HBO1 is required for the maintenance of leukaemia stem cells [shRNA screen]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE139118 | GEO | 2019/12/18
REPOSITORIES: GEO
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Project description:Acute myeloid leukaemia (AML) is a heterogeneous disease characterised by transcriptional dysregulation resulting in a block in differentiation and increased malignant self-renewal. Various epigenetic therapies aimed at reversing these hallmarks of AML have progressed into clinical trials, with most showing modest efficacy due to an inability to effectively eradicate leukaemia stem cells (LSC). To specifically identify novel dependencies in LSC we screened a bespoke library of small hairpin RNAs (shRNAs) targeting chromatin regulators in a unique ex vivo model of LSC. We identified the MYST acetyltransferases HBO1 (KAT7) and several known members of the HBO1 protein complex as critical regulators of LSC maintenance ex vivo and conditional ablation of HBO1 confirmed its requirement for LSC maintenance in vivo. CRISPR domain screening identified the histone acetyltransferases (HAT) domain of HBO1 as being essential to acetylate histone H3K14, which is required for the expression of the key genes including HOXA9 and HOXA10 that maintain the immature phenotype and self-renewal properties of LSC. To leverage this dependency therapeutically we developed highly potent small molecule inhibitors of HBO1 and provide structural data to demonstrate their mode of activity as competitive analogues of acetyl-CoA. These inhibitors phenocopy our genetic data and show efficacy in a broad range of human cell lines and primary patient samples encompassing the most common genetic subtypes of AML.
2019-12-18 | GSE120812 | GEO
Project description:Acute myeloid leukaemia (AML) is a heterogeneous disease characterised by transcriptional dysregulation resulting in a block in differentiation and increased malignant self-renewal. Various epigenetic therapies aimed at reversing these hallmarks of AML have progressed into clinical trials, with most showing modest efficacy due to an inability to effectively eradicate leukaemia stem cells (LSC). To specifically identify novel dependencies in LSC we screened a bespoke library of small hairpin RNAs (shRNAs) targeting chromatin regulators in a unique ex vivo model of LSC. We identified the MYST acetyltransferases HBO1 (KAT7) and several known members of the HBO1 protein complex as critical regulators of LSC maintenance ex vivo and conditional ablation of HBO1 confirmed its requirement for LSC maintenance in vivo. CRISPR domain screening identified the histone acetyltransferases (HAT) domain of HBO1 as being essential to acetylate histone H3K14, which is required for the expression of the key genes including HOXA9 and HOXA10 that maintain the immature phenotype and self-renewal properties of LSC. To leverage this dependency therapeutically we developed highly potent small molecule inhibitors of HBO1 and provide structural data to demonstrate their mode of activity as competitive analogues of acetyl-CoA. These inhibitors phenocopy our genetic data and show efficacy in a broad range of human cell lines and primary patient samples encompassing the most common genetic subtypes of AML.
2019-12-18 | GSE120811 | GEO
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic mechanisms balance normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic regulators are considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in human LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly prognostic for patient survival. Gain- and loss-of-function analyses demonstrated that miR-126 restrained cell cycle progression, prevented differentiation, and increased self-renewal of human LSC. By targeting the G0 to G1 gatekeeper CDK3, miR-126 preserved LSC quiescence and promoted chemotherapy resistance. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC.
2016-03-31 | PXD001994 | Pride
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic regulation balances normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic modifiers are now considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly predictive of patient survival. Gain of function genetic analysis demonstrated that miR-126 restrained cell cycle progression, prevented LSC differentiation, and increased LSC self-renewal. miR-126 promoted chemo-resistance, preserving LSC quiescence in part through suppression of the G0 to G1 gatekeeper, CDK3. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC. 74 primary patient normal karyotype AML samples were analyzed for miRNA expression.
2016-02-01 | E-GEOD-55770 | biostudies-arrayexpress
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic regulation balances normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic modifiers are now considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly predictive of patient survival. Gain of function genetic analysis demonstrated that miR-126 restrained cell cycle progression, prevented LSC differentiation, and increased LSC self-renewal. miR-126 promoted chemo-resistance, preserving LSC quiescence in part through suppression of the G0 to G1 gatekeeper, CDK3. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC.
