UMLS:C0019204 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

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

The gene encoding rat kallikrein-binding protein (RKBP), a serine protease inhibitor, has been isolated and analyzed with the aid of the polymerase chain reaction. The gene is approximately 10 kilobases in length with four introns of approximately 2.2, 1.8, 0.9, and 0.84 kilobases. This gene is composed of five exons and encodes a polypeptide of 416 amino acid residues. The reactive center region of RKBP is encoded by the fifth exon with the putative P1-P1' residues being Lys-Ser. The organization of the RKBP gene is homologous to those of human alpha 1-antitrypsin and alpha 1-antichymotrypsin in size and arrangement of exons and introns, suggesting that they belong to the same subgroup of serpins. In the 5'-flanking region of the RKBP gene, a variant TATA box sequence, ATAAATA, is found 20 base pairs upstream from the transcription initiation site. The 5'-flanking region of the RKBP gene was able to direct transcription of the reporter gene chloramphenicol acetyltransferase when transfected into a rat hepatoma cell line. An internal promoter-like region was found in the first intron of the RKBP gene, downstream from the transcription initiation site and upstream from the translation initiation codon, however, it was unable to direct expression of the chloramphenicol acetyltransferase reporter gene in our experiments. The expression of RKBP in rat liver was induced by sex hormone treatment as indicated by dot-blot analysis. A genomic Southern blot using an RKBP cDNA probe revealed multiple bands suggesting that the RKBP gene belongs to a family of highly conserved genes.
...
PMID:Molecular cloning and analysis of the rat kallikrein-binding protein gene. 187 45

Formation of the covalently stabilized complex of alpha 1-antitrypsin (alpha 1-AT) with neutrophil elastase, the archetype of serine proteinase inhibitor serpin-enzyme complexes, is associated with structural rearrangement of the alpha 1-AT molecule and hydrolysis of a reactive-site peptide bond. An approximately 4-kDa carboxyl-terminal cleavage fragment is generated. alpha 1-AT-elastase complexes are biologically active, possessing chemotactic activity and mediating increases in expression of the alpha 1-AT gene in human monocytes and macrophages. This suggested that structural rearrangement of the alpha 1-AT molecule, during formation of a complex with elastase, exposes a domain that is recognized by a specific cell surface receptor or receptors. To test this hypothesis, the known three-dimensional structure of alpha 1-AT and comparisons of the primary structures of the serpins were used to select a potentially exteriorly exposed and highly conserved region in the complexed form of alpha 1-AT as a candidate ligand (carboxyl-terminal fragment, amino acids 359-374). We show here that synthetic peptides based on the sequence of this region bind specifically and saturably to human hepatoma cells and human monocytes (Kd = 4.0 X 10(-8) M, 4.5 X 10(5) plasma membrane receptors per cell) and mediate increases in synthesis of alpha 1-AT. Binding of peptide 105Y (Ser-Ile-Pro-Pro-Glu-Val-Lys-Phe-Asn-Lys-Pro-Phe-Val-Tyr-Leu-Ile) is blocked by alpha 1-AT-elastase complexes, antithrombin III (AT III)-thrombin complexes, alpha 1-antichymotrypsin (alpha 1-ACT)-cathepsin G complexes, and, to a lesser extent, complement component C1 inhibitor-C1s complexes, but not by the corresponding native proteins. Binding of peptide 105Y is also blocked by peptides with sequence corresponding to carboxy-terminal fragments of the serpins AT III and alpha 1-ACT, but not by peptides having the sequence of the extreme amino terminus of alpha 1-AT. The results also show that peptide 105Y inhibits binding of 125I-labeled alpha 1-AT-elastase complexes. Thus, these studies demonstrate an abundant, relatively high-affinity cell surface receptor which recognizes serpin-enzyme complexes (SEC receptor). This receptor is capable of modulating the production of at least one of the serpins, alpha 1-AT. Since the ligand specificity is similar to that previously described for in vivo clearance of serpin-enzyme complexes, the SEC receptor may also be involved in the clearance of certain serpin-enzyme complexes.
...
PMID:Identification of a serpin-enzyme complex receptor on human hepatoma cells and human monocytes. 216 76

