Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tyrosine phosphorylation is important in the transmission of growth and differentiation signals; known tyrosine kinases include several oncoproteins and growth factor receptors. Interestingly, some differentiated cell types, such as erythrocytes and platelets contain high amounts of phosphotyrosine. We analyzed tyrosine kinases expressed in the K-562 chronic myelogenous leukemia cell line, which has a bipotential erythroid and megakaryoblastoid differentiation capacity. Analysis of 359 polymerase chain reaction-amplified cDNA clones led to the identification of 14 different tyrosine kinase-related sequences (JTK1-14). Two of the clones (JTK2 and JTK4) represent unusual members of the fibroblast growth factor receptor gene family, and the clones JTK5, JTK11, and JTK14 may also belong to the family of receptor tyrosine kinases but lack a close relationship to any known tyrosine kinase. Each of these different genes has its own characteristic expression pattern in K-562 cells and several other human tumor cell lines. In addition, the JTK11 and JTK14 mRNAs are induced during the megakaryoblastoid differentiation of K-562 cells. These tyrosine kinases may have a role in the differentiation of megakaryoblasts or in the physiology of platelets.
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PMID:Putative tyrosine kinases expressed in K-562 human leukemia cells. 224 64

The c-kit proto-oncogene encodes a receptor tyrosine kinase that is considered to play important roles in hematopoiesis. The proto-oncogene c-kit product is expressed on various types of human cell lines derived from leukemic cells of erythroid, megakaryocytic and mast-cell lineages. Also, the c-kit product is detectable in blast cells in most cases of acute myeloblastic leukemia (AML) and in some cases of chronic myelogenous leukemia (CML) in blastic crisis (BC). By contrast, little or no expression of c-kit is observed in human leukemia cell lines of lymphoid lineage and in blast cells in acute lymphoblastic leukemia (ALL). Tyrosine phosphorylation and activation of the c-kit product with the ligand for c-kit (stem cell factor: SCF) results in proliferation of some human leukemia cell lines, such as M07E, and blast cells in a substantial fraction of AML cases. In addition, SCF appears to have an activity in inducing differentiation of certain types of leukemic cells. In some cases, further, the c-kit product is found to be activated in leukemic cells even before the stimulation with SCF. These results suggest that c-kit may be involved in excessive proliferation and aberrant differentiation of human leukemia cells.
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PMID:Expression, function and activation of the proto-oncogene c-kit product in human leukemia cells. 769 Jun 31

The p210bcr/abl tyrosine kinase appears to be responsible for initiating and maintaining the leukemic phenotype in chronic myelogenous leukemia (CML) patients. p21ras-p120GAP interactions play a central role in transducing mitogenic signals. Therefore, we investigated whether p21ras and p120GAP are regulated by p210bcr/abl, and whether this activation is functionally significant for CML cell proliferation. We report that transient expression of p210bcr/abl in fibroblast-like cells induces simultaneous activation of p21ras and inhibition of GTPase-promoting activity of p120GAP, and confirm these data showing that downregulation of p210bcr/abl expression in CML cells with bcr/abl antisense oligodeoxynucleotides induces both inhibition of p21ras activation and stimulation of GTPase-promoting activity of p120GAP. Tyrosine phosphorylation of two p120GAP-associated proteins, p190 and p62, which may affect p120GAP activity, also depends on p210bcr/abl tyrosine kinase expression. Direct dependence of these effects on the kinase activity is proven in experiments in which expression of c-MYB protein in fibroblast-like cells or downregulation of c-MYB expression resulting in analogous inhibition of CML cell proliferation does not result in the same changes. Use of specific antisense oligodeoxynucleotides to downregulate p21ras expression revealed a requirement for functional p21ras in the proliferation of Philadelphia chromosome-positive CML primary cells. Thus, the p210bcr/abl-dependent regulation of p120GAP activity is responsible, in part, for the maintenance of p21ras in the active GTP-bound form, a crucial requirement for CML cell proliferation.
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PMID:Negative regulation of p120GAP GTPase promoting activity by p210bcr/abl: implication for RAS-dependent Philadelphia chromosome positive cell growth. 819 13