2016-02-01 | GSE55770 | GEO
Project description:Bromodomain and Extra Terminal protein (BET) inhibitors are first-in-class targeted therapies that deliver a new therapeutic paradigm by directly targeting epigenetic readers1,2. Early clinical trials have shown significant promise especially in acute myeloid leukaemia (AML)3; therefore the evaluation of resistance mechanisms, an inevitable consequence of cancer therapies, is of utmost importance to optimise the clinical efficacy of these drugs. Using primary murine stem and progenitor cells immortalised with MLL-AF9, we have used an innovative approach to generate 20 cell lines derived from single cell clones demonstrating stable resistance, in vitro and in vivo, to the prototypical BET inhibitor, I-BET. Resistance to I-BET confers cross-resistance to chemically distinct BET inhibitors such as JQ1, as well as resistance to genetic knockdown of BET proteins. Resistance is not mediated through increased drug efflux or metabolism but is demonstrated to emerge from leukaemia stem cells (LSC). Resistant clones display a leukaemic granulocyte-macrophage progenitor (L-GMP) phenotype (Lin-, Sca-, cKit+, CD34+, Fc³RII/RIII+) and functionally exhibit increased clonogenic capacity in vitro and markedly shorter leukaemia latency in vivo. Chromatin bound BRD4 is globally reduced in resistant cells, however expression of key target genes such as MYC remains unaltered, highlighting the existence of alternative mechanisms to regulate transcription. We demonstrate that resistance to BET inhibitors is in part a consequence of increased Wnt/²-catenin signaling. Negative regulation of this pathway results in differentiation of resistant cells into mature leukaemic blasts, inhibition of MYC expression and restoration of sensitivity to I-BET in vitro and in vivo. Finally, we show that the sensitivity of primary human AML cells to I-BET correlates with the baseline expression of Wnt/²-catenin target genes. Together these findings provide novel insights into the biology of AML, highlight the potential therapeutic limitations of BET inhibitors and identify strategies that may overcome resistance and enhance the clinical utility of these unique targeted therapies. Comparison of iBET resistant and sensitive cell lines
2015-09-15 | E-GEOD-63681 | biostudies-arrayexpress
Project description:Bromodomain and Extra Terminal protein (BET) inhibitors are first-in-class targeted therapies that deliver a new therapeutic paradigm by directly targeting epigenetic readers1,2. Early clinical trials have shown significant promise especially in acute myeloid leukaemia (AML)3; therefore the evaluation of resistance mechanisms, an inevitable consequence of cancer therapies, is of utmost importance to optimise the clinical efficacy of these drugs. Using primary murine stem and progenitor cells immortalised with MLL-AF9, we have used an innovative approach to generate 20 cell lines derived from single cell clones demonstrating stable resistance, in vitro and in vivo, to the prototypical BET inhibitor, I-BET. Resistance to I-BET confers cross-resistance to chemically distinct BET inhibitors such as JQ1, as well as resistance to genetic knockdown of BET proteins. Resistance is not mediated through increased drug efflux or metabolism but is demonstrated to emerge from leukaemia stem cells (LSC). Resistant clones display a leukaemic granulocyte-macrophage progenitor (L-GMP) phenotype (Lin-, Sca-, cKit+, CD34+, Fc³RII/RIII+) and functionally exhibit increased clonogenic capacity in vitro and markedly shorter leukaemia latency in vivo. Chromatin bound BRD4 is globally reduced in resistant cells, however expression of key target genes such as MYC remains unaltered, highlighting the existence of alternative mechanisms to regulate transcription. We demonstrate that resistance to BET inhibitors is in part a consequence of increased Wnt/²-catenin signaling. Negative regulation of this pathway results in differentiation of resistant cells into mature leukaemic blasts, inhibition of MYC expression and restoration of sensitivity to I-BET in vitro and in vivo. Finally, we show that the sensitivity of primary human AML cells to I-BET correlates with the baseline expression of Wnt/²-catenin target genes. Together these findings provide novel insights into the biology of AML, highlight the potential therapeutic limitations of BET inhibitors and identify strategies that may overcome resistance and enhance the clinical utility of these unique targeted therapies. Comparison of iBET resistant and sensitive cell lines
2015-09-15 | E-GEOD-63682 | biostudies-arrayexpress
