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

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.
 ...
PMID:New understanding of the pathogenesis of CML: a prototype of early neoplasia. 952 44

In Philadelphia chromosome (Ph1)-positive human leukemia, the c-Abl tyrosine kinase is activated by fusion to sequences encoded by the breakpoint cluster region (bcr) gene. Two major types of Bcr-Abl fusion proteins have been found in human leukemia. Fusion of the N-terminal 426 amino acids of Bcr generates p190(Bcr-Abl) which is mostly found in acute lymphocytic leukemia (ALL), whereas fusion of the N-terminal 902 or 927 amino acids of Bcr generates p210(Bcr-Abl) mostly found with chronic myelogenous leukemia (CML). Previous studies have demonstrated that both the Bcr and the Abl functional domains contribute to the oncogenic activity of Bcr-Abl proteins. Present in both p190 and p210 is the N-terminal coiled-coil of Bcr (aa 1-63), which is shown here to be functionally replaceable with the leucine zipper of the yeast transcription factor GCN4. The ZIP-Bcr-Abl protein transforms Rat-1/myc cells, is autophosphorylated on tyrosine and localized predominantly to actin filaments. Thus, formation of homo-oligomers through either Bcr or GCN4 coiled-coil can activate the tyrosine kinase and F-actin binding functions of Abl. We also found that a Bcr-Abl fusion containing only Bcr amino acids (1-191) can efficiently transform Rat-1/myc cells. Fusion of additional Bcr sequences (aa 192-923) did not affect the transformation of Rat-1/myc cells but progressively reduced the disruptive effect on the actin cytoskeleton. In particular, the Dbl homology domain present in p210(Bcr-Abl) but not in p190(Bcr-Abl) contributes to the stabilization of actin fibers. The modulatory effect of Bcr sequences on actin structure may underlie the apparent pathogenic variations between the different Bcr-Abl fusion proteins.
 ...
PMID:Effect of Bcr sequences on the cellular function of the Bcr-Abl oncoprotein. 934 95

We have isolated signal transduction inhibitors of low molecular weight from microorganisms and plants. Since inducers of differentiation and apoptosis may be developed as new anticancer agents, we have studied induction of differentiation and apoptosis in neoplastic cells by our signal transduction inhibitors. Aristeromycin isolated as an Abl function inhibitor induced erythroid differentiation in human CML K562 cells. Aristeromycin may induce differentiation by inhibition of methylating reactions in the cell. We isolated dephostatin from Streptomyces as a tyrosine phosphatase inhibitor, and synthesized its stable analogue, 3,4-dephostatin. The stable analogue, 3,4-dephostatin, potentiated NGF-induced morphological differentiation in rat pheochromocytoma PC12h cells, possibly by inhibition of tyrosine dephosphorylation of MAPK. Erbstatin, a tyrosine kinase inhibitor, induced morphological apoptosis and internucleosomal DNA fragmentation in mouse leukemia L1210 and human SCLC cells. Erbstatin was shown to induce apoptosis by hydrogen peroxide formation. Thus, these signal transduction inhibitors appear to be useful tools for the mechanistic study of cellular differentiation and apoptosis.
 ...
PMID:Induction of cellular differentiation and apoptosis by signal transduction inhibitors. 938 83

Chronic myelogenous leukemia (CML) is a malignant disease of the human hematopoietic stem cell caused by the BCR/ABL gene rearrangement. The only curative therapy is allogeneic transplantation. Although autologous transplants may prolong survival, most patients relapse because of disease persisting in the host and in the graft. Continued administration of chemotherapy after transplant could reduce the incidence of relapse provided that the autograft can be protected by transfer of a drug-resistance gene. However, CML autografts will almost certainly contain malignant stem cells that will also be rendered drug-resistant. The presence of the BCR/ABL oncoprotein is necessary and sufficient for malignant transformation seen in CML. We thus hypothesized that transfer of a vector that combines a drug-resistance gene with anti-BCR/ABL antisense (AS) sequences may allow for posttransplant chemotherapy to decrease persistent disease while rendering inadvertently transduced CML stem and progenitor cells functionally normal. We constructed a retroviral vector, LasBD, that combines the methotrexate (MTX)-resistant tyrosine-22 dihydrofolate-reductase (tyr22-DHFR) gene and AS sequences directed at the b3a2 BCR/ABL breakpoint. b3a2 BCR/ABL containing 32D and MO7e cells were transduced with LasBD and selected in MTX for 14 days. Expression of the AS sequences reduced BCR/ABL mRNA and p210(BCR/ABL) protein levels by 6- to 10-fold in most cells. This subsequently led to the restoration of normal function of BCR/ABL cDNA+ cells: they grew significantly slower in the presence of interleukin-3 (IL-3); they underwent apoptotic cell death when cultured without IL-3; and they had restored expression and function of adhesion receptors. These effects were specific, because LasBD-containing AS sequences directed at the b3a2 BCR/ABL breakpoint did not affect p190(BCR/ABL)-containing cells. LasBD also rendered 20% to 30% of primary Ph- and Ph+ CD34(+) cells MTX-resistant and decreased BCR/ABL mRNA levels in MTX resistant Ph+ CD34(+) cells by 10-fold. Expression of the MTX-resistant DHFR gene and the AS sequences has been stable for at least 1 year in vitro and for more than 70 days in vivo. Finally, LasBD decreased tumorigenicity of 32DBCR/ABL cells in vivo by 3 to 4 logs. In conclusion, the tyr22-DHFR gene in the LasBD vector can protect normal hematopoietic cells from MTX-mediated toxicity, whereas the AS sequences in LasBD can suppress expression of the BCR/ABL gene and restore normal function of BCR/ABL cDNA-containing cells. The LasBD vector may therefore prove to be an extremely useful adjunct in autologous transplantation for CML.
 ...
PMID:Gene therapy for chronic myelogenous leukemia (CML): a retroviral vector that renders hematopoietic progenitors methotrexate-resistant and CML progenitors functionally normal and nontumorigenic in vivo. 938 83

