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)

Supernates of thymic epithelial cell culture (STEC) strongly inhibit aggregation induced by addition of adenosine diphosphate (ADP: 1 microM) or thrombin (0.5 unit per ml) to washed platelet suspensions and accelerated the restoration from ADP-triggered aggregation. At the same time, STEC increased the level of platelet adenosine 3',5'-cyclic monophosphate (cyclic AMP) in a dose-dependent manner. Depending on the concentration used, thymosin fraction 5 increased the level of intracellular cyclic AMP ranging between 5 and 100 micrograms per ml, as well as inhibiting ADP-induced platelet aggregation. The activities of both STEC and thymosin fraction 5 were found to act exclusively on cyclic AMP phosphodiesterase activity in platelets. In contrast the supernates from Chang, HeLa, or HCC-M cells did not affect platelet aggregation induced by ADP, but slightly increased the cyclic AMP level (Chang, HeLa). Within 2 min after the treatment with STEC, more than 50% of the maximum inhibitory activity on platelet aggregation and increases in intracellular cyclic AMP were observed. These activities disappeared following STEC treatment with pronase E. STEC activity was found predominantly in the 1,000-50,000-dalton fractions. These activities were not altered when STEC was treated by adenosine deaminase. The level of prostaglandin E (PGE) derivatives in STEC was about two times that found in the control culture medium. These data suggest that the biological activity of STEC in the platelets might be attributed to thymosinlike polypeptides and PGE1.
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PMID:In vitro effect of a thymic epithelial culture supernate or thymosin fraction 5 on rabbit platelet aggregation and intracellular cyclic AMP levels. 282 98

We have isolated three cDNA clones for human alpha 2-plasmin inhibitor (alpha 2-PI). Two clones are from human hepatoma cell line, Hep G2, and cover the entire protein coding region plus the 3'-flanking region up to the poly(A) sequence, and the other clone is from human liver and contains the carboxyl-terminal half. The total length of the cDNAs is 2.29 kb, corresponding to more than 95% of the full-length mRNA. alpha 2-PI seems to consist of 452 amino acid residues plus 39 amino acid residues for the signal peptide. The amino acid sequence shows 23 to 28% homology to those of five other protease inhibitors, plasminogen activator inhibitor (PAI), protein C inhibitor (PCI), alpha 1-antitrypsin (alpha 1-AT), antithrombin III (AT III), and alpha 1-antichymotrypsin (alpha 1-AC). alpha 2-PI seems to be the most distantly related among these inhibitors. Comparison of the phylogenetic trees of proteases and their inhibitors indicates that four proteases, namely elastase (or trypsin), chymotrypsin, plasminogen activator, and thrombin, may have evolved concurrently with the corresponding inhibitors. However, alpha 2-PI and PCI seem to have evolved asynchronously from their substrates. The data suggest that alpha 2-PI may originally have inhibited some protease other than plasmin, and protein C may have had an inhibitor different from the present one early in its evolutionary history.
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PMID:Structure of human alpha 2-plasmin inhibitor deduced from the cDNA sequence. 283 Feb 48

Incubation of HTC rat hepatoma cells with the synthetic glucocorticoid dexamethasone rapidly inhibits plasminogen activator (PA) activity secondary to the induction of a specific acid-stable inhibitor of plasminogen activation (Cwikel, B. J., Barouski-Miller, P.A., Coleman, P.L., and Gelehrter, T.D. (1984) J. Biol. Chem. 259, 6847-6851). We have further characterized this inhibitor with respect to its interaction with both urokinase and tissue plasminogen activator, and its protease specificity. The HTC PA inhibitor rapidly inhibits urokinase and tissue plasminogen activator with an apparent second-order rate constant of 3-5 x 10(7) M-1 X s-1. The inhibitor forms stable covalent complexes with both urokinase and tissue plasminogen activator, with which plasmin, trypsin, and factor Xa apparently do not compete. Complex formation is saturable and requires the active site of the PA. The mass of the inhibitor-PA complex is 50,000 daltons greater than that of PA alone, consistent with an Mr for the PA inhibitor of 50,000 as demonstrated directly by reverse fibrin autography. The HTC PA inhibitor does not inhibit thrombin and differs in its kinetic and biochemical properties from protease nexin.
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PMID:Characterization of the dexamethasone-induced inhibitor of plasminogen activator in HTC hepatoma cells. 293 42

Human plasma heparin cofactor II (HCII) inhibits thrombin by rapidly forming a stable, equimolar complex in the presence of heparin or dermatan sulfate. Cultured human hepatoma-derived cells (PLC/PRF-5) secreted (approximately equal to 200 ng/ml in 3 days) a protein of MW - 72 kD that was immunoisolated and immunoblotted with anti-HCII, co-migrated on SDS-PAGE with human plasma HCII, and formed covalent complexes with thrombin (MW - 101 kD) in the presence but not absence of heparin or dermatan sulfate; these complexes co-migrated with those obtained by incubating thrombin with human plasma under the same conditions. HCII was not detectable (less than 0.13 ng/ml) in post-culture medium from cultured human umbilical vein endothelial cells or human foreskin fibroblasts.
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PMID:Biosynthesis of functionally active heparin cofactor II by a human hepatoma-derived cell line. 299 59

