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)

Serum leptin levels are elevated in subjects with exogenous obesity, indicating that obesity is associated with leptin resistance. Since in man no abnormalities have yet been found in either the genes for leptin or its receptor, the mechanism of leptin resistance in obesity remains unknown. To determine if resistance might be related to leptin binding by a serum component, we assessed the carrier status of leptin in serum. The presence of a specific leptin binding factor in human serum has been established by (1) demonstrating [125I]-leptin binding to a serum component that is saturable and specifically displaceable only by unlabeled leptin and not by human growth hormone, pork insulin, insulin-like growth factors I and II, luteinizing or follicle stimulating hormones, transforming growth factor-beta 1, interleukin-6, or leukemia inhibiting factor; (2) fractionating the leptin bound serum complex and the serum leptin binding component on a molecular sieving column revealing a mass of approximately 450 kDa; and (3) identifying an inverse correlation between the concentration of serum leptin and the quantity of the leptin binding component. It is suggested that binding of leptin by this serum component may influence the physiologic response to leptin.
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PMID:Demonstration of a leptin binding factor in human serum. 916 40

The leptin receptor is a member of the cytokine receptor superfamily, and is expressed in CD34 haemopoietic stem cells. We examined expression of the leptin receptor in fresh human leukaemia cells. Northern blot analysis showed the leptin receptor was expressed in leukaemic cells from patients with acute myeloblastic leukaemia, acute lymphoblastic leukaemia and chronic myeloid leukaemia (CML). In CML, higher expression was observed in blast crisis than in chronic phase. The expression of leptin receptor decreased during in vitro differentiation of leukaemic blast cells. It appeared that expression of the leptin receptor was associated with immature leukaemic blast cells. Our findings may indicate the possibility that leptin has some role in leukaemia.
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PMID:Expression of the leptin receptor in human leukaemic blast cells. 972 1

The receptor for the gene product of the obesity gene, leptin, was recently reported to be expressed on murine and human hematopoietic progenitor cells. Therefore, we studied the expression of the leptin receptor, OB-R, in normal myeloid precursors, human leukemia cell lines, and primary leukemic cells using reverse-transcriptase polymerase chain reaction. In normal hematopoiesis, OB-R was expressed in CD34(+) cells. Normal promyelocytes (CD34(-)33(+) and CD34(-)13(+)) expressed only very low levels of the short, presumably nonsignaling isoform. Both the long and short isoforms of OB-R were expressed in 10 of 22 samples from patients with newly diagnosed primary or secondary acute myeloid leukemia (AML), with a higher incidence of the long isoform in primary AML (87.6% v 28.6%; P =.01). The incidence of OB-R expression was higher in recurrent than in newly diagnosed AML (P <.001), and samples from four patients with refractory AML showed strong expression of both isoforms. Both OB-R isoforms were also expressed in newly diagnosed and recurrent acute promyelocytic leukemia cells but were essentially absent in samples of chronic or acute lymphocytic leukemia. In vitro growth of myeloid leukemic cell lines and of blasts from 14 primary AMLs demonstrated that recombinant human leptin alone induced low level proliferation, significantly (P <.05) increased proliferation induced by recombinant human granulocyte colony-stimulating factor, interleukin 3, and stem cell factor in a subset of AML and increased colony formation (P <.005). Also, leptin reduced apoptosis induced by cytokine withdrawal in MO7E and TF-1 cells. Serum leptin levels correlated only with body mass index (P <. 001) and gender (P =.03). Results confirm the reported expression of leptin receptor in normal CD34(+) cells and demonstrate the frequent expression of leptin receptors in AML blasts. While normal promyelocytes lack receptor expression, leukemic promyelocytes express both isoforms. We also demonstrate proliferative effects of leptin alone and in combination with other physiologic cytokines, and anti-apoptotic properties of leptin. These findings could have implications for the pathophysiology of AML.
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PMID:Expression and function of leptin receptor isoforms in myeloid leukemia and myelodysplastic syndromes: proliferative and anti-apoptotic activities. 1002 96

