Project description:Leukemias with MLL-rearrangements are characterized by high expression of the homeo box gene MEIS1. In these studies, we knocked down Meis1 expression by shRNA lentivirus transduction in murine Mll-AF9 leukemia cells. Meis1 knockdown resulted in decreased proliferation and survival of murine Mll-AF9 leukemia cells. We also observed reduced clonogenic capacity and increased monocytic differentiation. The establishment of leukemia in transplant recipients was significantly delayed by Meis1 knockdown. Gene expression profiling of cells transduced with Meis1 shRNA showed reduced expression of genes associated with cell cycle entry and progression. shRNA mediated knockdown of MEIS1 in human MLL-fusion gene leukemia cell lines resulted in reduced cell growth. These results show that MEIS1 expression is important for MLL-rearranged leukemias and suggest that MEIS1 promotes cell cycle entry. Targeting MEIS1 may have therapeutic potential for treating leukemias expressing this transcription factor. Keywords: Gene expression
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:The pathogenesis of MLL-fusion gene leukemias has been linked to upregulated expression of HOX genes and of the HOX-cofactor Meis1.The functions of the HOX/MEIS1 complex in leukemia however remain unclear. Here, we used inducible MEIS1-knockout mice coupled with MLL-AF9 knockin mice to decipher the role of MEIS1 in leukemia. We found that MEIS1 was critically required for established leukemia. Further, MEIS1 loss led to increased oxygen flux and apoptosis, while hypoxia reversed these effects. Finally, we identify HLF as a downstream mediator of MEIS1 in leukemia. Overexpression of HLF prevents oxygen flux and rescues the leukemia phenotype in MEIS1-deficient cells. Thus, the oncogenic effects of MEIS1 are at least partly mediated by an HLF-driven hypoxic state.
Project description:HOXA9 and MEIS1 are essential downstream effectors of the MLL-AF9 oncoprotein during leukaemia induction. Leukaemia derived from MLL-AF9-transduced LSK cells has a more aggressive phenotype than that derived from HOXA9/MEIS1-transduced LSK cells. To determine differential gene expression that contributes to increased aggressiveness in MLL-AF9-induced leukaemia, microarray was performed on LSK cells transduced with MLL-AF9 versus HOXA/MEIS1 oncogenes.
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.
Project description:TET1, the founding member of the TET family of enzymes (TET1/2/3) that convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), was first identified as a partner gene in MLL-rearranged leukemia, but its definitive pathological role in leukemia is unclear. The down-regulation of all three TET genes and loss-of-function mutations of TET2 have been frequently observed in various cancers, and it was thought that they all play tumor-suppressor roles in tumorigenesis. Here we show that TET1 is likely a direct target of MLL and significantly up-regulated in MLL-rearranged leukemia, associated with an increased level of 5hmC. Our further in vitro and in vivo studies demonstrate that Tet1 plays an indispensable oncogenic role in MLL-rearranged leukemia, through cooperating with MLL fusion proteins in regulating their co-targets including the Hoxa/Meis1/Pbx3/Flt3 genes. Our data delineate a MLL-fusion/Tet1/Hoxa/Meis1/Pbx3/Flt3 signaling axis in MLL-rearranged leukemia, and highlight TET1 as a potential therapeutic target in treating this presently therapy-resistant disease. We report genome-wide 5hmC enrichment profiles and RNA-Seq gene expression in MLL-AF9 transformed and control mouse bone marrow mononuclear cells. These 5hmC profiles are derived from selctive chemical labeling and enrichment of 5hmC containing genomic DNA fragments, while the RNA-Seq expression profiles are generated from polyA enriched RNA
Project description:This SuperSeries is composed of the following subset Series: GSE30745: Expression data from murine acute myeloid leukemia (AML) cells following shRNA-mediated suppression of Myb GSE30746: Expression data from murine Tet-off MLL-AF9/Ras acute myeloid leukemia cell lines following withdrawal of MLL-AF9 Refer to individual Series
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).