The hematopoietic cellular kinase (Hck) is a member of the Src family of non-receptor protein-tyrosine kinases that is expressed predominantly in granulocytes, monocytes and macrophages. Recent observations suggest that Hck may be activated in HIV-infected macrophages and in chronic myelogenous leukemia cells that express Bcr-Abl. In order to increase our understanding of the structural basis for regulation of Hck activity under normal and pathological conditions, we have solved the solution structure of the uncomplexed Hck SH2 domain using NMR spectroscopy. A novel procedure that uses intraresidue HN-H alpha distances as references for converting NOE intensities into distance restraints has been described. A total of 1757 significant experimental restraints were derived from NMR spectroscopic data including 238 medium-range and 487 long-range distance restraints and 177 torsion angle restraints. These restraints were used in a simulated annealing procedure to generate 20 structures with the program DYANA. Superimposition of residues 5-104 upon the mean coordinate set yielded an average atomic rmsd values of 0.42 +/- 0.08 A for the N,C alpha,C' atoms and 0.81 +/- 0.08 A for all heavy atoms. Rmsd values for those residues in the regions of ordered secondary structure were 0.27 +/- 0.04 A for the N,C alpha,C' atoms and 0.73 +/- 0.06 A for all heavy atoms.
 ...
PMID:Three-dimensional structure of the Hck SH2 domain in solution. 939 Apr 4

Glycation and subsequent Maillard or browning reactions of glycated proteins, leading to the formation of advanced glycation end products (AGEs), are involved in the chemical modification of proteins during normal aging and have been implicated in the pathogenesis of diabetic complications. Oxidative conditions accelerate the browning of proteins by glucose, and AGE proteins also induce oxidative stress responses in cells bearing AGE receptors. These observations have led to the hypothesis that glycation-induced pathology results from a cycle of oxidative stress, increased chemical modification of proteins via the Maillard reaction, and further AGE-dependent oxidative stress. Here we show that the preparation of AGE-collagen by incubation with glucose under oxidative conditions in vitro leads not only to glycation and formation of the glycoxidation product Nepsilon-(carboxymethyl)lysine (CML), but also to the formation of amino acid oxidation products on protein, including m-tyrosine, dityrosine, dopa, and valine and leucine hydroperoxides. The formation of both CML and amino acid oxidation products was prevented by anaerobic, anti-oxidative conditions. Amino acid oxidation products were also formed when glycated collagen, prepared under anti-oxidative conditions, was allowed to incubate under aerobic conditions that led to the formation of CML. These experiments demonstrate that amino acid oxidation products are formed in proteins during glycoxidation reactions and suggest that reactive oxygen species formed by redox cycling of dopa or by the metal-catalysed decomposition of amino acid hydroperoxides, rather than by redox activity or reactive oxygen production by AGEs on protein, might contribute to the induction of oxidative stress by AGE proteins.
 ...
PMID:Presence of dopa and amino acid hydroperoxides in proteins modified with advanced glycation end products (AGEs): amino acid oxidation products as a possible source of oxidative stress induced by AGE proteins. 946 15

In patients with chronic myeloid leukemia (CML), the neoplastic (BCR-ABL+) progenitor cells are characterized by an increased proliferative activity. Whether these cells are also resistant to apoptosis and if so, under what conditions remains controversial. We now show that highly purified populations of very primitive neoplastic progenitor cells obtained directly from CML patients survive and proliferate in vitro for several weeks in the absence of any added growth factors (except insulin). In contrast, purified primary normal progenitors maintained under the same conditions die rapidly. Nevertheless, both primary CML cells and BCR-ABL+ BAF3 cells show the same dose-dependent sensitivity to TNF-alpha or ceramide-induced apoptosis as their respective normal counterparts. In fact, time course studies demonstrated an even faster onset of apoptosis in ceramide-treated BCR-ABL+ BAF3 cells as compared to normal controls. BCR-ABL+ cells treated with ceramide also showed a rapid and sequential increase in the tyrosine phosphorylation of p210(BCR-ABL), p46-56SHC and p120Cbl. These findings suggest growth factor deprivation and treatment with TNF-alpha or ceramide trigger different initial events both of which can lead to apoptosis in factor-dependent hematopoietic cells. However, in the first case, activation of apoptosis is blocked by the basal activity of p210(BCR-ABL), whereas in the second, the presence of p210(BCR-ABL) appears to accelerate the onset of apoptosis by a mechanism that may involve an activation of its kinase function.
 ...
PMID:BCR-ABL accelerates C2-ceramide-induced apoptosis. 946 42

