Project description:ERG has been identified as an essential factor for the function and maintenance of adult hematopoietic stem cells and high ERG expression is a negative prognostic marker for treatment outcome in AML. The molecular function of ERG and its interplay with other factors is however largely unknown. Here we demonstrate that ERG has cell type specific distributions in normal CD34+ myeloid progenitors and in AML cells and identify ERG as a potential pioneering protein for binding of oncofusion protein complexes. In addition, we identify H3 acetylation as the epigenetic mark preferentially associated with ERG binding. This intimate connection between ERG binding and H3 acetylation implies that one of the molecular strategies of the oncofusion proteins PML-RARa and AML1-ETO could involve the targeting of histone deacetylase activities to ETS factor bound hematopoietic regulatory sites. Examination of AML1-ETO, RUNX1, CBFb, HEB, FLI1 and ERG binding sites (ChIP-seq) in leukemic and normal hematopoietic cells, association with chromatin modifications and expression (RNA-seq) analysis of an AML1-ETO expressing cell line (SKNO-1)
Project description:ERG has been identified as an essential factor for the function and maintenance of adult hematopoietic stem cells and high ERG expression is a negative prognostic marker for treatment outcome in AML. The molecular function of ERG and its interplay with other factors is however largely unknown. Here we demonstrate that ERG has cell type specific distributions in normal CD34+ myeloid progenitors and in AML cells and identify ERG as a potential pioneering protein for binding of oncofusion protein complexes. In addition, we identify H3 acetylation as the epigenetic mark preferentially associated with ERG binding. This intimate connection between ERG binding and H3 acetylation implies that one of the molecular strategies of the oncofusion proteins PML-RARa and AML1-ETO could involve the targeting of histone deacetylase activities to ETS factor bound hematopoietic regulatory sites.
Project description:The AML1/ETO fusion protein is essential to the development of acute myeloid leukemia (AML), and is well recognized for its dominant-negative effect on the co-existing wild-type protein AML1. However, the involvement of wild-type AML1 in AML1/ETO-driven leukemogenesis remains elusive. Through chromatin immunoprecipitation sequencing, computational analysis plus a series of experimental validations, we report here that AML1 is able to orchestrate the expression of AML1/ETO targets regardless of being activated or repressed, via forming a complex with AML1/ETO and via recruiting the cofactor. 4 ChIP-seq assays were used to identify the high confidence binding regions of AML1-ETO and AML1 in t(8;21) AML Kasumi-1 cell lines. The anti-AML1 (N20) antibody targets the N-terminus of AML1 and recognizes both AML1 and AML1/ETO; the anti-AML1 (C19) antibody targets the C-terminus of AML1 and recognizes AML1 but not AML1/ETO; the anti-ETO (C20) antibody targets the C-terminus of ETO and specifically recognizes AML1/ETO. 2 ChIP-seq assays were used to identify the binding regions of AML1 in human macrophage U937 cell lines. And the total input was used as control.
Project description:The t(8;21) acute myeloid leukemia associated oncoprotein AML1-ETO is a transcription factor that aberrantly regulates the pathways that lead to myeloid differentiation. Here, we set out to investigate the effects of AML1-ETO on gene expression and the epigenome in patient blast cells. We identify two modules, one in which AML1-ETO binds promoter regions of active genes and one represented by non-promoter binding to accessible, yet inactive chromatin regions. Using genome-wide binding analysis and mass spectrometry interaction studies we identify ERG, FLI1, TAL1 and RUNX1 as common binding factors of all AML1-ETO occupied genomic regions, while LYL1 and LMO2 show preferential binding in the context of non promoter regions. Epigenetically, reduced histone acetylation levels at non-promoter regions seems HDAC dependent, as treatment with an HDACi increases acetylation and induces cell death. Both AML1-ETO modules are represented in most aberrantly regulated pathways, including many signaling pathways, self-renewal and apoptosis. For the latter, the expression of the wild type transcription factors RUNX1 and ERG is required, as alterations in expression are associated with the onset of an apoptosis program. Interestingly, upon RUNX1 or ERG knockdown this onset seems to be dependent on increased AML1-ETO expression as combinatorial knockdown of RUNX1/AML1-ETO or ERG/AML1-ETO results in rescue from apoptosis. Together our results show that the balanced interplay of the epigenetic environment and transcription factors retains an anti apoptotic phenotype in t(8;21) AML cells.
