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

A factor that stimulates the incorporation of 75Selenomethionine into the newly formed platelets of recipient mice (thrombopoietin, TPO) has been partially purified from the plasma of thrombocytopenic patients. The activity was precipitated at 60-80% ammonium sulfate saturation and further purified with hydrophobic interaction chromatography. Thrombopoietin was retained by concanavalin-A-Sepharose. Using HPLC size-exclusion chromatography, an approximate molecular weight of 40,000 dalton was calculated. The overall purification factor was about 2,100-fold. TPO was stable in a pH range from 5 to 9 and was heat-sensitive, and the biological activity was destroyed by trypsin treatment and by dithiothreitol. The partially purified molecule did not stimulate the proliferation of megakaryocyte progenitors in vitro and had no effect on the growth of erythroid or granulocyte-macrophage colonies; when administered in-vivo, TPO significantly affected the mean platelet volume and increased the number of small acetylcholinesterase cells in the bone marrow. TPO appears to be specific for the megakaryocytic lineage and active on the postmitotic compartment of megakaryocytes.
Leukemia 1988 Apr
PMID:Partial purification and biochemical characterization of human plasma thrombopoietin. 336 51

After 35 years of research, the physiological regulator of platelet production has been isolated and its gene cloned. This discovery originates from studies performed with the myeloproliferative leukemia virus (MPLV), a murine retrovirus which induces an acute myeloproliferative syndrome in adult mice. MPLV carries in its genome the v-mpl oncogene which corresponds to a truncated form the c-mpl proto-oncogene. c-mpl encodes a cytokine receptor (Mpl-R) belonging to the hematopoietin receptor superfamily. Among the hematopoietic cell lineages, Mpl-R is preferentially expressed on late megakaryocyte progenitors, megakaryocytes and platelets. The ligand for Mpl-R, called Mpl-L or TPO or MGDF or megapoietin, is a glycosylated hormone of 352 amino acids in human which comprises two domains: the N-terminus domain shares 50% similarity with erythropoietin and is responsible for the biological activity; the C-terminus part is required for secretion. Notwithstanding its major action on megakaryocytopoiesis and thrombocytopoiesis, Mpl-L also potentiates the action of other cytokines on several hematopoietic lineages. Mpl-L/TPO/MGDF, the homeostatic regulator of platelet production, might be a useful therapeutical cytokine to treat thrombocytopenia induced in patients by chemotherapy.
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PMID:[Mpl ligand (thrombopoietin) and platelet regulation]. 888 Nov 4

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases characterized by a cytopenia related to abnormal proliferation and differentiation of marrow precursor cells. Some subtypes of MDS are associated with thrombocytemia or abnormal megakaryopoiesis and certain specific karyotypic abnormalities. We report on four cases of MDS with normal or elevated blood platelet count and a recurring abnormality in chromosome 1p34. The gene involved appears to be different from c-mpl and TPO.
Leukemia 1996 Nov
PMID:Thrombocytemia and abnormal megakaryopoiesis associated with abnormality of chromosome 1p34 in myelodysplastic syndromes. 889 68

We studied the effects of stem cell factor (SCF) and flt3 ligand (FL) on the ex vivo expansion of human umbilical cord blood (CB)-derived CD34+ cells in combination with various cytokines, including interleukin (IL)-3, IL-6, IL-11, and c-Mpl ligand (thrombopoietin, TPO), in a short-term serum-free liquid suspension culture system. Among the two-factor combinations tested, SCF plus IL-3 most effectively expanded committed progenitor cells, including mixed colony-forming units (CFU-Mix). The expansion efficiency (EE) of FL for each progenitor was inferior to that of SCF in the presence of various cytokines, except TPO. IL-6 significantly increased the EE for granulocyte/macrophage colony-forming units (CFU-GM) obtained with SCF + IL-3 or FL + IL-3. Interestingly, TPO markedly augmented the EE for committed progenitors, including CFU-GM, erythroid burst-forming units (BFU-E), and CFU-Mix, in the presence of SCF + IL-3 or FL + IL-3. The combinations of SCF + IL-3 + TPO + IL-6 or IL-11 maximally stimulated the expansion of committed progenitors. The maximum EE for CFU-GM, BFU-E, and CFU-Mix was respectively 197-fold (day 14), 60-fold (day 7) and 51-fold (day 14). Other combinations of cytokines without IL-3 failed to expand effectively these committed progenitors. Our data demonstrate that it is possible to expand human CB-derived committed progenitors in vitro using SCF or FL with several other cytokines including TPO, and that IL-3 is the key cytokine promoting the expansion of human hematopoietic progenitors in the presence of SCF or FL.
Leukemia 1997 Apr
PMID:Thrombopoietin augments ex vivo expansion of human cord blood-derived hematopoietic progenitors in combination with stem cell factor and flt3 ligand. 909 93

