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)

The specificity of lactoperoxidase-catalyzed iodination for the proteins of the hepatoma tissue culture cell plasma membrane was examined by histochemical, biochemical, and cell fractionation techniques. Light microscope autoradiography of sectioned cells shows the incorporated label to be localized primarily at the periphery of the cell. Most of this label can be released from the cell by trypsin but not by collagenase or hyaluronidase. The label is recovered from the cells as either monoiodotyrosine or diiodotyrosine after hydrolysis of cell extracts with a mixture of proteolytic enzymes. The label co-purifies during cell fractionation with an authentic liver cell plasma membrane marker enzyme, 5'-nucleotidase. Thus, the incorporated iodide is itself a valid marker for those membrane polypeptides having tyrosine residues accessible to the lactoperoxidase. The polypeptide complexity of the purified plasma membrane was examined by high resolution dodecyl sulfate-polyacrylamide gel electrophoresis. At least 50 polypeptides in the membrane are accessible to iodination. These polypeptides probably represent the bulk of the protein mass of the membrane and iodinating them does not affect cell viability, growth rate, or cell function. Labeling experiments with fucose and glucosamine show that at least nine of the iodinated peptides may be glycoproteins.
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PMID:Proteins of the hepatoma tissue culture cell plasma membrane. 0 57

The ascites form of a chemically induced guinea pig hepatoma, line-10, was resistant to killing in vitro by xenogeneic antibody and guinea pig complement. Pretreatment of line-10 cells with certain proteolytic enzymes rendered tham susceptible to the killing action of antibody and guinea pig complement. The effects of enzyme pretreatment were dependent on enzyme concentration, temperature, and could be blocked by addition of competitive or non-competitive inhibitors. The effect of the enzyme treatment could reversed by incubating the treated cells at 37 degrees C (but not at 0 degrees C), in the absence of the enzyme. Effective enzymes included ficin, bromelain, pronase, elastase, papain, trypsin, collagenase, lipases type I and type VI, and the neuraminidase preparation isolated from Clostridium perfringens. The activity of the lipase preparations and the neuraminidase preparation isolated from Clostridium perfringens appeared to be caused by proteolytic enzyme contamination. Enzyme preparations that proved ineffecitve in rendering the line-10 cells sensitive to killing by antibody and guinea pig complement included DNase, RNase, beta-glucuronidase type 6A or type B10, hyaluronidase type V or type VI, and pectinesterase.
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PMID:Lysis of tumor cells by antibody and complement. VI. Enhanced killing of enzyme-pretreated tumor cells. 17 70

The mechanism of albumin biosynthesis was studied in Morris hepatoma 5123tc in vivo and in hepatoma cell suspensions obtained by solubilizing the intercellular matrix with collagenase and hyaluronidase. In the in vivo experiments, L-[-14C]leucine was injected i.v. into rats bearing hepatomas in the muscles of both hind legs. After 14 min, tumors were removed and homogenized. A protein fraction quantitatively precipitable with antialbumin was isolated from the homogenate by acetone fractionation and precipitation with antiserum against serum albumin. This protein fraction was not homogeneous. With the use of 3 consecutive chromatographies on diethylaminoethyl cellulose, a very highly radioactive albumin-like protein could be separated from a large amount of only slightly radioactive albumin. In hepatoma cell suspensions incubated with L-[1-14C]leucine followed by a chase with excess nonradioactive L-leucine, radioactivity was incorporated first into the albumin-like protein and transferred thereafter into albumin, suggesting that albumin was synthesized via the albuminlike protein as precursor. In vivo, 1.8% of newly synthesized hepatoma protein was albumin or its precursor, compared with 1.2% in cell suspensions.
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PMID:Biosynthesis of albumin via a precursor protein in Morris hepatoma 5123tc. 18 40