In the cultured human hepatoma HepG2, Ca2+ ionophores block secretion of different secretary proteins to different extents, alpha 1-antitrypsin secretion being more sensitive to A23187 and ionomycin than is alpha 1-antichymotrypsin, and albumin secretion the least of the three proteins studied. As judged by subcellular fractionation experiments and by treatment of pulse chase labeled protein with endoglycosidase H, A23187 and ionomycin cause newly made secretory proteins to remain within the rough endoplasmic reticulum (ER). Experiments in which A23187 is added at different times during a pulse or chase show that secretion of newly made alpha 1-antitrypsin becomes resistant to the ionophore, on average, 15 min after synthesis; this is about 20 min before it reaches the trans-Golgi, and while it is still within the rough ER. We speculate that a high concentration of Ca2+ within the ER may be essential for certain secretory proteins to fold properly, that folding is inhibited when ER Ca2+ levels are lowered by ionophore treatment, and that unfolded proteins, particularly alpha 1-antitrypsin, cannot exit the rough ER. Treatment of murine 3T3 fibroblasts or human hepatoma HepG2 cells with the Ca2+ ionophores A23187 or ionomycin also induces a severalfold accumulation of the ER lumenal protein Bip (Grp78). These findings disagree with a recent report that Ca2+ ionophores cause secretion of Bip and other resident ER proteins, but is consistent with other reports that A23187 causes accumulation of mRNAs for Bip and other ER lumenal proteins.
...
PMID:Perturbation of cellular calcium blocks exit of secretory proteins from the rough endoplasmic reticulum. 216 23

Induction of C-reactive protein (CRP) by conditioned medium from lipopolysaccharide-stimulated human monocytes in two human hepatoma-cell lines, Hep 3B and NPLC/PRF/5, was potentiated 3-6-fold by the methylxanthine caffeine. The induction observed in the presence of conditioned medium plus caffeine was as much as 180-fold, comparable with that seen after many stimuli in vivo. This potentiation was accompanied by an increase in the levels of CRP mRNA. By contrast, no potentiating effect on CRP induction by conditioned medium was found when we tested theophylline, forskolin, 8-bromo cyclic AMP or two Ca2+ ionophores, namely ionomycin and A23187. None of the above compounds, including caffeine, when tested alone, had any detectable effect on the synthesis and secretion of CRP. Our previous study [Ganapathi, May, Schultz, Brabenec, Weinstein, Sehgal & Kushner (1988) Biochem. Biophys. Res. Commun. 157, 271-277], employing defined cytokines, had shown that induction of CRP in Hep 3B cells requires IL(interleukin)-6 plus IL-1, whereas, in the NPLC/PRF/5 cell line, IL-6 alone is effective. Caffeine similarly potentiated induction of CRP by these defined cytokine signals in these two cell lines. Changes in synthesis of other acute-phase proteins, including serum amyloid A (SAA), alpha 1-proteinase inhibitor, alpha 1-antichymotrypsin and albumin, induced by conditioned medium or, in some cases, by IL-6 and/or IL-1 alpha, were only minimally affected by caffeine. Thus these results indicate that the mechanism by which caffeine potentiates CRP induction by cytokines appears to be independent of increases in intracellular concentrations of the two second messengers, cyclic AMP and Ca2+; the precise nature of this mechanism is unclear at the present time. Our results also indicate that the intracellular mechanisms by which cytokines regulate synthesis of CRP may differ from those regulating synthesis of some other acute-phase proteins. The differential response of CRP and SAA to caffeine is of particular interest, since induction of both of these two major acute-phase proteins can be accomplished by identical extracellular signals.
...
PMID:Induction of C-reactive protein by cytokines in human hepatoma cell lines is potentiated by caffeine. 216 98

[35S]Sulfate labeling of the human hepatoma cell line HepG2 showed it to contain many sulfated proteins of diverse molecular weight range. The isolation of tyrosine O-sulfate indicated the supernatant fraction to contain a 5- to 7-fold higher level than the cellular fraction at the end of a 24-hr incubation. The proteins in the supernatant fraction were immunoprecipitated and examined for sulfation. Of 15 proteins tested, 7 were found to be sulfated as indicated by [35S]sulfate incorporation into proteins separated by NaDodSO4/PAGE and detected by autoradiography. The 35S-labeled bands were excised from the dried gel and subjected to extensive Pronase hydrolysis and the hydrolysates were analyzed for tyrosine [35S]sulfate by a two-dimensional procedure combining high-voltage electrophoresis and thin-layer chromatography [Liu, M. C. & Lipmann, F. (1984) Proc. Natl. Acad. Sci. USA 81, 3695-3698]. Of the sulfated proteins, three--fibrinogen, alpha-fetoprotein, and fibronectin--were found to contain tyrosine O-sulfate. The simultaneous presence of carbohydrate-bound sulfate, however, could not be exactly determined, but the other four [35S]sulfate-containing proteins--alpha 1-antitrypsin, alpha 1-antichymotrypsin, alpha 2-macroglobulin, and transferrin--did not reveal any tyrosine O-sulfate and might be sulfated on their carbohydrate moieties.
...
PMID:Tyrosine sulfation of proteins from the human hepatoma cell line HepG2. 241 72

