Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ability of somatic stem cells to self-renew and differentiate into downstream lineages is dependent on specialized chromatin environments that keep stem cell-specific genes active and key differentiation factors repressed but poised for activation. The epigenetic factors that provide this type of regulation remain ill-defined. Here we provide the first evidence that the SNF2-like ATPase Mi-2beta of the Nucleosome Remodeling Deacetylase (NuRD) complex is required for maintenance of and multilineage differentiation in the early hematopoietic hierarchy. Shortly after conditional inactivation of Mi-2beta, there is an increase in cycling and a decrease in quiescence in an HSC (hematopoietic stem cell)-enriched bone marrow population. These cycling mutant cells readily differentiate into the erythroid lineage but not into the myeloid and lymphoid lineages. Together, these effects result in an initial expansion of mutant HSC and erythroid progenitors that are later depleted as more differentiated proerythroblasts accumulate at hematopoietic sites exhibiting features of erythroid leukemia. Examination of gene expression in the mutant HSC reveals changes in the expression of genes associated with self-renewal and lineage priming and a pivotal role of Mi-2beta in their regulation. Thus, Mi-2beta provides the hematopoietic system with immune cell capabilities as well as with an extensive regenerative capacity.
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PMID:The role of the chromatin remodeler Mi-2beta in hematopoietic stem cell self-renewal and multilineage differentiation. 1845 Nov 7

Co-transplantation of mesenchymal stem cells (MSCs) and hematopoietic stem cells ameliorate hematopoietic reconstitution and induce tolerance. The immunomodulatory properties of MSCs have been demonstrated both in vivo and in vitro. MSCs can modulate function of immune cells such as T lymphocytes, antigen-presenting cells and natural killer cells. However, it is unknown whether MSCs given to patients that have undergone HSC transplantation could alleviate graft versus leukemia effect or could increase the risk of the infection. Proper characterization of MSC immunomodulatory mechanisms are crucial to anticipate the possible effect of MSC in the host. In the current report, interesting and contradictory results in the literature are reviewed in an attempt to understand the underlying mechanism. Differences in experimental designs and models used seem to be the underlying causes of discrepancy in reported results. Results of the few in vivo studies are controversial and further clinical studies are needed to confirm the efficiency and safety of MSCs in transplantation management.
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PMID:Immunomodulatory effect of mesenchymal stromal cells: possible mechanisms. 1858 75

In addition to its role in megakaryocyte production, signaling initiated by thrombopoietin (TPO) activation of its receptor, myeloproliferative leukemia virus protooncogene (c-Mpl, or Mpl), controls HSC homeostasis and self-renewal. Under steady-state conditions, mice lacking the inhibitory adaptor protein Lnk harbor an expanded HSC pool with enhanced self-renewal. We found that HSCs from Lnk-/- mice have an increased quiescent fraction, decelerated cell cycle kinetics, and enhanced resistance to repeat treatments with cytoablative 5-fluorouracil in vivo compared with WT HSCs. We further provide genetic evidence demonstrating that Lnk controls HSC quiescence and self-renewal, predominantly through Mpl. Consistent with this observation, Lnk-/- HSCs displayed potentiated activation of JAK2 specifically in response to TPO. Biochemical experiments revealed that Lnk directly binds to phosphorylated tyrosine residues in JAK2 following TPO stimulation. Of note, the JAK2 V617F mutant, found at high frequencies in myeloproliferative diseases, retains the ability to bind Lnk. Therefore, we identified Lnk as a physiological negative regulator of JAK2 in stem cells and TPO/Mpl/JAK2/Lnk as a major regulatory pathway in controlling stem cell self-renewal and quiescence.
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PMID:Lnk controls mouse hematopoietic stem cell self-renewal and quiescence through direct interactions with JAK2. 1861 18

