ABSTRACT: To identify the target genes of Runx1 in MLL fusion leukemia, we performed microarray analysis using control and Runx1-deficient MLL-ENL leukemia cells.
Project description:To identify the target genes of Runx1 in MLL fusion leukemia, we performed microarray analysis using control and Runx1-deficient MLL-ENL leukemia cells. Runx1 intact and excised bone marrow cells were transduced with MLL-ENL and transplanted into congenic mice. Leukemic cells were harvested from moribund mice, and gene expression was compared using 3 independent leukemia cells for each genotype.
Project description:To identify the target genes of Runx1/Cbfb in MLL fusion leukemia, we performed microarray analysis using control and Runx1/Cbfb-deleted MLL-AF9 cells.
Project description:To identify the target genes of Runx1/Cbfb in MLL fusion leukemia, we performed microarray analysis using control and Runx1/Cbfb-deleted MLL-AF9 cells. c-Kit(+) bone marrow cells derived from Runx1/Cbfb double floxed mice were transduced with MLL-AF9 and CreERT2 (coexpressing Puromycin). After several rounds of replating with Puromycin, EtOH (control) or 4OHT was added to induce gene deletion. Two independent experiments with 2 independent clones were performed, and gene-expression was compared using the 4 sets of samples 24 hours after 4OHT addition.
Project description:The t(11;19)(q23;p13.3) translocation leading to the expression of an MLL-ENL fusion is one of the most prevalent alterations affecting the mixed lineage leukemia 1 (MLL1) gene, mostly associated with B-cell acute lymphoblastic leukemia (ALL). Using a doxycycline (DOX)-inducible transgenic mouse model (“iMLL-ENL”) we show that direct induction or induction following transplantation of hematopoietic stem cells (HSC) but not of committed myeloid granulocyte-macrophage progenitors (GMP) leads to reversible acute mixed lineage leukemia. Disease induction was associated with iMLL-ENL levels exceeding the endogenous Mll1. iMLL-ENL leukemia was composed of small B220High cells with higher leukemia-initiating potential than co-existing larger-sized B220Low cells. Collectively, characterization of a novel transgenic mouse model indicates that the cell-of-origin and the expression levels above Mll1/MLL1 are both critical determinants for mixed lineage leukemia induced by the MLL-ENL fusion.
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.
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.
Project description:To investigate the contribution of ENL YEATS domain and downstream sequences in MLL-ENL leukemogenesis program, we generated MLL-ENL and MLL-ENL ∆YEATS (ENL aa372-559) cell lines by retrovirally introducing these constructs into lineage negative hematopoietic stem and progenitor cells (HSPCs).
Project description:Infant and adult MLL-rearranged (MLLr) leukemia represents a disease with few treatment options and a dismal prognosis. Here, we present an in-depth proteomic characterization of in utero-initiated and adult-onset MLLr leukemia in a mouse model of MLL-ENL-mediated leukemogenesis. We characterize early proteomic events of MLL-ENL-mediated transformation in fetal and adult progenitors.
Project description:RNA-Seq of 1) human AML samples; 2) sorted, uncultured distinct population from human cord blood (CB); 3) short-term (ST) cultured sorted CB cells transduced with MLL-ENL, MLL-AF6 or untransduced; and 4) cultured (LT) sorted CB cells transformed with MLL-ENL or MLL-AF6. Cells from MLL-fusion AML patients are bulk. Several cords were used for the sorting (CB1, CB2, CB3, 135, 141...) and these represent biological replicates. Several samples were sequenced several times in different lanes and results were merged together for the analysis (rep1,rep2...). Samples were used to determine the different effect of MLL-fusions in different celltypes just after the transduction, and after a longer time period when cells were transformed. Sorted CB samples, uncultured as well as transformed by MLL-fusions, were used in machine learning approach to predict which of the patients originated from which cell-type of origin.
Project description:Activation of the MLL-ENL-ERtm oncogene initiates aberrant proliferation of myeloid progenitors. Here, we show induction of a fail-safe mechanism mediated by the DNA damage response (DDR) machinery that results in activation of the ATR/ATM-Chk1/Chk2-p53/p21 checkpoint and cellular senescence at early stages of cellular transformation caused by a regulatable MLL-ENL-ERtm in mice. Furthermore, we identified the transcription program underlying this intrinsic anti-cancer barrier, and DDR-induced inflammatory regulators that fine-tune the signaling towards senescence, thereby modulating the fate of MLL-ENL-immortalized cells in a tissue-environment-dependent manner. Our results indicate that DDR is a rate-limiting event for acquisition of stem cell-like properties in MLL-ENL-ERtm-mediated transformation, as experimental inhibition of the barrier accelerated the transition to immature cell states and acute leukemia development. We created a mouse model wherein the protein function of the MLL-ENL oncogene depends on tamoxifen due to fusion with the mutated estrogen-binding domain of the estrogen receptor (ERtm). After 7 months of tamoxifen administration, the MLL-ENL-ERtm mice developed a myeloproliferative disease, which progressed into the terminal stage after a long period (mean survival: 592 ± 112 days) of continuous tamoxifen provision. We have profiled gene expression at three time-points of tamoxifen treatment corresponding to three distinct cellular states of the MLL-ENL-ERtm-induced myeloproliferation in the bone marrow: 1. 7 months - high proliferation state with low DDR signaling (4 biological replicates), 2. 7-8 months - the transition period of lower proliferation and high DDR activity (4 biogical replicates) and 3. 8 months - the senescence (3 biological replicates). Time-matched tamoxifen-treated wild-type bone marrow analysed in 4 biological replicates. We have profiled gene expression in three disease stages in the spleen: 1. 7 months - early stage - induced proliferation and DDR (3 biological replicates), 2. 9-10 months - progression - partial senescence and DDR is maintained (3 biological replicates) and 3. 16-23 months - terminal stage - proliferation, low or absent DDR and no senescence (3 biological replicates). Time-matched tamoxifen-treated and age-matched wild-type spleens analysed in 5 biological replicates.