Project description:The transcription factor Meis1 drives myeloid leukemogenesis in the context of Hox gene overexpression but is currently considered undruggable. We therefore investigated whether myeloid progenitor cells transformed by Hoxa9 and Meis1 become addicted to targetable signaling pathways. A comprehensive (phospho)proteomic analysis revealed that Meis1 increased Syk protein expression and activity. Syk upregulation occurs through a Meis1-dependent feed-forward loop. By dissecting this loop, we show that Syk is a direct target of miR-146a, whose expression is indirectly regulated by Meis1 through the transcription factor PU.1. In the context of Hoxa9 overexpression, Syk induces Meis1, recapitulating several leukemogenic features of Hoxa9/Meis1-driven leukemia. Finally, we show that Syk inhibition disrupts the identified regulatory loop, prolonging survival of mice with Hoxa9/Meis1-driven leukemia.
Project description:OBJECTIVE: The microRNA miR-155 is upregulated in Hoxa9 and Meis1 leukemia inducing cells (LIC) , and miR-155 accelerates the onset of acute myeloid leukemia (AML) together with Hoxa9 but through largely unknown molecular mechanisms. The impact of miR-155 on accelerated onset of leukemia in the context of Hoxa9 and Meis1 is also unclear. To further resolve this, we performed a gene expression profiling, in the context of Hoxa9 and Meis1 leukemogenesis with miR-155 knocked out. RESULTS: Gene expression profiling of Hoxa9/Meis1 LIC without miR-155 does not delay the onset of AML and the gene expression changes are small
Project description:HOXA9/MEIS1 plays a synergistic causative role and overexpresses frequently in acute myeloid leukemia (AML). Hoxa9/Meis1 transgenic murine results in rapid leukemic transformation of primary bone marrow cells. However, murine model is not suitable to perform a high-throughput phenotypic screen in vivo and identify compounds for AML therapy. A transgenic zebrafish overexpresses hoxa9/meis1 need to generate. We have engineered an inducible transgenic line Tg (drl:hoxa9;hsp70:meis1) harboring hoxa9/meis1 under the draculin (drl) promoter. The downregulation of runx1, c-myb, mpx, mfap4, and gata1 in Tg (drl:hoxa9;hsp70:meis1) embryos indicated enforced hoxa9/meis1 perturbs embryonic hematopoiesis. Importantly, adult Tg (drl:hoxa9;hsp70:meis1) develops malignant myeloid disease with an abundance of myeloid precursor cells, anemia, and high mortality after a latency period (~5-months-aged) with comparable to murine model and human AML patients. Genome-wide transcription changes analysis indicated arrested differentiation genes such as gata2b, notch1b, and gfi1ab are upregulated. Leflunomide, inhibitor of enzyme dihydroorotate dehydrogenase (DHODH) which is a potential option for differentiation therapy of AML, relieves defective hematopoiesis in transgenic embryos and larvae. Collectively, we have identified an inducible malignant myeloid disease transgenic zebrafish model similar to AML and provided a unique opportunity for high-throughput in vivo chemical screening for AML therapy and study the related mechanisms.
Project description:OBJECTIVE: MEIS1, a HOX cofactor, collaborates with multiple HOX proteins, such as HOXA9, to accelerate the onset of acute myeloid leukemia (AML) through largely unknown molecular mechanisms. To further resolve these mechanisms, we conducted a structure-function analysis of Meis1 and gene expression profiling, in the context of Hoxa9 leukemogenesis. RESULTS: We show, in a murine bone marrow transplantation model, that the homeodomain of Meis1 is required for leukemogenic collaboration with Hoxa9. Gene expression profiling of a Hoxa9 preleukemic cell line transduced with wild-type or Meis1 homeodomain mutant reveal deregulation of multiple genes including a set not previously implicated as Meis1 targets.
Project description:OBJECTIVE: MEIS1, a HOX cofactor, collaborates with multiple HOX proteins, such as HOXA9, to accelerate the onset of acute myeloid leukemia (AML) through largely unknown molecular mechanisms. To further resolve these mechanisms, we conducted a structure-function analysis of Meis1 and miRNA expression profiling, in the context of Hoxa9 leukemogenesis. RESULTS: We show, in a murine bone marrow transplantation model, that the homeodomain of Meis1 is required for leukemogenic collaboration with Hoxa9. miRNA expression profiling of a Hoxa9 preleukemic cell line transduced with wild-type or Meis1 homeodomain mutant reveal deregulation of multiple miRNA including a set not previously implicated as Meis1 targets.
Project description:OBJECTIVE: MEIS1, a HOX cofactor, collaborates with multiple HOX proteins, such as HOXA9, to accelerate the onset of acute myeloid leukemia (AML) through largely unknown molecular mechanisms. To further resolve these mechanisms, we conducted a structure-function analysis of Meis1 and gene expression profiling, in the context of Hoxa9 leukemogenesis. RESULTS: We show, in a murine bone marrow transplantation model, that the homeodomain of Meis1 is required for leukemogenic collaboration with Hoxa9. Gene expression profiling of a Hoxa9 preleukemic cell line transduced with wild-type or Meis1 homeodomain mutant reveal deregulation of multiple genes including a set not previously implicated as Meis1 targets. Murine bone marrow cells transduced with Hoxa9-GFP + empty MIY vector were compared to Hoxa9+Meis1 cells or Hoxa9+Meis1 with deleted homeodomain (DHD) cells and cultured for three or four weeks before harvest for miRNA expression array. Four independent experiments were performed for each of the three different conditions included in the study. Cells from all samples were also transplanted into lethally irradiated mice to test for their transforming and leukemic potential.
Project description:YTHDF2 is overexpressed in a broad spectrum of human acute myeloid leukemias (AML). To study the role of YTHDF2 in leukemia, c-Kit+ cells from foetal livers of Ythdf2fl/fl;Vav-iCre (Ythdf2CKO) and Ythdf2fl/fl (Ythdf2CTL) 14.5 dpc embryos were transduced with Meis1 and Hoxa9 oncogenes and serially re-plated to generate pre-leukemic cells. Total RNA from Ythdf2CKO (n=5) and Ythdf2CTL (n=5) pre-leukemic cells were used for Affymetrix global gene expression analysis.
Project description:YTHDF2 is overexpressed in a broad spectrum of human acute myeloid leukemias (AML). To study the role of YTHDF2 on translation regulation in leukemia, c-Kit+ cells from foetal livers of Ythdf2fl/fl; Vav-iCre (Ythdf2CKO) and Ythdf2fl/fl (Ythdf2CTL) 14.5 dpc embryos were transduced with Meis1 and Hoxa9 oncogenes and serially re-plated to generate pre-leukemic cells. RIBO-seq libraries were then prepared from Ythdf2CKO (n=3) and Ythdf2CTL (n=3) pre-leukemic cells.