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Zinc finger protein 521 overexpression is a feature of MLL-rearranged acute myeloid leukemia and contributes to the maintenance of myeloid differentiation block

ABSTRACT: ZNF521 is a multiple zinc finger transcription factor previously identified because abundantly and selectively expressed in normal CD34+ hematopoietic stem and progenitor cells. From microarray datasets, aberrant expression of ZNF521 has been reported in both pediatric and adult acute myeloid leukemia (AML) patients with MLL gene rearrangements. However, a proper validation of microarray data is lacking, likewise ZNF521 contribution in MLL-rearranged AML is still uncertain. In this study, we show that ZNF521 is significantly upregulated in MLL translocated AML patients from a large pediatric cohort, regardless of the type of MLL translocations such as MLL-AF9, MLL-ENL, MLL-AF10 and MLL-AF6 fusion genes. Our in vitro functional studies demonstrate that ZNF521 play a critical role in the maintenance of the undifferentiated state of MLL-rearranged cells. Furthermore, analysis of the ZNF521 gene promoter region shows that ZNF521 is a direct downstream target of both MLL-AF9 and MLL-ENL fusion proteins. Gene expression profiling of MLL-AF9-rearranged THP-1 cells after depletion of ZNF521 reveals correlation with several expression signatures including stem cell-like and MLL fusion dependent programs. These data suggest that MLL fusion proteins activate ZNF521 expression to maintain the undifferentiated state and contribute to leukemogenesis. ZNF521 is required to block differentiation in MLL-rearranged AML cells

ORGANISM(S): Homo sapiens

PROVIDER: GSE79110 | GEO | 2017/03/31

SECONDARY ACCESSION(S): PRJNA314964

REPOSITORIES: GEO

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ZNF521 enhances MLL-AF9-dependent hematopoietic stem cell transformation in acute myeloid leukemias by altering the gene expression landscape

Project description:Leukemias derived from the MLL-AF9 rearrangement rely on deranged transcriptional networks. ZNF521, a transcription co-factor implicated in the control of hematopoiesis, has been proposed to sustain leukemic transformation in collaboration with other oncogenes. We demonstrate here that ZNF521 mRNA levels correlate with specific genetic aberrations: in particular, the highest expression is observed in AMLs bearing MLL rearrangements, while the lowest is detected in AMLs with FLT3-ITD, NPM1 or CEBPα double mutations. In cord blood-derived CD34+ cells, enforced expression of ZNF521 provides a significant proliferative advantage, and acts synergistically when co-expressed with MLL-AF9 throughout the proliferation and expansion of leukemic progenitor cells. Transcriptome analysis of primary CD34+ cultures displayed subsets of genes upregulated by MLL-AF9 or ZNF521 single transgene overexpression as well as in MLL-AF9/ZNF521 combinations, either at early or late time points of an in vitro model of leukemogenesis. Silencing of ZNF521 in MLL-AF9+ THP-1 cell line coherently results in an impairment of growth and clonogenicity, recapitulating effects observed in primary cells. Taken together, these results underscore a role for ZNF521 in sustaining self-renewal of the AML immature compartment, most likely through the perturbation of the gene expression landscape which ultimately favors the expansion of MLL-AF9 transformed leukemic clones.

2022-03-24 | GSE181006 | GEO

TGIF1 is a negative regulator of MLL-rearranged acute myeloid leukemia

Project description:The aim of the study was to investigate the role of TGIF1 in MLL-AF9 transformed cells Members of the TALE (Three-amino acid loop extension) family of atypical homeodomain-containing transcription factors are prominent downstream effectors of oncogenic fusion proteins generated from translocations involving the mixed lineage leukemia (MLL) gene. A particular well-characterized member of this protein family is MEIS1, which together with HOXA proteins, orchestrates a transcriptional program required for the maintenance of MLL-rearranged acute myeloid leukemia (AML). Although TALE family proteins are mainly described as transcriptional activators TGIF1 (TGF-β induced factor) / TGIF2 are considered as transcriptional repressors. However, as their function in MLL-rearranged AML is largely unknown, we tested the potential importance of TGIF1 in the maintenance of MLL-rearranged AML. We find that expression of TGIF1 in MLL-AF9 transformed cells (MAF9) leads to cell cycle exit and differentiation in vitro and delayed leukemic onset in vivo. In accordance, MLL-rearranged patient blasts display lower levels of TGIF1 and TGIF1 expression in general correlates positively with survival. Mechanistically, we show that TGIF1 interferes with a MEIS1-dependent transcriptional program by associating to MEIS1-bound region in a competitive manner. Collectively, these findings demonstrate that TALE family members can act both positively and negatively on transcriptional programs responsible for the maintenance of MLL-rearranged AML.