The receptor for leptin, the gene product of the obese gene, is expressed in hematopoietic stem cells. Leptin stimulates normal myeloid and erythroid development, and is secreted from bone marrow adipocytes, which occupy most of the marrow cavity in humans. Leptin might thus play an important role in the control of the expansion and differentiation of primitive hematopoietic cells through paracrine interaction in the bone marrow microenvironment. Leukemic cells of some patients with acute myeloblastic leukemia, acute lymphoblastic leukemia, and chronic myeloid leukemia (CML) also express the leptin receptor. In cases of CML, higher expression of leptin receptor is observed during blast crisis than in chronic phase. Leptin alone and in combination with other cytokines has stimulative effects on proliferation of leukemia cells as well as anti-apoptotic effects. These findings suggest the possibility that leptin plays roles in the pathophysiology of leukemia.
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PMID:Leptin receptor and leukemia. 1078 89

Leptin, the product of the ob gene, is a pleiotropic molecule that regulates food intake as well as metabolic and endocrine functions. Leptin also plays a regulatory role in immunity, inflammation, and hematopoiesis. Alterations in immune and inflammatory responses are present in leptin- or leptin-receptor-deficient animals, as well as during starvation and malnutrition, two conditions characterized by low levels of circulating leptin. Both leptin and its receptor share structural and functional similarities with the interleukin-6 family of cytokines. Leptin exerts proliferative and antiapoptotic activities in a variety of cell types, including T lymphocytes, leukemia cells, and hematopoietic progenitors. Leptin also affects cytokine production, the activation of monocytes/macrophages, wound healing, angiogenesis, and hematopoiesis. Moreover, leptin production is acutely increased during infection and inflammation. This review focuses on the role of leptin in the modulation of the innate immune response, inflammation, and hematopoiesis.
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PMID:Leptin in the regulation of immunity, inflammation, and hematopoiesis. 1103 63

Endothelial cells and fibroblasts are important constituents of the haemopoietic microenvironment. Growth and function of these cells are controlled by a variety of cytokines, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). We analysed the effects of novel tyrosine kinase inhibitors targeting the VEGF and PDGF receptors (compounds SU5614 and SU5768) on the performance of long-term cultures from normal human bone marrow. In developing cultures, the inhibitors induced a dose-dependent reduction in stromal fibroblasts, macrophages and endothelial cells with a concomitant decrease in blood cell production and an increase in fat cells. For SU5614, the concentration inhibiting stroma formation by 50% (IC50) was 123nM, and the IC50 for haemopoietic colony forming cell output was 186 nM. For SU5768, the respective values were 871 nM and 331 nM. Changes in stroma composition and inhibition of haemopoietic cell production were also demonstrable after delayed addition of the inhibitors to established cultures. By contrast, haemopoietic colony formation in clonogenic agar cultures was unimpaired (IC50 not reached at 100 microM). Immunofluorescence studies and time course analyses suggested that the primary effect of the inhibitors was interference with the proliferation and function of fibroblasts and endothelial cells which in turn resulted in decreased haemopoiesis and increased adipogenesis. This was associated with decreased levels in conditioned media of granulocyte-macrophage colony-stimulating factor, interleukin-6 and leptin. VEGF and PDGF may play a hitherto underestimated role in the control of blood cell formation. VEGF/PDGF receptor inhibitors may have therapeutic potential in stroma diseases such as myelofibrosis. Since they weaken the stimulatory signals provided by the microenvironment, they may also be of value in the treatment of leukaemia and other neoplastic bone marrow diseases.
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PMID:Effects of vascular endothelial and platelet-derived growth factor receptor inhibitors on long-term cultures from normal human bone marrow. 1167 6

Gelatinase A and B (MMP-2 and MMP-9) are secreted by cytotrophoblast (CTB); these enzymes digest the major constituents of the endometrial extracellular matrices (ECM). Direct evidence links the expression of MMPs to the metastatic phenotype of tumour cells and tissue inhibitor of metalloproteinases (TIMP) to the inhibition of metastatisation. Gelatinase B (MMP-9, and no other MMP) has been shown in vitro to mediate CTB invasion. ECM components are known to influence adhesion, spreading, migration and differentiation of cells through specific cell surface receptors called integrins. While CTB migrate from the villous into the decidua they modulate their integrin repertoire, secrete MMP-9 and acquire the capacity to digest their environment. Although CTB behave like metastatic cells, in vivo they are only transiently invasive (first trimester) and their invasion is essentially limited to the endometrium and to the proximal myometrium. This temporal and spatial regulation seems to be mediated in a paracrine way by uterine factors and in an autocrine way by trophoblastic factors. We investigated the effects of endometrial regulators such as leukaemia inhibitory factor (LIF), tumour necrosis factor (TNF), transforming growth factor beta (TGFb), interleukin-1 and 6 (IL-1, IL-6) and insulin-like growth factor binding protein-1 (IGFBP-1) as well as trophoblastic factors such as hCG and leptin. All these factors markedly influenced the secretion and/or activation of MMP-2 and MMP-9. Most cytokines influence cell behaviour by modulating phosphorylation of transcription factors. Among these we identified two oncogene products (Jun and Fos) which were activated by TNF or phorbol esters and which promoted the synthesis of MMP-9. We conclude that decidual and trophoblastic products are autocrine or paracrine regulators of trophoblastic invasion of the endometrium and that some of these products act by activating the transcription of early response genes such as transcription factors.
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PMID:Endocrine, paracrine and autocrine regulation of trophoblastic metalloproteinases. 1175 1

