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: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:Compare the gene expression profile among human CD34+ cord blood cells infected with MIGR1, MIGR1-AML1-ETO or MIGR1-AML1-ETO∆NHR1 AML1-ETO promotes the self-renewal of human hematopoietic stem/progenitor cells (HSPCs). We found deletion of NHR1 domain abrogates AML1-ETO induced expasion of HSPCs.
Project description:Compare the gene expression profile among human CD34+ cord blood cells infected with MIGR1, MIGR1-AML1-ETO or MIGR1-AML1-ETO∆NHR1 AML1-ETO promotes the self-renewal of human hematopoietic stem/progenitor cells (HSPCs). We found deletion of NHR1 domain abrogates AML1-ETO induced expasion of HSPCs. GFP+CD34+ human cord blood cells were sorted by FACS 72 hours after the infection for RNA extraction and hybridyzation for Affymetrix microarrays.
Project description:Blocking the self-renewal of pre-leukemia stem cells could prevent AML relapse. In this study we show that FOXO1 is an essential self-renewal factor in leukemic and pre-leukemic cells expressing the t(8;21)-associated oncogene AML1-ETO (AE). FOXO1 is consistently upregulated in t(8;21) AML and functions as a critical oncogenic mediator rather than a tumor suppressor. Expression of FOXO1 in human CD34+ cells promotes a pre-leukemic state, partially phenocopying the cellular and transcriptional effects of AE expression. The DNA binding ability of FOXO1 is essential for these features. AE and FOXO1 co-occupy the majority of their binding sites, whereby FOXO1 binds to multiple crucial self-renewal genes and is required for their activation. In concordance with this observation, loss of FOXO1 inhibits the long-term proliferation and clonogenicity of AE cells. Thus, increased FOXO1 represents a new mechanism for acquiring aberrant self-renewal by pre-leukemia stem cells and provides a novel target for therapeutic intervention.
Project description:To gain the underlying insight into the functional impact of AML1-ETO expressed in HSPCs, RNA-seq was performed on purified LT-HSCs and GMPs from the bone marrow (BM) of both AML1-ETO expressed (AML1/ETO) and Wild-Type (control) C57 mice. Our work suggested that AML1-ETO resulted in impaired hematopoietic reconstitution and increased self-renewal ability.The oxidative phosphorylation and glycolysis decreased significantly in AML1/ETO LT-HSCs accompanied by increased HSC quiescence and reduced cell cycling. Furthermore, it was observed that HSCs expressing AML1-ETO exhibited an increased requirement for fatty acids when they differentiated.
Project description:U937 AML cells that express an inducible AML1-ETO construct under the control of the tetracycline promoter. Microarrays used to discover an AML1-ETO signature for a GE-HTS screen to identify AML1-ETO modulators.