A novel human myeloid leukaemia cell line (HNT-34) was established from the peripheral blood of a 45-year-old female patient with acute myelogenous leukaemia (AML) transformed from chronic myelomonocytic leukaemia (CMMoL) with 3q21q26 syndrome. Morphologically, the HNT-34 cells were undifferentiated blasts which were negative for myeloperoxidase. The HNT-34 cells were positive for CD4, CD13, CD33 and CD34, but negative for CD41a and CD42b. The cells actively proliferated in suspension with a doubling time of 26-27h in the absence of any growth factors. Neither proliferative advantage nor differentiation was observed with the addition of G-CSE GM-CSF, IL-3, TPO, DMSO or PMA. Cytogenetic analysis showed 46,XX. t(3;3)(q21;q26), t(9;22)(q34;q11),20q-. Molecular analysis showed expression of EVI1 gene, P210 and P190 BCR/ABL chimaeric transcripts. The chromosomal breakpoint at 3q26 of HNT-34 cell line was located to approximately 200 kb 5' of FIM3 locus and more upstream of the MDS1. which is the same region as that of somatic cell hybrid line H10C. The breakpoint at 3q21 was located within the 390 kb centromeric from the breakpoint cluster region. These results suggest that the HNT-34 cell line may be a useful tool for the elucidation of the mechanisms of leukaemogenesis which involve the 3q21q26 syndrome and Ph1 chromosome.
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PMID:Establishment of a novel human myeloid leukaemia cell line (HNT-34) with t(3;3)(q21;q26), t(9;22)(q34;q11) and the expression of EVI1 gene, P210 and P190 BCR/ABL chimaeric transcripts from a patient with AML after MDS with 3q21q26 syndrome. 926 39

The 9;22 chromosomal translocation characteristic of CML results in a fused bcr/abl gene and an abnormal fusion protein, p210bcr/abl. Relative to normal c-abl, p210bc1/abl has elevated tyrosine kinase activity that is essential for its transforming activity. We recently reported a prominent 62 kDa GAP-associated P-tyr protein and five additional consistent but less prominent P-tyr proteins as well as five more minor P-tyr proteins that are constitutively tyrosine phosphorylated in primary primitive lineage negative (lin-) chronic phase CML blasts but not in comparable primary lin- normal blasts. The GAP-associated p62 protein has now been purified, sequenced and its gene has been cloned; it is a previously unidentified protein and is currently being characterized. In analyzing P-tyr proteins in primary lin- normal blasts in response to various hematopoietic cytokines, we found a striking similarity in the tyrosine phosphorylation of four major and three minor proteins after stimulation with c-kit ligand (KL) and the P-tyr proteins that are constitutively phosphorylated in primary primitive lin- chronic phase CML blasts. Other cytokines tested (ie GM-CSF, G-CSF, IL-3, FLT3 ligand, TPO, EPO) were much less active or stimulated phosphorylation of other proteins. KL/c-kit and bcr/abl have some similar activities including enhancing survival and expansion of hematopoietic progenitor cells, probably acting primarily on early progenitors at the time of lineage commitment rather than on self-renewing stem cells. Activation of growth factor receptors promote a cascade of protein phosphorylations that can ultimately result in a wide range of cellular responses. Sustained activation of discrete signaling pathways in some types of cells results in differentiation, whereas transient activation instead causes a proliferative response; in other cell types, the converse is true. It may be postulated that stem cells and primitive progenitors are at a particularly susceptible stage of development that renders them especially responsive to sustained bcr/abl-induced phorphorylation of a number of signaling proteins that are components of critical regulatory pathways, including c-kit. The affected pathways control and coordinate multiple diverse cell processes including proliferation, differentiation, maturation and apoptosis, processes that are normally tightly regulated and integrated. Perturbation of these key pathways in primitive progenitors would be expected to seriously disrupt orderly hematopoiesis and could also explain the multiple subtle pleiotropic biological abnormalities characteristically observed in later maturing CML compartments that we have collectively designated 'discordant maturation'. The true situation is undoubtedly very complex and involves interaction of multiple cytokines and signaling pathways that we are now trying to define. Constitutive downstream activation of critical pathways in susceptible early progenitors that normally require KL or other factors for activation could explain most if not all features of the disease.
Leukemia 1997 Sep
PMID:New understanding of the pathogenesis of CML: a prototype of early neoplasia. 952 44

