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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methodology has been developed that enables virtually complete purification and recovery of early hematopoietic progenitors from human adult blood, a minority of which is multipotent and endowed with self-renewal capacities, i.e., exhibits stem cell properties. This report briefly reviews: (i) the key steps involved in the progenitor purification and assay procedure; (ii) the characterization of "pure" progenitors at the level of membrane antigen pattern and response to HGFs; (iii) the development of a liquid suspension culture for the pure progenitors, which allows synchronized and selective erythroid or GM differentiation, and hence may be utilized for the analysis of molecular mechanisms underlying early and late stages of hematopoiesis; (iv) the study of the expression and modulation of HGFRs expressed on progenitors.
Leukemia 1992 Nov
PMID:Cellular and molecular studies on the early stages of human hematopoietic differentiation in culture of pure progenitors. 143 30

Avian erythroblastosis virus, AEV-ES4, provides an ideal in vitro system to study oncogene co-operation in the development of erythroid leukaemias in chickens. Two oncogenes that use distinct signal transduction pathways have been identified; these act to produce a highly malignant phenotype and are an oncogenic version of a plasma membrane growth factor receptor that regulates haematopoietic progenitor self renewal and a mutated version of a transcription factor that suppresses specific gene expression. These two diverse types of oncogenes act together to generate a more malignant phenotype than would be expected merely from a summation of the individual oncogene effects. The aspects of normal growth control and the regulation of differentiation, which are altered in this system to generate the leukaemic phenotype, include changes in the balance between proliferation versus maturation, altered expression of differentiation genes and changes in growth factor responsiveness. These are exactly those features that are altered in human leukaemias. Thus, the avian leukaemia virus model has taught us important lessons that will help us to understand the basic molecular mechanisms that give rise to human leukaemia.
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PMID:Avian erythroblastosis: a model system to study oncogene co-operation in leukemia. 145 Nov 14

A patient developed pure red cell aplasia after ABO incompatible BMT for leukemia. He did not respond to plasma exchange. Antilymphocyte globulin therapy was followed by complete and permanent erythroid recovery with disappearance of recipient-derived isoagglutinins.
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PMID:Antilymphocyte globulin for treatment of pure red cell aplasia after major ABO incompatible marrow transplant. 146 14

The UT-7 cell line was established from a patient with a megakaryoblastic leukemia (Komatsu et al, Cancer Res 51: 341, 1991). Its proliferation is strictly dependent on the presence of hematopoietic growth factors including erythropoietin (Epo), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3). We investigated the differentiation capacities of this cell line under the action of several growth factors, using immunomarkers, flow cytometry, and ultrastructural techniques. In the presence of GM-CSF and IL-3, eosinophil and basophil promyelocytes were detected, as well as a few cells with erythroid and megakaryocytic (MK) differentiation features. In contrast, Epo induced a marked erythroid differentiation with an increase of glycophorin A expression, accompanied by a few hemoglobinized cells. Differentiation induced by the growth factors took 24 to 48 hours to begin, and increased with cell passages to a plateau at 2 weeks of culture. However, this was not only due to a cell selection because the differential effects of Epo and GM-CSF were observed from a single cell clone and the phenotype could be reversed by opposite growth factors, even after a long period of culture. We subsequently investigated the phenotype of UT-7 in the presence of combinations of Epo, IL-3, and GM-CSF, and showed that GM-CSF and IL-3 act predominantly over Epo. This effect was mediated by a rapid downmodulation of Epo receptors by GM-CSF at messenger RNA and binding sites levels, without a change in receptor affinities. On the other hand, Epo had no effect on number and affinity of GM-CSF receptors. This study shows that UT-7 is a growth factor-dependent pluripotent cell line in which commitment may be directed by a hierarchical action of growth factors through an early and rapid transmodulation of growth factor receptors.
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PMID:Granulocyte-macrophage colony-stimulating factor and erythropoietin act competitively to induce two different programs of differentiation in the human pluripotent cell line UT-7. 146 15

Expression of the normally cryptic blood group antigen Tn has occasionally been reported in hematologic disease, but the true frequency of this change is not known. A mouse monoclonal antibody (FBT3) and immunohistochemistry were used to examine expression of the Tn antigen. Expression was not detected in 35 normal bone marrow aspirates examined, but it was detected in 5 of 725 abnormal bone marrow aspirates, including 2 (3.6%) of 55 cases of de novo acute nonlymphocytic leukemia and 2 cases that terminated in acute nonlymphocytic leukemia. In two patients, one with acute myeloblastic leukemia and the other in blast transformation of chronic myeloid leukemia, the Tn antigen was expressed on 2 percent of blast cells. In one case of non-Hodgkin's lymphoma, 4 percent of normal myeloid cells expressed the antigen. In the other two cases, one of acute myelomonocytic leukemia and the other of myelodysplasia, only 2 to 8 percent of myeloid and erythroid cells initially were Tn positive. Subsequent serial immunohistochemical studies of bone marrow aspirates and peripheral blood in these two cases showed increasing numbers of Tn-positive erythroid and myeloid cells 8 to 12 months before polyagglutination was detected serologically. Tn-positive cells increased to > 90 percent in the terminal phase in both cases of both diseases. The results suggest that Tn expression in these two patients may have conferred a growth advantage to the cells and could be related to disease progression.
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PMID:Expression of the Tn antigen in myelodysplasia, lymphoma, and leukemia. 147 Dec 47

