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PRC2 is required for acute myeloid leukemias initiated by MLL-AF9

ABSTRACT: The transcriptional activating and repressive functions performed by Trithorax and Polycomb group complexes, respectively, are critical for to maintain cellular fates in ontogeny and in cancer. Here we report that leukemias initiated by a Trithorax-related oncogene, MLL-AF9, depend upon the Polycomb Repressive Complex 2 (PRC2) to sustain a transformed cellular state. RNAi mediated suppression of PRC2 subunits is sufficient to inhibit proliferation of MLL-AF9 leukemias, with little impact on growth of non-transformed cells. This requirement is partly due to PRC2-mediated transcriptional repression of several anti-self-renewal regulators, including Cdkn2a. These results suggest that, unlike the classical antagonism generally observed between Polycomb and Trithorax group proteins during development, the activities of these two pathways can cooperate to promote myeloid neoplasia.

ORGANISM(S): Mus musculus

PROVIDER: GSE34183 | GEO | 2013/07/01

SECONDARY ACCESSION(S): PRJNA149697

REPOSITORIES: GEO

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PRC2 is required for acute myeloid leukemias initiated by MLL-AF9

Project description:The transcriptional activating and repressive functions performed by Trithorax and Polycomb group complexes, respectively, are critical for to maintain cellular fates in ontogeny and in cancer. Here we report that leukemias initiated by a Trithorax-related oncogene, MLL-AF9, depend upon the Polycomb Repressive Complex 2 (PRC2) to sustain a transformed cellular state. RNAi mediated suppression of PRC2 subunits is sufficient to inhibit proliferation of MLL-AF9 leukemias, with little impact on growth of non-transformed cells. This requirement is partly due to PRC2-mediated transcriptional repression of several anti-self-renewal regulators, including Cdkn2a. These results suggest that, unlike the classical antagonism generally observed between Polycomb and Trithorax group proteins during development, the activities of these two pathways can cooperate to promote myeloid neoplasia. In order to understand downstream targets of PRC2 complex in MLL-AF9 leukemia, we performed array in murine MLL-AF9/NrasG12D cell line under the condition that two subunits of PRC2(Eed and Suz12) were suppressed by using shRNAs.

2013-07-01 | E-GEOD-34183 | biostudies-arrayexpress

POLR2M-mediated paused transcription silences tumor suppressor MIR139 in MLL-AF9 AML

Project description:MIR139 is a critical tumor suppressor and commonly silenced in human cancer, including acute myeloid leukemia (AML). Here, we found that depletion of identified MIR139 targets affects AML outgrowth. We unraveled the mechanism of MIR139 gene inactivation in AML expressing the Mixed-Lineage Leukemia (MLL)-AF9 oncogene. Epigenetic analyses revealed two well-conserved putative enhancer regions in close proximity of transcriptional start sites (TSS) of MIR139. These regions were silenced by the Polycomb-Repressive Complex-2 (PRC2) downstream of MLL-AF9. Genomic deletion of these regions abolished MIR139 transcriptional regulation in normal and oncogenic conditions. Genome-wide knockout screens revealed the transcriptional pausing factor of RNA Polymerase-II, POLR2M, as a critical MIR139-silencing factor. Furthermore, direct POLR2M binding to the MIR139 TSS induced paused transcription, which was abrogated upon PRC2 inhibition. We present evidence for an oncogenic POLR2M-mediated MIR139 silencing mechanism, downstream of MLL-AF9 and PRC2. Together, our findings highlight the importance of POLR2M-mediated paused transcription in AML.

2021-11-11 | PXD022488 | Pride

Expression data from Ezh2-null leukemic cells

Project description:The polycomb group (PcG) proteins function in gene silencing through histone modifications. They form chromatin-associated multiprotein complexes, termed polycomb repressive complex (PRC) 1 and PRC2. These two complexes work in a coordinated manner in the maintenance of cellular memories through transcriptional repression of target genes. EZH2 is a catalytic component of PRC2 and trimethylates histone H3 at lysine 27 to transcriptionally repress the target genes. PcG proteins have been characterized as general regulators of stem cells, but recent works also unveiled their critical roles in cancer. Purified leukemic cells from BM of recipient mice transplanted with wild-type and Ezh2-/- leukemic cells transformed with MLL-AF9 leukemic fusion gene were subjected to RNA extraction and hybridization on Affymetrix microarrays.