Human squamous carcinoma (COLO-16) cells release factors which specifically stimulate the synthesis of major acute-phase plasma proteins in human and rodent hepatic cells. Anion exchange, hydroxyapatite, lectin, and gel chromatography of conditioned medium of COLO-16 cells result in separation into three distinct forms of hepatocyte-stimulating factors (designated HSF-I, HSF-II, and HSF-III) with apparent molecular weights of 30,000, 50,000 and 70,000, respectively. None of the preparations contains detectable amounts of thymocyte-stimulating activity. Each of the three HSF forms stimulates the accumulation of mRNA for alpha 1-antichymotrypsin in the human hepatoma cell line, HepG2. When the same factors were added to primary cultures of adult rat hepatocytes, the expression of the same set of plasma proteins was modulated as by nonfractionated medium. The hormonally induced accumulation of mRNA for acute phase proteins is qualitatively comparable to that occurring in the liver of inflamed rats. Unlike in human cells, in rat liver cells dexamethasone acts additively and synergistically with HSFs. The only functional difference between the three HSF forms lies in the level of maximal stimulation. HSF-I represents the predominant form produced by normal human keratinocytes and closely resembles in molecular size and isoelectric point the activity produced by activated peripheral blood monocytes while the larger molecular weight forms are more prevalent in human as well as mouse squamous carcinoma cells. The observation that HSFs from different sources elicit essentially the same pleiotropic response in hepatic cells led to the hypothesis that the species-specific reaction of adult liver cells to inflammatory stimuli is pre-programmed and that the function of any HSF is to trigger and tune the execution of this fixed cellular process.
...
PMID:Regulation of major acute-phase plasma proteins by hepatocyte-stimulating factors of human squamous carcinoma cells. 241 29

The monokine, cachectin/tumor necrosis factor (TNF) differs from interleukin 1 (IL-1) in primary structure and in recognition by a distinct cellular receptor. It does, however, encode effector functions that are similar to those of IL-1 and characteristic of the host response to inflammation or tissue injury. Accordingly, we examined the possibility that recombinant-generated human TNF regulates hepatic acute-phase gene expression. In picomolar concentrations, TNF mediated reversible, dose- and time-dependent increases in biosynthesis of complement proteins factor B and C3, alpha 1 antichymotrypsin, and decreases in biosynthesis of albumin and transferrin in human hepatoma cell lines (Hep G2, Hep 3B). Biosynthesis of complement proteins C2 and C4, and alpha 1 proteinase inhibitor were not affected by TNF. TNF also increased factor B gene expression, but had no effect on C2 gene expression, in murine fibroblasts transfected with cosmid DNA bearing the human C2 and factor B genes. The effect of TNF on acute-phase protein expression (C3, factor B, albumin) was pre-translational as shown by changes in specific messenger RNA content.
...
PMID:Cachectin/tumor necrosis factor regulates hepatic acute-phase gene expression. 242 91

A subline of the rat hepatoma (H-35) cells has been identified which responds to hepatocyte-stimulating factors (HSFs) of human squamous carcinoma cells by increased synthesis of all major rat acute phase plasma proteins. The regulation occurs at the level of mRNA. Two HSFs (HSF-I and HSF-II) have been purified from conditioned medium of the squamous carcinoma cells. HSF-I is a protein with an Mr = 18,000 and pI 5.5, and HSF-II is a glycoprotein with an Mr = 34,000 and a broad, neutral to basic charge. In H-35 cells, HSF-I predominantly stimulates the synthesis of complement C3 and haptoglobin and acts synergistically with dexamethasone to stimulate alpha 1-acid glycoprotein. HSF-II stimulates cysteine protease inhibitor, alpha 1-antichymotrypsin, alpha 1-antitrypsin, fibrinogen, and hemopexin, and acts synergistically with dexamethasone to stimulate alpha 2-macroglobulin. Each HSF is between 10 and 100 times less effective in regulating proteins of the other set. Human tumor necrosis factor and interleukin-1 increase complement C3, haptoglobin, and alpha 1-acid glycoprotein, as does HSF-I, but are unable to modulate any of the other acute phase proteins. The monokines differ from HSF-I is their low activity in HepG2 cells and rat hepatocytes.
...
PMID:Distinct sets of acute phase plasma proteins are stimulated by separate human hepatocyte-stimulating factors and monokines in rat hepatoma cells. 243 11

