UMLS:C0019204 - FACTA Search

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Query: UMLS:C0019204 (hepatocellular carcinoma)
71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute inflammation is characterized by increased liver output of acute phase proteins (APP). Several cytokines including IL-6, leukemia inhibitory factor, and IL-11 are capable of stimulating APP synthesis by hepatocytes and hepatoma cells. We have tested the activity of a separate and unique cytokine oncostatin M (OM) and have found potent APP-inducing activity of human recombinant OM on hepatocytes. OM acted in a dose-dependent fashion (ED50 5 to 10 ng/ml) in stimulating APP synthesis in human HepG2 cells, rat H35 cells, and primary rat hepatocyte cultures, but not human Hep3B cells. Human OM induced equivalent to or greater responses than IL-6 in HepG2 cells, however, it was less effective than human IL-6 in stimulating rat cells. Northern analysis showed that OM stimulated mRNA levels of haptoglobin and alpha 1-antichymotrypsin in HepG2 cells. OM induced CAT activity in HepG2 cells transfected with CAT constructs containing IL-6-responsive elements, suggesting that OM induces transcription of native proteins through mechanisms involving IL-6-responsive element-like sequences in gene promoters. OM was also shown to act additively with IL-6 or leukemia inhibitory factor and synergistically with glucocorticoid or IL-1 in the induction of specific APP. These results suggest that OM plays a role as a mediator of APP synthesis in inflammatory responses.
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PMID:Recombinant oncostatin M stimulates the production of acute phase proteins in HepG2 cells and rat primary hepatocytes in vitro. 137 87

Oncostatin M is a growth regulatory protein secreted by macrophages and activated T lymphocytes. In a hepatoma cell line (HepG2) the polypeptide very potently increased low density lipoprotein (LDL) uptake with an EC50 of 0.1-0.2 nM. The stimulation of LDL uptake was detectable by 2 h, was maximal by 8 h, and remained elevated through 20 h of oncostatin M incubation. In a similar fashion, oncostatin M also increased the number of cell surface LDL receptors by a mechanism that was inhibited by cycloheximide or the protein kinase C inhibitor H-7. Oncostatin M stimulation of LDL uptake and receptor protein occurred regardless of the state of cholesterol-dependent regulation of HepG2 LDL receptor (i.e. cells incubated in medium containing lipoproteins responded to the same extent as did cells incubated in the absence of lipoproteins). No significant effects were observed on sterol synthesis over 8 h or on DNA synthesis over 24 h. Oncostatin M induced rapid alterations in HepG2 phospholipid metabolism. Within 5-15 min there was a 20-50% increase in incorporation of 32P into several classes of phospholipids, including the phosphoinositides. Radiolabeled diacylglycerol levels were elevated 20% by 2 min and nearly 50% by 15 min. In addition, the polypeptide induced rapid increased (within 1 min) in phosphorylation of HepG proteins on tyrosine residues. Stimulation of both phosphotyrosine and LDL receptor up-regulation by oncostatin M was decreased by the tyrosine kinase inhibitor genistein. We propose that oncostatin M up-regulates HepG2 LDL receptor expression by a mechanism that includes stimulation of a tyrosine kinase followed by generation of phospholipid-related second messengers.
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PMID:Oncostatin M up-regulates low density lipoprotein receptors in HepG2 cells by a novel mechanism. 165 40

Mutagenesis of a region of human interleukin (IL)-6 which is important for triggering signal transduction via the IL-6 receptor beta-chain (gp130) has lead to the isolation of a variant of human IL-6 (IL-6.Q160E/T163P), which could antagonize the biological activity of wild type IL-6 on the human EBV transformed B cell line CESS and the human hepatoma cell line HepG2. Surprisingly this antagonistic IL-6 variant had an agonistic effect on the human myeloma cell line XG-1, albeit at a 1000-fold higher concentration than wild type IL-6. This residual activity of the mutant arose from triggering gp130, because it could be inhibited by a gp130 specific mAb. Extensive mutagenesis of residues between Q153 and H165 of human IL-6, a region which is partly homologous in cytokines which also signal via gp130 (oncostatin M, ciliary neurotrophic factor, leukaemia inhibitory factor, IL-11), did result in the isolation of a second antagonist for IL-6 activity on CESS and HepG2 cells. However on XG-1 cells this variant was active as well. These results suggest that (an) additional region(s) of the IL-6 molecule might be involved in gp130 triggering. Recently we indeed found that residues Lys42-Ala57 are also important for gp130 triggering. Inhibition experiments with neutralizing IL-6R alpha-chain specific mAb show that this region can be functionally separated from the Q153-H165 region. These findings have important implications for the development of receptor antagonists of IL-6 and IL-6 family members.
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PMID:Functional distinction of two regions of human interleukin 6 important for signal transduction via gp130. 757 77