Two distinct classes of cell surface FGF-binding proteins have been identified. These receptors differ in both mode of interaction and in affinity for the FGFs. cDNAs that encode the low-affinity receptor were isolated from a hamster kidney cell line cDNA library by expression cloning. Transfected cells that contained these heparan sulfate proteoglycan FGF receptor cDNAs were enriched for by panning on basic FGF-coated plates. The analogous human cDNA was isolated from a hepatoma cell line cDNA library. The homology of our hamster cDNAs to the previously described murine integral membrane proteoglycan syndecan, together with an exact amino acid sequence match of our human-cDNA-encoded product to human syndecan, clearly indicates the identity of these independently isolated proteoglycans. Further confirmation that the expressed molecule serves as a proteoglycan core protein was achieved by immunoprecipitation of 35SO4-labeled material from solubilized transfected cells. Nitrous acid treatment and chondroitinase digestion revealed that 77% of the label was associated with heparan sulfate chains and 22% with chondroitin sulfate chains. These heparan sulfate chains contributed to the fivefold increase in the total heparan sulfate found to be present on the surface of the transfected cells compared with cells transfected with a vector lacking the cDNA insert.
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PMID:The molecular biology of heparan sulfate fibroblast growth factor receptors. 166 83

The binding and internalization of endogenous growth hormone in Chang hepatoma cells were localized on the cell surface and in the Golgi-endoplasmic reticulum-lysosome (GERL) area by various indirect immunocytochemical labeling techniques, namely, peroxidase or colloidal gold conjugated to secondary antibody, and avidin-biotin complex methods. Rabbit antiserum and monoclonal antibodies raised against HPLC-purified porcine growth hormone were used in this study. In fixed material, antigen-antibody complexes were found to be homogeneously distributed along the cell membrane. Control groups showed negative binding on the cell surface. Trypsin treatment before immunolabeling removed antibody binding completely, but hyaluronidase was ineffective. Pretreatment of lectins did not block the recognition of primary antibody to antigen molecules on cell surface. Internalization of the antigen-antibody peroxidase or gold complexes was demonstrated in the cells, which were immunolabeled at 4 degrees C, and then reincubated for 0-30 min at 37 degrees C before fixation. After reincubation, the internalized ligand complexes were found in vesicles near the cell surface or in the GERL area near the Golgi apparatus which, however, did not label for peroxidase. These findings suggest that the trypsin-sensitive growth hormone, specifically bound and internalized into Chang hepatoma cells, is localized in the GERL instead of the Golgi apparatus and might be involved in the mechanism of tumor cell growth.
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PMID:Immunocytochemical demonstration of the binding and internalization of growth hormone in GERL of Chang hepatoma cells. 207 35

We have investigated the glycosaminoglycan composition of normal human liver, focal nodular hyperplasia, hepatic adenoma, and hepatocellular carcinoma. Uronic acid increased about 4 fold in the benign and reactive lesions, and greater than 7 fold in the carcinoma. Whereas in focal nodular hyperplasia and adenoma dermatan sulfate was the predominant glycosaminoglycan, in hepatocellular carcinoma chondroitin sulfate was the predominant species; it increased 24 fold over normal liver and 3-5 fold over all the other tissues. HPLC analysis of chondroitinase ABC or AC digests showed a 58 fold increase in Delta-Di-OS disaccharides in hepatocellular carcinoma, indicating significant undersulfation of chondroitin sulfate. Surprisingly, the normal-appearing liver surrounding the carcinoma showed glycosaminoglycan changes similar to adenoma and nodular hyperplasia. These results thus indicate that specific glycosaminoglycan changes occur in hepatocellular carcinoma, and suggest for the first time that proteoglycan metabolism is also altered in the non-cirrhotic, hepatic parenchyma adjacent to liver carcinoma.
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PMID:Altered glycosaminoglycan composition in reactive and neoplastic human liver. 215 32

The use of a hyaluronic acid-binding proteoglycan (hyaluronectin) as a probe for the detection of hyaluronic acid has facilitated the development of an indirect enzymo-immunological assay for hyaluronidase. Plastic microtest ELISA plates were coated with hyaluronic acid. Incubation with hyaluronidase led to the destruction of insolubilized hyaluronic acid in proportion to the hyaluronidase concentration of samples. Residual hyaluronic acid was assayed by its capacity to bind immune complexes made up of hyaluronectin supplemented with alkaline phosphatase-conjugated anti-hyaluronectin antibodies. The technique was very sensitive and permitted the detection of as little as 10(-10) NFU of bovine testicular hyaluronidase. Hyaluronidase was detected by this technique in human sera, bee venom and culture medium of human hepatoma cell lines.
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PMID:An indirect enzymoimmunological assay for hyaluronidase. 331 96

