Project description:In this study, we use pre-malignant cells from different Cebpa mutant acute myeloid leukemia (AML) models. We have used conditional KO models (CreLoxP) and isolated hematopoietic cells shortly after induction of recombination, in order to look at pre-leukemic cells, which have acquired the first hit, but not yet undergone full malignant transformation. We have sorted granulocyte-macrophage progenitors (GMPs) and the more immature population pre-granulocyte-macrophages (preGMs) from pre-leukemic mice. We analyzed gene-expression profiles in order to find deregulated genes, which make the cells more prone to undergo transformation.
Project description:The key myeloid transcription factor (TF) CEBPA is frequently mutated in acute myeloid leukemia (AML), but the molecular ramifications of this leukemic driver mutation remain elusive. To investigate CEBPA mutant AML, we compared gene expression changes in human CEBPA mutant AML and in the corresponding CebpaLp30 mouse model, and identified a conserved cross-species transcriptional program. ChIP-seq revealed aberrantly activated enhancers, exclusively occupied by the leukemia-associated CEBPA-p30 isoform. One leukemic-enhancer upstream of Nt5e, encoding CD73, was physically and functionally linked to this conserved AML gene, and could be activated by CEBPA. Targeting of CD73-adenosine signaling increased AML survival in transplanted mice. Our data indicate a first-in-class link between a TF cancer driver mutation and a druggable, direct transcriptional target.
Project description:IDH1 and IDH2 are frequently mutated in various cancers, including acute leukemias. However, the distinct mechanisms by which mutant IDH1 or IDH2 drive hematopoietic neoplasms remain poorly understood. Here, we analyzed DNA methylation in IDH1- and IDH2-mutant AML and found neutrophil lineage-specific epigenetic alterations in IDH1-mutant cases that went along with severely impaired neutrophil differentiation. Transcriptional analysis of normal hematopoiesis in humans and mice revealed a strong physiological upregulation of IDH1/Idh1 in myeloid progenitors. To study the functional effects of Idh1 mutations on hematopoiesis in a pre-leukemic setting, we used a genetically engineered inducible mouse model expressing a heterozygous Idh1 mutation under control of the endogenous promotor. Our study revealed a cell-intrinsic block in neutrophil differentiation caused by repression of myeloid transcription programs in neutrophil progenitors. This included impaired expression of Cebpe, which encodes a key transcription factor regulating neutrophil differentiation. Reactivation of Cebpe expression, by overexpression of its upstream regulator Cebpa or following treatment with hypomethylating agents restored differentiation, indicating that the differentiation block is reversible. In summary, we found a reversible, pre-leukemic impairment of neutrophil differentiation in IDH1-mutant hematopoiesis that correlates with elevated IDH1 expression in myeloid progenitors and likely explains the strong association of IDH1 mutations with myeloid neoplasms.
Project description:IDH1 and IDH2 are frequently mutated in various cancers, including acute leukemias. However, the distinct mechanisms by which mutant IDH1 or IDH2 drive hematopoietic neoplasms remain poorly understood. Here, we analyzed DNA methylation in IDH1- and IDH2-mutant AML and found neutrophil lineage-specific epigenetic alterations in IDH1-mutant cases that went along with severely impaired neutrophil differentiation. Transcriptional analysis of normal hematopoiesis in humans and mice revealed a strong physiological upregulation of IDH1/Idh1 in myeloid progenitors. To study the functional effects of Idh1 mutations on hematopoiesis in a pre-leukemic setting, we used a genetically engineered inducible mouse model expressing a heterozygous Idh1 mutation under control of the endogenous promotor. Our study revealed a cell-intrinsic block in neutrophil differentiation caused by repression of myeloid transcription programs in neutrophil progenitors. This included impaired expression of Cebpe, which encodes a key transcription factor regulating neutrophil differentiation. Reactivation of Cebpe expression, by overexpression of its upstream regulator Cebpa or following treatment with hypomethylating agents restored differentiation, indicating that the differentiation block is reversible. In summary, we found a reversible, pre-leukemic impairment of neutrophil differentiation in IDH1-mutant hematopoiesis that correlates with elevated IDH1 expression in myeloid progenitors and likely explains the strong association of IDH1 mutations with myeloid neoplasms.
Project description:In this study, we use pre-malignant cells from different Cebpa mutant acute myeloid leukemia (AML) models. We have used conditional KO models (CreLoxP) and isolated hematopoietic cells shortly after induction of recombination, in order to look at pre-leukemic cells, which have acquired the first hit, but not yet undergone full malignant transformation.
