UMLS:C0019204 - FACTA Search

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Query: UMLS:C0019204 (hepatocellular carcinoma)
71,386 document(s) hit in 31,850,051 MEDLINE articles (0.01 seconds)

Leukemia inhibitory factor (LIF) is structurally related to interleukin-6 (IL-6), oncostatin M (OSM), and ciliary neurotrophic factor (CNTF). Since LIF-deficient mice do not exhibit overt phenotypic effects in cell types known to be targets for LIF action in vitro, we examined the ability of IL-6, OSM, and CNTF to reproduce the effects of LIF in five different bioassays. OSM, CNTF, and LIF are able to promote embryonic stem cell growth and to maintain them in an undifferentiated state as marked by a high alkaline phosphatase activity (ED50 are, respectively, 0.5, 3 and 1 ng/ml). Whereas LIF and OSM maintain close to 100% of ES cells in an undifferentiated state, CNTF, at optimal concentrations, prevents differentiation of only 60% of the ES population. Murine 7TD1 hybridoma cell growth is induced only in the presence of IL-6 (ED50 = 0.1 ng/ml). Both LIF and OSM stimulate DA1a cell proliferation (ED50 are, respectively, 1 and 12 ng/ml). OSM appears, therefore, to act as a weak agonist of LIF-dependent processes on murine cells, however, with a 10-fold lower specific activity than that of LIF, which is in agreement with human OSM cross-reacting with the murine LIF-R. Though IL-6, LIF, and OSM all stimulate haptoglobin and fibrinogen production by human HepG2 hepatoma cells, the dose-response curves of these three factors exhibit very different characteristics. CNTF stimulates acute-phase protein production by HepG2 cells only at high concentrations (greater than 1 microgram/ml). A549 epithelial cells are subjected to growth inhibition only in the presence of OSM (ED50 = 6 ng/ml), even though they expressed LIF-R and gp130 transcripts. These data suggest that OSM and LIF act on human cells through different receptors. Altogether, these results indicate that none of the factors examined in this study are precisely interchangeable in terms of their biological actions.
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PMID:Are LIF and related cytokines functionally equivalent? 805 Apr 91

Oncostatin M (OM) and interleukin 6 (IL-6) are functionally related cytokines, which trigger similar biological responses because they share gp130 as a common signal transducing transmembrane receptor. While IL-6 recruits gp130 only upon binding to its specific receptor subunit (IL-6R alpha), reconstitution and cross-linking experiments on cell membranes suggest that OM can directly interact with gp130 and that this interaction is necessary but not sufficient to stimulate cells. However, the issue of the direct binding between gp130 and OM, in the absence of any additional membrane component, remained essentially unclarified. In this paper we show that, uniquely among the family of cytokines that transduce through gp130, OM directly binds in vitro with a 10(-8) M affinity sgp130, a soluble form of gp130. Moreover, titration of sgp130 with OM inhibits the formation of a ternary complex comprising IL-6, sIL-6R alpha, and sgp130. These in vitro properties of OM are consistent with the additional finding that on human hepatoma Hep3B cells, which express gp130 but not functional OM receptors, OM does not mimic IL-6 activity, but rather behaves, at high doses, as an IL-6 antagonist.
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PMID:Oncostatin M binds directly to gp130 and behaves as interleukin-6 antagonist on a cell line expressing gp130 but lacking functional oncostatin M receptors. 815 24