In this study we have investigated the ability of transforming growth factor-beta 3 (TGF-beta 3, 1000 pM) to protect hematopoietic bone marrow (BM) progenitor cells from the cytotoxic activity of 4-hydroperoxycyclophosphamide (4-HC, 100 microM) in vitro. Hematopoietic progenitors were purified by negative depletion of accessory and maturing cells or enriched by positive (CD 34+ cells) selection. For comparison the same treatment was tested on three different lymphoid cell lines CEM, SK-DHL-2, and LY-16. The experimental protocol was designed to mimic ex vivo purging conditions. Therefore, tumor cells and enriched hematopoietic precursors were mixed with irradiated BM cells. Our results demonstrated that preincubation of enriched progenitor cells with TGF-beta 3 for up to 72 h followed by 4-HC treatment resulted in an increased survival of colonies derived from granulocyte-macrophage (CFU-GM) and erythroid (BFU-E) colony-forming cells, whereas a substantially lower number of colonies was observed in the control group. Similar results were observed when BM cells were first treated with 4-HC followed by TGF-beta 3 incubation for 24 or 48 h. In contrast, TGF-beta 3 provided no protection to the 4-HC cytotoxicity toward the lymphoma and leukemia cell lines. Three to four log of tumor cell killing was induced by 4-HC in the presence or absence of preincubation with TGF-beta 3. These data suggest that TGF-beta 3 is able to protect normal BM progenitors from the cytotoxic activity of an alkylating agent (4-HC) in vitro, whereas it does not offer any protection to lymphoma cell lines. These findings will have important implications for developing better purging conditions for autologous GM transplantation.
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PMID:TGF-beta 3 protects normal human hematopoietic progenitor cells treated with 4-hydroperoxycyclophosphamide in vitro. 149 54

Experiments were undertaken to investigate the molecular basis of primitive hematopoietic progenitor cell regulation in both the long-term culture system and in methylcellulose, particularly with a view to characterizing factors either able or unable to influence the behaviour of primitive leukemic cells from patients with chronic myeloid leukemia (CML). Long-term cultures of CML cells with or without irradiated normal marrow feeder layers were initiated from peripheral blood cells of CML patients with high white blood cell counts. Three weeks later the effect of exogenously added transforming growth factor-beta 1 (TGF-beta 1) on progenitor cycling status was examined. A single addition of 5 ng/ml TGF-beta 1 was able to reversibly arrest the otherwise uninterrupted turnover of primitive leukemic erythroid and granulopoietic progenitors for a period of up to 7 days both in the presence and absence of a normal adherent cell population. When TGF-beta 1 was incorporated into methylcellulose cultures, its ability to inhibit colony formation by CML progenitors showed the same differential activity on primitive cell types exhibited by normal progenitors. Dose-response curves for analogous populations of normal and leukemic cells were indistinguishable. Increasing the concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF) in methylcellulose colony assays decreased the sensitivity displayed by normal clonogenic cells to TGF-beta 1 and no differences were detectable when CML cells were used in such regulator competition experiments. These findings support a general model of primitive hematopoietic cell regulation in which entry into S-phase is determined at the intracellular level by multiple convergent pathways that may deliver either positive or negative signals from activated cell surface receptors for distinct extracellular factors. The present study shows for the first time that primitive CML progenitors exposed to TGF-beta 1 in vitro can be transiently blocked in a noncycling state for several days without loss of viability and that the mechanisms responsible for the emergence and maintenance of a clonal population of CML cells in vivo do not appear to involve changes in their sensitivity to TGF-beta 1. It is thus unlikely that the heightened proliferative activity exhibited by primitive CML progenitors both in vivo and in long-term culture can be explained by an abnormality in the intracellular mechanisms normally activated by TGF-beta 1 receptor-ligand binding. We suggest that primitive CML cells are either defective in their ability to see (or activate) endogenously produced TGF-beta 1, or are defective in their responsiveness to another, undefined, regulator.
Leukemia 1992 Sep
PMID:Granulocyte-macrophage colony-stimulating factor modulation of the inhibitory effect of transforming growth factor-beta on normal and leukemic human hematopoietic progenitor cells. 151 2

