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An oncogenic Ezh2 mutation cooperates with particular genetic alterations to induce tumors in mice and redistributes H3K27m3 through the genome [RNA-seq]

ABSTRACT: B-cell lymphoma and melanoma harbor recurrent mutations in the gene encoding the EZH2 histone methyltransferase, but the carcinogenic role of these mutations is unclear. Here we describe a mouse model in which the most common somatic EZH2 gain-of-function mutation (Y646F in human, Y641F in the mouse) can be conditionally expressed. Expression of Ezh2Y641F in mouse B-cells or melanocytes caused high-penetrance lymphoma or melanoma, respectively. Bcl2 overexpression or p53 loss, but not c-Myc overexpression, further accelerated lymphoma progression, and expression of mutant B-Raf but not mutant N-Ras further accelerated melanoma progression. Although expression of Ezh2Y641F increased abundance of global H3K27 trimethylation (H3K27me3), it also caused a widespread redistribution of this repressive mark, including a loss of H3K27me3 associated with increased transcription at many loci. These results suggest that Ezh2Y641F induces lymphoma and melanoma through a vast reorganization of chromatin structure inducing both repression and activation of polycomb-regulated loci.

ORGANISM(S): Mus musculus

PROVIDER: GSE79035 | GEO | 2016/05/13

SECONDARY ACCESSION(S): PRJNA314772

REPOSITORIES: GEO

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An oncogenic Ezh2 mutation cooperates with particular genetic alterations to induce tumors in mice and redistributes H3K27m3 through the genome [RNA-seq]

Project description:B-cell lymphoma and melanoma harbor recurrent mutations in the gene encoding the EZH2 histone methyltransferase, but the carcinogenic role of these mutations is unclear. Here we describe a mouse model in which the most common somatic EZH2 gain-of-function mutation (Y646F in human, Y641F in the mouse) can be conditionally expressed. Expression of Ezh2Y641F in mouse B-cells or melanocytes caused high-penetrance lymphoma or melanoma, respectively. Bcl2 overexpression or p53 loss, but not c-Myc overexpression, further accelerated lymphoma progression, and expression of mutant B-Raf but not mutant N-Ras further accelerated melanoma progression. Although expression of Ezh2Y641F increased abundance of global H3K27 trimethylation (H3K27me3), it also caused a widespread redistribution of this repressive mark, including a loss of H3K27me3 associated with increased transcription at many loci. These results suggest that Ezh2Y641F induces lymphoma and melanoma through a vast reorganization of chromatin structure inducing both repression and activation of polycomb-regulated loci. B cells: 4 WT vs 4 Y641F samples, Melanoma: WT (480, 855) vs Y641F (480D, 855D) isogenic cell lines differing only for the presence of WT vs Y641F Ezh2.

2016-05-13 | E-GEOD-79035 | biostudies-arrayexpress

An oncogenic Ezh2 mutation induces tumors in mice through redistribution of global H3K27 trimethylation

Project description:B cell lymphoma and melanoma harbor recurrent mutations in the gene encoding the EZH2 histone methyltransferase (EZH2), but the carcinogenic role of these mutations is unclear. Here we describe a mouse model in which the most common somatic Ezh2 gain-of-function mutation (EZH2Y646F in human; Ezh2Y641F in mouse) is conditionally expressed. Expression of Ezh2Y641F in mouse B cells or melanocytes caused high-penetrance lymphoma or melanoma, respectively. Overexpression of the anti-apoptotic protein Bcl2, but not the oncoprotein Myc, or loss of the tumor suppressor protein p53 (encoded by Trp53 in mice) further accelerated lymphoma progression. Expression of mutant Braf oncoprotein but not mutant Nras oncoprotein further accelerated melanoma progression. Although expression of Ezh2Y641F globally increased the abundance of trimethylated Lys27 of histone H3 (H3K27me3), it also caused a widespread redistribution of this repressive mark, including a loss of H3K27me3 that was associated with increased transcription at many loci. These results suggest that Ezh2Y641F induces lymphoma and melanoma through a vast reorganization of chromatin structure, inducing both repression and activation of polycomb-regulated loci.

2016-05-02 | GSE79034 | GEO

Affinify Purification of EZH2 and phosphodeficient EZH2 identifies phosphorylation dependent interactions of EZH2

Project description:Overexpression of EZH2 in estrogen receptor negative (ER-) breast cancer promotes metastasis. EZH2 has been mainly studied as the catalytic component of the Polycomb Repressive Complex 2 (PRC2) that mediates gene repression by trimethylating histone H3 at lysine 27 (H3K27me3). However, how EZH2 drives metastasis despite the low H3K27me3 levels observed in ER- breast cancer is unknown. We have shown that in human invasive carcinomas and distant metastases, cytoplasmic EZH2 phosphorylated at T367 is significantly associated with ER- disease and low H3K27me3 levels. Here, we explore the interactome of EZH2 and of a phosphodeficient mutant EZH2_T367A. We identified novel interactors of EZH2, and identified interactions that are dependent on the phosphorylation and cellular localization of EZH2 that may play a role in EZH2 dependent metastatic progression.

2018-07-03 | PXD010073 | Pride

EZH2 is required for germinal center formation and somatic EZH2 mutations promote lymphoid transformation

Project description:The EZH2 histone methyltransferase is highly expressed in germinal center (GC) B-cells and targeted by somatic mutations in B-cell lymphomas. Here we find that EZH2 deletion or pharmacologic inhibition suppresses GC formation and functions in mice. EZH2 represses proliferation checkpoint genes and helps establish bivalent chromatin domains at key regulatory loci to transiently suppress GC B-cell differentiation. Somatic mutations reinforce these physiological effects through enhanced silencing of EZH2 targets in B-cells, and in human B-cell lymphomas. Conditional expression of mutant EZH2 in mice induces GC hyperplasia and accelerated lymphomagenesis in cooperation with BCL2. GCB-type DLBCLs are mostly addicted to EZH2, regardless of mutation status, but not the more differentiated ABC-type DLBCLs, thus clarifying the therapeutic scope of EZH2 targeting. RNA sequencing and H3K27me3 ChIP sequencing of human DLBCL cell lines and murine BCL1 cell line. RNA sequencing, H3K27me3 and H3K4me3 ChIP sequencing of B cells from de-identified human tonsills.