Interleukin-6 (IL-6), leukemia inhibitory factor, oncostatin M, IL-11, and ciliary neurotropic factor are a family of cytokines and neuronal differentiation factors which bind to composite plasma membrane receptors sharing the signal transducing subunit gp130. We have shown recently that IL-6 and leukemia inhibitory factor rapidly activate a latent cytoplasmic transcription factor, acute-phase response factor (APRF), by tyrosine phosphorylation, which then binds to IL-6 response elements of various IL-6 target genes. Here we demonstrate that APRF is activated by all cytokines acting through gp130 and is detected in a wide variety of cell types, indicating a central role of this transcription factor in gp130-mediated signaling. APRF activation is also observed in vitro upon addition of IL-6 to cell homogenates. Protein tyrosine kinase inhibitors block both the tyrosine phosphorylation and DNA binding of APRF. The factor was purified to homogeneity from rat liver and shown to consist of a single 87-kDa polypeptide, while two forms (89 and 87 kDa) are isolated from human hepatoma cells. As reported earlier, the binding sequence specificity of APRF is shared by gamma interferon (IFN-gamma) activation factor, which is formed by the Stat91 protein. Partial amino acid sequence obtained from purified rat APRF demonstrated that it is likely to be related to Stat91. In fact, an antiserum raised against the amino-terminal portion of Stat91 cross-reacted with APRF, suggesting the relatedness of APRF and Stat91. Altogether, these data indicate that APRF belongs to a growing family of Stat-related proteins and that IFN-gamma and IL-6 use similar signaling pathways to activate IFN-gamma activation factor and APRF, respectively.
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PMID:The interleukin-6-activated acute-phase response factor is antigenically and functionally related to members of the signal transducer and activator of transcription (STAT) family. 816 74

The receptor for leukemia inhibitory factor (LIFR), in combination with the signal-transducing subunit for interleukin-6-type cytokine receptors, gp130, and LIF, activates transcription of acute-phase plasma protein genes in human and rat hepatoma cells and the vasoactive intestinal peptide gene in a human neuroblastoma cell line. To identify the regions within the cytoplasmic domain of LIFR that initiate signal transduction independently of gp130, we constructed a chimeric receptor by linking the extracellular domain of the granulocyte colony-stimulating factor receptor (G-CSFR) to the transmembrane and cytoplasmic domain of human LIFR. The function of the chimeric receptor protein in transcriptional activation was assessed by G-CSF-mediated stimulation of cotransfected cytokine-responsive reporter gene constructs in hepatoma and neuroblastoma cells. By using the full-length cytoplasmic domain and mutants with progressive carboxy-terminal deletions, internal deletions, or point mutations, we identified the first 150 amino acid residues of LIFR as the minimal region necessary for signaling. The signaling reaction appears to involve a cooperativity between the first 70-amino-acid region containing the two sequence motifs conserved among hematopoietin receptors (box 1 and box 2) and a critical sequence between residues 141 and 150 (box 3). Analogous analyses of the cytoplasmic domains of G-CSFR and gp130 indicated similar arrangements of functional domains in these receptor subunits and the requirement of a box 3-related motif for signaling.
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PMID:Multiple regions within the cytoplasmic domains of the leukemia inhibitory factor receptor and gp130 cooperate in signal transduction in hepatic and neuronal cells. 826 82

Recombinant human 125I-interleukin-6 (IL-6) was cross-linked with the homobifunctional reagent disuccinimidyl suberate to human hepatoma cells (HepG2). Three recombinant human 125I-IL-6-containing complexes of apparent molecular masses of 100, 120, and 200 kDa were immunoprecipitated with specific antibodies to human IL-6 or to the 80-kDa IL-6 receptor subunit. We show by immunoprecipitation, peptide mapping, and by the use of a cleavable heterobifunctional cross-linker (Denny-Jaffe reagent) that different polypeptides are involved in the formation of the 100- and 120-kDa IL-6-containing complexes. The molecular compositions of the 100- and 120-kDa cross-linked complexes were identified. The 100-kDa complex consisted of one ligand and one IL-6 receptor subunit, glycoprotein 80 (gp80), whereas the 120-kDa complex was found to be composed of one ligand and a polypeptide which was immunoprecipitable with the monoclonal antibody AM64 directed against gp130. Exposure of HepG2 cells to phorbol 12-myristate 13-acetate (PMA) or PMA-dexamethasone led to an increase in the 80-kDa IL-6 receptor mRNA and functional receptor protein. Whereas treatment of HepG2 cells with PMA led to an increase in the formation of gp80.gp130.IL-6 complexes determined by cross-linking, no corresponding increase in high affinity binding sites was found. The existence of a third IL-6 receptor subunit present in limiting amounts on HepG2 cells is proposed to explain this discrepancy. Evidence is presented that the 80-kDa IL-6 receptor up-regulation by PMA-dexamethasone is caused by the depletion of protein kinase C since the protein kinase C inhibitor staurosporine mimics the effect of PMA-dexamethasone.
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PMID:The hepatic interleukin-6 receptor. Studies on its structure and regulation by phorbol 12-myristate 13-acetate-dexamethasone. 844 Jul 9

