UMLS:C0023473 - FACTA Search

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Query: UMLS:C0023473 (chronic myeloid leukemia)
18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent in vitro studies indicate that bone marrow mesenchymal elements, residing in close proximity to hematopoietic cell populations, elaborate a network of cytokines that are, at least partially, responsible for modulating the growth and maturation of the latter compartment. Leukemia inhibitory factor (LIF), a molecule with both positive and negative regulatory activities, has been implicated in murine embryogenesis and hematopoiesis. We demonstrate that cultured normal human bone marrow stromal cells constitutively express LIF message. Further, exposure of these cells to other hematopoietic modulators including interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), transforming growth factor-beta (TGF-beta), and tumor necrosis factor-alpha (TNF-alpha) (but not interferon-alpha [IFN alpha]) increases the level of LIF RNA. Interestingly, cultured stromal cells derived from three of four patients with chronic myelogenous leukemia showed enhanced LIF expression. These observations suggest that LIF may participate, either alone or through interaction with other cytokines, in the bone marrow microenvironment-mediated influence on both normal and malignant hematopoietic processes.
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PMID:Constitutive expression of leukemia inhibitory factor RNA by human bone marrow stromal cells and modulation by IL-1, TNF-alpha, and TGF-beta. 170 8

Previous studies have revealed a consistent defect in the cycling behavior of primitive neoplastic progenitor cells in patients with Philadelphia chromosome (Ph1)-positive chronic myeloid leukemia (CML). This is manifested both in vivo and in long-term cultures of CML cells as an increased rate of turnover amongst Ph1-positive progenitor cell types whose counterparts in normal individuals are mainly quiescent. To determine whether this deregulated proliferative activity of primitive Ph1-positive cells might be explained by a perturbation in the production of growth factors that regulate the turnover of primitive normal cells, the possibility of either autocrine or paracrine mechanisms of Ph1-positive cell stimulation was investigated. Northern blot analysis of total cellular RNA extracted from various CML blood cell populations showed no evidence of increased expression of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage-CSF (GM-CSF), interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-3, IL-6, or tumor necrosis factor-alpha (TNF-alpha) compared with analogous normal peripheral blood cell populations in which transcripts for most of these growth factors are not detectable. A similar analysis of RNA extracted from the adherent layer of 4-week-old long-term cultures established from CML marrow (in which the Ph1-positive cells typically disappear) or from CML blood seeded onto normal marrow adherent layers (in which Ph1-positive cells typically persist) also revealed no difference in growth factor production compared with analogous cultures established with exclusively normal cells. For some of the growth factors studied, the assessment of bioactivity detectable in the medium confirmed the RNA data. There was also no evidence of a decreased production of putative inhibitors of primitive hematopoietic cells, i.e. transforming growth factor-beta and macrophage inflammatory protein-1 alpha by CML versus normal cells or cultures. These results do not support the existence of BCR-ABL induced autocrine or paracrine mechanisms in CML and suggest that constitutive activation of events normally dependent on growth factor receptor stimulation is more likely to underlie the lack of proliferation control exhibited by primitive Ph1-positive cells.
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PMID:Lack of evidence for abnormal autocrine or paracrine mechanisms underlying the uncontrolled proliferation of primitive chronic myeloid leukemia progenitor cells. 196 Oct 20

Peripheral mononuclear cells from adult T cell leukemia (ATL) patients were analyzed in comparison with other types of leukemia cells, for the expression of transforming growth factor-beta (TGF-beta) mRNA, for the presence of TGF-beta activity (colony stimulating activity for normal rat kidney fibroblasts [NRK]) in conditioned medium and for their susceptibility to exogenous TGF-beta. Highly elevated TGF-beta mRNA levels were observed in all five ATL cell samples tested; however, in three acute myelogenous leukemia (AML) samples, in one acute lymphatic leukemia (ALL), and one chronic myelogenous leukemia (CML), TGF-beta expression was relatively lower. In normal peripheral mononuclear cells TGF-beta mRNA was weakly detectable. Colony stimulating activity for NRK found in the conditioned medium from ATL cells as well as other leukemia cells correlated well with the levels of TGF-beta mRNA expression. In all three ATL samples tested, stimulation of 3H-thymidine uptake by purified TGF-beta from platelets was apparent. These results suggest that ATL cells are secreting active TGF-beta in a relatively high amount, as compared with other leukemia cells, and may proliferate in response to the factor via an autocrine manner. Furthermore, considering that TGF-beta stimulates bone resorption, we can speculate that the relatively high amount of TGF-beta in ATL cells contributes to the hypercalcemia frequently seen in ATL patients.
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PMID:Expression of TGF-beta gene in adult T cell leukemia. 289 88