Cord blood (CB) is an attractive alternative to bone marrow or peripheral blood as a source of transplantable hematopoietic tissue. However, because of the reduced volume, the stem cell content is limited; therefore its use as a graft for adult patients might require ex vivo manipulations. Two systems have been described that identify these stem cell populations in vitro in both mice and humans: (1) the long-term culture-initiating cells (LTC-IC), thus named because of their ability to support the growth of hematopoietic colonies (colony-forming cell (CFC)) for 5-6 weeks when co-cultured on stromal layers; (2) the generation of hematopoietic progenitors (CFC) from stroma-free liquid cultures for extended periods of time, which provides further indirect evidence of the presence of primitive stem cells. Both systems detect largely overlapping but not identical populations of stem cells. Thus the identification of the growth factor requirements for the maintenance and amplification of both systems is relevant. On this basis, analysis of the effects of 18 cytokine combinations on stroma-free liquid cultures of CB CD34+ cells, showed that: (1) after 7- and 14 day-incubation periods, several growth factor combinations expanded the LTC-IC pool to a similar extent; as compared to the LTC-IC, the generation of CFC was not impressive; (2) time-course analysis of the LTC-IC expansion demonstrated that, by extending the incubation period, only a few growth factor combinations, containing FL, TPO, KL and IL6, could support a further, increasingly greater LTC-IC expansion (up to 270000-fold of the initial value). In similar culture conditions, CFC production underwent continuous expansion, which persisted for over 7 months and reached values of one million-fold of the initial value. The simultaneous presence of FL and TPO was both necessary and sufficient to support this phenomenon. The addition of KL+/-IL6 did not appear to substantially modify the extent of LTC-IC expansion; nevertheless, it played an important role in sustaining an even more massive and prolonged output of CFU-GM, CFU-Mk and BFU/CFU-GEMM (up to 100 million-fold); (3) the presence of IL3 was found to be negative, in that it inhibited both the extent of LTC-IC expansion and the long-term generation of CFC. Thus, FL and TPO appear as two unique growth factors that preferentially support the self-renewal of primitive stem cells; the additional presence of KL and IL6 seems to enhance the proliferative potential of at least one subpopulation of daughter stem cells, which may follow three differentiation pathways. Far from being definitive, our data demonstrated that massive stem cell expansion, in cord blood, can be obtained in reasonably well-defined culture conditions. This could represent an initial step towards larger scale cultures for transplantation and gene therapy protocols.
Leukemia 1998 May
PMID:Differential growth factor requirement of primitive cord blood hematopoietic stem cell for self-renewal and amplification vs proliferation and differentiation. 959 70