The neutrophil superoxide (O2-)-producing capacity in 57 patients with chronic myeloproliferative disorders (MPDs) and eight patients with chronic myelomonocytic leukemia (CMML) was investigated. O2- release in neutrophils stimulated by chemotactic peptide was markedly increased in all types of chronic MPD, including chronic myelogenous leukemia in both chronic phase and blastic crisis, polycythemia vera, and essential thrombocythemia, but was normal in CMML, which is thought to be a myelodysplastic disorder rather than MPD. Increase in O2(-)-producing capacity in MPD was also observed when other receptor-mediated agonists such as interleukin-8 and concanavalin A were used, but not when phorbol ester, a direct activator of protein kinase C, was used as the triggering agonist of O2- release. Priming effects of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), and tumor necrosis factor (TNF) on chemotactic peptide-induced O2- release was observed in all patients with MPD and CMML, though fold enhancement of priming effects was much less in MPD compared with normal subjects. In addition, the priming effects of TNF were less than those of GM-CSF in 10 cases, whereas the priming effects of TNF were consistently and markedly greater than those of GM-CSF in normal subjects. Tyrosine phosphorylation of 42-kDa protein stimulated by G-CSF, GM-CSF, and TNF was observed in CML neutrophils to be identical to that in normal neutrophils. Present results indicate specific potentiation of the receptor-mediated route of signaling that is linked to the respiratory burst and downregulated responsiveness to cytokines in neutrophils in patients with all types of chronic MPD, suggesting in vivo priming of patient neutrophils via certain mechanism by cytokines or related stimuli in these hematological disorders.
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PMID:Increased neutrophil respiratory burst in myeloproliferative disorders: selective enhancement of superoxide release triggered by receptor-mediated agonists and low responsiveness to in vitro cytokine stimulation. 898 3

Temperature-sensitive mutants of BCR/ABL tyrosine kinase have been extensively used to study the mechanisms of cell transformation and signal transduction. However, little is known about the effect of temperature on the activity of wild-type BCR/ABL gene product. In this study, we demonstrate that in vivo tyrosine kinase activity of p210, p190 BCR/ABL and v-abl are temperature-sensitive when expressed in hematopoietic cells and decline when temperature is raised 2 degrees C above normal range. In vitro tyrosine kinase activities of purified recombinant Abl and immunoprecipitated p210 BCR/ABL were also sensitive to increased temperature. Tyrosine phosphorylation of cellular proteins was markedly reduced in BCR/ABL transformed cells after 16 h at 39 degrees C, whereas the expression of BCR/ABL was unchanged. Temperature-induced downregulation of BCR/ABL kinase activity was reversible when cells were shifted back to 37 degrees C. The downregulation of Abl tyrosine kinase activity was not influenced by mutation or deletion of SH2 or SH3 domains or mutation of the GRB2 binding site. No increase in functional activity or expression of protein-tyrosine phosphatases, PTP-1B, SH-PTP1 or SH-PTP2 was detected in cells grown at 39 degrees C. Temperature-induced downregulation in tyrosine kinase activity correlated with decline in phosphotyrosine-associated PI 3-kinase whereas there was no change in growth factor independence of transformed hematopoietic cells. In conclusion, Abl tyrosine kinase has intrinsic sensitivity to temperature and BCR/ABL expressed in hematopoietic cells is downregulated by increasing temperature 2 degrees C. These observations provide a unique opportunity to identify cellular factor(s) which regulate BCR/ABL kinase in vivo and suggests possible novel treatment of CML by a mild hyperthermia.
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PMID:Inactivation of wild-type BCR/ABL tyrosine kinase in hematopoietic cells by mild hyperthermia. 1080 16