The bone marrow microenvironment supports and regulates the proliferation and differentiation of hematopoietic cells. Dysregulated hematopoiesis in chronic myelogenous leukemia (CML) is caused, at least in part, by abnormalities in CML hematopoietic progenitors leading to altered interactions with the marrow microenvironment. The role of the microenvironment itself in CML has not been well characterized. We examined the capacity of CML stroma to support the growth of long-term culture-initiating cells (LTC-IC) obtained from normal and CML marrow. The growth of normal LTC-IC on CML stroma was significantly reduced compared with normal stroma. This did not appear to be related to abnormal production of soluble factors by CML stroma because normal LTC-IC grew equally well in Transwells above CML stroma as in Transwells above normal stroma. In addition, CML and normal stromal supernatants contained similar quantities of both growth-stimulatory (granulocyte colony-stimulating factor (CSF), interleukin-6, stem cell factor, granulocyte-macrophage CSF, and interleukin-1 beta) and growth-inhibitory cytokines (transforming growth factor-beta, macrophage inflammatory protein-1 alpha, and tumor necrosis factor-alpha). The relative proportion of different cell types in CML and normal stroma was similar. However, polymerase chain reaction and fluorescence in situ hybridization studies showed the presence of bcr-abl-positivo cells in CML stroma, which were CD14+ stromal macrophages. To assess the effect of these malignant macrophages on stromal function, CML and normal stromal cells were separated by fluorescence-activated cell sorting into stromal mesenchymal cell (CD14-) and macrophage (CD14+) populations. CML and normal CD14- cells supported the growth of normal LTC-IC equally well. However, the addition of CML macrophages to normal or CML CD14- mesenchymal cells resulted in impaired progenitor support. This finding indicates that the abnormal function of CML bone marrow stroma is related to the presence of malignant macrophages. In contrast to normal LTC-IC, the growth of CML LTC-IC on allogeneic CML stromal layers was not impaired and was significantly better than that of normal LTC-IC cocultured with the same CML stromal layers. These studies demonstrate that, in addition to abnormalities in CML progenitors themselves, abnormalities in the CML marrow microenvironment related to the presence of malignant stromal macrophages may contribute to the selective expansion of leukemic progenitors and suppression of normal hematopoiesis in CML.
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PMID:Abnormal function of the bone marrow microenvironment in chronic myelogenous leukemia: role of malignant stromal macrophages. 778 Jan 47

The long-term marrow culture (LTC) system allows the sustained production of primitive normal and neoplastic (chronic myeloid leukemia [CML]) hematopoietic cells in vitro for many weeks. This is achieved in the absence of exogenously added hematopoietic growth factors because of the presence in the cultures of supportive "stromal" cells of the fibroblast-endothelial-adipocyte lineages. These latter cells form a confluent adherent layer with which the most primitive hematopoietic cells become associated and which locally regulates their behavior. The LTC system has thus been considered as a model of the microenvironment of the bone marrow and used to delineate potentially physiologically relevant mechanisms that regulate the proliferation, self-renewal and differentiation of primitive normal hematopoietic cells. It has also been used to analyze the molecular basis of the altered proliferative behavior that characterizes primitive neoplastic cells from patients with CML. Most of the information obtained to date has emerged from experiments designed to shift the balance of stimulatory and inhibitory factors present in order to favor either the cycling or quiescence of primitive normal or CML cells in LTC. This has been achieved either by addition of soluble factors (or antagonists) to the LTC medium or by the use of genetically engineered factor-producing stromal cells. Such experiments have allowed the identification of a number of cytokines that promote one or the other of these responses (i.e., primitive progenitor cycling or quiescence), including some that are involved in control mechanisms endogenous to the LTC system. Recent studies suggest that the retention of primitive normal cells in a reversible G(o) state in this system is mediated by the cooperating action of limiting concentrations of at least two endogenously produced inhibitory factors (transforming growth factor-beta (TGF-beta) and macrophage inflammatory protein-1 alpha (MIP-1 alpha)), either of which, however, if added exogenously at a sufficient concentration, can exert this action on its own. Interestingly, the heightened turnover characteristic of primitive CML cells appears to be due to a selective unresponsiveness to only one of these two inhibitors (MIP-1 alpha). These findings are consistent with a complex model of the extrinsic regulation of primitive hematopoietic cells in which a multiplicity of intracellular signaling intermediates within the target cells converge at different points ultimately to control their entry into S phase. Our findings further suggest that only some of these pathways may be affected by intracellular expression of the BCR-ABL fusion gene.
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PMID:Differential manipulation of normal and chronic myeloid leukemia stem cell proliferation in vitro. 799 64