Human hepatoma (HepG2) cells respond to unfractionated conditioned media of human squamous carcinoma (COLO-16) cells and lipopolysaccharide-stimulated human peripheral blood monocytes by increasing the synthesis of alpha 1-acid glycoprotein, haptoglobin, complement C3, alpha 1-antichymotrypsin, alpha 1-antitrypsin, and fibrinogen, while decreasing the synthesis of albumin. The regulation of the acute phase proteins is mediated by hepatocyte-stimulating factors (HSF) and interleukin 1 (IL-1) present in the conditioned medium. Purified HSF-I from COLO-16 cells stimulates preferentially alpha 1-acid glycoprotein synthesis, whereas COLO-HSF-II stimulates preferentially the synthesis of haptoglobin, fibrinogen, and alpha 1-antitrypsin. HSF from monocytes, which has been identified as interferon-beta 2 (B cell stimulating factor-2), displayed the same activity as COLO-HSF-II. Dexamethasone alone had no effect on acute phase plasma protein synthesis but enhanced the response to various HSF severalfold. IL-1 had a relatively low stimulatory activity on the synthesis of alpha 1-acid glycoprotein, haptoglobin, and alpha 1-antichymotrypsin but strongly reduced the basal expression of fibrinogen. The only synergistic action between IL-1 and HSF (or interferon-beta 2) was noted for the synthesis of alpha 1-acid glycoprotein. Tumor necrosis factor active on other hepatic cells failed to modulate significantly the expression of any plasma proteins in HepG2 cells. These studies showed that for an optimal HepG2-cell response a combination of HSF (or interferon-beta 2), IL-1, and dexamethasone is needed. This finding might indicate the identity of some of those hormones involved in regulation of the hepatic acute phase response in vivo.
...
PMID:Interaction among hepatocyte-stimulating factors, interleukin 1, and glucocorticoids for regulation of acute phase plasma proteins in human hepatoma (HepG2) cells. 244 59

Because a number of different cytokines have been reported to regulate the synthesis of human, murine, and rat acute phase proteins (APP), we studied the effect of cytokines on production of several major human APP in a single system, the human hepatoma cell line Hep 3B. Conditioned medium (CM) prepared from human blood monocytes activated with LPS in the presence of dexamethasone led to substantial induction of serum amyloid A (SAA) and C-reactive protein (CRP) synthesis whereas the defined cytokines IL-1 beta, TNF alpha, and medium from a human keratinocyte cell line (COLO-16), containing hepatocyte-stimulating factor activity, failed to induce these two major APP. Induction of SAA and CRP was accompanied by an increase in concentration of their specific mRNA. Size fractionation of CM from activated monocytes by fast protein liquid chromatography indicated that SAA- and CRP-inducing activity eluted as a single peak with a Mr of approximately 18 kDa. alpha 1-Antitrypsin, which also failed to respond to IL-1 beta or TNF alpha, was induced by both CM and medium from COLO-16 cells. The induction of AT by CM was accompanied by an increase in specific mRNA. Induction of ceruloplasmin and alpha 1-antichymotrypsin and decrease in the synthesis of albumin was achieved by both CM and IL-1 beta. Ceruloplasmin and albumin responded in a comparable fashion to both TNF alpha and medium from COLO-16 cells; the response of ACT to these cytokines was not evaluated. These results indicate that human SAA and CRP are induced in Hep 3B cells by products of activated monocytes but not by IL-1 beta, TNF-alpha, or some hepatocyte-stimulating factor preparations and that a group of heterogeneous mechanisms are involved in the induction of the various human APP.
...
PMID:Heterogeneous nature of the acute phase response. Differential regulation of human serum amyloid A, C-reactive protein, and other acute phase proteins by cytokines in Hep 3B cells. 245 96

<< Previous 1 2 3 4 5 6 Next >>