2014-11-11 | GSE55713 | GEO

RNA sequencing expression analysis of murine MLL-AF9;NRAS acute myeloid leukemia cells silenced for E2-2.

2016-06-29 | GSE80745 | GEO

RNA sequencing expression analysis of murine MLL-AF9;NRAS acute myeloid leukemia cells silenced for E2-2.

Project description:We investigated the role of the transcriptional regulators Id2 and E2-2 (encoded by Tcf4) in the context of MLL-rearranged acute myeloid leukemia (AML). Using an AML mouse model driven by a Tet-off inducible MLL-AF9 allele co-expressed with oncogenic NRASG12D, we demonstrated that MLL-AF9 regulates the E protein pathway by suppressing Id2, while activating the expression of its target E2-2. Moreover, we found that Id2 over-expression in MLL-AF9 AML cells results inhibition of leukemia growth, loss of leukemia stem cell-associated gene expression pattern and induction of differentiation. E2-2 silencing phenocopies Id2 overexpression in MLL-AF9-AML cells. To study the gene expression changes associated with E2-2 depletion in the context of MLL-rearranged AML, RNA sequencing analysis was performed on MLL-AF9;NRAS AML cells transduced with vectors expressing hairpins against E2-2 (shTcf4#654 and shTcf4#3646) or a control hairpin against Renilla luciferase (shRen). Primary AMLs driven by MLL/AF9 expression linked to cherry reporter, in association with oncogenic NRASG12D (MLL/AF9;NRAS) were generated by reconstituting lethally irradiated congenic mice with fetal liver cells co-transduced with the MSCV-MLL/AF9-IRES-cherry retroviral vector and a second vector co-expressing NRASG12D together with luciferase (MSCV-luciferase-IRES-NRASG12D). RNA sequencing analysis sequencing analysis was performed on MLL-AF9;NRAS AML cells transduced in vitro with vectors expressing hairpins against E2-2 (shTcf4#654 and shTcf4#3646) or a control hairpin against Renilla luciferase (shRen) linked to the reporter GFP. Viable GFP-positive cells were FACS-sorted 2 days after transduction and used for RNA sequencing analysis. Two independent biological replicates of the experiment were used for the RNA sequencing (9-5-14 and 14-4-14).

2016-06-29 | E-GEOD-80745 | biostudies-arrayexpress

Protein Interactions of 7 MLL-fusion Proteins

Project description:MLL-fusions represent a large group of leukemia drivers, whose diversity originates from the vast molecular heterogeneity of C-terminal fusion partners of MLL protein. While studies of selected MLL-fusions have revealed critical molecular pathways, unifying mechanisms across all MLL-fusions remain poorly understood. We present the first comprehensive survey of protein-protein interactions of seven distantly related MLL-fusion proteins: MLL-AF1p, MLL-AF4, MLL-AF9, MLL-CBP, MLL-EEN, MLL-ENL and MLL-GAS7.

2018-05-25 | PXD009338 | Pride

Development of MLL-rearranged leukemia is dependent on a transcriptional program orchestradt by C/EBPα

Project description:Translocations involving the MLL genes are frequently found in Acute Myeloid Leukemia (AML) and are associated with poor prognosis. The MLL fusion proteins act as aberrant transcription factor activating a transcriptional program that transforms the cells, potentially through collaboration with other transcription factors. To investigate this we searched gene expression profiles from patients with MLL-rearranged AML compared with normal hematopoietic progenitor cells for transcriptional regulators and found targets of C/EBPα to be up-regulated in the AML samples, suggesting that C/EBPα might collaborate with MLL fusion proteins in the initial transformation process. We could show that transformation by MLL fusion proteins is dependent on C/EBPα activity both in early progenitors as well as in GMPs. In contrast, C/EBPα was found to be indispensable in an already established leukemia. These results suggest that C/EBPα play an important role in the early transforming event of leukemogenesis. We used microarray to study the early transcriptional changes induced by MLL-ENL expression and we identified a combined C/EBPα / MLL-ENL transcriptional signature. 3 Cebpaflox/flox;Mx1Cre and 3 Cebpaflox/flox;Mx1Cre- mice were sacrificed 14 days after pIpC injection and bone marrow cells were harvested, enriched for cKit-expression and transduced with a pMIG retroviral vector expressing the MLL-ENL fusion protein and GFP. 72 h post first transduction, GFP-positive or negative PreGM cells were sorted.