A new method to assay des-gamma-carboxyprothrombin (DCP) activity is described, using staphylocoagulase on undiluted citrated plasma after adsorption with bentonite (to remove fibrinogen), then with aluminium hydroxide. The thrombin-coagulase which is formed is measured by following the increase in optical density per minute of a chromogenic substrate. The results are expressed in milliunits (m.U.). The new method is sensitive and specific. It confirms the usefulness of the DCP assay for the diagnosis of hepatocellular carcinoma (Liebman et al.). Ninety-six normal subjects had levels of DCP ranging from 0 to 12 m.U. Out of 42 patients with hepatocarcinoma, 30 (71%) had DCP levels higher than 15 m.U. The increased DCP appears to be complementary to alpha-foetoprotein, since one or the other marker were positive in 37 out of 40 cases (92.5%) of hepatocellular carcinoma. Chronic hepatitis or cirrhosis (36 cases) and non-hepatocellular liver cancer (9 cases) gave normal DCP values.
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PMID:[A new method of functional assay of des-gamma-carboxyprothrombin using staphylocoagulase. Application to the diagnosis of hepatocellular carcinoma]. 300 86

The clearance of thrombin-antithrombin (TAT) complexes from blood by the liver is through a receptor mediated pathway. We have used the established human hepatoma cell line, Hep G2, to determine if these hepatocytes have the capacity to bind this enzyme-inhibitor complex. The TAT complex was bound to the cells in a time and temperature dependent manner, reaching an apparent steady state at 90 minutes at both 4 and 37 degrees C. Binding at 4 degrees C was 5-7-fold less extensive than at 37 degrees C. The bound TAT was structurally similar to the added ligand. This interaction was specific, as it was inhibited by nonlabeled TAT but not by 50-fold molar excesses of unrelated proteins or by the individual constituents, thrombin or antithrombin. Factor Xa- antithrombin complex inhibited the binding reactions slightly. Specific binding isotherms at 37 degrees C were subjected to Scatchard plots. The apparent dissociation constant was 247 +/- 74 nM, and the number of TAT molecules bound per cell was 5.19 +/- 0.89 X 10(5). Bound TAT complexes did not undergo degradation at 4 or 37 degrees C for up to 2.5 hr, as greater than 85% of the bound ligand was acid precipitable during the time course of binding. Internalization of the TAT complex was compared with transferrin, a molecule known to be internalized by Hep G2 cells, by resistance of the cell-bound ligands to degradation by trypsin or pronase. In contrast to transferrin, most of the TAT complexes remained cell-surface associated for at least 2 hr at both 4 degrees and 37 degrees C, indicating that TAT was not substantially internalized by the Hep G2 cells.
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PMID:Specific association of thrombin-antithrombin complexes with a human hepatoma cell line. 300 66

A new method for assaying the activity of des-gamma-carboxyprothrombin (DCP), using staphylocoagulase on undiluted adsorbed plasma, is described. The thrombin-coagulase formed is measured on a chromogenic substrate, and the results are expressed in milliunits per milliliter of increment of the optical density following the release of p-nitroaniline. Levels of DCP in 96 normal subjects were under 10 mU/ml (mean, 3.58 mU/ml). Of 70 nonhepatectomized patients with hepatocellular carcinomas, 74% had increased DCP levels of between 20 and 420 mU/ml (most of the values were between 20 and 100 mU/ml). Des-carboxyprothrombin and alpha-fetoprotein measurements gave complementary information, one marker or the other being positive in 87% of hepatocellular carcinoma. Fourteen of 15 patients with metastatic carcinoma of the liver had normal DCP levels, as did 95 patients with liver cirrhosis and 13 patients with chronic hepatitis. When the level of "total factor II" is below 40%, it is recommended that a second determination of DCP be performed 5 days after the injection of vitamin K, to exclude any vitamin K deficiency (in the case of hepatocellular carcinoma the DCP level will remain elevated). The DCP assay appears more sensitive and more specific than the alpha-fetoprotein assay for the diagnosis of hepatocellular carcinoma; furthermore, both tests are complementary.
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PMID:A new method to assay des-gamma-carboxyprothrombin. Results obtained in 75 cases of hepatocellular carcinoma. 301 18