The long-term culture (LTC) system has been useful for analyzing mechanisms by which stromal cells regulate the proliferative activity of primitive normal, but not chronic myeloid leukemia (CML), hematopoietic progenitor cells. In previous studies, we identified two endogenous inhibitors in this system. One is transforming growth factor-beta (TGF-beta), which is equally active on primitive normal and CML progenitors. The other we now show to be monocyte chemoattractant protein-1 (MCP-1). Thus, MCP-1, when added to LTC, blocked the activation of primitive normal progenitors but did not arrest the cycling of primitive CML progenitors. Moreover, the endogenous inhibitory activity of LTC stromal layers could be overcome by the addition of neutralizing antibodies to MCP-1, but not to macrophage inflammatory protein-1alpha (MIP-1alpha). However, neither of these antibodies antagonized the inhibitory activity of NAc-Ser-Asp-Lys-Pro (AcSDKP) on primitive normal but not CML progenitor cycling in this system. Moreover, none of six other -C-C- or -C-X-C- chemokines, previously shown to inhibit primitive normal human CFC proliferation in semisolid assays, were found to act as negative regulators when added to normal LTC. These results provide further support for the concept that primitive CML progenitor cell proliferation is deregulated when these cells are exposed to limiting concentrations of multiple inhibitors, only some of which have differential actions on normal and Ph+/BCR-ABL+ cells.
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PMID:MCP-1, not MIP-1alpha, is the endogenous chemokine that cooperates with TGF-beta to inhibit the cycling of primitive normal but not leukemic (CML) progenitors in long-term human marrow cultures. 974 72

The t(3;21)(q26;q22) chromosomal translocation associated with blastic crisis of chronic myelogenous leukemia results in the formation of the AML1/Evi-1 chimeric protein, which is thought to play a causative role in leukemic transformation of hematopoietic cells. Here we show that AML1/Evi-1 represses growth-inhibitory signaling by transforming growth factor-beta (TGF-beta) in 32Dcl3 myeloid cells. The activity of AML1/Evi-1 to repress TGF-beta signaling depends on the two separate regions of the Evi-1 portion, one of which is the first zinc finger domain. AML1/Evi-1 interacts with Smad3, an intracellular mediator of TGF-beta signaling, through the first zinc finger domain, and represses the Smad3 activity, as Evi-1 does. We also show that suppression of endogenous Evi-1 in leukemic cells carrying inv(3) restores TGF-beta responsiveness. Taken together, AML1/Evi-1 acts as an inhibitor of TGF-beta signaling by interfering with Smad3 through the Evi-1 portion, and both AML1/Evi-1 and Evi-1 repress TGF-beta-mediated growth suppression in hematopoietic cells. Thus, AML1/Evi-1 may contribute to leukemogenesis by specifically blocking growth-inhibitory signaling of TGF-beta in the t(3;21) leukemia.
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PMID:The t(3;21) fusion product, AML1/Evi-1, interacts with Smad3 and blocks transforming growth factor-beta-mediated growth inhibition of myeloid cells. 983 2