Chronic myeloid leukaemia is a haemopoietic stem cell disorder, the hallmark of which is the expression of the Bcr-Abl Protein Tyrosine Kinase (PTK). We have previously reported that activation of a temperature sensitive Bcr-Abl PTK in the multipotent haemopoietic cell line FDCP-Mix for short periods resulted in subtle changes including, a transient suppression of apoptosis and no inhibition of differentiation. In contrast, activation of the Bcr-Abl PTK for 12 weeks results in cells that display a delay in differentiation at the early granulocyte stage. Flow cytometric analysis also indicates that the expression of cell surface differentiation markers and nuclear morphology are uncoupled. Furthermore, a significant number of the mature neutrophils display abnormal morphological features. Prolonged exposure to Bcr-Abl PTK results in interleukin-3 independent growth and decreased p53 protein levels. FDCP-Mix cells expressing a dominant negative p53 and p53null FDCP-Mix cells demonstrate that the reduction in p53 is causally related to the delay in development. Returning the cells to the restrictive temperature restores the p53 protein levels, the growth factor dependence and largely relieves the effects on development. We conclude that prolonged Bcr-Abl PTK activity within multipotent cells results in a reduction of p53 that drives a delayed and abnormal differentiation.
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PMID:Bcr-Abl protein tyrosine kinase activity induces a loss of p53 protein that mediates a delay in myeloid differentiation. 1111 26

We have previously reported that the Jak2 tyrosine kinase but not Jak1 is tyrosine phosphorylated in the absence of IL-3 in Bcr-Abl positive M3.16 cells, which are rendered IL-3 independent by BCR-ABL gene expression. We have explored the involvement of Jak2 tyrosine phosphorylation in Bcr-Abl oncogenic effects. Our results indicate that Jak2 became tyrosine-phosphorylated in a number of cell lines expressing Bcr-Abl, when maintained in medium lacking IL-3, whereas Bcr-Abl negative cells lacked Jak2 tyrosine phosphorylation. Jak2 was poorly tyrosine-phosphorylated in cells expressing the SH2 deletion mutant of Bcr-Abl compared to either wild-type Bcr-Abl or its SH3 deletion mutant. Moreover, tyrosine phosphorylation of Jak2 by Bcr-Abl was inhibited by the Abl tyrosine kinase inhibitor, STI 571, in a dose-dependent manner. This inhibition of Bcr-Abl kinase by the drug did not interfere with the ability of Jak2 and Bcr-Abl to form a complex. Studies with deletion mutants of Bcr-Abl indicated that the C-terminal domain of Abl within Bcr-Abl was involved in complex formation with Jak2. Similarly, GST-Abl pull-down assays confirmed the strong binding to Jak2 by the C-terminus of Abl. Jak2 peptide substrate studies indicated that the Bcr-Abl and Abl tyrosine kinases specifically phosphorylated Y1007 of Jak2 but only poorly phosphorylated Y1008. Phosphorylation of Y1007 of Jak2 is known to be critical for its tyrosine kinase activation. Tyrosine residue 1007 of Jak2 was phosphorylated in 32Dp210 cells as measured by Western blotting with a phosphotyrosine 1007 sequence-specific antibody. A kinase-inactive Jak2 mutant blocked the colony forming ability of K562 cells. Tumor formation of K562 cells in nude mice was similarly inhibited by this kinase-inactive Jak2 mutant. This inhibition was independent of Stat5 tyrosine phosphorylation. Furthermore, tyrosine-phosphorylated Jak2 was detected in blood cells from CML patients in blast crisis but not in a normal marrow sample. In summary, these findings provide strong evidence that the Jak2 tyrosine kinase is a critical factor in Bcr-Abl malignant transformation.
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PMID:Involvement of Jak2 tyrosine phosphorylation in Bcr-Abl transformation. 1159 27

