Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antisense oligonucleotides have been covalently attached to asialoglycoprotein (ASGP) via disulfide bond conjugation chemistry. These conjugates were characterized extensively by an array of chemical, chromatographic, and spectroscopic means. Multiple (approximately six) oligonucleotides can be conjugated to each ASGP molecule. The molecular conjugates were used to deliver antisense oligonucleotides complementary to the mRNA of the interleukin 6 signal transduction protein (gp130) to modulate the acute phase response of hepatoma (HepG2) cells in vitro. These conjugates were biologically active, as measured by inhibition of the cytokine-stimulated up-regulation of the acute phase protein haptoglobin. The level of inhibition was comparable to that found with previous technology featuring noncovalent complexes of ASGP-poly(L-lysine) and oligonucleotide. Because of the ability to control the stoichiometry of the conjugate and its unimolecular nature (as opposed to bimolecular for the noncovalent conjugates), this methodology holds great promise for further development and application.
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PMID:Covalent protein-oligonucleotide conjugates for efficient delivery of antisense molecules. 940 69

Signals propagated via the gp130 subunit of the interleukin-6 (IL-6)-type cytokine receptors mediate, among various cellular responses, proliferation of hematopoietic cells and induction of acute-phase plasma protein (APP) genes in hepatic cells. Hematopoietic growth control by gp130 is critically dependent on activation of both STAT3 and protein tyrosine phosphatase 2 (SHP-2). To investigate whether induction of APP genes has a similar requirement for SHP-2, we constructed two chimeric receptors, G-gp130 and G-gp130(Y2F), consisting of the transmembrane and cytoplasmic domains of gp130 harboring either a wild-type or a mutated SHP-2 binding site, respectively, fused to the extracellular domain of the granulocyte colony-stimulating factor (G-CSF) receptor. Rat hepatoma H-35 cells stably expressing the chimeric receptors were generated by retroviral transduction. Both chimeric receptors transmitted a G-CSF-induced signal characteristic of that triggered by IL-6 through the endogenous gp130 receptor; i.e., both activated the appropriate JAK, induced DNA binding activity by STAT1 and STAT3, and up-regulated expression of the target APP genes, those for alpha-fibrinogen and haptoglobin. Notwithstanding these similarities in the patterns of signaling responses elicited, mutation of the SHP-2 interaction site in G-gp130(Y2F) abrogated ligand-activated receptor recruitment of SHP-2 as expected. Moreover, the tyrosine phosphorylation state of the chimeric receptor, the associated JAK activity, and the induced DNA binding activity of STAT1 and STAT3 were maintained at elevated levels and for an extended period of time in G-gp130(Y2F)-expressing cells following G-CSF treatment compared to that in cells displaying the G-gp130 receptor. H-35 cells ectopically expressing G-gp130(Y2F) were also found to display an enhanced sensitivity to G-CSF and a higher level of induction of APP genes. Overexpression of the enzymatically inactive SHP-2 enhanced the signaling by the wild-type but not by the Y2F mutant G-gp130 receptor. These results indicate that gp130 signaling for APP gene induction in hepatic cells differs qualitatively from that controlling the proliferative response in hematopoietic cells in not being strictly dependent on SHP-2. The data further suggest that SHP-2 functions normally to attenuate gp130-mediated signaling in hepatic (and, perhaps, other) cells by moderating JAK action.
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PMID:Protein tyrosine phosphatase 2 (SHP-2) moderates signaling by gp130 but is not required for the induction of acute-phase plasma protein genes in hepatic cells. 948 69

Interleukin 6 (IL-6) belongs to a family of cytokines using receptors sharing a common signal-transducing chain, gp130 and containing a specific ligand-binding chain (IL-6R alpha). It was shown that both the membrane-bound and the soluble form (sIL-6R) of this ligand specific receptor chain occurs naturally. The soluble form of IL-6 receptor was found to be able to associate with the membrane-bound gp130 and to generate active IL-6 receptor complex capable of inducing signal transduction. This study on a human hepatoma cell line and primary rat hepatocytes examined how the effectiveness of IL-6 is modified by the presence of soluble IL-6 receptor and whether the sIL-6R in the absence of IL-6 acts on hepatocytes. The authors studied the gene expression of junB, a member of the Jun family of transcription factors, and the production of fibrinogen in response to IL-6 and sIL-6R. The data show that in hepatic cells, endogeneously expressing IL-6R, the IL-6 induced junB and fibrinogen expression is inhibited by the presence of sIL-6R. In addition we found that sIL-6R alone (in the absence of IL-6) induced junB mRNA expression, but had no effect on fibrinogen production.
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PMID:Soluble interleukin 6 (IL-6) receptor influences the expression of the protooncogene junB and the production of fibrinogen in the HepG2 human hepatoma cell line and primary rat hepatocytes. 972 35