2013-12-10 | E-GEOD-46534 | biostudies-arrayexpress

TGIF1 is a negative regulator of MLL-rearranged acute myeloid leukemias

Project description:Members of the TALE (Three-amino acid loop extension) family of atypical homeodomain-containing transcription factors are prominent downstream effectors of oncogenic fusion proteins generated from translocations involving the mixed lineage leukemia (MLL) gene. A particular well-characterized member of this protein family is MEIS1, which together with HOXA proteins, orchestrates a transcriptional program required for the maintenance of MLL-rearranged acute myeloid leukemia (AML). Although TALE family proteins are mainly described as transcriptional activators TGIF1 (TGF-β induced factor) / TGIF2 are considered as transcriptional repressors. However, as their function in MLL-rearranged AML is largely unknown, we tested the potential importance of TGIF1 in the maintenance of MLL-rearranged AML. We find that expression of TGIF1 in MLL-AF9 transformed cells (MAF9) leads to cell cycle exit and differentiation in vitro and delayed leukemic onset in vivo. In accordance, MLL-rearranged patient blasts display lower levels of TGIF1 and TGIF1 expression in general correlates positively with survival. Mechanistically, we show that TGIF1 interferes with a MEIS1-dependent transcriptional program by associating to MEIS1-bound region in a competitive manner. Collectively, these findings demonstrate that TALE family members can act both positively and negatively on transcriptional programs responsible for the maintenance of MLL-rearranged AML.

2014-11-11 | GSE55287 | GEO

Expression data from conditionally immortalized MLL-AF9 and MLL-ENL hematopoietic progenitor cells following loss of MLL-fusion oncogene

Project description:Chromosomal translocations encoding the MLL-AF9 and MLL-ENL fusion transcription factors are prevalent in infant acute leukaemia and therapy-related leukaemia. In order to conditionally express the MLL-fusion oncogene in primary haematopoietic progenitor cells (HPC), retroviral delivery of the Tet-off expression system was used (Horton et al., Cancer Res, 2005). Treatment of the conditional cells with Doxycycline caused a decrease in MLL-AF9/ENL mRNA and protein expression, and resulted in terminal differentiation of the cells. By analysing global changes in gene expression after treatment of cells with Doxycycline we were able to identify a number of potential transcriptional target genes of the MLL-AF9 and MLL-ENL fusion oncogenes.

2014-12-01 | GSE59236 | GEO

RNA sequencing expression analysis of murine Tet-off MLL-AF9;NRAS acute myeloid leukemia cells over-expressing Id2 and upon MLL-AF9 withdrawal

Project description:We investigated the role of the transcriptional regulator Id2 in the context of MLL-rearranged acute myeloid leukemia (AML). Using an AML mouse model driven by tet-regulated MLL-AF9 co-expressed with oncogenic NRASG12D (Tet-off MLL-AF9), we demonstrated that MLL-AF9 regulates the E protein pathway by suppressing Id2, while activating the expression of its target E2-2. Moreover, we found that Id2 over-expression in Tet-Off MLL-AF9 AML cells in vitro partially phenocopies MLL-AF9 depletion and results inhibition of leukemia growth, loss of leukemia stem cell-associated gene expression pattern and induction of differentiation. To compare gene expression changes associated with enforced Id2 expression and MLL-AF9 withdrawal, RNA sequencing analysis was performed on Tet-off MLL-AF9 cells transduced with an Id2 over-expressing or a control vector, or upon MLL-AF9 dox-inducible knock-down.

2016-06-29 | GSE68462 | GEO

Hes1 is responsible for Notch signaling-mediated suppression of acute myeloid leukemia development

Project description:In leukemogenesis Notch signaling can be up- and down-regulated in a context-dependent manner. Here we report that deletion of hairy and enhancer of split-1 (Hes1) promotes acute myeloid leukemia (AML) development induced by the MLL-AF9 fusion protein. Subsequently, the FMS-like tyrosine kinase 3 (FLT3) was up-regulated in mouse cells of a Hes1- or RBP-J-null background. MLL-AF9-expressing Hes1-null AML cells showed enhanced proliferation and ERK phosphorylation following FLT3 ligand stimulation. FLT3 inhibition efficiently abrogated proliferation of MLL-AF9-induced Hes1-null AML cells. Furthermore, an agonistic anti-Notch2 antibody induced apoptosis of MLL-AF9-induced AML cells in a Hes1-wild type but not a Hes1-null background. These observations demonstrate that Hes1 mediates tumor suppressive roles of Notch signaling in AML development by down-regulating FLT3 expression. 4 samples are analyzed, two pairs of MLL-AF9/Hes1-/- and MLL-AF9/Hes1+/+ leukemic bone marrows.

2017-05-02 | E-GEOD-50234 | biostudies-arrayexpress

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