SRPX2 (Sushi repeat containing protein, X-linked 2) was first identified as a downstream molecule of the E2A-HLF fusion gene in t(17;19)-positive leukemia cells and the biological function of this gene remains unknown. We found that SRPX2 is overexpressed in gastric cancer and the expression and clinical features showed that high mRNA expression levels were observed in patients with unfavorable outcomes using real-time RT-PCR. The cellular distribution of SRPX2 protein showed the secretion of SRPX2 into extracellular regions and its localization in the cytoplasm. The introduction of the SRPX2 gene into HEK293 cells did not modulate the cellular proliferative activity but did enhance the cellular migration activity, as shown using migration and scratch assays. The conditioned-medium obtained from SRPX2-overexpressing cells increased the cellular migration activity of a gastric cancer cell line, SNU-16. In addition, SRPX2 protein remarkably enhanced the cellular adhesion of SNU-16 and HSC-39 and increased the phosphorylation levels of focal adhesion kinase (FAK), as shown using western blotting, suggesting that SRPX2 enhances cellular migration and adhesion through FAK signaling. In conclusion, the overexpression of SRPX2 enhances cellular migration and adhesion in gastric cancer cells. Here, we report that the biological functions of SRPX2 include cellular migration and adhesion to cancer cells.
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PMID:SRPX2 is overexpressed in gastric cancer and promotes cellular migration and adhesion. 1906 54

Autologous hematopoietic stem cell transplantation (HSCT) has proved efficient to treat hematological malignancies. However, some patients fail to mobilize HSCs. It is known that the microenvironment may undergo damage after allogeneic HSCT. However little is known about how chemotherapy and growth factors contribute to this damage. We studied the stromal layer formation (SLF) and velocity before and after HSC mobilization, through long-term bone marrow culture from 22 patients and 10 healthy donors. Patients' SLF was similar at pre- (12/22) and post-mobilization (9/20), however for controls this occurred more at pre-mobilization (9/10; p=0.03). SLF velocity was higher at pre than post-mobilization in both groups. Leukemias and multiple myeloma showed faster growth of SLF than lymphomas at post-mobilization, the latter being similar to controls. These findings could be explained by less uncommitted HSC in controls than patients at post-mobilization. Control HSCs may migrate more in response to mobilization, resulting in a reduced population by those cells.
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PMID:Does mobilization for autologous stem cell transplantation damage stromal layer formation? 1929 18

Mastic is a resinous exudate obtained from the stem and the main leaves of Pistacia lentiscus. We have reported the antiplaque effect of mastic-containing chewing gum on the oral cavity. We hypothesize that mastic may be a multifunctional food which has some beneficial pharmaceutical properties. The aim of this study was to assess the biological activity of solid and liquid types of mastic by cytotoxicity against fibroblasts, radical-scavenging activities and inhibitory effect on cell death of oral polymorphonuclear leukocytes (OPMNs). Mastic showed selective antibacterial action against Porphyromonas gingivalis and Prevotella melaninogenica, but no anti-HIV activity. Among a total of thirteen human cell types, promyelocytic leukemia HL-60 was the most sensitive to the cytotoxicity of mastic, followed by myeloblastic leukemia (ML-1, KG-1), erythroleukemia (K-562), oral squamous cell carcinoma (HSC-2, HSC-3, HSC-4), hepatocellular carcinoma (HepG2), glioblastoma (T98G, U87MG) and normal oral cells (gingival fibroblast, pulp cell, periodontal ligament fibroblast, most resistant). Mastic did not induce the differentiation of myelogenous leukemic cells into maturing cells with higher nitroblue tetrazolium-reducing activity, but induced apoptotic cell death, characterized by internucleosomal DNA fragmentation, caspase-3 activation and a decline in the intracellular concentration of putrescine. The cytotoxicity of mastic against leukemic cells did not diminish during its storage. On the other hand, mastic inhibited the spontaneous apoptosis of OPMNs. Mastic showed hydroxyl radical-scavenging activity. The selective antibacterial and apoptosis-modulating activity of mastic suggests its possible beneficial effects on oral health.
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PMID:Selective antibacterial and apoptosis-modulating activities of mastic. 1941 6