IL-6 is a multifactorial cytokine mediating acute inflammatory responses in the liver. When IL-6 binds to a specific receptor (IL-6R), the IL-6/IL-6R complex associates with the signal transducer gp130, initiating intracellular signaling. A soluble form of the IL-6R (sIL-6R) renders target cells sensitive to IL-6 that do not express the IL-6R on their surfaces. A designer cytokine, termed Hyper-IL-6, consisting of IL-6 covalently linked to the sIL-6R was fully active on gp130-expressing cells at 100- to 1000-fold lower concentrations than unlinked IL-6 and IL-6R. Mice were injected i.p. with Hyper-IL-6 or IL-6. Upon injection of Hyper-IL-6 into mice, the acute phase response, as measured by haptoglobin mRNA expression in the liver, was markedly increased and lasted significantly longer compared with that in mice injected with a 10-fold higher dose of IL-6 alone. On human hepatoma cells, Hyper-IL-6 caused similar effects, indicating that the longer lasting response to the fusion protein could not only be explained by the longer plasma half-life of the fusion protein. Experiments using iodinated IL-6 and Hyper-IL-6 revealed that Hyper-IL-6 bound with high affinity to gp130 and was less efficiently internalized. This effect might explain the longer lasting activity of this protein on cells. The highly active IL-6/sIL-6R designer protein might be of significant clinical importance for the stimulation of cells that are more responsive to the IL-6/sIL-6R complex than to IL-6 alone. Such cells include hemopoietic progenitor cells and hepatocytes.
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PMID:In vivo and in vitro activities of the gp130-stimulating designer cytokine Hyper-IL-6. 975 79

Interleukin (IL)-6 is a major regulator of hepatic acute-phase plasma protein (APP) genes. The membrane-proximal 133-amino acid cytoplasmic domain of glycoprotein (gp) 130, containing one copy of the Box3 motif, is sufficient to transmit a productive signal to endogenous APP genes in rat hepatoma H-35 cells. In contrast, a mutant gp130 domain lacking the Box3 motif activates Janus kinases to a normal level but fails to activate signal transducer and activator of transcription 3 and to up-regulate a number of APP genes, including thiostatin, fibrinogen, hemopexin, and haptoglobin. However, in the absence of Box3, gp130 still stimulates the expression of alpha2-macroglobulin and synergizes with IL-1 to up-regulate alpha1-acid glycoprotein. The Box3 motif is not required for activation of the SH2-containing protein tyrosine phosphatase 2 or the mitogen-activated protein kinase (MAPK), nor is the immediate induction of egr-1 and junB significantly altered. Surprisingly, gp130 without any functional Box3 stimulates prolonged activation of MAPK, leading to an extended period of up-regulation of egr-1 and to an extracellularly regulated kinase-mediated reduction in the IL-6-stimulated production of thiostatin. IL-6 reduces proliferation of H-35 cells through signaling by the Box3. In addition, cells expressing Box3-deficient gp130 showed distinct morphologic changes upon receptor activation. Taken together, these results indicate that Box3-derived and Box3-independent signals cooperate in the control of hepatic APP genes and that Box3 may be involved in the modulation of MAPK activity in gp130 signaling.
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PMID:The STAT3-independent signaling pathway by glycoprotein 130 in hepatic cells. 1007 71

Signal transduction in response to interleukin-6 (IL-6) results from homodimerization of gp130. This dimerization occurs after binding of IL-6 to its surface receptor (IL-6R) and can also be triggered by the complex of soluble IL-6R and IL-6. We fused IL-6 to the constant region of a human IgG1 heavy chain (Fc). IL-6Fc was expressed in COS-7 cells and purified via Protein A Sepharose. Using three different assays we found that the biological activity of this dimeric IL-6 protein is comparable with monomeric IL-6. Recently, we described the designer cytokine Hyper-IL-6 (H-IL-6) in which soluble IL-6R and IL-6 are connected via a flexible peptide linker. This molecule turned out to be 100-1000 times more effective than unlinked IL-6 and soluble IL-6R. Hyper-IL-6 acts on cells only expressing gp130 and is a potent stimulator of in vitro expansion of early hematopoietic precursors. Here we show that a Fc fusion protein of H-IL-6 (H-IL-6Fc) has the same biological activity on BAF/gp130 cells as H-IL-6. Furthermore, both H-IL-6 forms have a similar ability to induce the synthesis of acute phase proteins in human hepatoma cells HepG2 and in mice in vivo. The introduction of a thrombin cleavage site between H-IL-6 and the Fc portion of H-IL-6Fc made it possible to specifically recover biologically active monomeric H-IL-6 by limited proteolysis of the fusion protein. A more general use of cleavable immunoadhesins expressed in mammalian cells is discussed.
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PMID:Immunoadhesins of interleukin-6 and the IL-6/soluble IL-6R fusion protein hyper-IL-6. 1008 96