Leptin is secreted by bone marrow (BM) adipocytes and stromal cells and was shown to stimulate myeloid proliferation. We here report that primary acute promyelocytic leukemia (APL) cells express high levels of the leptin-receptor (OB-R) long isoform. In cells with regulated promyelocytic leukemia-retinoic acid receptor (PML-RARalpha) expression, inducing PML-RARalpha was found to increase OB-R levels. We then investigated the effects of leptin produced by BM adipocytes on APL cells using a coculture system with mesenchymal stem cell (MSC)-derived adipocytes. In PML-RARalpha-expressing cells, all-trans retinoic acid (ATRA)- and doxorubicin-induced apoptosis were significantly reduced by coculture with adipocyte-differentiated MSCs. This antiapoptotic effect required direct cell-to-cell interactions, was associated with phosphorylation of signal transducer and activator of transcription-3 (STAT3) and mitogen-activated protein kinase (MAPK), and was reduced by blocking OB-R. This report provides a mechanistic basis for the BM adipocyte-leukemia cell interaction and suggests that OB-R receptor blockade may have therapeutic use in APL.
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PMID:PML-RARalpha is associated with leptin-receptor induction: the role of mesenchymal stem cell-derived adipocytes in APL cell survival. 1463 Aug 13

Leptin was described as a protein produced mostly by adipocytes which participates in regulation of caloric intake. This protein has further many physiological regulatory functions especially in hematopoesis and reproduction. The role of leptin in diseases is also considered. Maybe leptin is a part of the pathogenic mechanism or its metabolism can be influenced secondary to disease. Malignant tumours are the important area where leptin can acts. This imagination is supported by recent in vitro studies and some clinical observations. It is consider that some parameters of leptin metabolism can serve as usable marker for diagnosis and monitoring of some malignant tumours--especially breast cancer or some types of leukemia. The authors give a review of actual information of leptin metabolism changes in oncological diseases.
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PMID:[The importance of leptin in oncology--hypothesis or facts?]. 1563 91

Leptin alone and in combination with other cytokines has a stimulatory effect on proliferation of leukaemic cells. This effect may be due to prevention of apoptosis of progenitor cells or upregulation of specific receptors on leukaemic precursors that make them more responsive to stimuli. This work investigates the relationship between serum leptin level, serum interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) in acute leukaemic patients. The relationship to blood cell counts, haemoglobin and response to chemotherapy was also investigated. The study included 25 acute leukaemic male patients [15 acute myeloid leukaemia (AML) and 10 acute lymphoblastic leukaemia (ALL)] and 15 age and sex matched healthy controls. All were subjected to thorough history taking, clinical examination, complete blood picture, hepatic and renal function tests and determination of serum leptin, IL-6 and VEGF levels. In addition, patients were subjected to bone marrow aspiration, cytochemistry and immunophenotyping study and serum leptin assay after chemotherapy. Serum leptin level showed statistically significant elevation only in AML group (p<0.01). This elevation was unrelated to the presence of extramedullary infiltration or response to chemotherapy and correlated only with body mass index (p<0.05). In ALL, the mean serum leptin level was insignificantly different from the controls. In both AML and ALL, there was no significant difference in serum leptin level before and after treatment. Statistically significant elevation of IL-6 and VEGF, uncorrelated with serum leptin level was detected in AML patients when compared with the controls. No correlation was found between serum leptin level and any of the studied haematological parameters. It is concluded that the release of leptin, IL-6 and VEGF may be regulated by different mechanisms leading to diversity in clinical features of the disease.
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PMID:Leptin in acute leukaemias: relationship to interleukin-6 and vascular endothelial growth factor. 1571 23


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