Project description:Using an acute myeloid leukemia (AML) mouse model driven by tet-regulated MLL-AF9 (fusion between the gene MLL1 (KMT2A/MLL) and MLLT3 (AF9)) co-expressed with oncogenic NRASG12D (Tet-off MLL-AF9), we investigated the effect of modulating the expression of the MLL-AF9 fusion oncogene on the transcriptome and proteome of established murine AML. Treatment in vitro or in vivo of these Tet-off MLL-AF9 AMLs with doxycycline (DOX) results in the efficient down-regulation of the expression of the driver oncogene MLL-AF9. RNA sequencing analysis was performed on primary Tet-Off MLL-AF9 AML cells obtained from the spleen of leukemic animals and cultured in vitro for either 2 or 4 days in the presence of doxycycline (1μg/ml) (DOX= down-regulation of MLL-AF9) or left untreated (UT).
Project description:Using RNA-seq we examined the transcriptional changes following MLL-AF9 degradation in MLL-AF9-HA-FKPB12 transformed murine (BM2222) and human (HCB1) cells. We also examined transcriptional changes in human MLL-AF9-HA-FKBP12 transformed cells (HCB1) and MOLM13 cells in response to DOT1L inhibition, Menin-MLL inhibition, and the combination of DOT1L and Menin-MLL inhibition. Lastly we assessed gene expression in murine neutrophils isolated directly from mice.
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.
Project description:This SuperSeries is composed of the following subset Series: GSE34959: Expression profiling of primary wild type (WT), Ezh2-null and Eed-null murine MLL-AF9 AML GSE34961: Expression profiling of secondary wild type (WT) and Ezh2-null murine MLL-AF9 AML GSE34962: Epigenetic profiling of WT and Ezh2-null MLL-AF9 murine leukemic cells Refer to individual Series
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.
Project description:Mutant RAS oncoproteins activate signaling molecules that drive oncogenesis in multiple human tumors including acute myelogenous leukemia (AML). However, the specific function of these pathways in AML is unclear. To elucidate the downstream functions of activated NRAS in AML, we employed a murine model of AML harboring Mll-AF9 and NRASG12V. We found that NRASG12V enforced leukemia self-renewal gene expression signatures and was required to maintain an MLL-AF9 and MYB-dependent gene expression program. In a multiplexed analysis of RAS-dependent signaling intermediates, the leukemia stem cell compartment was preferentially sensitive to RAS withdrawal. Use of RAS-pathway inhibitors showed that NRASG12V maintained leukemia self-renewal through mTOR and MEK pathway activation, implicating these pathways as potential targets for cancer stem cell-specific therapies. Mice harboring NRASG12V/Mll-AF9 AML were treated with doxycyline to abolish NRASG12V expression. Leukemia samples were harvested at 24 hour intervals after doxycyline treatment.
Project description:Mutant RAS oncoproteins activate signaling molecules that drive oncogenesis in multiple human tumors including acute myelogenous leukemia (AML). However, the specific function of these pathways in AML is unclear. To elucidate the downstream functions of activated NRAS in AML, we employed a murine model of AML harboring Mll-AF9 and NRASG12V. We found that NRASG12V enforced leukemia self-renewal gene expression signatures and was required to maintain an MLL-AF9 and MYB-dependent gene expression program. In a multiplexed analysis of RAS-dependent signaling intermediates, the leukemia stem cell compartment was preferentially sensitive to RAS withdrawal. Use of RAS-pathway inhibitors showed that NRASG12V maintained leukemia self-renewal through mTOR and MEK pathway activation, implicating these pathways as potential targets for cancer stem cell-specific therapies. Primary NRASG12V-Mll-AF9 AML cells were treated in vitro for 24 hours with Ras-pathway inhibitors. RNA was extracted from these cells and submitted for RNA sequencing.
Project description:Disulfiram and niclosamide were identified as drugs that induced depletion of an MLL-AF9-luciferase fusion protein in THP-1 AML cells, in a bioluminescence sreen. MLL-fusion protein depletion was confirmed in AML and ALL cell lines expressing different MLL-fusion proteins. Combination of disulfiram with niclosamide was found to enhance depletion of MLL-fusion proteins. To investigate whether this enhanced depletion resulted in increased suppression of downstream target genes. MLL-AF6 expressing SHI-1 cells were exposed to disulfiram/copper, nciclosamide or combined drugs. SHI-1 cells were treated for 16 hours with 0.3uM disulfiram / 1uM copper, 5uM niclosamide or combined drugs and RNAseq performed on isolated RNA.
Project description:A knockdown screen of chromatin regulatory genes in human THP1 MLL-AF9 AML cells identified EPC1 and EPC2 as required for cell survival. Normal myeloid progenitor cells did not require EPC1 or EPC2 for their function. To determine the transcriptional consequences of EPC knockdown, normal murine granulocyte-macrophage progenitor (GMP) cells, or murine MLL-AF9 AML GMP-like cells, were FACS purified from mice and infected with lentiviral vectors targeting EPC1 or EPC2 for knockdown, or a non-tageting control. 42 hours later knockdown or control cells were FACS purified and exon array analysis was performed on the sorted populations.
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.