Aberrant chromatin acetylation in MLL-AF9 leukemia mediates the response to HDAC inhibition (ChIP-Seq)
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ABSTRACT: We studied the chromatin modification patterns induced by the presence of the MLL-AF9 fusion protein in a model of human hematopoietic stem/progenitor cells (HSPC) transduced with retrovirus expressing MLL-AF9cDNA (HSPC-MA9). Comparative ChIP-seq analysis between HSPC-MA9 and control HSPC, revealed a massive hyperacetylation of histones that was consistent with the transcriptional profile in the presence of MLL-AF9 fusion protein. Furthermore, we identified 66 MLL-AF9 targets, and found that H4ac was present along with H3K4me3 and H3K79me2 chromatin marks in over 50% of the MLL-AF9 target genes. Examination of histone aceylation and methylation changes upon expression of MLL-AF9 fusion protein in human hematopoietic stem/progenitor cells.
Project description:We investigated the response of acute myeloid cells (AML) expressing MLL-AF9 fusion gene to the pan-HDACi panobinostat (LBH589), and found that low conentrations of panobinostat lead to MLL-AF9 cell toxicity and rapid changes in gene expression. Human hematopoietic stem/progenitor cells (HSPC) expressing MLL-AF9 fusion protein (Wei et al, Cancer Cell 2008) were cultured with 30 nM panobinostat during 6 and 24 hours. The different gene expression between cells treated and untreated was studied by gene expression analysis. Three independent HSPC-MA9 clones were used, for each two replicates of cells after culture with 30 nM panobinostat for 6 and 24 hours and one untreated were used. A total of 16 samples were analyzed.
Project description:This study report that miR-150, a key hematopoietic regulatory microRNA (miRNA) and one of the most downregulated miRNAs in MLL-associated leukemias, acts as a tumor suppressor to block the leukemogenic potency of leukemic stem cells. When expression of miR-150 was restored, a significantly suppressed leukemic stem cell potency of MLL-AF9 cells was observed both in vivo and in vitro. To investigate the tumor suppressive function of miR-150 in MLL-AF9 cells, we isolated three batches of MLL-AF9 cells infected with MDH empty vector or MDH-miR-150 expression retrovirus. Total RNA were extracted and applied for Agilent array analysis. Gene profiling analysis demonstrated that elevated miR-150 altered various aspects of gene expression patterns in MLL-AF9 cells, including stem cell signatures, cancer pathways, and cell survival. miR-150-MLL-AF9 and MDH-MLL-AF9 isolated cells were compared for gene expression patterns. Triplicates using three batches of FACS sorted cells were compared in pairs on the array. MDH-MLL-AF9 samples were labeld with Cy3 and miR-150-MLL-AF9 samples were labled with Cy5.
Project description:We studied the chromatin modification patterns induced by the presence of the MLL-AF9 fusion protein in a model of human hematopoietic stem/progenitor cells (HSPC) transduced with retrovirus expressing MLL-AF9cDNA (HSPC-MA9). Comparative ChIP-seq analysis between HSPC-MA9 and control HSPC, revealed a massive hyperacetylation of histones that was consistent with the transcriptional profile in the presence of MLL-AF9 fusion protein. Furthermore, we identified 66 MLL-AF9 targets, and found that H4ac was present along with H3K4me3 and H3K79me2 chromatin marks in over 50% of the MLL-AF9 target genes.
Project description:Using a mouse model of human MLL-AF9 leukemia, we identified the lysine-specific demethylase KDM1A (LSD1 or AOF2) as an essential regulator of leukemia stem cell (LSC) potential. KDM1A acts at genomic loci bound by MLL-AF9 to sustain expression of the associated oncogenic program, thus preventing differentiation and apoptosis. In vitro and in vivo pharmacologic targeting of KDM1A using tranylcypromine analogues active in the nanomolar range phenocopied Kdm1a knockdown in both murine and primary human AML cells exhibiting MLL translocations. By contrast, the clonogenic and repopulating potential of normal hematopoietic stem and progenitor cells was spared. Our data establish KDM1A as a key effector of the differentiation block in MLL leukemia which may be selectively targeted to therapeutic effect. To investigate the effects of Kdm1a KD on histone modifications, we performed chromatin immunoprecipitation followed by next-generation sequencing (ChIP-Seq) in control and Kdm1a KD MLL-AF9 AML cells for dimethyl-H3K4 and dimethyl-H3K9, as well as for trimethyl-H3K4 and trimethyl-H3K9. Dimethyl-H3K4 and dimethyl-H3K9 are targeted for demethylation by KDM1A. For each of these histone modifications, we compared the mean ChIP-Seq signal across and around protein coding genes bound by the MLL-AF9 oncoprotein (Bernt et al., 2011) with the mean signal from genes not bound by MLL-AF9 expressed at high, middle or low levels.