We investigated the ability of endothelial cells (EC) to support hematopoiesis in contact and non-contact cocultures with isolated CD34+ or CD34/CD38low cells. In the absence of exogenous cytokines, umbilical vein EC (HUVEC) efficiently support proliferation of hematopoietic cells and generation of colony-forming cells (CFC). Cytokines (IL-6, LIF, G-CSF, GM-CSF, M-CSF, but not IL-1, IL-3, IL-7) were detected in HUVEC coculture supernatants. Neutralization of these cytokines profoundly inhibited the ability of EC supernatants to support the differentiation of hematopoietic progenitors and led to an accumulation of immature cells. Contact cocultures were significantly more efficient than non-contact cocultures. The expanded cell population essentially belonged to the myeloid and monocytic lineages. Contact cocultures generated cells expressing the CD61 or CD41 antigens. Interleukin-1alpha (IL-1alpha) augmented EC capacity to support hematopoiesis, this property resulting from the upregulation of cytokine expression. Glucocorticoids (GC) reduced this capacity by downregulating the biosynthesis of cytokines by EC and not by a direct effect on the progenitor cells. EC from the bone marrow microvasculature (BMEC) support the proliferation and the differentiation of hematopoietic progenitors. Synergistic increase in progenitor cells expansion and generation of CFC occurred when EC cocultures were added with exogenous cytokines. Supernatants of IL-1alpha-stimulated EC potentiated the effects of an association of IL-1, IL-3, IL-6, LIF, SCF, Flt3-ligand, TPO, G-CSF, GM-CSF, M-CSF and IL-11 on the proliferation of hematopoietic progenitors suggesting that EC may produce other soluble growth factors potentiating the action of the above set of cytokines.
Leukemia 1998 Aug
PMID:Endothelial cell support of hematopoiesis is differentially altered by IL-1 and glucocorticoids. 969 75

We have studied the effects of recombinant human thrombopoietin (TPO, mpl ligand) on the megakaryocyte colony formation from control human bone marrow cells, human leukemia cells at diagnosis, and human bone marrow cells after induction chemotherapy for acute leukemias. In the control human bone marrow cells from four adults and nine children who had localized malignancy and histologically normal-looking marrow. TPO alone effectively stimulated megakaryocyte colony formation, and interleukin-3 (IL-3) synergized this. In 17 patients (13 adults and four children) with acute myeloid leukemia (AML) at diagnosis, TPO stimulated leukemic colony formation in only one patient with FAB M7 subtype. In 11 children with acute lymphoblastic leukemia (ALL) at diagnosis, TPO did not enhance leukemic colony formation. After 17 courses of induction chemotherapy, nine for AML and eight for ALL, TPO stimulated megakaryocyte colony formation to a level of 51%, of that in the control human bone marrow cells. This may suggest that the administration of TPO to patients with M7 subtype warrants caution, whereas it is probably safe to give TPO at any time to patients with ALL. The administration of TPO to patients with acute leukemias after induction chemotherapy could stimulate megakaryocytopoiesis.
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PMID:Effects of thrombopoietin on megakaryocyte colony formation from leukemic cells at diagnosis and from marrow cells after induction chemotherapy for acute leukemias. 976 Jan 50

The voltammetric behavior of human mammalian cells was studied by choosing human leukemia cells (HL60) and human erythroleukemia cells (HEL). The voltammetric response of the cells was found having relation with cell metabolic viability in culture course. For example, the fluctuations of peak currents of HL60 were parallel with the nutrients replenished or not, which can reflect cell health state; the voltammetric response of HL60 regulated by the anti-metabolic drug 5F-Uriacil (5F-U) in culture course behaved in a much decreased manner, by which a voltammetric method for evaluating cytotoxicity is proposed. In this paper, the relation between HEL cell metabolism and the activation of receptor Mpl by its ligand TPO was also studied. Moreover, the mechanism of cell voltammetric behavior was discussed.
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PMID:Voltammetric behavior of mammalian tumor cells and bioanalytical applications in cell metabolism. 1022 90


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