Project description:MIR139 is a critical tumor suppressor and commonly silenced in human cancer, including acute myeloid leukemia (AML). Here, we found that depletion of identified MIR139 targets affects AML outgrowth. We unraveled the mechanism of MIR139 gene inactivation in AML expressing the Mixed-Lineage Leukemia (MLL)-AF9 oncogene. Epigenetic analyses revealed two well-conserved putative enhancer regions in close proximity of transcriptional start sites (TSS) of MIR139. These regions were silenced by the Polycomb-Repressive Complex-2 (PRC2) downstream of MLL-AF9. Genomic deletion of these regions abolished MIR139 transcriptional regulation in normal and oncogenic conditions. Genome-wide knockout screens revealed the transcriptional pausing factor of RNA Polymerase-II, POLR2M, as a critical MIR139-silencing factor. Furthermore, direct POLR2M binding to the MIR139 TSS induced paused transcription, which was abrogated upon PRC2 inhibition. We present evidence for an oncogenic POLR2M-mediated MIR139 silencing mechanism, downstream of MLL-AF9 and PRC2. Together, our findings highlight the importance of POLR2M-mediated paused transcription in AML.
Project description:Immunoediting describes the dynamic sculpting of cancer cells to evade cancer immune control, thereby enabling the development of tumors in an immunocompetent host resulting in the outgrowth of cancer cells with reduced immunogenicity.
Project description:We performed a liquid chromatography-tandem mass spectrometry analysis of endogenous TWIST1 immunoprecipitates in the LSCs isolated from MLL-AF9-driven AML mice
Project description:The Wnt/beta-catenin pathway is required for the development of leukemia stem cells in MLL-AF9 AML. We evaluated the dependance on beta-catenin for KrasG12DMLL-AF9 leukemia. Lin-Kit+ bone marrow cells obtained from mice transplanted with primary MLL-AF9 leukemia cells and KRasG12DMLL-AF9 leukemia cells were assessed for gene expression in the presence or absence of beta-catenin
Project description:P2X7 was significantly up-regulated in leukemia patients, especially in AML (MLL-AF9) and often related to poor prognosis.We compared the transcriptomic changes in MLL-AF9 induced mouse AML and overexpressed wP2X7 in MLL-AF9 induced AML. Engaged to explore the mechanism of P2X7 in leukemia progression. Mouse AML was induced by expressing MLL-AF9 in mouse HSPCs. Leukemia cells were divided into two groups, c-kit+ and c-kit-. Due to leukemia cells were nearly 95% c-kit+ in P2X7-overexpressed AML cells, we set up four groups of leukemia cells, namely leukemia total cells (V total), leukemia c-kit positive cells (V c-kit+), leukemia c-kit negative cells (V c-kit-), overexpressed wide type P2X7 leukemia cells (wP2X7).
Project description:Using an acute myeloid leukemia (AML) mouse model driven by tet-regulated MLL-AF9 (fusion between the gene MLL1 (KMT2A/MLL) and MLLT3 (AF9)) co-expressed with oncogenic NRASG12D (Tet-off MLL-AF9), we investigated the effect of modulating the expression of the MLL-AF9 fusion oncogene on the transcriptome and proteome of established murine AML. Treatment in vitro or in vivo of these Tet-off MLL-AF9 AMLs with doxycycline (DOX) results in the efficient down-regulation of the expression of the driver oncogene MLL-AF9. RNA sequencing analysis was performed on primary Tet-Off MLL-AF9 AML cells obtained from the spleen of leukemic animals and cultured in vitro for either 2 or 4 days in the presence of doxycycline (1μg/ml) (DOX= down-regulation of MLL-AF9) or left untreated (UT).
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. Primary AMLs driven by Tet-off inducible MLL/AF9 expression linked to dsRED reporter, in association with oncogenic NRASG12D (Tet-off MLL-AF9) were generated by reconstituting lethally irradiated congenic mice with foetal liver cells co-transduced with a Tet-Off-MLL-AF9-dRED retroviral vector and a second vector co-expressing NRASG12D together with the Tet-Off responsive transcriptional activator. RNA sequencing analysis sequencing analysis was performed on Tet-Off MLL-AF9/dsRED+ AML cells treated in vitro with doxycycline (DOX) for 4 days to inactivate MLL-AF9 expression or left untreated (UT). For the Id2 over-expression experiment, Tet-Off MLL-AF9/dsRED+ AML cells were transduced in vitro with an Id2-GFP or a control-GFP retroviral vector. Viable GFP-positive cells were FACS-sorted 2 days after transduction and used for RNA sequencing analysis.
Project description:The Wnt/beta-catenin pathway is required for the development of leukemia stem cells in MLL-AF9 AML. We evaluated the dependance on beta-catenin for KrasG12DMLL-AF9 leukemia.
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.
Project description:A t(9;11)(p22;q23) translocation produces the MLL-AF9 fusion protein, which is found in up to 25% of de novo AML cases in children. Despite major advances, obtaining a comprehensive under-standing of context-dependent MLL-AF9-mediated gene programs during early hematopoiesis is challenging. Here, we generated a human inducible pluripotent stem cell (hiPSC) model with a doxycycline dose-dependent MLL-AF9 expression. We exploited MLL-AF9 expression as an onco-genic hit to uncover epigenetic and transcriptomic effects on iPSC-derived hematopoietic develop-ment and the transformation into (pre-)leukemic states. In doing so, we observed a disruption in early myelomonocytic development. Accordingly, we identified gene profiles that were consistent with primary MLL-AF9 AML and uncovered high-confidence MLL-AF9-associated core genes that are faithfully represented in primary MLL-AF9 AML, including known and presently unknown factors. Using single-cell RNA-sequencing, we identified an increase of CD34 expressing early hematopoietic progenitor-like cell states as well as granulocyte-monocyte progenitor-like cells upon MLL-AF9 activation. Our system allows for careful chemically controlled and stepwise in vitro hiPSC-derived differentiation under serum-free and feeder-free conditions. For a disease that cur-rently lacks effective precision medicine, our system provides a novel entry-point into exploring po-tential novel targets for personalized therapeutic strategies.