In human hepatoma HepG2 cells, the serum inter-alpha-trypsin inhibitor (ITI)-like protein is synthesized from two protein precursors, the heavy chain (H) H2 and the light chain (L). Both of them carry sulphate groups involved in the chondroitin sulphate glycosaminoglycan (GAG) linkage, as demonstrated by [35S]sulphate labelling, chondroitinase digestion and inhibition with beta-D-xyloside, an artificial GAG acceptor. While inhibition of N-glycosylation prevented neither the maturation nor the secretion of the ITI-related entities, brefeldin A induced the accumulation of H and L precursors in the cells, therefore blocking subsequent association and maturation of the precursors before their secretion. The enzyme system involved in the ester linkage between H and L chains is localized in the trans-Golgi network since no ITI-like protein could be obtained in the presence of monensin; instead free heavy-chain protein forms and bikunin were secreted in culture supernatants. The ITI-like protein synthesized by HepG2 cells is therefore composed of two heavy chains HC2 linked to two bikunin chains by chondroitin sulphate bridges, although the GAG linkage between HC2 chains is presumably different. Further, a different maturation route leading to restricted heavy-chain forms, Hm and Hd, could be shown.
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PMID:Post-translational processing of the inter-alpha-trypsin inhibitor in the human hepatoma HepG2 cell line. 752 38

The biological activity of many cytokines is regulated by binding proteins present at the cell surface, in extracellular matrices or in soluble phase. We describe here a TGF-beta binding protein that is both an extracellular matrix and a cell surface protein. When intact extracellular matrices of HEP-G2 cells were affinity cross-linked with 125I-TGF-beta 1, two major binding components were seen: a 250-kD, proteoglycan-like molecule, presumed to be betaglycan, and a 60-kD protein. The 60-kD TGF-beta-binding protein was also present at the cell surface. It could be released from the cell surface by treating cells with high salt, heparin, chondroitin sulfate, heparitinase, or chondroitinase, indicating that it is bound to heparan sulfate and chondroitin sulfate proteoglycans. The 60-kD protein bound TGF-beta 1 with an apparent dissociation constant of 1.6 nM, and there were 30,000 binding sites per cell at the cell surface. In addition to the HEP-G2 cells and another hepatoma cell line, the 60-kD protein was also found in a human colon carcinoma (HT-29) cell line but not in rat kidney (NRK-49F) or human fibroblast (HUT-12) cell lines. The 60-kD protein could be extracted from cells containing it and transferred to the surface of previously negative cells. The 60-kD protein may serve to regulate the binding of TGF-beta to its signal transducing receptors by targeting TGF-beta to appropriate locations in the microenvironment of cells.
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PMID:A 60-kD protein mediates the binding of transforming growth factor-beta to cell surface and extracellular matrix proteoglycans. 833 95

The presence of hyaluronidase was detected at pH 3.8 in eight out of twelve human cancer cell line culture media. Eight cell lines derived from primary tumours and four from metastases. In three culture media the enzymatic activity was lower than 0.035 pU/cell/h. In five others (in a hepatoma cell line and in four metastasis-derived cell lines) the activity was higher than 0.057 pU/cell/h. A tumour-derived fibroblast culture was negative. The optimal activity was observed at a pH comprised between 3.6 and 4. Salt inhibition of hyaluronidase was reversible. The enzyme was denaturated by a 10-min heating at 70 degrees C. The enzyme was not strictly specific for hyaluronan hydrolysis but also digested chondroitin sulfates. PH20, a spermatozoid protein that has homologies with the bee venom hyaluronidase, was not expressed by cell lines tested.
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PMID:[Production of hyaluronidase by cultured human tumor cells]. 943 34


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