Project description:Bromodomain and Extra Terminal protein (BET) inhibitors are first-in-class targeted therapies that deliver a new therapeutic paradigm by directly targeting epigenetic readers. Early clinical trials have shown significant promise especially in acute myeloid leukaemia (AML)3; therefore the evaluation of resistance mechanisms, an inevitable consequence of cancer therapies, is of utmost importance to optimise the clinical efficacy of these drugs. Using primary murine stem and progenitor cells immortalised with MLL-AF9, we have used an innovative approach to generate 20 cell lines derived from single cell clones demonstrating stable resistance, in vitro and in vivo, to the prototypical BET inhibitor, I-BET. Resistance to I-BET confers cross-resistance to chemically distinct BET inhibitors such as JQ1, as well as resistance to genetic knockdown of BET proteins. Resistance is not mediated through increased drug efflux or metabolism but is demonstrated to emerge from leukaemia stem cells (LSC). Resistant clones display a leukaemic granulocyte-macrophage progenitor (L-GMP) phenotype (Lin-, Sca-, cKit+, CD34+, FcγRII/RIII+) and functionally exhibit increased clonogenic capacity in vitro and markedly shorter leukaemia latency in vivo. Chromatin bound BRD4 is globally reduced in resistant cells, however expression of key target genes such as MYC remains unaltered, highlighting the existence of alternative mechanisms to regulate transcription. We demonstrate that resistance to BET inhibitors is in part a consequence of increased Wnt/β-catenin signaling. Negative regulation of this pathway results in differentiation of resistant cells into mature leukaemic blasts, inhibition of MYC expression and restoration of sensitivity to I-BET in vitro and in vivo. Finally, we show that the sensitivity of primary human AML cells to I-BET correlates with the baseline expression of Wnt/β-catenin target genes. Together these findings provide novel insights into the biology of AML, highlight the potential therapeutic limitations of BET inhibitors and identify strategies that may overcome resistance and enhance the clinical utility of these unique targeted therapies. Total RNA obtained from iBET resistant and sensitive cells
2015-09-15 | E-GEOD-63575 | biostudies-arrayexpress
Project description:Histone acetyltransferases (HAT) assemble into multisubunit complexes in order to target distinct lysine residues on nucleosomal histones. Here, we characterize native HAT complexes assembled by the BRPF-family of scaffold proteins. Their PHD-ZnKnuckle-PHD domain is essential for binding chromatin and restricted to unmethylated H3K4, a specificity that is reversed by the associated ING subunit. Native BRPF1 complexes can contain either MOZ/MORF or HBO1 as catalytic acetyltransferase subunit. Interestingly, while the previously reported HBO1 complexes containing JADE scaffold proteins target histone H4, the HBO1-BRPF1 complex acetylates only H3 in chromatin. We mapped a small region at the N-terminus of scaffold proteins responsible for histone tail selection on chromatin. Thus, alternate choice of subunits associated with HBO1 can switch its specificity from H4 to H3 tails, highlighting a crucial new role of associated subunits within HAT complexes, previously thought to be intrinsic to the catalytic subunit. Genome-wide mapping of MYST acetyltransferases subunits and H3K4me3 histone mark in RKO cells.
2013-10-09 | E-GEOD-47190 | biostudies-arrayexpress
Project description:RNA binding protein (RBP)-directed post-transcriptional control of stem cell fate represents an underexplored mechanism driving hematopoietic stemness and transformation. We show that a unique set of RBPs are specifically enriched in leukemic stem cells (LSCs) of human primary acute myeloid leukemia (AML) but repressed in normal hematopoietic stem cells. Using an in vivo CRISPR-Cas9-mediated screening approach, we identify 33 key RBPs specifically essential for LSC-mediated MLL-AF9/NrasG12D AML. Knock-down/genetic ablation of the hit RBP Elavl1 in genetically distinct leukemias significantly reduced LSC numbers, and hampered leukemic engraftment. In human AML we show impairment of LSC-driven in vivo leukemic reconstitution and selective depletion of AML progenitors upon ELAVL1 targeting, highlighting the potential clinical importance of our findings. Profiling of the leukemic ELAVL1-mRNA interactome revealed hematopoietic differentiation, RNA splicing and mitochondrial metabolism as major pathways impacted by ELAVL1. Altogether, this work demonstrates that Elavl1 and other RBPs are critical regulators of LSC-survival and self-renewal.
2023-01-18 | GSE127944 | GEO