Interleukin-11 is a hematopoietic cytokine that signals via the signal transducer gp130. Although gp130 is ubiquitously expressed, interleukine-11 responsiveness is restricted to cells that express the interleukine-11 receptor alpha-subunit. The interleukine-11 receptor alpha-subunit can be functionally replaced by its soluble form indicating that the transmembrane and cytoplasmic parts are not required for signal transduction. Here, we show that a recombinant fusion protein of a fragment of the human interleukine-11 receptor alpha-subunit ectodomain linked to human interleukine-11 acts as a superagonist on cells expressing gp130 but lacking the membrane-bound interleukine-11 receptor alpha-subunit. It induces acute phase protein synthesis in hepatoma cells and efficiently promotes proliferation of Ba/F3 cells stably, transfected with gp130. In these bioassays, the fusion protein of a fragment of the human interleukine-11 receptor alpha-subunit ectodomain linked to human interleukine-11 is 50 times more potent than the combination of interleukine-11 and the soluble interleukine-11 receptor alpha-subunit. Thus, our findings support the concept that covalent fusion of two soluble proteins required for receptor activation dramatically increases their bioactivity.
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PMID:A fusion protein of interleukin-11 and soluble interleukin-11 receptor acts as a superagonist on cells expressing gp130. 1035 68

The human papillomavirus type 18 (HPV-18) upstream regulatory region (URR) controls cell type-specific expression of the viral oncoproteins E6 and E7. The HPV-18 URR is active in the cervical carcinoma cell line HeLa but inactive in the hepatoma cell line HepG2. C/EBPss (NF-IL-6) was shown to participate as an important regulator in HPV transcription dependent on the cell type. The finding that C/EPBss is critical for HPV-18 URR activity and that C/EPBss is induced by IL-6 offers the opportunity of manipulating HPV activity by specific cytokine treatment. In this report, we show that treatment with IL-6 results in activation of HPV-18 URR activity in HepG2 cells. In contrast, the HPV-18 URR is not inducible by IL-6 in three cervical carcinoma cell lines. In all three cell lines we found decreased expression of the IL-6 receptor compared to the IL-6-responsive HepG2 cells, whereas the level of expression of the signal transduction component gp130 is present in all cells. These results suggest that cervical carcinoma cells may circumvent the IL-6-induced cellular defense mechanism through downregulation of the IL-6-receptor.
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PMID:Response to IL-6 of HPV-18 cervical carcinoma cell lines. 1036 71

Receptors for interleukin-6 (IL-6) occur in body fluids in soluble form, as well. This is an approx. 50 kDa protein with the ability to bind IL-6. The soluble IL-6 receptor (sIL-6R)/IL-6 complex can attach to membrane anchored gp130, a molecule associated with the signal transduction induced by IL-6 and by other related cytokines. Earlier we described the appearance of sIL-6R in various body fluids of autoimmune patients. In this study using reverse transcriptase polymerase chain reaction (RT-PCR) we isolated and characterised a truncated form of amplified cDNA reverse-transcribed from IL-6 receptor mRNA both from human hepatoma cell line HepG2 and mononuclear cells from inflammatory bowel disease (IBD) patients. Using digestion by Pvu II restriction endonuclease and direct nucleotide sequencing we conclude that alternative splicing is likely involved in generation of sIL-6R. Our further experiments suggest that IL-6 and recombinant sIL-6R themselves do not influence the alternative splicing of IL-6 receptor gene.
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PMID:Generation of 'truncated' interleukin-6 receptor (IL-6R) mRNA by alternative splicing; a possible source of soluble IL-6R. 1039 66

One of the major actions of interleukin-6 (IL-6) is the transcriptional activation of acute-phase plasma proteins (APP) genes in liver cells. Signaling by the IL-6 receptor is mediated through the signal transducing subunit gp130 and involves the activation of Janus-associated kinases (JAKs), signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein (MAP) kinase. Functional analysis of gp130 in rat hepatoma cells by using transduced chimeric G-CSFR-gp130 receptor constructs demonstrates that SHP-2, the Src homology 2 (SH2) domain-containing protein tyrosine phosphatase, acts as a negative regulator of the JAK/STAT signaling in part by downregulating JAK activity, thereby indirectly moderating the induction of STAT3-dependent APP genes. This study shows that in hepatoma cells, the recruitment and tyrosine phosphorylation of SHP-2, but not SHC, is the primary signaling event associated with the activation of MAP kinases (ERK1/2) by gp130. Overexpression of truncated SHP-2 that lacks Grb2-interacting sites, but not the full-length catalytically inactive SHP-2, reduces ERK activation by IL-6, confirming the signal-mediating role of SHP-2. Activation of ERK1/2 is correlated with induction of the immediate-early response genes. Stimulation of the c-fos, c-jun, and egr-1 genes is essentially absent in cells expressing gp130 with a Y759F mutation, which is unable to recruit SHP-2. Interestingly, both JAK/STAT and SHP-2 pathways regulate the induction of the junB gene. Moreover, disengagement of SHP-2 from gp130 signaling not only enhances APP gene induction but also further reduces cell proliferation, in part correlated with the attenuated expression of immediate-early response genes. These results suggest that IL-6 regulation of APP genes is affected by SHP-2 in two ways: SHP-2 acts as a phosphatase on the JAK/STAT pathway and serves as linker to the MAP kinase pathway, which in turn moderates APP production.
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PMID:Dual signaling role of the protein tyrosine phosphatase SHP-2 in regulating expression of acute-phase plasma proteins by interleukin-6 cytokine receptors in hepatic cells. 1040 24


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