Chronic myelogenous leukemia (CML) is a disease characterized by the presence of p210(bcr-abl), a chimeric protein with tyrosine kinase activity. Substrates for p210(bcr-abl) are likely to be involved in the pathogenesis of CML. Here we describe the purification, cDNA cloning, and characterization of a 56-kDa tyrosine phosphorylated protein, p56(dok-2) (Dok-2), from p210(bcr-abl) expressing cells. The human dok-2 cDNA encodes a 412-amino acid protein with a predicted N-terminal pleckstrin homology domain as well as several other features of a signaling molecule, including 13 potential tyrosine phosphorylation sites, six PXXP motifs, and the ability to bind to p120(RasGAP). Dok-2 was shown to be 35% identical to p62(dok-1), a recently identified RasGAP binding protein from CML cells, and analysis of the expressed sequence tag data base revealed the presence of at least four additional proteins containing a Dok homology sequence motif. Dok mRNAs were primarily expressed in tissues of hematopoietic origin. These findings strongly suggest that a family of Dok-related proteins exists that bind to RasGAP and may mediate the effects of p210(bcr-abl) in CML.
 ...
PMID:Molecular cloning and characterization of p56dok-2 defines a new family of RasGAP-binding proteins. 947 21

The Philadelphia (Ph) chromosome can be detected in chronic myelogenous leukemia (CML) and a significant number of acute lymphoblastic leukemia (ALL) cases. Generation of p210bcr/abl, a chimeric protein with enhanced kinase activity, is thought to be involved in the pathogenesis of these diseases. To elucidate the biological properties of p210bcr/abl and to create an animal model for human Ph1-positive leukemias, we generated transgenic mice expressing p210bcr/abl driven by the promoter of the tec gene, a cytoplasmic tyrosine-kinase preferentially expressed in the hematopoietic lineage. The founder mice showed excessive proliferation of lymphoblasts shortly after birth and were diagnosed as suffering from ALL based on surface marker and Southern blot analyses. Expression and enhanced kinase activity of the p210bcr/abl transgene product were detected in the leukemic tissues. In contrast, transgenic progeny exhibited marked granulocyte hyperplasia with thrombocytosis after a long latent period and developed myeloproliferative disorders (MPDs) closely resembling human CML. Expression of p210(bcr/abl) mRNA in the proliferating granulocytes was detected by RT-PCR. In particular, one MPD mouse showed remarkable proliferation of blast cells in the lung, which might represent an extramedullar blast crisis. The results demonstrate that the expression of p210bcr/abl in hematopoietic progenitor cells in transgenic mice can contribute to two clinically distinct hematopoietic malignancies, CML and ALL, indicating that this transgenic system provides a novel transgenic model for human Ph1-positive leukemias.
 ...
PMID:Development of acute lymphoblastic leukemia and myeloproliferative disorder in transgenic mice expressing p210bcr/abl: a novel transgenic model for human Ph1-positive leukemias. 949 Jun 92

The p210 bcr-abl protein tyrosine kinase (PTK) appears to be directly responsible for the initial manifestations of chronic myelogenous leukemia (CML). In contrast to the extensive characterization of the PTK and its effects on cell function, relatively little is known about the nature of the protein tyrosine phosphatases (PTPs) that may modulate p210 bcr-abl-induced signalling. In this study, we have demonstrated that expression of PTP1B is enhanced specifically in various cells expressing p210 bcr-abl, including a cell line derived from a patient with CML. This effect on expression of PTP1B required the kinase activity of p210 bcr-abl and occurred rapidly, concomitant with maximal activation of a temperature-sensitive mutant of the PTK. The effect is apparently specific for PTP1B since, among several PTPs tested, we detected no change in the levels of TCPTP, the closest relative of PTP1B. We have developed a strategy for identification of physiological substrates of individual PTPs which utilizes substrate-trapping mutant forms of the enzymes that retain the ability to bind to substrate but fail to catalyze efficient dephosphorylation. We have observed association between a substrate-trapping mutant of PTP1B (PTP1B-D181A) and p210 bcr-abl, but not v-Abl, in a cellular context. Consistent with the trapping data, we observed dephosphorylation of p210 bcr-abl, but not v-Abl, by PTP1B in vivo. We have demonstrated that PTP1B inhibited binding of the adapter protein Grb2 to p210 bcr-abl and suppressed p210 bcr-abl-induced transcriptional activation that is dependent on Ras. These results illustrate selectivity in the effects of PTPs in a cellular context and suggest that PTP1B may function as a specific, negative regulator of p210 bcr-abl signalling in vivo.
 ...
PMID:Protein tyrosine phosphatase 1B antagonizes signalling by oncoprotein tyrosine kinase p210 bcr-abl in vivo. 956 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>