Search results for "topoi"
showing 10 items of 701 documents
STAT5 is crucial to maintain leukemic stem cells in acute myelogenous leukemias induced by MOZ-TIF2.
2012
Abstract MOZ-TIF2 is a leukemogenic fusion oncoprotein that confers self-renewal capability to hematopoietic progenitor cells and induces acute myelogenous leukemia (AML) with long latency in bone marrow transplantation assays. Here, we report that FLT3-ITD transforms hematopoietic cells in cooperation with MOZ-TIF2 in vitro and in vivo. Coexpression of FLT3-ITD confers growth factor independent survival/proliferation, shortens disease latency, and results in an increase in the number of leukemic stem cells (LSC). We show that STAT5, a major effector of aberrant FLT3-ITD signal transduction, is both necessary and sufficient for this cooperative effect. In addition, STAT5 signaling is essent…
Role of SHP2 for FLT3-dependent proliferation and transformation in 32D cells.
2008
Fms-like tyrosine kinase 3 (FLT3) is a class III receptor tyrosine kinase, which plays a role in proliferation and differentiation of B-cell progenitors, myelomonocytic and dendritic cells, as well as in the maintenance of pluripotent hematopoietic stem cells (reviewed in Stirewalt and Radich,1and Schmidt-Arras et al.2). Recently, FLT3 has received much attention as an important oncoprotein. Mutations in FLT3 that lead to constitutive activation are among the most common molecular lesions found in acute myeloid leukemia.3 The most prevalent type of mutations result in internal tandem duplications (ITD) of amino-acid stretches in the juxtamembrane domain of FLT3. FLT3-ITD is constitutively a…
SOCS2 controls proliferation and stemness of hematopoietic cells under stress conditions and its deregulation marks unfavorable acute leukemias
2015
Abstract Hematopoietic stem cells (HSC) promptly adapt hematopoiesis to stress conditions, such as infection and cancer, replenishing bone marrow–derived circulating populations, while preserving the stem cell reservoir. SOCS2, a feedback inhibitor of JAK–STAT pathways, is expressed in most primitive HSC and is upregulated in response to STAT5-inducing cytokines. We demonstrate that Socs2 deficiency unleashes HSC proliferation in vitro, sustaining STAT5 phosphorylation in response to IL3, thrombopoietin, and GM-CSF. In vivo, SOCS2 deficiency leads to unrestricted myelopoietic response to 5-fluorouracil (5-FU) and, in turn, induces exhaustion of long-term HSC function along serial bone marro…
3054 – MONOCYTE SUBSET PRODUCTION DURING AGING
2020
A growing body of evidence suggests that monocytes are more heterogenous than previously appreciated and that monocyte subsets play distinct roles in both health and disease. We have previously demonstrated that two separate pathways of monocyte production by granulocyte-monocyte progenitors (GMPs) and monocyte-dendritic cell progenitors (MDPs) yield functionally distinct monocyte subsets in mouse bone marrow. GMPs produce classical monocytes with neutrophil-like properties, and MDPs yield classical monocytes that give rise to monocyte-derived DCs (moDCs). We also showed that Toll-like receptor agonists differentially promote production of these monocyte subsets during emergency monopoiesis…
MLL-Rearranged Leukemia Is Dependent on Aberrant H3K79 Methylation by DOT1L
2011
SummaryThe histone 3 lysine 79 (H3K79) methyltransferase Dot1l has been implicated in the development of leukemias bearing translocations of the Mixed Lineage Leukemia (MLL) gene. We identified the MLL-fusion targets in an MLL-AF9 leukemia model, and conducted epigenetic profiling for H3K79me2, H3K4me3, H3K27me3, and H3K36me3 in hematopoietic progenitor and leukemia stem cells (LSCs). We found abnormal profiles only for H3K79me2 on MLL-AF9 fusion target loci in LSCs. Inactivation of Dot1l led to downregulation of direct MLL-AF9 targets and an MLL translocation-associated gene expression signature, whereas global gene expression remained largely unaffected. Suppression of MLL translocation-a…
Broad-spectrum Cross-resistance to Anticancer Drugs Mediated by Epidermal Growth Factor Receptor
2019
BACKGROUND The oncogenic role of epidermal growth factor receptor (EGFR) has been intensively studied. However, its emerging role in drug resistance has not been fully addressed. MATERIALS AND METHODS This study systematically investigated the correlation of mRNA and protein expression of EGFR, as well as gene amplification and mutations with the log-transformed half-maximal inhibitory concentration (log10IC50) values obtained from the NCI panel of 60 human tumor cell lines against 83 standard anticancer agents and the top 10 natural cytotoxic products previously screened by us. RESULTS EGFR protein expression, rather than other measurements, was most frequently associated with drug respons…
Progressive multifocal encephalopathy in a patient with non-Hodgkin follicular lymphoma
2020
Progressive multifocal leukoencephalopathy (PML) is a rare and often fatal demyelinating disease of the central nervous system caused by John Cunningham virus (JCV). We present a case report of patient with non-Hodgkin follicular lymphoma, who developed PML after hematopoietic stem cell transplantation and rituximab-bendamustine therapy. JCV DNA was proven both in peripheral blood and cerebrospinal fluid. Patient with 4 years history of follicular lymphoma presented with progressing weakness in the right arm and leg and postural instability. Magnetic resonance imaging scans showed bilateral hyperintense lesions in the cerebellum and centrum semiovale consistent with findings in PML. JCV DNA…
Sodium phenylbutyrate induces apoptosis in human retinoblastoma Y79 cells: The effect of combined treatment with the topoisomerase I-inhibitor topote…
2001
Our results demonstrate that sodium phenylbutyrate, a compound with a low degree of toxicity, exerted a cytotoxic effect on human retinoblastoma Y79 cells in a time- and dose-dependent manner. Treatment of Y79 cells for 72 h with phenylbutyrate reduced cell viability by 63% at 2 mM and 90% at 4 mM. Cell death caused by phenylbutyrate exhibited the typical features of apoptosis, as shown by light and fluorescent microscopy. Western blot analysis demonstrated that exposure of Y79 cells to phenylbutyrate decreased the level of the antiapoptotic factor Bcl-2 and induced the activation of caspase-3, a key enzyme in the execution phase of apoptosis. Moreover, treatment with phenylbutyrate markedl…
Topotecan-triggered degradation of topoisomerase I is p53-dependent and impacts cell survival.
2005
Abstract The anticancer drug topotecan belongs to the group of topoisomerase I (topo I) inhibitors. In the presence of topotecan, topo I cleaves the DNA but is unable to religate the single-strand break. This leads to stabilization of topo I-DNA–bound complexes and the accumulation of DNA strand breaks that may interfere with DNA replication. The molecular mechanism of controlling the repair of topo I-DNA covalent complexes and its impact on sensitivity of cells to topotecan is largely unknown. Here, we used mouse embryonic fibroblasts expressing wild-type p53 and deficient in p53, in order to elucidate the role of p53 in topotecan-induced cell death. We show that p53-deficient mouse embryo…