Ciliary neurotrophic factor (CNTF) has been described as a neuro-active cytokine that shares functional similarities with the leukemia inhibitory factor (LIF). We demonstrate here that, like LIF, CNTF stimulates expression of acute phase plasma proteins in rat H-35 hepatoma cells. Transfection of the LIF receptor into Hep3B hepatoma cells reconstituted LIF and oncostatin M regulation of acute phase plasma protein genes. Co-expression of the LIF receptor and the CNTF receptor, but not expression of either subunit alone, generated CNTF responsiveness in Hep3B cells, suggesting cooperativity of these receptor subunits. Evidence is presented for direct interaction of the LIF receptor with the intracellular signal transduction machinery.
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PMID:Reconstitution of the response to leukemia inhibitory factor, oncostatin M, and ciliary neurotrophic factor in hepatoma cells. 768 51

The pleiotropic cytokine interleukin 6 (IL-6) plays a role in the pathogenesis of various diseases, such as multiple myeloma, autoimmune and inflammatory diseases and osteoporosis. Therefore, specific inhibitors of IL-6 may have clinical applications. We previously succeeded in developing receptor antagonists of IL-6 that antagonized wild-type IL-6 activity on the human Epstein-Barr virus (EBV)-transformed B cell line CESS and the human hepatoma cell line HepG2. However, these proteins still had agonistic activity on the human myeloma cell line XG-1. We here report the construction of a novel mutant protein of IL-6 in which two different mutations are combined that individually disrupt the association of the IL-6/IL-6 receptor (R) alpha complex with the signaltransducing "beta" chain, gp130, but leave the binding of IL-6 to IL-6R alpha intact. The resulting mutant protein (with substitutions of residues Gln160 to Glu, Thr163 to Pro, and replacement of human residues Lys42-Ala57 with the corresponding residues of mouse IL-6) was inactive on XG-1 cells and weakly antagonized wild-type IL-6 activity on these cells. By introducing two additional substitutions (Phe171Leu, Ser177Arg), the affinity of the mutant protein for IL-6R alpha was increased fivefold, rendering it capable of completely inhibiting wild-type IL-6 activity on XG-1 cells. Moreover, this mutant also antagonized the activity of IL-6, but not that of leukemia inhibitory factor, oncostatin M, or GM-CSF on the human erythroleukemia cell line TF-1, demonstrating its specificity for IL-6. These data demonstrate the feasibility of developing specific IL-6R antagonists. The availability of such antagonists may offer an approach to specifically inhibit IL-6 activity in vivo.
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PMID:Development of an interleukin (IL) 6 receptor antagonist that inhibits IL-6-dependent growth of human myeloma cells. 796 14

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

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

Tissue inhibitor of metalloproteinases (TIMP-1) is a potent inhibitor of activated matrix metalloproteinases (MMP) such as collagenase, stromelysin, and gelatinase, and thus helps to control extracellular matrix metabolism and deposition by connective tissue cells. Since various cytokines and growth factors can modify the production of MMP and TIMP-1, we explored the action of oncostatin M (OM), a unique lymphocyte- and monocyte-derived cytokine, on expression of these proteins. We examined the regulation of TIMP-1 expression in cultured human fibroblasts by cytokines including OM, IL-6, leukemia inhibitory factor (LIF), and IL-1 alpha. When used at levels of 5 to 50 ng/ml, OM, IL-6, LIF, and IL-1 alpha elevated the TIMP-1 expression at the RNA level in fibroblasts of lung or synovial origin. Interestingly, OM stimulation resulted in highest levels of TIMP-1 RNA and protein synthesis. However, unlike IL-1 alpha, the cytokines OM, IL-6, and LIF did not induce MMP or PGE2 release. OM also enhanced TIMP-1 mRNA levels in the H2981 lung carcinoma and HepG2 hepatoma cell lines. The results suggest that OM as well as IL-6 and LIF, other cytokines acting through similar receptor pathways, may act to inhibit net MMP activity by specifically up-regulating TIMP-1 expression. The selective induction of TIMP-1 by OM may be influential in altering matrix destruction in chronic inflammation and tumor metastasis.
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PMID:Selective regulation of metalloproteinase inhibitor (TIMP-1) by oncostatin M in fibroblasts in culture. 851 78

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

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