The initiation and regulation of fibrinolysis has been studied by reconstitution of fibrinolytic activity in human plasma in vitro. Depletion of tissue plasminogen activator (tPA) antigen by immunoadsorption of human plasma with anti-tPA Ig Sepharose 4B leads to total loss of spontaneous fibrinolytic activity determined by lysis of a thrombin-induced clot. Addition of physiological concentrations of purified tPA to tPA-depleted plasma restores fibrinolytic activity as a function of the length of time between tPA addition and clotting. Addition of free tPA to tPA-depleted plasma followed by immediate clotting results in a high rate of fibrinolysis. In contrast, when free tPA is allowed to incubate in plasma for 10 to 60 minutes prior to clot formation, the fibrinolytic activity of tPA is gradually lost. The loss of tPA-induced fibrinolytic activity in unclotted plasma is accompanied by decreased partitioning of tPA antigen into fibrin after clotting and is kinetically correlated with the formation of a 100 kilodalton (kDa) tPA complex as demonstrated by SDS-gel electrophoresis and fibrin-agar zymography. These results suggest that free tPA is susceptible to complexation by the plasma inhibitor in the absence of a clot. Fibrin formation renders tPA relatively inaccessible to inhibition. The tPA antigen isolated from stored plasma consists mainly of 100 kDa activity in SDS-gel electrophoresis and zymography, indicating that the tPA complex is resistant to dissociation by SDS. Upon rezymography of the sliced gel, only a 60 kDa tPA activity is found, suggesting that the activity at 100 kDa is at least partly due to free tPA dissociated from the complex during the first zymography. Conversion of tPA complex to enzymatically active free tPA also occurs with brief SDS exposure followed by incubation in the presence of excess Triton X-100 or by hydroxylamine treatment. These results reconcile the apparent discrepancy of the 100 kDA inhibitor-tPA complex manifesting plasminogen activation activity during zymography. The plasma tPA-inhibitor complex is precipitated strongly by antisera against plasminogen activator inhibitors (PAIs) of human Hep G2 hepatoma and HT-1080 fibrosarcoma cells and weakly by antiserum against bovine aortic endothelial cell PAI but not by antiserum against a placental PAI (PAI-2) suggesting that the plasma inhibitor is immunologically related to Hep G2, HT-1080 and possibly endothedial cell PAIs. Based on the above findings, a simple model for the initiation and regulation of plasma fibrinolysis at the PA level has been formulated.
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PMID:Initiation and regulation of fibrinolysis in human plasma at the plasminogen activator level. 310 19

The aims of the present investigation were to characterize the binding and inhibition of thrombin and factor Xa to bovine vascular endothelial cells (EC), bovine smooth muscle cells (SMC), and rat hepatoma cells (RHC), and to evaluate the effects of plasma constituents on their inhibition. The enzymatic activities of bovine thrombin and factor Xa were assayed using chromogenic substrates. After 10 min incubation with the cells, thrombin activity in the solution had decreased by about 20% and was subsequently recovered on the cell surfaces. When the cells with the surface-bound thrombin were incubated with defibrinogenated plasma or antithrombin III (AT-III) for 30 sec only about 10% and 20-40%, respectively, of the initial activity could be recovered. In similar experiments with factor Xa, initial activity in the solution had decreased by 10% after 10 min incubation, and was subsequently recovered from the cell surfaces. After 30 sec incubation with AT-III, no cell surface-bound factor Xa activity was detected, whereas 10% of the bound factor Xa activity was recovered after incubation with defibrinogenated plasma. It is concluded that thrombin and factor Xa are taken up and inhibited by EC, SMC and RHC cell surfaces in similar ratios, suggesting that cell surface-mediated inhibition of clotting factors is not restricted to vascular wall cells. The inactivation of factor Xa was dependent on AT-III, however, the inactivation of thrombin was further promoted by an additional unidentified plasma constituent.
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PMID:Interaction of thrombin and factor Xa with bovine vascular endothelial cells, smooth muscle cells and rat hepatoma cells. 321 15

Tyrosine sulfate was identified as a constituent of human heparin cofactor II by analysis of sulfate-labeled protein secreted by a human hepatoma-derived cell line and of purified protein from human plasma. Alkaline hydrolysis of heparin cofactor II released tyrosine sulfate as demonstrated by anion-exchange high performance liquid chromatography of hydrolysates. Two sites of sulfation were identified, and the amino acid sequences of the sites were established by sequential Edman degradation of sulfate-containing tryptic peptides that were isolated by reverse-phase high performance liquid chromatography. Each peptide contains only a single tyrosine residue so that the sites of sulfation can be assigned unambiguously. The two sites of sulfation are separated by 13 residues and represent an internal sequence repeat in the heparin cofactor II molecule. The two sites have the following sequences. Glu56-Asp-Asp-Asp-Tyr(SO4)-Leu-Asp62 Glu69-Asp-Asp-Asp-Tyr(SO4)-Ile-Asp75 Sulfate-labeled heparin cofactor II formed a covalent complex with thrombin in a heparin-dependent manner. Thus, the sulfate-containing form of the protein was shown to be biologically active. The characteristic sulfate-containing segment of heparin cofactor II, which contains 17 acidic amino acid residues over a span of 30 residues, may contribute to the unique properties of this thrombin inhibitor.
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PMID:Identification of two sites of sulfation of human heparin cofactor II. 378 93


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