Chemically induced differentiation of Friend murine erythroleukemia cells (F-MELC) is a multistep process with a latent period of about 12 h preceding irreversible commitment to terminal maturation. To gain understanding of the early genetic response of F-MELC to the dimethyl sulfoxide (DMSO) inducer of F-MELC differentiation, we have investigated by Northern blot analysis the expression of fos and jun family genes that encode components of the transcription factor AP-1 complex. Our results show that c-jun mRNA is not detected at any time in untreated and DMSO-treated F-MELC. In contrast, DMSO-induced differentiation of F-MELC is associated with an early and transient induction of c-fos and junB mRNAs by 2 to 8 h treatment while in presence of dexamethasone, an inhibitor of F-MELC commitment, c-fos mRNA is not detected and junB mRNA remains at basal levels. junD mRNA is detected at low levels in untreated F-MELC and remains unchanged during DMSO treatment. Furthermore, DMSO treatment in a F-MELC cell line resistant to DMSO-differentiation does not result in an early induction of c-fos and junB mRNAs. Taken together, these results indicate that the DMSO-induced F-MELC differentiation is accompanied by an early co-induction of c-fos and junB during the latent period preceding the commitment to erythroid maturation.
Leukemia 1992 Sep
PMID:Co-induction of c-fos and junB during the latent period preceding commitment of Friend erythroleukemia cells to differentiation. 151 4

Fanconi's anemia is an autosomal recessive disorder with a high incidence (greater than 90%) of aplastic anemia and a premalignant component with a greater than 10% risk of leukemia or solid tumors. The diagnosis of Fanconi's anemia depends on increased chromosomal breakage in lymphocytes following treatment with a DNA cross-linking agent; patients have been identified who are clinically well and whose physical appearance is normal. Although bone marrow or cord blood transplants can be curative, treatment for the aplastic anemia usually depends on androgens. Close to 20 patients with Fanconi's anemia have delivered normal babies, and the mothers' hematologic status was not significantly adversely affected by the pregnancy. A few patients have clonal cytogenetic abnormalities in their bone marrow that do not necessarily indicate leukemic transformation, but further follow-up is important. Studies of in vitro erythropoiesis indicate a correlation between the clinical hematologic status and the presence of erythroid progenitors in the blood or bone marrow. Certain hematopoietic growth factors do increase growth in vitro, suggesting that new types of therapy may become available. Not every patient has a poor prognosis. There are now many adults with Fanconi's anemia, some with families of their own.
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PMID:Fanconi's anemia. Current concepts. 153 Jan 23

We previously demonstrated that 3'-azido-3'-deoxythymidine (AZT) inhibits hemoglobin (Hb) synthesis and globin gene transcription in butyric acid-induced K-562 leukemia cells, suggesting that these effects may play a role in the AZT-induced anemia observed in patients [Mol. Pharmacol. 38:797-804 (1990)]. The recent discovery by our group of a novel metabolite of AZT. 3'-amino-3'-deoxythymidine (AMT), which exhibits a high degree of toxicity toward human hemopoietic cells [Mol. Pharmacol. 39:258-266 (1991); Antimicrob. Agents Chemother. 35:801-807 (1991)], has led us to explore potential effects of this AZT metabolite on Hb production, globin mRNA expression, and heme synthesis in butyric acid-induced K-562 human erythroleukemia cells. AMT inhibited Hb synthesis by approximately 21%, as measured by benzidine staining, at concentrations as low as 25 microM, with slightly increased inhibition at higher AMT concentrations. The inhibition of Hb production by AMT was substantially lower, compared with that of AZT. AMT inhibited globin mRNA steady state levels in a dose-dependent manner to a similar extent as did the parent drug, with approximately 50% inhibition by each compound at a concentration of 100 microM. Nuclear run-on transcription assays demonstrated that inhibition by AMT of globin mRNA synthesis was associated with a decreased rate of globin-specific gene transcription. Globin mRNA stability was not affected by either 100 microM AZT or AMT, as measured after blockage of transcription with actinomycin D. To gain insight into potential mechanism(s) responsible for the different quantitative effects of AZT and AMT on Hb synthesis, the effect of each compound on induction of heme synthesis in K-562 cells was determined. Although heme induction was not affected by AMT, a significant inhibition approximating 20% was observed in the presence of 100 microM AZT. In addition, AZT down-regulated mRNA steady state levels under conditions where heme synthesis was inhibited by succinylacetone. These data suggest that inhibition by AZT of globin gene expression is a direct effect and is not secondary to inhibition of heme synthesis. This study emphasizes the role of AMT in the pharmacodynamic properties of AZT, in relation to its toxicity, and suggest that both AMT and AZT may be involved in the inhibition of erythroid differentiation observed in vivo, through changes in gene expression.
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PMID:Comparative effects of 3'-azido-3'-deoxythymidine and its metabolite 3'-amino-3'-deoxythymidine on hemoglobin synthesis in K-562 human leukemia cells. 153 5


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