The steady-state mRNA levels of the interleukin 6 receptor (IL-6R, gp80) and its signal transducing molecule, gp130, were examined in the rat hepatoma cell line, H-35, stimulated by cytokines IL-6, IL-1, oncostatin M (OSM) and/or Dexamethasone (Dex). In contrast to our previous findings in vivo [Geisterfer et al., 1993, Cytokine, 5:1] in vitro Dex seemed to be the major stimulator of IL-6R mRNA expression, whereas IL-6 seemed to have little effect on the expression of its own receptor mRNA levels. However, the presence of other cytokines influenced the Dex mediated stimulation of IL-6R expression. OSM stimulated IL-6R mRNA levels. At 6 h, cells stimulated with OSM showed a 2.1-fold increase in IL-6R mRNA expression. This stimulation was additive with the Dex-mediated stimulation of IL-6R mRNA levels. In contrast, IL-1 inhibited the Dex-mediated stimulation of IL-6R mRNA. At the same time, IL-1 stimulated the presence of a second smaller mRNA transcript. This mRNA species contained the extracellular domain but lacked both the transmembrane and cytoplasmic domains of the IL-6R, suggesting alternate splicing, possibly coding for a soluble form of gp80. Unlike the gp80 IL-6R molecule, the expression of the gp130 molecule normally expressed as two species of mRNA was not regulated to any major extent in vitro. IL-1 and OSM stimulated both mRNA bands (7.5 and 9.0 kb) approximately 2-fold, whereas IL-6 stimulated mainly the upper 9.0 kb mRNA band.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cytokines oncostatin M and interleukin 1 regulate the expression of the IL-6 receptor (gp80, gp130). 858 Mar 65

An inhibitor of IL-6 binding to the human hepatoma line HepG2 and myeloma cell line U266 was identified in a saline extract of the marine sponge, Callyspongia sp. Functional activity, measured through the increase in haptoglobin production by HepG2 cells stimulated with IL-6, could be strongly inhibited by the extract. Similarly, IL-6-induced production of IgM by the B cell line SKW6.4 was substantially reduced. In neither cell line was there evidence of toxicity produced by the extract. Other sponges of the Callyspongia species were found to contain analogous activity. The activity was destroyed by trypsin treatment or boiling of the extract, suggesting that the inhibition is due to a protein. When the binding of IL-6 to its receptor complex was dissected in vitro, inhibition of binding of IL-6 to soluble receptor by the extract was not detected, but binding of the IL-6-sIL-6R complex to soluble gp130 was inhibited in a dose-dependent fashion. This was borne out in cellular assays since the extract inhibited activation of HepG2 cells stimulated with oncostatin M or leukemia inhibitory factor, cytokines which also use gp130 for signal transduction. These results suggest that the Callyspongia extract contains a protein which blocks the interaction of the IL-6 family of cytokines with their signal transduction moiety, gp130. Elucidation of the structure and mode of action of such a protein would be helpful in designing gp130 antagonists to inhibit the functions of this cytokine family, overproduction of which has been associated with cancer and pathologies of autoimmune disease and AIDS.
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PMID:Characterization of an interleukin 6 cytokine family antagonist protein from a marine sponge, Callyspongia sp. 863 42

