Functional roles of RUNX1::ERG in K562 myeloid leukemia cells [K562_RUNX1-ERG]
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ABSTRACT: To investigate the functional significance and transcriptional impacts associated with RUNX1::ERG, we overexpressed the fusion gene in K562 myeloid leukemia cells and analysed global gene expression changes using RNA-seq.
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:To investigate the functional significance of STIM1::MXD3, we overexpressed the fusion gene in K562 myeloid leukemia cells and analysed global gene expression changes using RNA-seq.
Project description:ERG is a transcriptional factor, which is recombined with promoter of TMPRSS2 and prominently overexpressed in half of human prostate cancers. The mechanisms of ERG-mediated oncogenesis are not completely understood. We performed an unbiased Mass Spectrometry screen for ERG-binding proteins and found that ERG binds to MTDH/SND1 protein complex in prostate cancer cells. We determined that ERG binds to the SND1/MTDH protein complex via SND1 and this interaction plays a critical role in ERG-mediated cancer.
Project description:Fusion proteins involving the ETS factor ERG have been associated with multiple cancers such as Ewing's sarcoma and prostate cancer. In acute myeloid leukemias harboring t(16;21) another ERG fusion protein is expressed, FUS-ERG. Here, we found that this FUS-ERG oncofusion protein acts in the context of a heptad of proteins (ERG, FLI1, GATA2, LYL1, LNMO2, RUNX1 and TAL1) central to proper expression of genes involved in maintaining a stem cell hematopoietic phenotype. Moreover, in t(16;21) FUS-ERG co-occupies genomic regions bound by the nuclear receptor heterodimer RXR-RARA inhibiting target gene expression and interfering with hematopoietic differentiation. All-Trans Retinoic Acid treatment of t(16;21) cells as well as FUS-ERG knock down alleviate the myeloid differentiation block. Together, the results suggest that FUS-ERG acts as a transcriptional repressor of the retinoic acid signaling pathway. Cell lines were used for RNA extraction for RNA-seq and ChIP experiments for ChIP-seq.
Project description:BACKGROUND: Our previous studies showed that RUNX1 and ASXL1 mutations were frequently co-existed in chronic myelomonocytic leukemia (CMML) and clonal evolution of RUNX1 and/or ASXL1 occurred most frequently in chronic myeloid leukemia (CML) with myeloid blastic crisis. The molecular pathogenesis of cooperation of RUNX1 and ASXL1 mutations has not been reported yet. METHODS: Lentiviral-mediated stable transduction of RUNX1-WT/MT (R135T) in K562 cells which harboring ASXL1-MT (Y591X). RNA was extracted from stable cell line and used for gene-expression microarray analysis. RESULTS: For in vitro study, we overexpressed RUNX1-WT/MT (R135T) in K562 cells which harboring ASXL1-MT (Y591X). We found that RUNX1-MT augmented cell proliferation, colony formation, HOXA gene expression and inhibited megakaryocytic differentiation in ASXL1-MT K562 cells compared to RUNX1-WT or empty vector control. We performed gene expression profile of K562 cells overexpressed with EV, RUNX1-WT and RUNX1-R135T mutation. Gene expression microarray data revealed that 147 genes upregulated more than 2-fold in RUNX1-R135T expressing K562 cells compared to EV control cells. From gene expression data analysis, we found that inhibitor of DNA binding 1 (ID1), a key transcriptional regulator of hematopoietic stem cell (HSC) lineage commitment, is upregulated in RUNX1-R135T-transduced K562 cells compared to EV and RUNX1-WT-expressing cells.
Project description:Fusion proteins involving the ETS factor ERG have been associated with multiple cancers such as Ewing's sarcoma and prostate cancer. In acute myeloid leukemias harboring t(16;21) another ERG fusion protein is expressed, FUS-ERG. Here, we found that this FUS-ERG oncofusion protein acts in the context of a heptad of proteins (ERG, FLI1, GATA2, LYL1, LNMO2, RUNX1 and TAL1) central to proper expression of genes involved in maintaining a stem cell hematopoietic phenotype. Moreover, in t(16;21) FUS-ERG co-occupies genomic regions bound by the nuclear receptor heterodimer RXR-RARA inhibiting target gene expression and interfering with hematopoietic differentiation. All-Trans Retinoic Acid treatment of t(16;21) cells as well as FUS-ERG knock down alleviate the myeloid differentiation block. Together, the results suggest that FUS-ERG acts as a transcriptional repressor of the retinoic acid signaling pathway.
Project description:The goal of this project was to analyze the global gene expression profiles of RWPE1 and VCAP cells following transfection of GFP, GFP-ERG at 48 and 72hrs time points and stable ERG shRNA, scramble shRNA, respectively. RWPE1 cells were transfected with GFP or GFP-ERG. VCAP cells were transfected with ERG lenti-shRNA or scramble shRNA. Transfections were performed in duplicate. Total cellular RNA was isolated with Trizol and quality analysed by the bioanalyser kit.
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:Despite absent expression in normal hematopoiesis, the Forkhead factor FOXC1, a critical mesenchymal differentiation regulator, is highly expressed in ~30% of HOXAhigh AML to confer blocked monocyte/macrophage differentiation. Through integrated proteomics and bioinformatics, we discovered that FOXC1 and RUNX1 interact through Forkhead and Runt domains respectively and cooccupy primed and active enhancers distributed close to differentiation genes. FOXC1 stabilises association of RUNX1, HDAC1 and Groucho repressor TLE3 to limit enhancer activity: FOXC1 knockdown induced loss of repressor proteins, gain of CEBPA binding, enhancer acetylation and upregulation of nearby genes, including KLF2. Furthermore, it triggered genome-wide redistribution of RUNX1, TLE3 and HDAC1 from enhancers to promoters leading to repression of self-renewal genes including MYC and MYB. Our studies highlight RUNX1 and CEBPA transcription factor swapping as a feature of leukemia cell differentiation, and reveal that FOXC1 prevents this by stabilising enhancer binding of a RUNX1/HDAC1/TLE3 transcription repressor complex, to oncogenic effect.