of DIPG cells in part through silencing of tumor suppressor gene WT1.
2018-07-02 | GSE94834 | GEO
Project description:Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive brain tumour that is located in the pons and primarily affects children. Whole-exome sequencing studies have identified recurrent driver mutations in H3F3A (H3.3) and HIST1H3B (H3.1), leading to the expression of histone H3 in which lysine 27 is substituted with methionine (H3K27M) in nearly 80% of DIPGs1-5. H3K27M has been shown to inhibit Polycomb Repressive Complex 2 (PRC2) activity by binding to its catalytic subunit EZH2, and although DIPGs with H3K27M mutation show global loss of H3 with trimethylated lysine 27 (H3K27me3), several genes retain H3K27me3 (Refs. 1-8). Here, we describe a mouse DIPG model in which H3K27M potentiates tumourigenesis. Using this model and primary patient-derived DIPG cell lines, we show that H3K27M expressing tumours require PRC2 for proliferation. Furthermore, we demonstrate that small molecule EZH2 inhibitors abolish tumour cell growth through a mechanism that is dependent on the induction of the tumour suppressor protein p16INK4A. Genome-wide enrichment analyses show that the genes that retain H3K27me3 in H3K27M cells are strong polycomb targets and are highly enriched for H3K27me3/PRC2/PRC1 in cells prior to H3K27M expression. Furthermore, we find a highly significant overlap between genes that retain H3K27me3 in the mouse DIPG model and in human primary DIPGs expressing H3K27M. Taken together, these results show that residual PRC2 activity is required for the proliferation of H3K27M positive DIPGs, and inhibition of EZH2 is as a potential therapeutic strategy for the treatment of these tumours.
2017-02-28 | GSE85386 | GEO
Project description:Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive brain tumour that is located in the pons and primarily affects children. Whole-exome sequencing studies have identified recurrent driver mutations in H3F3A (H3.3) and HIST1H3B (H3.1), leading to the expression of histone H3 in which lysine 27 is substituted with methionine (H3K27M) in nearly 80% of DIPGs1-5. H3K27M has been shown to inhibit Polycomb Repressive Complex 2 (PRC2) activity by binding to its catalytic subunit EZH2, and although DIPGs with H3K27M mutation show global loss of H3 with trimethylated lysine 27 (H3K27me3), several genes retain H3K27me3 (Refs. 1-8). Here, we describe a mouse DIPG model in which H3K27M potentiates tumourigenesis. Using this model and primary patient-derived DIPG cell lines, we show that H3K27M expressing tumours require PRC2 for proliferation. Furthermore, we demonstrate that small molecule EZH2 inhibitors abolish tumour cell growth through a mechanism that is dependent on the induction of the tumour suppressor protein p16INK4A. Genome-wide enrichment analyses show that the genes that retain H3K27me3 in H3K27M cells are strong polycomb targets and are highly enriched for H3K27me3/PRC2/PRC1 in cells prior to H3K27M expression. Furthermore, we find a highly significant overlap between genes that retain H3K27me3 in the mouse DIPG model and in human primary DIPGs expressing H3K27M. Taken together, these results show that residual PRC2 activity is required for the proliferation of H3K27M positive DIPGs, and inhibition of EZH2 is as a potential therapeutic strategy for the treatment of these tumours.
2017-02-28 | GSE85385 | GEO
Project description:Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive brain tumour that is located in the pons and primarily affects children. Whole-exome sequencing studies have identified recurrent driver mutations in H3F3A (H3.3) and HIST1H3B (H3.1), leading to the expression of histone H3 in which lysine 27 is substituted with methionine (H3K27M) in nearly 80% of DIPGs1-5. H3K27M has been shown to inhibit Polycomb Repressive Complex 2 (PRC2) activity by binding to its catalytic subunit EZH2, and although DIPGs with H3K27M mutation show global loss of H3 with trimethylated lysine 27 (H3K27me3), several genes retain H3K27me3 (Refs. 1-8). Here, we describe a mouse DIPG model in which H3K27M potentiates tumourigenesis. Using this model and primary patient-derived DIPG cell lines, we show that H3K27M expressing tumours require PRC2 for proliferation. Furthermore, we demonstrate that small molecule EZH2 inhibitors abolish tumour cell growth through a mechanism that is dependent on the induction of the tumour suppressor protein p16INK4A. Genome-wide enrichment analyses show that the genes that retain H3K27me3 in H3K27M cells are strong polycomb targets and are highly enriched for H3K27me3/PRC2/PRC1 in cells prior to H3K27M expression. Furthermore, we find a highly significant overlap between genes that retain H3K27me3 in the mouse DIPG model and in human primary DIPGs expressing H3K27M. Taken together, these results show that residual PRC2 activity is required for the proliferation of H3K27M positive DIPGs, and inhibition of EZH2 is as a potential therapeutic strategy for the treatment of these tumours.
2017-02-28 | GSE85388 | GEO