Project description:We exploited the extensive genomic diversity of the Leucegene cohort of primary human AML specimens to provide an overview of the human AML surfaceome. Due to high cell number requirements, surface proteomics has been underexploited in AML so far, although surface proteome analysis of AML cell lines and small cohorts of primary human AML specimens paved the way for antigen identification23-25. Herein, we compared global and surface proteomic datasets generated from primary human AML specimens and show that surfaceome analysis uniquely identifies a larger subset of cell surface proteins compared to global proteomics. We therefore built a cohort of 100 primary human AML specimens that was subjected to surface proteome analysis and served as a primary dataset for antigen identification. A significant portion of the cohort also underwent single-cell RNA sequencing, which allowed the exploration of antigen expression at the population level and the selection of AML antigens expressed by primitive blasts. These analyses led to the identification of novel AML antigens expressed by the majority of AML specimens of the cohort, of antigens overexpressed by specific AML subgroups, as well as of previously uncovered potential leukemia stem cell (LSC) markers, and represents the first large-scale surface proteomic study in AML.
Project description:We exploited the extensive genomic diversity of the Leucegene cohort of primary human AML specimens to provide an overview of the human AML surfaceome. Due to high cell number requirements, surface proteomics has been underexploited in AML so far, although surface proteome analysis of AML cell lines and small cohorts of primary human AML specimens paved the way for antigen identification23-25. Herein, we compared global and surface proteomic datasets generated from primary human AML specimens and show that surfaceome analysis uniquely identifies a larger subset of cell surface proteins compared to global proteomics. We therefore built a cohort of 100 primary human AML specimens that was subjected to surface proteome analysis and served as a primary dataset for antigen identification. A significant portion of the cohort also underwent single-cell RNA sequencing, which allowed the exploration of antigen expression at the population level and the selection of AML antigens expressed by primitive blasts. These analyses led to the identification of novel AML antigens expressed by the majority of AML specimens of the cohort, of antigens overexpressed by specific AML subgroups, as well as of previously uncovered potential leukemia stem cell (LSC) markers, and represents the first large-scale surface proteomic study in AML.
Project description:Eukaryotic ribosomal RNA carries diverse posttranscriptional modifications, among which the evolutionarily conserved 2’-O-methylation (2’-O-Me) occurs at more than 100 sites and is essential for ribosome biogenesis. Plasticity of 2´-O-Me in ribosomes and its functional consequences in human disease are not yet known. Here, we present the full rRNA 2’-O-Me landscape (ribomethylome) of human acute myeloid leukemia (AML) through profiling 94 patient samples as well as 21 normal hematopoietic samples of 5 different lineages. While interior modification sites in functional centers are persistently fully 2’-O-methylated in human AMLs, methylation on ribosome exterior sites is unprecedentedly dynamic. Higher 2’-O-methylation on exterior dynamic sites is associated with leukemia stem cell (LSC) signatures. Forced expression of enzymatically active but not of the catalytic defect 2’-O-methyltransferase FBL induces AML stemness and accelerates leukemogenesis in patient-derived xenografts. Mechanistically, ribomethylome dynamics shifted mRNA ribosome translation preferences. High rRNA 2’-O-Me enhances translation of amino acid transporters enriched in optimal codons and subsequently increases intra-cellular amino acid levels. Methylation on a single exterior modification site affects leukemia stem cell activity. The Guanosine 1447 on the small subunit ribosomal RNA is the most variable site in primary AMLs. Gm1447 is increased in leukemia stem cell populations compared to non-leukemogenic blast cells and AML specimens with higher Gm1447 are enriched for leukemia stem cell genes. Comparison of Gm1447high and Gm1447low ribosome structure solved by cryo-electron microscopy demonstrated disassociation of LYAR from Gm1447low ribosomes. Suppression of Gm1447 alone is sufficient to suppress translation of amino acid transporters, resulting in decreased cellular amino acid levels and leukemia stem cell activity. Taken together, our data reveal the dynamic FBL-mediated rRNA 2'-O-Me landscape as a novel epitranscriptomic level of control employed by leukemic stem cells and may enable new strategies to target human AML.
