The Wnt/beta-catenin pathway is required for the development of leukemia stem cells in MLL-AF9 AML.
KRas(G12D)-evoked leukemogenesis does not require β-catenin.
Specimen part
View SamplesActivation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development
The Wnt/beta-catenin pathway is required for the development of leukemia stem cells in AML.
Specimen part
View SamplesLeukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biological characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias utilizing RNAi. Gene expression profiling after HOXA9 suppression demonstrated co-downregulation of a program highly expressed in human MLL-AML (this study) and murine MLL-leukemia (Krivtsov et al. 2006) stem cells including HOXA10, MEIS1, PBX3 and MEF2C. Our data indicates an important role for HOXA9 in human MLL-rearranged leukemias, and suggests targeting HOXA9 or downstream programs may be a novel therapeutic option.
HOXA9 is required for survival in human MLL-rearranged acute leukemias.
No sample metadata fields
View SamplesEnhancer activation is a critical step for gene activation. Here we report a novel epigenetic crosstalk at enhancers between the UTX (H3K27 demethylase)-MLL4 (H3K4 methyltransferase) complex and the histone acetyltransferase p300. We demonstrate that UTX, in a demethylase activity-independent manner, facilitates conversion of naïve (unmarked) enhancers in embryonic stem cells to an active (H3K4me1+/H3K27ac+) state by recruiting and coupling the enzymatic functions of MLL4 and p300. Loss of UTX leads to attenuated enhancer activity, characterized by reduced levels of H3K4me1 and H3K27ac as well as impaired transcription. The UTX-MLL4 complex enhances p300-dependent H3K27 acetylation through UTX-dependent stimulation of p300 recruitment while MLL4-mediated H3K4 monomethylation, reciprocally, requires p300 function. Importantly, MLL4-generated H3K4me1 further enhances p300-dependent transcription. This work reveals a previously unrecognized cooperativity among enhancer-associated chromatin modulators, including a unique function for UTX, in establishing an “active enhancer landscape” and defines a mechanism for the joint deposition of H3K4me1 and H3K27ac. Overall design: RNA-sequencing of mouse ES cells.
A UTX-MLL4-p300 Transcriptional Regulatory Network Coordinately Shapes Active Enhancer Landscapes for Eliciting Transcription.
Subject
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemia initiating cells (LICs) of acute myeloid leukemia (AML) may arise from self-renewing hematopoietic stem cells (HSCs) and from committed progenitors. However, it remains unclear how leukemia-associated oncogenes instruct LIC formation from cells of different origins and if differentiation along the normal hematopoietic hierarchy is involved. Here, using murine models with the driver mutations MLL-AF9 or MOZ-TIF2, we found that regardless of the transformed cell types, myelomonocytic differentiation to the granulocyte macrophage progenitor (GMP) stage is critical for LIC generation. Blocking myeloid differentiation through disrupting the lineage-restricted transcription factor C/EBPa eliminates GMPs, blocks normal granulopoiesis, and prevents AML development. In contrast, restoring myeloid differentiation through inflammatory cytokines rescues AML transformation. Our findings identify myeloid differentiation as a critical step in LIC formation and AML development, thus guiding new therapeutic approaches.
Hematopoietic Differentiation Is Required for Initiation of Acute Myeloid Leukemia.
Specimen part
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesWe created a mouse model where conditional expression of physiologic levels of an Mll-AF4 fusion oncogene induces development of acute lymphoblastic (ALL) or acute myeloid leukemias (AML). Immunophenotypic and gene expression analysis of the ALL cells demonstrated bone marrow replacement with B-precursor cells which express a gene expression profile that has significant overlap with profiles in human MLL-rearranged ALL.
H3K79 methylation profiles define murine and human MLL-AF4 leukemias.
Specimen part
View Samples