Project description:How the stemness of adult stem cells and cancer stem cells is regulated by environmental cues through surface receptors is poorly understood. In this gene expression analysis, we found that, in the mouse MLL-AF9 acute myeloid leukemia (AML) model, a deficiency in intracellular signaling of inhibitory receptor PIR-B resulted in increased differentiation and decreased stemness of leukemia stem cells, revealing that PIR-B supports leukemia development. Our study indicates unexpected functional significance of a classical immune inhibitory receptor in the maintenance of stemness of cancer stem cells. Total RNA obtained from wild-type MLL-AF9 LSCs compared to PirBTM MLL-AF9 LSCs
Project description:Through targeted metabolomics analysis of bulk leukemia cells and leukemia stem cells (LSCs) derived from the MLL-AF9-driven acute myeloid leukemia (AML) model, in comparison with normal granulocyte-monocyte progenitor (GMP) cells and whole bone marrow (WBM) cells from normal mice, we identified enhanced purine metabolism in AML LSCs. Pharmacological targeting of the purine metabolism using mycophenolate mofetil (MMF) resulted in decreased levels of purine metabolites crucial for nucleolus rRNA synthesis. Importantly, inhibition of purine metabolism or disruption of the nucleolus rRNA synthesis, achieved by inhibiting pol I activity with CX-5461, triggered myeloid differentiation in the MLL-AF9-driven AML LSCs. These findings unveil a regulatory axis involving purine metabolism and nucleolar rRNA synthesis in maintaining AML LSC activity.
Project description:The genetic programs that promote retention of self-renewing leukemia stem cells (LSCs) at the apex of cellular hierarchies in acute myeloid leukemia (AML) are not known. In a mouse model of human AML, LSCs exhibit variable frequencies that correlate with the initiating MLL oncogene and are maintained in a self-renewing state by a transcriptional sub-program more akin to that of embryonic stem cells (ESCs) than adult stem cells. The transcription/chromatin regulatory factors Myb, Hmgb3 and Cbx5 are critical components of the program and suffice for Hoxa/Meis-independent immortalization of myeloid progenitors when co-expressed, establishing the cooperative and essential role of an ESC-like LSC maintenance program ancillary to the leukemia initiating MLL/Hox/Meis program. Enriched expression of LSC maintenance and ESC-like program genes in normal myeloid progenitors and poor prognosis human malignancies links the frequency of aberrantly self-renewing progenitor-like cancer stem cells to prognosis in human cancer. Experiment Overall Design: Samples are from five separate cohorts of mice where leukemia was initiated using distinct MLL fusion oncogenes: MLL-AF1p (n=9), MLL-AF10 (n=8), MLL-GAS7 (n=5), MLL-AF9 (n=5) and MLL-ENL (n=7). Four normal BM samples were also used as controls.
Project description:Targeted metabolomics analysis of bulk leukemia cells and leukemia stem cells (LSCs) derived from the MLL-AF9-driven acute myeloid leukemia (AML) model, and normal granulocyte-monocyte progenitor (GMP) cells and whole bone marrow (WBM) cells from healthy mice, revealed an enhanced purine metabolism in AML LSCs. Inhibiting the purine biosynthetic pathway using mycophenolate mofetil (MMF) promoted myeloid differentiation and induced alterations in the chromatin accessibility landscape. These findings underscore the pivotal role of purine metabolism in regulating LSC activity.
Project description:Acute myeloid leukemia (AML) is initiated and propagated by leukemia stem cells (LSCs), a self-renewing population of leukemia cells. Here we performed an in vivo CRISPR screen and identified the facilitated glucose transporter type 1 (GLUT1) as a critical metabolic dependency for murine MLL::AF9 LSCs. GLUT1 disruption by genetic ablation or by pharmacological inhibition with BAY-876 led to suppression of leukemia progression and improved survival in an MLL::AF9 mouse model of AML. Glut1 inhibition further resulted in glycolytic suppression, decreased levels of tricarboxylic cycle intermediates, and elevated levels of amino acids. These changes in metabolic profile coincided with increased autophagic activity and differentiation of AML cells. Notably, dual inhibition of GLUT1 and oxidative phosphorylation exhibited synergistic anti-leukemic effects in human AML cells. Collectively, these findings increase our understanding of how murine LSCs are metabolically regulated and highlight GLUT1 inhibition as a promising therapeutic adjuvant approach in AML.
Project description:This SuperSeries is composed of the following subset Series: GSE30745: Expression data from murine acute myeloid leukemia (AML) cells following shRNA-mediated suppression of Myb GSE30746: Expression data from murine Tet-off MLL-AF9/Ras acute myeloid leukemia cell lines following withdrawal of MLL-AF9 Refer to individual Series
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.
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.
Project description:Beta-catenin signaling is required for establishment of leukemic stem cells (LSCs) in acute myeloid leukemia (AML), yet the upstream regulators that can augment this pathway are unknown. Through genome-wide gene expression analysis and functional studies, we identified an important role for GPR84 in MLL AML. Suppression of GPR84 significantly inhibited cell growth in pre-LSCs, reduced LSC frequency and impaired reconstitution of MLL AML. Furthermore, GPR84 conferred a growth advantage to Hoxa9/Meis1a transduced hematopoietic stem cells (HSCs). Our microarray analysis demonstrated that GPR84 overexpression significantly up-regulated a small set of MLL-fusion targets and beta-catenin co-effectors, and down-regulated a hematopoietic cell cycle inhibitor. These data thus reveal a previously unrecognized role of GPR84 in the maintenance of fully developed AML by sustaining aberrant beta-catenin signaling in LSCs. HSC-derived Hoxa9/Meis1a pre-LSCs were transduced with GPR84 cDNA or empty vector, and replated in methylcellulose supplemented with cytokines. Each group contains triplicate samples.
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.