Project description:Leukemia is characterized by genetic and epigenetic mutations resulting in selection of cancer stem cells, which are unable to differentiate. While genetic alterations are difficult to target, the epigenome is intrinsically dynamic and readily offers new therapeutic strategies. Thus, identifying cancer-specific context-dependent targets and unraveling their biological function may open up new therapeutic perspectives. Here, we identify bromodomain-containing protein 9 (BRD9) as a critical target required in acute myeloid leukemia (AML). We show that BRD9 is overexpressed in AML cells including ex vivo primary blasts compared to CD34+. By targeting BRD9 expression in AML, we observed an alteration in proliferation and survival, ultimately resulting in the induction of apoptosis. Intriguingly, genome-wide profiling revealed that BRD9 binds enhancer regions in a cell type-specific manner, regulating cell type-related processes. We unveil a novel BRD9-sustained STAT5 pathway activation via regulation of SOC3 expression levels. Our findings identify a previously undescribed BRD9-STAT5 axis as critical for leukemia maintenance, suggesting BRD9 as a potential therapeutic target.
Project description:Acute myeloid leukemia (AML) is a heterogeneous neoplastic disorder, in which only a subset of cells have function as leukemia-initiating cells (LICs). In this study, we prospectively evaluated leukemia-initiating capacity of fractionated subpopulations of AML cells depending on expression of a nucleolar GTP binding protein, Nucleostemin (NS). To monitor NS expression in living AML cells, we generated a mouse AML model using a transgenic mouse, in which green florescence protein (GFP) is expressed under the control of particular region of NS promoter (NS-GFP). In AML cells, NS-GFP levels were correlated with endogenous NS mRNA. AML cells with the highest expression of NS-GFP were very immature blast-like cells, efficiently formed leukemia colonies in vitro, and exhibited high leukemia-initiating capacity in vivo. Gene expression profiling analysis revealed that cell cycle regulators and nucleotide metabolism-related genes were highly enriched in a gene set associated with leukemia-initiating capacity, i.e., leukemia stem cell gene signature. Furthermore, we found that the leukemia stem cell gene signature stratified human AML patients into two distinct clusters, reflecting prognosis. These data demonstrate that the mouse leukemia stem cell gene signature is significantly associated with malignant properties of human AML patients. Further analyses of gene regulation related with leukemia stem cells would provide novel insights for the progress in diagnostic and therapeutic approach of AML patients.
Project description:To explore the function of Mitochondrial Fission 1 (FIS1) in acute myeloid leukemia (AML), we used shRNA to knock down the expression of FIS1 in primary human AML cells and performed RNA-seq experiments to profile global gene expression changes upon FIS1 depletion.
Project description:Acute myeloid leukemia (AML) is a heterogeneous neoplastic disorder, in which only a subset of cells have function as leukemia-initiating cells (LICs). In this study, we prospectively evaluated leukemia-initiating capacity of fractionated subpopulations of AML cells depending on expression of a nucleolar GTP binding protein, Nucleostemin (NS). To monitor NS expression in living AML cells, we generated a mouse AML model using a transgenic mouse, in which green florescence protein (GFP) is expressed under the control of particular region of NS promoter (NS-GFP). In AML cells, NS-GFP levels were correlated with endogenous NS mRNA. AML cells with the highest expression of NS-GFP were very immature blast-like cells, efficiently formed leukemia colonies in vitro, and exhibited high leukemia-initiating capacity in vivo. Gene expression profiling analysis revealed that cell cycle regulators and nucleotide metabolism-related genes were highly enriched in a gene set associated with leukemia-initiating capacity, i.e., leukemia stem cell gene signature. Furthermore, we found that the leukemia stem cell gene signature stratified human AML patients into two distinct clusters, reflecting prognosis. These data demonstrate that the mouse leukemia stem cell gene signature is significantly associated with malignant properties of human AML patients. Further analyses of gene regulation related with leukemia stem cells would provide novel insights for the progress in diagnostic and therapeutic approach of AML patients. A mouse acute myeloid leukemia model was generated by introduction of HoxA9/Meis1 to bone marrow cells from a transgenic mouse, in which green florescence protein (GFP) is expressed under the control of particular region of NS promoter (NS-GFP).The leukemia cells were fractionated into 4 subpopulations based on NS-GFP level and c-Kit expression, (a) c-Kit-NS-GFPlow, (b) c-Kit-NS-GFPmiddle, (c) c-Kit+NS-GFPmiddle and (d) c-Kit+NS-GFPhigh cells.