2012-05-31 | E-GEOD-33808 | biostudies-arrayexpress

Leukemias of different origins

2011-03-31 | GSE18483 | GEO

ZNF521 enhances MLL-AF9-dependent hematopoietic stem cell transformation in acute myeloid leukemias by altering the gene expression landscape

Project description:Leukemias derived from the MLL-AF9 rearrangement rely on deranged transcriptional networks. ZNF521, a transcription co-factor implicated in the control of hematopoiesis, has been proposed to sustain leukemic transformation in collaboration with other oncogenes. We demonstrate here that ZNF521 mRNA levels correlate with specific genetic aberrations: in particular, the highest expression is observed in AMLs bearing MLL rearrangements, while the lowest is detected in AMLs with FLT3-ITD, NPM1 or CEBPα double mutations. In cord blood-derived CD34+ cells, enforced expression of ZNF521 provides a significant proliferative advantage, and acts synergistically when co-expressed with MLL-AF9 throughout the proliferation and expansion of leukemic progenitor cells. Transcriptome analysis of primary CD34+ cultures displayed subsets of genes upregulated by MLL-AF9 or ZNF521 single transgene overexpression as well as in MLL-AF9/ZNF521 combinations, either at early or late time points of an in vitro model of leukemogenesis. Silencing of ZNF521 in MLL-AF9+ THP-1 cell line coherently results in an impairment of growth and clonogenicity, recapitulating effects observed in primary cells. Taken together, these results underscore a role for ZNF521 in sustaining self-renewal of the AML immature compartment, most likely through the perturbation of the gene expression landscape which ultimately favors the expansion of MLL-AF9 transformed leukemic clones.

2022-03-24 | GSE181006 | GEO

Next generation sequencing of RNA of WT, KO and MLL-AF9 transformed HSPCS

Project description:MIR139 is a tumor suppressor and commonly silenced in Acute myeloid leukemia (AML). Reactivating the expression of MIR139 eliminates AML cells. Here, we investigated the mechanism of MIR139 gene inactivation in AML expressing the Mixed-Lineage Leukemia (MLL)-AF9 oncogene. We found that MLL-AF9-mediated repression of MIR139 is a selective event in leukemogenesis. Analyses of Histone marks revealed two well-conserved enhancer regions, which are epigenetically silenced by the Polycomb-Repressive Complex-2 (PRC2) downstream of MLL-AF9. Genomic deletion of these enhancer regions abolished transcriptional regulation of MIR139. Genome-wide knockout screens revealed the transcriptional pausing factor of RNA Polymerase-II, POLR2M, as a critical MIR139 silencing factor. Furthermore, POLR2M-binding to the MIR139 transcriptional start site induces paused transcription, which is abrogated upon PRC2 inhibition. Together, we present evidence for a POLR2M-mediated MIR139 silencing mechanism, downstream of MLL-AF9 and PRC2. The findings in this study highlight the importance of the transcriptional deregulation in malignant transformation.

2021-11-01 | GSE160404 | GEO

Next generation sequencing of DNA of WT or Mir139KO MLL-AF9 cells transduced with lenticrisprv2 gecko library

2021-11-01 | GSE160403 | GEO

Next generation sequencing of RNA of MLL-AF9-139 cells treated with and without Doxycycline

2021-11-01 | GSE160405 | GEO

Leukemias of different origins

Project description:We generated MLL-AF9 mediated murine leukemias that originate either from hematopoietic stem or committed progenitors cells. The luekemia stem cell fraction in these two type of leukemias shared exactly the same immunophenotype but their genetic programs differ. Total RNA from HSC(KLS), CMP, MEP, and GMP, and from leukemia stem cells (LGMP) was isolated and hybridized to Affymetrix expresison microarrays.

2011-03-31 | E-GEOD-18483 | biostudies-arrayexpress

Expression data of MLL-AF9-transformed murine leukemia progenitor cells, following treatment with UNC1999, a dual Ezh1 and Ezh2 inhibitor, or knockdown of EED

Project description:Ezh2 and EZH1 are histone H3 lysine 27 specific methyltransferase. Their hyperactive mutations and overexpression were found in cancer including various hematological malignancies. UNC1999 is a highly selective inhibitor for both enzymes. It suppresses H3K27 tri- and di-methylation globally and inhibits growth of MLL-rearranged acute leukemia cell lines. UNC2400, a di-methylated derivative of UNC1999, is employed an inactive analog compound for assessment of off-target effects. EED knockdown was used to demonstrate gene targets of PRC2. Here we performed microarray analysis in MLL-AF9 transformed acute leukemia cells following treatment with DMSO, UNC2400 or UNC1999, or after induction of EED shRNA (Renilla shRNA as control). This study allows us to identify UNC1999-responsive gene signatures as well as their overlap with PRC2 targets in MLL-AF9-bearing leukemia cells. We analyzed 5 of DMSO-treated, 5 of UNC2400 (inactive analog of UN1999)-treated, and 6 of UNC1999-treated MLL-AF9 leukemia cell samples to identify UNC1999-responsive gene signatures. We also performed microarray in 3 of shRNA control lines (Renilla or Ren) and 3 of shEED lines to identify downstream targets of PRC2 complex in MLL-AF9 leukemia cells.

2014-10-10 | E-GEOD-62198 | biostudies-arrayexpress

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