Acute myeloid leukemia (AML) is caused by the cooperation between class I, mostly mutated receptor tyrosine kinases (RTK), and class II oncoproteins, chimeric transcription factors derived from chromosomal translocations. The blasts of 80-90% of AML-patients are positive for the RTK c-Kit. In about 50% of the 'core binding factor' (CBF)-AMLs, c-Kit harbors additional gain-of-function mutations, whereas the t(15;17)-positive AML-M3 (100% c-Kit positive) presents virtually no c-Kit mutations. In all c-Kit-positive AMLs, c-Kit signaling is activated. Here, we investigated the role of c-Kit in the determination of the leukemic phenotype in a model of CBF-AML and AML-M3. We studied the role of aberrant c-Kit signaling on normal and leukemic murine stem cells by RNA interference, the c-Kit-inhibitor Imatinib and a constitutively-activated c-Kit mutant in well-established stem cell assays. Effects of the AML-M3-associated PML/RARalpha and the AML-1/ETO as a model for CBF-AML on c-Kit signaling were investigated in trans-activation assays on the Kit promoter. The contribution of activated c-Kit signaling to PML/RARalpha- and AML-1/ETO-induced leukemogenesis was investigated in a murine transduction/transplantation leukemia model. We report that: i) the inhibition of c-Kit impaired the stem cell capacity of PML/RARalpha- and AML-1/ETO-positive HSC; ii) PML/RARalpha was able to activate the c-Kit promoter; iii) constitutively-activated c-Kit increased the stem cell capacity of HSC; and iv) constitutively-activated c-Kit increased the leukemogenic potential of PML/RARalpha- and AML-1/ETO-positive HSC. Our data provide evidence that c-Kit does not have to be mutated to contribute to the determination of the leukemic phenotype in AML.
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PMID:Cooperation between constitutively activated c-Kit signaling and leukemogenic transcription factors in the determination of the leukemic phenotype in murine hematopoietic stem cells. 1942 69

A number of experimental studies have shown that natural killer (NK) cells can eliminate cancer cells and the mechanisms involved in this effect have been uncovered during the last two decades. Clinical data from haploidentical haematopoietic stem cell transplantation (haplo-HSCT) revealed that NK cells were responsible for remarkably favourable effects in both adult and paediatric high-risk leukaemias. NK receptors specific for major histocompatibility complex (MHC) class I molecules, including killer immunoglobulin (Ig)-like receptors (KIR) and CD94/NKG2A, play a major role in the anti-leukaemia effect (mediating either inhibitory or activating signals). Haplo- HSCT requires a heavy conditioning regimen for the patient and the use of large numbers of T cell-depleted HSC to be grafted. After transplantation, natural killer cells develop from HSC shortly after engraftment and may include 'alloreactive' NK cells that kill leukaemic cells and prevent graft-versus-host disease (GvHD). Alloreactive NK cells are characterized by the expression of KIR that are not engaged by any of the human leucocyte antigen (HLA) class I alleles expressed by the patient. Their generation is dependent upon the existence of a KIR/HLA class I mismatch between donor and recipient. Novel important information on the function and specificity of different KIR has been obtained recently by the analysis of donor-derived alloreactive NK cells in a cohort of paediatric patients given haplo-HSCT to cure acute, high-risk leukaemias.
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PMID:Activating and inhibitory killer immunoglobulin-like receptors (KIR) in haploidentical haemopoietic stem cell transplantation to cure high-risk leukaemias. 1966 39

Two new spirostanol glycosides (1, 2) and a new furostanol glycoside (3), together with nine known steroidal glycosides (4-12) were isolated from the leaves of Furcraea foetida (Agavaceae). The structures of the new compounds were determined by spectroscopic analysis and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activities against HL-60 human leukemia cells, A549 human lung adenocarcinoma cells, HSC-2 human oral squamous carcinoma cells, and HSC-4 human oral squamous carcinoma cells.
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PMID:Steroidal glycosides from Furcraea foetida and their cytotoxic activity. 1980 82

We here use knockin mutagenesis in the mouse to model the spectrum of acquired CEBPA mutations in human acute myeloid leukemia. We find that C-terminal C/EBPalpha mutations increase the proliferation of long-term hematopoietic stem cells (LT-HSCs) in a cell-intrinsic manner and override normal HSC homeostasis, leading to expansion of premalignant HSCs. However, such mutations impair myeloid programming of HSCs and block myeloid lineage commitment when homozygous. In contrast, N-terminal C/EBPalpha mutations are silent with regards to HSC expansion, but allow the formation of committed myeloid progenitors, the templates for leukemia-initiating cells. The combination of N- and C-terminal C/EBPalpha mutations incorporates both features, accelerating disease development and explaining the clinical prevalence of this configuration of CEBPA mutations.
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PMID:Hematopoietic stem cell expansion precedes the generation of committed myeloid leukemia-initiating cells in C/EBPalpha mutant AML. 1987 71


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