Project description:In acute myeloid leukemia (AML), leukemia stem cells (LSC) play a central role in disease progression and recurrence due to their intrinsic capacity for self-renewal and chemotherapy resistance. Whereas epigenetic mechanisms balance normal blood stem cell self-renewal and fate decisions, mutation and dysregulation of epigenetic regulators are considered fundamental to leukemia initiation and progression. Alterations in miRNA function represent a non-canonical epigenetic mechanism influencing malignant hematopoiesis, however the function of miRNA in human LSC remains undetermined. Here we show that miRNA profiling of fractionated AML populations defines an LSC-specific signature that is highly prognostic for patient survival. Gain- and loss-of-function analyses demonstrated that miR-126 restrained cell cycle progression, prevented differentiation, and increased self-renewal of human LSC. By targeting the G0 to G1 gatekeeper CDK3, miR-126 preserved LSC quiescence and promoted chemotherapy resistance. Thus, in AML, miRNAs influence patient outcome through post-transcriptional regulation of stemness programs in LSC.
Project description:High-resolution proteomic analysis of acute myeloid leukemia (AML) stem cells identified phospholipase C- and Ca++-signaling pathways to be differentially regulated in AML1-ETO (AE) driven leukemia. Phospholipase C gamma 1 (Plcg1) could be identified as a direct target of the AE fusion. Genetic Plcg1 inactivation abrogated disease initiation by AE, reduced intracellular Ca++-release and inhibited AE-driven self-renewal programs. In AE-induced leukemia, Plcg1 deletion significantly reduced disease penetrance, number of leukemia stem cells and abrogated leukemia development in secondary recipient hosts. In human AE-positive leukemic cells inactivation of Plcg1 reduced colony formation and AML development in vivo. In contrast, Plcg1 was dispensable for maintenance of murine and human hematopoietic stem- and progenitor cells (HSPCs). Pharmacologic inhibition of Ca++-signaling downstream of Plcg1 resulted in impaired proliferation and self-renewal capacity in AE-driven AML. Thus, the Plcg1 pathway represents a novel specific vulnerability of AE-driven leukemia and poses an important new therapeutic target.
Project description:Acute myeloid leukemia (AML) is fatal in majority of adults. Identification of new therapeutic targets and their pharmacologic modulators are needed to improve outcomes. Previous studies had shown that immunization of rabbits with normal peripheral WBCs that had been incubated with fluorodinitrobenzene elicited high titer antibodies that bound to a spectrum of human leukemias. We report that proteomic analyses of immunoaffinity-purified lysates of primary AML cells showed enrichment of scaffolding protein IQGAP1. Immunohistochemistry and gene-expression analyses confirmed IQGAP1 mRNA overexpression in various cytogenetic subtypes of primary human AML compared to normal hematopoietic cells. shRNA knockdown of IQGAP1 blocked proliferation and clonogenicity of human leukemia cell-lines. To develop small molecules targeting IQGAP1 we performed in-silico screening of 212,966 compounds, selected 4 hits targeting IQGAP1-GRD domain, and conducted SAR of ‘fittest hit’ to identify UR778Br, a prototypical agent targeting IQGAP1. UR778Br inhibited proliferation, induced apotosis, G2/M arrest, and colony formation by leukemia cell-lines and primary-AML while sparing normal marrow cells. IQGAP1/F-actin showed co-localization and UR778Br induced filopodia formation in U937 cells. UR778Br exhibited favorable ADME/T profiles and drug-likeness to treat AML. In summary, AML shows dependency on IQGAP1 and UR778Br, identified through in-silico studies, selectively targeted AML cells while sparing normal marrow.