Project description:Activation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development We generated either MLL-AF9 mediated murine leukemias that originate from committed progenitor (GMP) cells or Hoxa9/Meis1a mediated murine leukemias that originate from hematopoietic stem cells (HSC). The leukemia stem cell fraction in these two type of leukemias shared a common self-renewal pathway with normal hematopoietic stem cells. Keywords: Cell type comparison Total RNA from HSC (KLS), CMP, and GMP, and from leukemia stem cells (LGMP) was isolated and hybridized to Affymetrix expresison microarrays.
Project description:Activation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development We generated either MLL-AF9 mediated murine leukemias that originate from committed progenitor (GMP) cells or Hoxa9/Meis1a mediated murine leukemias that originate from hematopoietic stem cells (HSC). The leukemia stem cell fraction in these two type of leukemias shared a common self-renewal pathway with normal hematopoietic stem cells. Keywords: Cell type comparison
Project description:High-resolution proteomic analysis of acute myeloid leukemia (AML) stem cells identified phospholipase C- and Ca++-signaling pathways to be differentially regulated in AML1-ETO (AE) driven leukemia. Phospholipase C gamma 1 (Plcg1) could be identified as a direct target of the AE fusion. Genetic Plcg1 inactivation abrogated disease initiation by AE, reduced intracellular Ca++-release and inhibited AE-driven self-renewal programs. In AE-induced leukemia, Plcg1 deletion significantly reduced disease penetrance, number of leukemia stem cells and abrogated leukemia development in secondary recipient hosts. In human AE-positive leukemic cells inactivation of Plcg1 reduced colony formation and AML development in vivo. In contrast, Plcg1 was dispensable for maintenance of murine and human hematopoietic stem- and progenitor cells (HSPCs). Pharmacologic inhibition of Ca++-signaling downstream of Plcg1 resulted in impaired proliferation and self-renewal capacity in AE-driven AML. Thus, the Plcg1 pathway represents a novel specific vulnerability of AE-driven leukemia and poses an important new therapeutic target.
Project description:Leukemia stem cells are characterized by aberrant self-renewal capacity. Targeting oncogenic fusions that mediate this aberrant self-renewal capacity remains a therapeutic challenge. The t(8;21) translocation, resulting in the oncogenic fusion AML1-ETO (AE, RUNX1-RUNXT1) is among the most common chromosomal rearrangements found in acute myeloid leukemia (AML). By conducting high-resolution proteomic analysis on myeloid leukemia stem cells we identified Phospholipase C- and Ca++-signaling pathways to be differentially regulated in AE/t(8;21) AML. Phospholipase C gamma 1 (Plcg1) was specifically, and highly expressed in t(8;21) AML and could be identified as a direct target of the AML1(RUNX1)-ETO fusion. Genetic inactivation of Plcg1 resulted in abrogation of disease initiation by AE, reduction of intracellular Ca++ release and loss of AE-driven self-renewal programs. Plcg1 deletion after onset of AE-induced leukemia significantly reduced disease penetrance, number of leukemia stem cells and resulted in abrogation of leukemia development in secondary recipients. Inactivation of Plcg1 in human AE-positive AML cells by RNAi reduced colony formation and AML development in vivo. In contrast, Plcg1 was dispensable for steady state hematopoiesis and maintenance of murine and human hematopoietic stem cells (HSC). Translationally, we used pharmacologic inhibition of Ca++ signaling downstream of Plcg1 in AE-driven AML and this resulted in impaired proliferation and self-renewal capacity. The Plcg1 pathway represents a novel, specific vulnerability of AE-driven leukemia and represents an important new therapeutic target.
Project description:Leukemia stem cells are characterized by aberrant self-renewal capacity. Targeting oncogenic fusions that mediate this aberrant self-renewal capacity remains a therapeutic challenge. The t(8;21) translocation, resulting in the oncogenic fusion AML1-ETO (AE, RUNX1-RUNXT1) is among the most common chromosomal rearrangements found in acute myeloid leukemia (AML). By conducting high-resolution proteomic analysis on myeloid leukemia stem cells we identified Phospholipase C- and Ca++-signaling pathways to be differentially regulated in AE/t(8;21) AML. Phospholipase C gamma 1 (Plcg1) was specifically, and highly expressed in t(8;21) AML and could be identified as a direct target of the AML1(RUNX1)-ETO fusion. Genetic inactivation of Plcg1 resulted in abrogation of disease initiation by AE, reduction of intracellular Ca++ release and loss of AE-driven self-renewal programs. Plcg1 deletion after onset of AE-induced leukemia significantly reduced disease penetrance, number of leukemia stem cells and resulted in abrogation of leukemia development in secondary recipients. Inactivation of Plcg1 in human AE-positive AML cells by RNAi reduced colony formation and AML development in vivo. In contrast, Plcg1 was dispensable for steady state hematopoiesis and maintenance of murine and human hematopoietic stem cells (HSC). Translationally, we used pharmacologic inhibition of Ca++ signaling downstream of Plcg1 in AE-driven AML and this resulted in impaired proliferation and self-renewal capacity. The Plcg1 pathway represents a novel, specific vulnerability of AE-driven leukemia and represents an important new therapeutic target.
Project description:In an effort to identify novel drugs targeting fusion-oncogene induced acute myeloid leukemia (AML), we performed high-resolution proteomic analysis. In AML1-ETO (AE) driven AML we uncovered a deregulation of phospholipase C (PLC) signaling. We identified PLCgamma 1 (PLCG1) as a specific target of the AE fusion protein which is induced after AE binding to intergenic regulatory DNA elements. Genetic inactivation of PLCG1 in murine and human AML inhibited AML1-ETO dependent self-renewal programs, leukemic proliferation, and leukemia maintenance in vivo. In contrast, PLCG1 was dispensable for normal hematopoietic stem- and progenitor cell function. These findings are extended to and confirmed by pharmacologic perturbation of Ca++-signaling in AML1-ETO AML cells, indicating that the PLCG1 pathway poses an important therapeutic target for AML1-ETO positive leukemic stem cells.
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: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 12 hour intervals after doxycyline treatment. RNA was extracted from these samples and submitted for gene expression microarray 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. Primary leukemia cells harvested from spleens were sorted into immunophenotypic subpopulations (Mac-1High, Mac-1LowKit–Sca-1–, Mac-1LowKit+Sca-1–, and Mac-1LowKit+Sca-1+). RNA was extracted from this subpopulations of cells and submitted for RNA sequencing.