Genomic instability is one mechanism proposed to play a role in the disease progression of chronic myeloid leukemia (CML). Microsatellite regions in the type II transforming growth factor-beta receptor (TGF-beta RII) gene appear to be targets for mutation in some cancers displaying microsatellite instability (replication error phenotype, RER+). Furthermore, TGF-beta RII mutations in RER+ tumors have been associated with decreased TGF-beta RII mRNA levels. As TGF-beta is a potent negative growth regulator of hematopoietic cells, investigations were undertaken to determine whether inactivation of the receptor by microsatellite alteration might be involved in the progression of CML. Analysis of TGF-beta RII mRNA expression by RNase protection, with comparison of cells from the chronic, accelerated and blast phases of CML, showed no change in TGF-beta RII transcript levels during disease progression. However, during each phase of the disease, low levels of TGF-beta RII were detected when compared with the hematopoietic cells of normal donors. Furthermore, this decreased expression was also observed in the other myeloproliferative disorders, polycythemia rubra vera (PRV) and essential thrombocythemia (ET). The leukemia cell lines K562 and HL-60 had no detectable TGF-beta RII mRNA. Two microsatellite regions found altered in RER+ colon cancers were analyzed to establish if these sequences were aberrant in CML. No alteration was detected in either of these regions in any phase of the disease. These results suggest that alterations of the microsatellite regions in the TGF-beta RII gene are not involved in the progression of CML. Decreased expression of TGF-beta RII in CML cells and leukemia cell lines raises the possibility that altered expression of the receptor may play a role in the initiation and/or maintenance of the disease state.
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PMID:The TGF-beta type II receptor in chronic myeloid leukemia: analysis of microsatellite regions and gene expression. 1021 59

A novel Philadelphia chromosome-positive cell line was established from the peripheral blood of a patient with chronic myelogenous leukemia in megakaryoblastic crisis. This cell line, designated TN922 showed the positive phenotypes for myeloid, monocyte-macrophage, erythroid and megakaryocytic markers. The stimulation with phorbol 12-myristate 13-acetate (PMA) increased the expression of megakaryocytic markers including the platelet peroxidase activity, dimethylsulfoxide or transforming growth factor-beta promoted up-regulation of the erythroid markers. Stimulation with PMA, tumor necrosis factor-alpha or interleukin-6 also brought about the expression of monocytoid markers. These findings indicated that TN922 cell line has the property of acting as multipotential progenitor cells. TN922 cells showed gradual growth in the absence of growth factors but the addition of granulocyte/macrophage colony-stimulating factor (GM-CSF) promoted cell growth. The message of GM-CSF was detected in TN922 cells and the neutralizing antibody against GM-CSF receptor alpha-subunit suppressed cell growth. These results indicated that TN922 cell line proliferates in an autocrine secretion of GM-CSF.
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PMID:A novel Philadelphia chromosome-positive cell line with multipotential properties. 1022 66

Chronic myeloid leukemia (CML) is a malignant stem cell disease characterized by an expansion of myeloid progenitor cells expressing the constitutively activated Bcr-Abl kinase. This oncogenic event causes a deregulation of apoptosis and cell cycle progression. Although the molecular mechanisms protecting from apoptosis in CML cells are well characterized, the cell cycle regulatory event is poorly understood. An inhibitor of the cyclin-dependent kinases, p27, plays a central role in the regulation of growth factor dependent proliferation of hematopoietic cells. Therefore, we have analyzed the influence of Bcr-Abl in the regulation of p27 expression in various hematopoietic cell systems. An active Bcr-Abl kinase causes down-regulation of p27 expression in murine Ba/F3 cells and human M07 cells. Bcr-Abl blocks up-regulation of p27 after growth factor withdrawal and serum reduction. In addition, p27 induction by transforming growth factor-beta (TGF-beta) is completely blocked in Bcr-Abl positive M07/p210 cells. This deregulation is directly mediated by the activity of the Bcr-Abl kinase. A Bcr-Abl kinase inhibitor completely abolishes p27 down-regulation by Bcr-Abl in both Ba/F3 cells transfected either with a constitutively active Bcr-Abl or with a temperature sensitive mutant. The down-regulation of p27 by Bcr-Abl depends on proteasomal degradation and can be blocked by lactacystin. Overexpression of wild-type p27 partially antagonizes Bcr-Abl-induced proliferation in Ba/F3 cells. We conclude that Bcr-Abl promotes cell cycle progression and activation of cyclin-dependent kinases by interfering with the regulation of the cell cycle inhibitory protein p27. (Blood. 2000;96:1933-1939)
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PMID:Bcr-Abl kinase down-regulates cyclin-dependent kinase inhibitor p27 in human and murine cell lines. 1096 97

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