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:Analysis of gene expression profile of Hoxa9/Meis1 leukemia cells 6 days after loss of Jmjd1c. Loss of Jmjd1c induces differentiation and Hoxa9/Meis1 leukemia cells. These results provide insight into the role of Jmjd1c in AML with elelvated expression of Hoxa9.
Project description:HOXA9 and MEIS1 are essential downstream effectors of the MLL-AF9 oncoprotein during leukemia induction. Leukemia derived from MLL-AF9-transduced LSK cells has a more aggressive phenotype than that derived from HOXA9/MEIS1-transduced LSK cells. To determine differential miRNA expression that contributes to increased aggressiveness in MLL-AF9-induced leukemia, miRCURY LNA microRNA Array was performed on LSK cells transduced with MLL-AF9 versus HOXA/MEIS1 oncogenes.
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:To investigate whether co-expression of PBX3/MEIS1 can mimic that of MLL-AF9, HOXA9/MEIS1 or HOXA9/PBX3 in inducing leukemogenesis, we conducted in vivo mouse bone marrow transplantation (BMT) assays. Briefly, normal mouse bone marrow (BM) progenitor (i.e., lineage negative; Lin-) cells collected from B6.SJL (CD45.1) donor mice (CD45.1) were retrovirally co-transduced with MSCVneo-MLL-AF9+MSCV-PIG (MLL-AF9), MSCVneo-HOXA9+MSCV-PIG (HOXA9), MSCVneo-HOXA9+MSCV-PIG-MEIS1 (HOXA9+MEIS1), MSCVneo-HOXA9+MSCV-PIG-PBX3 (HOXA9+PBX3), MSCV-PIG-PBX3+MSCVneo-MEIS1 (PBX3+MEIS1), MSCVneo+MSCV-PIG-PBX3 (PBX3) , MSCVneo+MSCV-PIG-MEIS1 (MEIS1), or MSCVneo+MSCV-PIG (normal control; NC). Retrovirally transduced cells then were cultured with cytokines as well as puromycin and G418. Seven days later, the donor cells were transplanted into lethally irradiated (960 rads) 8- to 10-week-old C57BL/6 (CD45.2) recipient mice. The transplanted mice were watched for leukemogenesis. Then, gene expression profiling was conducted with bone marrow samples collected from leukemia groups and control group.