2013-05-13 | E-GEOD-45982 | biostudies-arrayexpress

Epigenetic reprogramming in hepatic carcinogenesis

Project description:Genomic sequencing of hepatocellular carcinoma (HCC) uncovers a paucity of actionable mutations, underscoring the necessity to exploit epigenetic vulnerabilities for therapeutics. In HCC, EZH2-mediated H3K27me3 represents a major oncogenic chromatin modification, but how it modulates the therapeutic vulnerability of signaling pathways remains unknown. Here, we identified that EZH2 maintains H3K27 methylome through epigenetic silencing of specific gene sets. ChIP-seq revealed enrichment of EZH2/H3K27me3 at silenced loci in HBx-transgenic (TG) mouse-derived HCCs, including tumor suppressors whose down-regulation significantly correlated with EZH2 overexpression and poor survival of HCC patients. Defining the aberrant chromatin landscape of HCC sheds light into the mechanistic basis of effective EZH2-targeted inhibition.

2018-07-02 | GSE113326 | GEO

Loss of EZH2 results in enhanced recruitment of EZH1, Pol II and Stat5 and precocious mammary gland development

Project description:Establishment and differentiation of mammary alveoli during pregnancy are controlled by prolactin through the transcription factor STAT5. As pregnancy progresses mammary signature genes are activated in a defined temporal order, which coincides with the recruitment of STAT5 to respective regulatory sequences. This study addressed the question whether the methyltransferase and transcriptional co-activator EZH2 controls the differentiation clock of mammary epithelium. Ablation of Ezh2 from mammary stem cells resulted in precocious differentiation of alveolar epithelium and accelerated activation of mammary signature genes. This coincided with enhanced occupancy by EZH1, Pol II and STAT5 to mammary-specific loci. Notably, loss of EZH2 did not result in overt changes in genome-wide and gene-specific H3K27me3 patterns, suggesting that enhanced EZH1 recruitment can compensate for the loss of EZH2. However, differentiated mammary epithelia failed to form in the combined absence of EZH1 and EZH2. Transplantation experiments failed to demonstrate a role for EZH2 in the biology of mammary stem and progenitor cells. In summary, while EZH1 and EZH2 serve redundant functions in the establishment of H3K27me3 and formation of mammary alveoli, the presence of EZH2 is required to obtain controlled temporal differentiation of mammary epithelium. ChIP-seq EZH1, EZH2, PolIII; WT and E2KO mammary cells

2015-01-27 | E-GEOD-65284 | biostudies-arrayexpress

Aberrant MYCN expression drives oncogenic hijacking of EZH2 as a transcriptional activator in peripheral T cell lymphoma [ChIP-seq]

Project description:Peripheral T cell lymphoma (PTCL) is a heterogeneous group of hematological cancers arising from the malignant transformation of mature T cells. In a cohort of 28 PTCL cases, we identified recurrent overexpression of MYCN, a member of the MYC family of oncogenic transcription factors. Approximately half of all PTCL cases was characterized by a MYC expression signature. Inducible expression of MYCN in lymphoid cells in a mouse model caused T cell lymphoma that recapitulated human PTCL with a MYC expression signature. Integration of mouse and human expression data identified EZH2 as a key downstream target of MYCN. Remarkably, EZH2 was found to be an essential co-factor for the transcriptional activation of the MYCN-driven gene expression program, which was independent of methyltransferase activity, but dependent on phosphorylation by CDK1. MYCN-driven T cell lymphoma was sensitive to EZH2 degradation or CDK1 inhibition, which displayed synergy with FDA-approved HDAC inhibitors.

2022-09-01 | GSE198125 | GEO

Aberrant MYCN expression drives oncogenic hijacking of EZH2 as a transcriptional activator in peripheral T cell lymphoma [RNA-seq]

2022-09-01 | GSE198124 | GEO

Quantitative histone mass spectrometry identifies elevated histone H3 lysine 27 trimethylation in melanoma

Project description:Normal cell growth is characterized by a regulated epigenetic program that drives cellular activities such as gene transcription, DNA replication and DNA damage repair. Perturbation of this epigenetic program can lead to events such as mis-regulation of gene transcription and diseases such as cancer. To begin to understand the epigenetic program correlated to the development of melanoma, we performed a quantitative mass spectrometric analysis of histone posttranslational modifications mis-regulated in melanoma cell culture. Aggressive melanoma cells were found to have elevated histone H3 lysine 27 trimethylation (H3K27me3) as well as over-expressed methyltransferase EZH2 that adds the specific modification. The altered epigenetic program that led to elevated H3K27me3 in melanoma cell culture was found to directly silence transcription of the tumor suppressor gene RUNX3. The elevated level of H3K27me3 and silencing of RUNX3 transcription was also validated in advanced stage human melanoma tissues. The study presented underscores the utility of using high resolution mass spectrometry to identify mis-regulated epigenetic programs in diseases such as cancer, which could ultimately lead to the identification of biological markers for diagnostic and prognostic applications.

2015-12-02 | PXD002471 | Pride

Quantitative histone mass spectrometry identifies elevated histone H3 lysine 27 trimethylation in melanoma

2016-07-22 | MSV000079979 | MassIVE

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