Project description:Cancer cells maintain a sensitive balance between growth-promoting oncogenes and apoptosis inhibitors. We show that WT RUNX1 is required for survival of t(8;21)-Kasumi-1 and inv(16)-ME-1 AML cell lines. The malignant AML phenotype is sustained by a delicate AML1-ETO/RUNX1 balance that involves competition for common DNA binding sites regulating a subset of AML1-ETO/RUNX1 targets. Genomewide sequencing data is included herein: Transcription factors RUNX1 c-terminus and n-terminus which is shared with AML1-ETO were profiled independently), AML1-ETO and AP4 were profiled using ChIP-Seq in Kasumi-1 cells, as well as control ChIP-Seq experiments of non immune serum. Two replicates were performed for each transcription factor profiling and control experiment.
Project description:Cancer cells maintain a sensitive balance between growth-promoting oncogenes and apoptosis inhibitors. We show that WT RUNX1 is required for survival of t(8;21)-Kasumi-1 and inv(16)-ME-1 AML cell lines. The malignant AML phenotype is sustained by a delicate AML1-ETO/RUNX1 balance that involves competition for common DNA binding sites regulating a subset of AML1-ETO/RUNX1 targets. Genome expression was profiled after performing knockdown of RUNX1 and AML1-ETO in Kasumi-1 cells using specific siRNA-oligo nucleotides, and analyzed using Affymetrix Gene 1.0 ST arrays.
Project description:Approximately 20% of Acute Myelogenous Leukemia (AML) cases carry the t(8;21) translocation, which involves the AML1 and ETO genes, and express the resulting AML1/ETO fusion protein that functions as a transcriptional repressor by recruiting NCoR/SMRT/HDAC complexes to DNA. We used ChIP-chip to identify the determinants of AML1/ETO binding on a contiguous DNA region (chromosome 19). AML1/ETO binding regions are characterized by a specific sequence signature that includes the presence of the consensus binding sites for the AML1 and HEB transcription factors. We therefore assessed the binding patterns of AML1 and HEB on chromosome 19. A specific chromatin modification (tri-methylation of lysine 4 on histone 3 = 3MetK4) was also studied in U937 cells expressing AML1/ETO in order to correlate the identified binding profiles with active transcription sites. Keywords: ChIP-chip
Project description:The formation of the AML1-ETO fusion protein, resulting from the t(8;21) translocation, is considered to be among the t(8;21) acute myeloid leukemia (AML) initiating events. However, the mechanisms of the oncogenic activity of AML1-ETO remains unclear. In this study, we found that AML1-ETO triggers the heterochromatic silencing of UBXN8 by recognizing the AML1 binding sites and recruiting chromatin remodeling enzymes to the UBXN8 promoter region. Decitabine, a specific inhibitor of DNA methylation, upregulated the expression of UBXN8 in AML1-ETO+ AML cell lines. Overexpression of UBXN8 inhibited the proliferation and colony-forming ability and promoted cell cycle arrest in t(8;21) AML cell lines. Enhancement of UBXN8 level can significantly inhibit the tumor proliferation of AML1-ETO+ cells in vivo. Thus, our results indicated that epigenetic silencing of UBXN8 via its promoter region methylation mediated by the AML1-ETO fusion protein contributes to the leukemogenesis of t(8;21)AML. These results demonstrated the feasibility and effectiveness of the pharmacological disruption of AML1-ETO/HDACs/DNMTs complex and that the UBXN8 targeting maybe an potential therapeutic strategy for t(8;21)AML.
Project description:Cancer cells maintain a sensitive balance between growth-promoting oncogenes and apoptosis inhibitors. We show that WT RUNX1 is required for survival of t(8;21)-Kasumi-1 and inv(16)-ME-1 AML cell lines. The malignant AML phenotype is sustained by a delicate AML1-ETO/RUNX1 balance that involves competition for common DNA binding sites regulating a subset of AML1-ETO/RUNX1 targets.
Project description:Cancer cells maintain a sensitive balance between growth-promoting oncogenes and apoptosis inhibitors. We show that WT RUNX1 is required for survival of t(8;21)-Kasumi-1 and inv(16)-ME-1 AML cell lines. The malignant AML phenotype is sustained by a delicate AML1-ETO/RUNX1 balance that involves competition for common DNA binding sites regulating a subset of AML1-ETO/RUNX1 targets.