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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. 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.

ORGANISM(S): Mus musculus

SUBMITTER: Junwei Shi

PROVIDER: E-GEOD-34183 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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.

2013-07-01 | GSE34183 | GEO

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

Expression data from murine Tet-off MLL-AF9/Ras acute myeloid leukemia cell lines following withdrawal of MLL-AF9

Project description:To explore oncogene addiction programs in a genetically defined leukemia context we developed an AML mouse model driven by a conditional MLL-AF9 allele together with oncogenic Ras, which enabled us to examine the consequences of MLL-AF9 inhibition in established disease. In order to produce a tightly regulated system that was easy to monitor, we constructed two retroviral vectors containing dsRed-linked MLL-AF9 under control of a tetracycline response element promoter, and KrasG12D or NrasG12D linked to the “Tet-off” tet-transactivator, which activates TRE expression in a doxycycline repressible manner. Leukemias were generated by retroviral cotransduction of both vectors into hematopoietic stem and progenitor cells, which were transplanted into syngeneic mice. Cells harboring both constructs induced aggressive myelomonocytic leukemia. Five independent primary leukemia cell lines were established from bone marrow of terminal mice. Treatment of these lines with doxycycline rapidly turned off MLL-AF9 expression, and induced terminal myeloid differentiation and complete disease remission in vivo. To identify molecular mechanisms underlying addiction to MLL-AF9, we analyzed global gene expression changes following doxycycline-induced suppression of MLL-AF9. Independent primary acute myeloid leukemia lines induced by cotransduction of Tet-off MLL-AF9 together with either KrasG12D or NrasG12D were grown in culture and treated with doxycycline for 6 days to inactivate MLL-AF9 expression. In addition, primary acute myeloid leukemia lines with constitutive MLL-AF9 and KrasG12D were included to control for the effects of doxycycline. Untreated and treated cells were harvested for RNA extraction and hybridization to Affymetrix arrays.

2011-08-04 | E-GEOD-30746 | biostudies-arrayexpress

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

RNA sequencing expression analysis of murine Tet-off MLL-AF9;NRAS acute myeloid leukemia cells over-expressing Id2 and upon MLL-AF9 withdrawal

Project description:We investigated the role of the transcriptional regulator Id2 in the context of MLL-rearranged acute myeloid leukemia (AML). Using an AML mouse model driven by tet-regulated MLL-AF9 co-expressed with oncogenic NRASG12D (Tet-off MLL-AF9), we demonstrated that MLL-AF9 regulates the E protein pathway by suppressing Id2, while activating the expression of its target E2-2. Moreover, we found that Id2 over-expression in Tet-Off MLL-AF9 AML cells in vitro partially phenocopies MLL-AF9 depletion and results inhibition of leukemia growth, loss of leukemia stem cell-associated gene expression pattern and induction of differentiation. To compare gene expression changes associated with enforced Id2 expression and MLL-AF9 withdrawal, RNA sequencing analysis was performed on Tet-off MLL-AF9 cells transduced with an Id2 over-expressing or a control vector, or upon MLL-AF9 dox-inducible knock-down. Primary AMLs driven by Tet-off inducible MLL/AF9 expression linked to dsRED reporter, in association with oncogenic NRASG12D (Tet-off MLL-AF9) were generated by reconstituting lethally irradiated congenic mice with foetal liver cells co-transduced with a Tet-Off-MLL-AF9-dRED retroviral vector and a second vector co-expressing NRASG12D together with the Tet-Off responsive transcriptional activator. RNA sequencing analysis sequencing analysis was performed on Tet-Off MLL-AF9/dsRED+ AML cells treated in vitro with doxycycline (DOX) for 4 days to inactivate MLL-AF9 expression or left untreated (UT). For the Id2 over-expression experiment, Tet-Off MLL-AF9/dsRED+ AML cells were transduced in vitro with an Id2-GFP or a control-GFP retroviral vector. Viable GFP-positive cells were FACS-sorted 2 days after transduction and used for RNA sequencing analysis.

2016-06-29 | E-GEOD-68462 | biostudies-arrayexpress

RNA sequencing expression analysis of murine MLL-AF9;NRAS acute myeloid leukemia cells silenced for E2-2.

Project description:We investigated the role of the transcriptional regulators Id2 and E2-2 (encoded by Tcf4) in the context of MLL-rearranged acute myeloid leukemia (AML). Using an AML mouse model driven by a Tet-off inducible MLL-AF9 allele co-expressed with oncogenic NRASG12D, we demonstrated that MLL-AF9 regulates the E protein pathway by suppressing Id2, while activating the expression of its target E2-2. Moreover, we found that Id2 over-expression in MLL-AF9 AML cells results inhibition of leukemia growth, loss of leukemia stem cell-associated gene expression pattern and induction of differentiation. E2-2 silencing phenocopies Id2 overexpression in MLL-AF9-AML cells. To study the gene expression changes associated with E2-2 depletion in the context of MLL-rearranged AML, RNA sequencing analysis was performed on MLL-AF9;NRAS AML cells transduced with vectors expressing hairpins against E2-2 (shTcf4#654 and shTcf4#3646) or a control hairpin against Renilla luciferase (shRen). Primary AMLs driven by MLL/AF9 expression linked to cherry reporter, in association with oncogenic NRASG12D (MLL/AF9;NRAS) were generated by reconstituting lethally irradiated congenic mice with fetal liver cells co-transduced with the MSCV-MLL/AF9-IRES-cherry retroviral vector and a second vector co-expressing NRASG12D together with luciferase (MSCV-luciferase-IRES-NRASG12D). RNA sequencing analysis sequencing analysis was performed on MLL-AF9;NRAS AML cells transduced in vitro with vectors expressing hairpins against E2-2 (shTcf4#654 and shTcf4#3646) or a control hairpin against Renilla luciferase (shRen) linked to the reporter GFP. Viable GFP-positive cells were FACS-sorted 2 days after transduction and used for RNA sequencing analysis. Two independent biological replicates of the experiment were used for the RNA sequencing (9-5-14 and 14-4-14).

2016-06-29 | E-GEOD-80745 | biostudies-arrayexpress

Expression data from murine Tet-off MLL-AF9/Ras acute myeloid leukemia cell lines following withdrawal of MLL-AF9

2011-08-05 | GSE30746 | GEO