Project description:Acute Myeloid Leukemia (AML) is a heterogeneous disease from the molecular and biological standpoints, and even patients with a specific gene expression profile may present clinical and molecular heterogeneity. We studied the epigenetic profiles of a cohort of patients that shared a common gene expression profile but differed in that only half of them harbored mutations of the CEBPA locus, while the rest presented with silencing of this gene and co-expression of certain T cell markers. DNA methylation studies revealed that these two groups of patients could be readily segregated in an unsupervised fashion based on their DNA methylation profiles alone. Furthermore, CEBPA silencing was associated with the presence of an aberrant DNA hypermethylation signature, which was not present in the CEBPA mutant group. This aberrant hypermethylation occurred more frequently at sites within CpG islands. CEBPA silenced leukemias also displayed marked hypermethylation when compared with normal CD34+ hematopoietic cells, while CEBPA mutant cases showed only mild changes in DNA methylation when compared to these normal progenitors. Biologically, CEBPA silenced leukemias presented with a decreased response to myeloid growth factors in vitro. Experiment Overall Design: Direct comparison of gene expression in leukemic blasts from 8 patients with Acute Myeloid Leukemia (AML) carrying a CEBPA mutation and 8 patients with AML without CEBPA mutation but with silencing of CEBPA expression, and with 9 samples of T Acute Lymphoblastic Leukemia (T-ALL) patients.
Project description:Acute Myeloid Leukemia (AML) is a heterogeneous disease from the molecular and biological standpoints, and even patients with a specific gene expression profile may present clinical and molecular heterogeneity. We studied the epigenetic profiles of a cohort of patients that shared a common gene expression profile but differed in that only half of them harbored mutations of the CEBPA locus, while the rest presented with silencing of this gene and co-expression of certain T cell markers. DNA methylation studies revealed that these two groups of patients could be readily segregated in an unsupervised fashion based on their DNA methylation profiles alone. Furthermore, CEBPA silencing was associated with the presence of an aberrant DNA hypermethylation signature, which was not present in the CEBPA mutant group. This aberrant hypermethylation occurred more frequently at sites within CpG islands. CEBPA silenced leukemias also displayed marked hypermethylation when compared with normal CD34+ hematopoietic cells, while CEBPA mutant cases showed only mild changes in DNA methylation when compared to these normal progenitors. Biologically, CEBPA silenced leukemias presented with a decreased response to myeloid growth factors in vitro. Keywords: DNA methylation profiling Direct comparison of DNA methylation in leukemic blasts from 8 patients with Acute Myeloid Leukemia (AML) carrying a CEBPA mutation and 8 patients with AML without CEBPA mutation but with silencing of CEBPA expression. Two control groups are included: 8 CD34+ bone marrow samples from healthy donors and 9 samples of T Acute Lymphoblastic Leukemia (T-ALL) patients.
Project description:IDH1 and IDH2 are frequently mutated in various cancers, including acute leukemias. However, the distinct mechanisms by which mutant IDH1 or IDH2 drive hematopoietic neoplasms remain poorly understood. Here, we analyzed DNA methylation in IDH1- and IDH2-mutant AML and found neutrophil lineage-specific epigenetic alterations in IDH1-mutant cases that went along with severely impaired neutrophil differentiation. Transcriptional analysis of normal hematopoiesis in humans and mice revealed a strong physiological upregulation of IDH1/Idh1 in myeloid progenitors. To study the functional effects of Idh1 mutations on hematopoiesis in a pre-leukemic setting, we used a genetically engineered inducible mouse model expressing a heterozygous Idh1 mutation under control of the endogenous promotor. Our study revealed a cell-intrinsic block in neutrophil differentiation caused by repression of myeloid transcription programs in neutrophil progenitors. This included impaired expression of Cebpe, which encodes a key transcription factor regulating neutrophil differentiation. Reactivation of Cebpe expression, by overexpression of its upstream regulator Cebpa or following treatment with hypomethylating agents restored differentiation, indicating that the differentiation block is reversible.
Project description:IDH1 and IDH2 are frequently mutated in various cancers, including acute leukemias. However, the distinct mechanisms by which mutant IDH1 or IDH2 drive hematopoietic neoplasms remain poorly understood. Here, we analyzed DNA methylation in IDH1- and IDH2-mutant AML and found neutrophil lineage-specific epigenetic alterations in IDH1-mutant cases that went along with severely impaired neutrophil differentiation. Transcriptional analysis of normal hematopoiesis in humans and mice revealed a strong physiological upregulation of IDH1/Idh1 in myeloid progenitors. To study the functional effects of Idh1 mutations on hematopoiesis in a pre-leukemic setting, we used a genetically engineered inducible mouse model expressing a heterozygous Idh1 mutation under control of the endogenous promotor. Our study revealed a cell-intrinsic block in neutrophil differentiation caused by repression of myeloid transcription programs in neutrophil progenitors. This included impaired expression of Cebpe, which encodes a key transcription factor regulating neutrophil differentiation. Reactivation of Cebpe expression, by overexpression of its upstream regulator Cebpa or following treatment with hypomethylating agents restored differentiation, indicating that the differentiation block is reversible.