Tyrosine kinases are enzymes that regulate mitosis, differentiation, migration, neovascularization, and apoptosis. Their spectrum and association with specific malignancies offer multiple targets for therapeutic intervention. Chronic myelogenous leukemia (CML) represents an ideal target for a therapy using a selective inhibitor of the BCR-ABL tyrosine kinase. The 2-phenylpyrimidine derivative STI571 was rationally designed to inhibit ABL and BCR-ABL tyrosine kinase activities through competitive ATP-binding pocket interactions. Phase II data demonstrate hematologic and cytogenetic responses in interferon refractory chronic-phase, accelerated-phase and blast crisis patients. However, long-term observation is needed to confirm that response data result in prolongation of survival. STI571 is being studied in other malignancies, including leukemias characterized by expression of alternate molecular forms of BCR-ABL and those expressing protein tyrosine kinases with ATP-binding pockets structurally similar to ABL, e.g. c-kit and PDGF-R. Gastrointestinal stromal tumor (GIST) cells overexpress the stem cell factor receptor CD117, the product of the proto-oncogene c-kit. Inhibition of c-kit in vivo results in an immediate metabolic change of the tumor cells, detectable by positron emission tomography. Since c-kit overexpression is inhibited in small-cell lung cancer cell lines, a study with STI571 as second-line therapy of c-kit-positive small-cell lung cancer is in progress. Clinical studies are ongoing in malignancies associated with an enhanced activity of the PDGF-R, such as highgrade glioma, prostate cancer and leukemias with rearrangements of PDGF-R. The development of selective tyrosine kinase inhibitors is considered a promising approach for the design of new drugs. Clinical responses to STI571 in various malignancies may stimulate greater interest in the clinical use of tyrosine kinase inhibitors.
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PMID:[Selective inhibition of tyrosine kinases - a new therapeutic principle in oncology]. 1160 Aug 16

Tyrosine kinases are commonly mutated and activated in both acute and chronic myeloid leukemias. Here, we review the functions, signaling activities, mechanism of transformation, and therapeutic targeting of two prototypic tyrosine kinase oncogenes, BCR-ABL and FLT3, associated with chronic myeloid leukemia (CML) and acute myeloid leukemia (AML), respectively. BCR-ABL is generated by the Philadelphia chromosome translocation between chromosomes 9 and 22, creating a chimeric oncogene in which the BCR and c-ABL genes are fused. The product of this oncogene, BCR-ABL, has elevated ABL tyrosine kinase activity and transforms hematopoietic cells by exerting a wide variety of biological effects, including reduction in growth factor dependence, enhanced viability, and altered adhesion of chronic myelocytic leukemia (CML) cells. Elevated tyrosine kinase activity of BCR-ABL is critical for activating downstream signalling cascades and for all aspects of transformation, explaining the remarkable clinical efficacy of the tyrosine kinase inhibitor, imatinib mesylate (STI571). By comparison, FLT3 is mutated in about one third of all cases of AML, most often through a mechanism that involves an internal tandem duplication (ITD) of a small number of amino acid residues in the juxtamembrane domain of the receptor. As is the case for BCR-ABL, these mutations activate the kinase activity constitutively, activate multiple signaling pathways, and result in an augmentation of proliferation and viability. Transformation by FLT3-ITD can readily be observed in murine models, and FLT3 cooperates with other types of oncogenes to create a fully transformed acute leukemia. FLT3 tyrosine kinase inhibitors are currently being evaluated in clinical trials and may be very useful therapeutic agents in AML.
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PMID:Mutated tyrosine kinases as therapeutic targets in myeloid leukemias. 1290 54

The Werner syndrome protein (WRN) is a caretaker of the human genome, and the Abl kinase is a regulator of the DNA damage response. Aberrant DNA repair has been linked to the development of cancer. Here, we have identified a direct binding between WRN and c-Abl in vitro via the N-terminal and central regions of WRN and the Src homology domain 3 of c-Abl. After bleomycin treatment in culture, WRN and c-Abl are dissociated and followed by an Abl kinase-dependent WRN relocalization to the nucleoplasm. WRN is a substrate of c-Abl in vitro and in vivo. WRN is tyrosine phosphorylated either transiently by treatment of HeLa cells with bleomycin or constitutively in cells from chronic myeloid leukemia (CML) patients, and these phosphorylations are prevented by treatment with the Abl kinase inhibitor STI-571. Tyrosine phosphorylation of WRN results in inhibition of both WRN exonuclease and helicase activities. Furthermore, anti-WRN immunoprecipitates from CML cells treated with STI-571 show increased 3'-->5' exonuclease activity. These findings suggest a novel signaling pathway by which c-Abl mediates WRN nuclear localization and catalytic activities in response to DNA damage.
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PMID:Werner syndrome protein phosphorylation by abl tyrosine kinase regulates its activity and distribution. 1294 67


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