Project description:This SuperSeries is composed of the following subset Series: GSE36346: The histone demethylase KDM1A sustains the oncogenic potential of MLL-AF9 leukemia stem cells (ChIP-Seq data) GSE36347: The histone demethylase KDM1A sustains the oncogenic potential of MLL-AF9 leukemia stem cells (expression data) Refer to individual Series
Project description:MLL-fusions represent a large group of leukemia drivers, whose diversity originates from the vast molecular heterogeneity of C-terminal fusion partners of MLL protein. While studies of selected MLL-fusions have revealed critical molecular pathways, unifying mechanisms across all MLL-fusions remain poorly understood. We present the first comprehensive survey of protein-protein interactions of seven distantly related MLL-fusion proteins: MLL-AF1p, MLL-AF4, MLL-AF9, MLL-CBP, MLL-EEN, MLL-ENL and MLL-GAS7.
Project description:Despite the advanced understanding of disease mechanisms, the current therapeutic regimens fail to cure most patients with acute myeloid leukemia (AML). In the present study, we address the role of protein synthesis control in leukemia function and leukemia propagation. Using a transgenic eIF6 mouse strain that permits inducible and graded regulation of ribosomal subunit joining, we have generated a murine model of MLL-AF9 acute myeloid leukemia where the expression of transgenic eIF6 is doxycycline-inducible. Using this model system, we have performed scRNA-seq expression analysis to study the impact of eIF6 overexpression on leukemia cell function. scRNA-seq was performed using the 10x Chromium Next GEM Single Cell 3ʹ platform. BM cells were harvested from leukemia-engrafted mice that were administered doxycycline for six days and viable GFP+ leukemia cells were sorted into PBS containing 0.05 % BSA following the manusfacturer’s protocol. 5 samples: 2 control and 3 eIF6 overexpression.
Project description:We investigated the response of acute myeloid cells (AML) expressing MLL-AF9 fusion gene to the pan-HDACi panobinostat (LBH589), and found that low conentrations of panobinostat lead to MLL-AF9 cell toxicity and rapid changes in gene expression. Human hematopoietic stem/progenitor cells (HSPC) expressing MLL-AF9 fusion protein (Wei et al, Cancer Cell 2008) were cultured with 30 nM panobinostat during 6 and 24 hours. The different gene expression between cells treated and untreated was studied by gene expression analysis.
Project description:We conducted RNA sequencing with poly A RNA isolated from spleen mononuclear cells of MLL-AF9 (MA9) mouse models after treatment with PBS and FTO inhibitor CS1.
Project description:The MLL gene is a common target of chromosomal translocations found in human leukemia. MLL-fusion leukemias are consistently poor prognosis. One of the most common translocation partners is AF9 (a.k.a. MLLT3). MLL-AF9 recruits DOT1L, a histone 3 lysine 79 methyltransferase (H3K79me1/me2/me3), leading to aberrant gene transcription. We show that DOT1L has three AF9 binding sites, and present the NMR solution structure of a DOT1L-AF9 complex. We generated structure-guided point mutations with graded effects on recruitment of DOT1L to MLL-AF9. ChIP-Seq analyses of H3K79me2 and H3K79me3 show that graded reduction of the DOT1L interaction with MLL-AF9 results in selective losses in H3K79me2 and me3 marks at MLL-AF9 target genes. Furthermore, the degree of DOT1L recruitment defines the level of MLL-AF9 hematopoietic transformation. Hematopoietic progenitor cells isolated from mouse bone marrow were transduced with retrovirus expressing either wildtype MLL-AF9 (WT), mutants, MLL-AF9 (D544R) and MLL-AF9 (D546R). ChIP-Seq analyses were performed on these wildtype and mutant cells using H3K79me2 and H3K79me3 antibodies. 3 samples corresponding to ChIP-Seq with H3K79me2 antibody: 1) MLL-AF9 (WT) 2) MLL-AF9 (D544R) 3) MLL-AF9 (D546R) 3 Samples Corresponding to ChIP-Seq with H3K79me3 antibody: 4) MLL-AF9 (WT) 5) MLL-AF9 (D544R) 6) MLL-AF9 (D546R)