Mouse cardiotrophin-1 (CT-1) is a hypertrophy-inducing factor for cardiac myocytes and interacts with cell surface receptors that incorporate the signaling molecule gp130. Because other cytokines utilizing this receptor subunit stimulate acute-phase protein synthesis, we tested cardiotrophin-1 in in vitro assays of protein synthesis by primary rat hepatocytes, rat hepatoma cells (H35), and human hepatoma cells (HepG2). CT-1 showed a dose-dependent induction of protein synthesis by primary rat hepatocytes, with effective concentrations ranging from 0.1 to 100 ng/ml. Production of a number of acute-phase proteins, including alpha 1-cysteine proteinase inhibitor ( alpha 1-CPI), alpha 1-proteinase inhibitor (alpha 1-Pi), alpha 2-macroglobulin, and alpha 1-acid glycoprotein, was markedly increased at 48 and 72 h of cytokine stimulation. In rat H35 cells, CT-1 stimulated alpha 1-Pi and alpha 1-CPI protein production and upregulated alpha 1-CPI mRNA levels with similar potency. Compared with other IL-6-type human cytokines at optimal concentrations in parallel assays, CT-1 induced similar levels of acute-phase proteins as human oncostatin M (OM) and leukemia inhibitory factor (LIF), whereas human IL-6 induced the greatest levels of alpha 1-CPI or alpha 1-Pi production by H35 cells. When tested on human HepG2 cells, murine CT-1 was far less effective, in that it stimulated alpha 1-antichymotrypsin production only at very high concentrations (100 ng/ml) but did not alter haptoglobin or alpha 1-Pi. Human OM and IL-6 were effective at lower concentrations and induced much higher levels of acute-phase protein synthesis, whereas LIF activity was similar to that to CT-1. These results show that murine CT-1 is a strong acute-phase mediator for rat hepatocytes in vitro and its activity is similar to LIF on rat hepatocytes, H35 cells, and HepG2 cells.
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PMID:Murine cardiotrophin-1 stimulates the acute-phase response in rat hepatocytes and H35 hepatoma cells. 864 Apr 54

gP130 transducing receptor is involved in the formation of high affinity receptors for the cytokines of the interleukin-6 (IL-6) family. Recruitment of gp130 by IL-6 associated to its receptor leads to the dimerization of the transducing component. In the present study we did characterize the B-S12 monoclonal antibody raised against gp130 and able to elicit IL-6 type biological activities. B-S12 antibody triggered strongly the proliferation of TF1 and XGI hematopoietic cell lines and was able to increase the synthesis of acute phase proteins in HepG2 hepatoma cell line. B-S12 also behaved as a synergistic factor with granulocyte-macrophage colony-stimulating factor for both proliferation and differentiation of CD34-positive hematopoietic cell progenitors. By using a symmetric enzyme-linked immunosorbent assay, allowing the detection of dimeric forms of soluble gp130, we found that addition of B-S12 to gp130 led to its dimerization. Analysis of the tyrosine phosphorylation events in gp130 and Jak kinase family members revealed that B-S12 quickly induced the phosphorylation of gp130 in a neural derived cell line, and that Jak1 and Jak2 were also recruited. In conclusion, we show that gp130 cross-linking with the B-S12 monoclonal antibody was sufficient to generate functional IL-6 type responses in hematopoietic, neural, and hepatic cells.
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PMID:gp130 transducing receptor cross-linking is sufficient to induce interleukin-6 type responses. 866 9

Gp130 transducing protein was shown to be involved in the formation of the high affinity receptors for interleukin 6 (IL-6), interleukin-11 (IL-11), leukemia inhibitory factor, oncostatin M (OSM), ciliary neurotrophic factor (CNTF), and cardiotrophin-1. In the present study we have characterized the functional properties of antibodies directed against this protein and identified a group of monoclonal antibodies able to antagonize the biological activities of all the cytokines belonging to the IL-6 cytokine family. The B-R3 pan-blocking antibody weakly interfered with the binding of the radiolabeled ligands (with the exception of OSM, whose binding was abrogated in the presence of B-R3 monoclonal antibody) but inhibited the gp130 homodimerization or its association with gp190/leukemia inhibitory factor receptor, as well as the subsequent tyrosine phosphorylation events. In addition we identified antibodies that were able to neutralize only one single cytokine of the IL-6 family. This was the case for the B-K5 antibody, which antagonized the binding of OSM to gp130 but did not interfere with the signals provided by the related cytokines triggering the proliferation of the TF1 erythroleukemia cell line or the induction of haptoglobin synthesis in the HepG2 hepatoma cell line. Similarly, we also characterized two additional antibodies B-P8 and B-P4, which inhibited the TF1 cell proliferation observed in the presence of CNTF and IL-11, respectively. B-P8 antibody only faintly interfered with the binding of the gp130-ligands and might modulate the signal transduction pathways. This study indicates that in addition to functional site(s) required by the whole family of IL-6 type cytokines to transduce the signal insight the cell, specific cognate functional sites were recruited by OSM, CNTF, or IL-11.
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PMID:Interleukin-6 family of cytokines induced activation of different functional sites expressed by gp130 transducing protein. 866 18

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