Project description:Human leukemia cells treated with vitamin C for 12 and 72hrs and mouse hematopoietic progenitor cells with knockdown and Tet2 restoration
Project description:The genomes of myeloid malignancies are characterized by epigenomic abnormalities. Heterozygous, inactivating TET2 mutations and neomorphic IDH mutations are recurrent and mutually exclusive in acute myeloid leukemia (AML) genomes. Ascorbic Acid (vitamin C) has been shown to stimulate the catalytic activity of TET2 in vitro and thus we sought to explore its effect in a leukemic model expressing IDH1R132H. Vitamin C treatment induced an IDH1R132H dependent reduction in cell proliferation and an increase in expression of genes involved in leukocyte differentiation. Vitamin C induced differentially methylated regions (DMRs) that displayed a significant overlap with enhancers implicated in myeloid differentiation and were enriched in sequence elements for the hematopoietic transcription factors RUNX1 and PU.1. ChIP-seq of PU.1 and RUNX1 revealed a significant loss of PU.1 and increase of RUNX1 bound DNA elements accompanied by their demethylation following vitamin C treatment. Additionally, vitamin C induced an increase in H3K27ac flanking sites bound by RUNX1. Based on these data we propose a model of vitamin C induced epigenetic remodelling of transcription factor binding sites driving differentiation in a leukemic model.
Project description:We describe the proteomic composition of the secretome of fetal and adult hematopoietic progenitors during MLL-rearranged (MLLr) leukemia initiation as well as the pre-leukemic cells’ secretion response to the treatment with Fibulin (Fbln1) and/or Fibronectin (Fn1) using data-independent acquisition mass spectrometry analysis.
Project description:DNA methylation is tightly regulated throughout mammalian development and altered methylation patterns are a hallmark of cancer. The methylcytosine dioxygenase TET2 is frequently mutated in acute myeloid leukemia (AML) and has been suggested to protect CpG islands and promoters from aberrant methylation. By generating a novel mouse model of Tet2-deficient AML we show that loss of Tet2 in hematopoietic cells leads to progressive hypermethylation of active enhancer elements and altered expression of genes implicated in tumorigenesis. In contrast, CpG island and promoter methylation does not change in a Tet2-dependent manner. Furthermore, we confirm this specific enhancer hypermethylation phenotype in human AML patients. Thus, we propose that TET2 prevents leukemic transformation of hematopoietic cells by protecting enhancers from aberrant DNA methylation. Gene expression profiles from Tet2-/-;AML1-ETO and Tet2fl/fl;AML1-ETO in vitro-grown hematopoietic cells were compared using GeneChip Mouse Gene ST 2.0 Arrays (Affymetrix). Expression changes were investigated at early (passage 2) and late (passage 10) timepoints after Tet2 disruption.
Project description:DNA methylation is tightly regulated throughout mammalian development and altered methylation patterns are a hallmark of cancer. The methylcytosine dioxygenase TET2 is frequently mutated in acute myeloid leukemia (AML) and has been suggested to protect CpG islands and promoters from aberrant methylation. By generating a novel mouse model of Tet2-deficient AML we show that loss of Tet2 in hematopoietic cells leads to progressive hypermethylation of active enhancer elements and altered expression of genes implicated in tumorigenesis. In contrast, CpG island and promoter methylation does not change in a Tet2-dependent manner. Furthermore, we confirm this specific enhancer hypermethylation phenotype in human AML patients. Thus, we propose that TET2 prevents leukemic transformation of hematopoietic cells by protecting enhancers from aberrant DNA methylation. Enhanced Reduced Representation Bisulfite Sequencing (eRRBS) analysis of in vitro-grown hematopoietic cells transduced with AML1-ETO or MLL-AF9
Project description:DNA methylation is tightly regulated throughout mammalian development and altered methylation patterns are a hallmark of cancer. The methylcytosine dioxygenase TET2 is frequently mutated in acute myeloid leukemia (AML) and has been suggested to protect CpG islands and promoters from aberrant methylation. By generating a novel mouse model of Tet2-deficient AML we show that loss of Tet2 in hematopoietic cells leads to progressive hypermethylation of active enhancer elements and altered expression of genes implicated in tumorigenesis. In contrast, CpG island and promoter methylation does not change in a Tet2-dependent manner. Furthermore, we confirm this specific enhancer hypermethylation phenotype in human AML patients. Thus, we propose that TET2 prevents leukemic transformation of hematopoietic cells by protecting enhancers from aberrant DNA methylation. 5hmC-DIP-seq analysis for distribution of 5hmC in in vitro-grown hematopoietic cells transduced with AML1-ETO
Project description:DNA methylation is tightly regulated throughout mammalian development and altered methylation patterns are a hallmark of cancer. The methylcytosine dioxygenase TET2 is frequently mutated in acute myeloid leukemia (AML) and has been suggested to protect CpG islands and promoters from aberrant methylation. By generating a novel mouse model of Tet2-deficient AML we show that loss of Tet2 in hematopoietic cells leads to progressive hypermethylation of active enhancer elements and altered expression of genes implicated in tumorigenesis. In contrast, CpG island and promoter methylation does not change in a Tet2-dependent manner. Furthermore, we confirm this specific enhancer hypermethylation phenotype in human AML patients. Thus, we propose that TET2 prevents leukemic transformation of hematopoietic cells by protecting enhancers from aberrant DNA methylation. ChIP-seq analysis for distribution of H3K4me1, H3K27ac, and H3K4me3 histone marks in in vitro-grown hematopoietic cells transduced with AML1-ETO
Project description:We studied how leukemia-associated mutations subvert normal adult hematopoiesis by genetically inducing them in specifically in murine hematopoietic stem cells (HSC) followed by lineage tracing in native hosts. Leukemia-initiating mutations such as Tet2 or Dnmt3a deletions did not increase the net HSC contribution in the steady state, whereasTet2 deletion slightly accelerated HSC contribution to myeloid lineages following microbial stimulation. In contrast, the leukemia-transforming KrasG12D mutation dramatically accelerated the contribution of mutant HSC to all hematopoietic lineages, rapidly creating a pre-leukemic state. The acceleration was mediated by KrasG12D-carrying multipotent progenitors (MPP) that rapidly outcompeted normal MPP and showed increased proliferation but lacked self-renewal capacity. In addition, mutant progenitor cells expressed the secreted stem/progenitor regulator osteopontin and showed enhanced CXCR4-dependent motility, both of which contributed to the accelerated spread of the mutation to mature cells. Thus, transforming mutations may facilitate their spread from HSC to mature cells via hypercompetitive progenitors, creating a two-component stem/progenitor circuit that underlies leukemogenesis.
Project description:TET2 haploinsufficiency is a driving event in myeloid cancers and is associated with a worse prognosis in patients with AML. Enhancing residual TET2 activity using vitamin C increases oxidized 5-methylcytosine (mC) formation and promotes active DNA demethylation via BER that slows leukemia progression. We utilized genetic and compound library screening approaches to identify rational combination treatment strategies to improve the use of vitamin C as an adjuvant therapy for AML. In addition to increasing the efficacy of several FDA approved drugs, vitamin C treatment with PARPi elicited a strong synergistic effect at blocking AML self-renewal in murine and human AML models. Vitamin C-mediated TET activation combined with PARPi caused an enrichment of chromatin-bound PARP1 at oxidized mCs, and H2AX accumulation during mid-S phase leading to cell-cycle stalling and differentiation. Given most AML subtypes maintain residual TET2 expression, vitamin C could elicit broad efficacy as a PARPi therapeutic adjuvant.