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 activity of membrane-bound enzyme gamma-glutamyl transferase (GGT) is twice increased in the liver of normal and tumour-bearing rats after hydrocortisone intramuscular injections (10 mg/kg body weight). At the same time GGT activity is not increased in serum and hepatoma G-27. The glutathione-reductase activity and contents of G-SH and G-S-S-G in the rat liver and hepatoma are not altered by Hydrocortisone action at the different means of hormone administration. Effect of hydrocortisone is studied also on the GGT activity in the liver of newborn rats. The stimulation of GGT activity by hydrocortisone is probably due to an induction of protein synthesis.
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PMID:[Effect of hydrocortisone on gamma-glutamyl transferase activity of the rat liver and hepatoma]. 615 85

Using a direct immunofluorescence assay, we showed that alpha-fetoprotein (AFP) both in purified form and in hepatocellular carcinoma (HCC) sera was capable of binding onto 10-20% of T lymphocytes and 5-10% of B lymphocytes in human peripheral blood when these lymphocytes were preincubated in AFP-positive fluids at 4 degrees C in the presence of sodium azide. But when the preincubation temperature was raised to 37 degrees C, most of the membrane-bound AFP was internalized or shed, and, consequently, less than 3% of the cells showed positive membrane fluorescence. In addition, binding of AFP onto lymphocyte surface membrane and the continuous presence of large amounts of AFP in these lymphocyte cultures did not interfere with the action of cytotoxic antibodies directed against HLA determinants on the lymphocyte surface.
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PMID:Alpha-fetoprotein on human peripheral blood lymphocytes does not block complement-dependent lymphocytotoxicity. 617 19

Hematoxylin and eosin-stained sections representing ten cases of hepatocellular carcinoma showed many tumor cells with ground-glass cytoplasm identical to that found in hepatocytes containing hepatitis B surface antigen (HBsAg). However, the aldehyde fuchsin stain was negative, as were the were the immunoperoxisidase stains for HBsAg and core antigen (HBcAg). Electron microscopically, the ground-glass appearance corresponded to the presence of non-membrane-bound amorphous or fibrillar inclusions. Immunohistochemically, the ground-glass material reacted with antiserum to human fibrinogen, suggesting synthesis of this protein by the carcinoma cells. Although the ground-glass appearance in hepatocellular carcinomas may sometimes be associated with HBsAg, special stains or technics are necessary to confirm its presence.
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PMID:Ground-glass cells in hepatocellular carcinoma. 625 12

The incorporation of lysophosphatidylcholine into biological membranes and its effect on some membrane-bound enzymes of mitochondria and microsomes from rat liver and hepatoma were studied. It was shown that in the presence of lipid-exchange proteins of the liver a far greater amount of lysophosphatidylcholine is incorporated into the membranes than in the-iv absence. The increase of the lysophosphatidylcholine content in the membranes has no effect on the activity of mitochondrial monoamine oxidase, inhibits the activity of microsomal cytochrome P-450 and activates glucose-6-phosphatase.
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PMID:[New method of lysophospholipid incorporation into biological membranes. Effect of lysophosphatidylcholine on the activity of membrane-bound enzymes]. 626 66

Human hepatoma cells, infected by vesicular stomatitis virus, offer a good system to study simultaneously the intracellular localization of a well defined transmembrane glycoprotein (VSV-G), a secretory glycoprotein (transferrin), and a nonglycosylated secretory protein (albumin). We used monospecific antibodies in combination with 5- and 8-nm colloidal gold particles complexed with protein A to immunolabel these proteins simultaneously in thin frozen sections of hepatoma cells. VSV-G, transferrin, and albumin are present in the same rough endoplasmic reticulum cisternae, the same Golgi compartments, and the same secretory vesicles. In the presence of the ionophore monensin intracellular transport is blocked at the trans cisternae of the Golgi complex, and VSV-G, transferrin, and albumin accumulate in dilated cisternae, which are apparently derived from the trans-Golgi elements. Glycoproteins, synthesized and secreted in the presence of monensin, are less acidic than those in control cultures. This is probably caused by a less efficient contact between the soluble secretory proteins and the membrane-bound glycosyltransferases that are present in the most monensin-affected (trans) Golgi cisternae.
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PMID:Vesicular stomatitis virus glycoprotein, albumin, and transferrin are transported to the cell surface via the same Golgi vesicles. 631 44

The attachment and entry of Plasmodium berghei sporozoites to cultured human lung fibroblast (WI38) or hepatoma (HepG2-A16) cells in vitro has been visualized using an immunoperoxidase technique coupled with light microscopy. Attachment and entry was substantially more frequent with HepG2-A16 cells, and appeared to be mediated by the Pb44 sporozoite surface protective antigen. When sporozoites were incubated with intact monoclonal antibodies to Pb44 or their monovalent Fab fragments, attachment was inhibited, suggesting that this technique may be an in vitro assay of protective immunity. Sporozoites appeared to enter cells actively, rather than by cell phagocytosis. Once within a membrane-bound vacuole, the sporozoite transformed into a trophozoite. It was suggested that Pb44 recognized a specific cell receptor, and that this technique may permit receptor characterization.
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PMID:Entry of Plasmodium berghei sporozoites into cultured cells, and their transformation into trophozoites. 634 98

Liver cells obtained from newborn mice homozygous for any one of several overlapping deletions in chromosome 7 fail to express a number of liver-specific differentiated traits. Among these is the activity of the membrane-bound liver-specific enzyme glucose-6-phosphatase (Glc-6-Pase; D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9). Previous studies have led to the suggestion that the region of the genome covered by these deletions includes genes that normally regulate the expression of structural genes encoding liver-specific enzymes and proteins mapping elsewhere in the genome. To find out whether the deficiency of Glc-6-Pase may be caused by the deletion of the relevant structural gene, mouse liver cells homozygous for the deletion c14CoS were hybridized with 2S Faza rat hepatoma cells, and the hybrid cell cultures were analyzed for mouse and rat Glc-6-Pase activity. Hybrids showed expression of mouse Glc-6-Pase activity, proving that the structural gene for this enzyme is not included in the deletion c14CoS in chromosome 7. In the hybrid cells the rat hepatoma genome apparently contributes a factor that activates the structural gene of the mouse and corrects its failure of expression, which most likely resulted from the deletion of an essential regulatory or processing gene. By using as a marker glucose-6-phosphate isomerase (Glc-6-PIase; glucosephosphate isomerase, D-glucose-6-phosphate ketolisomerase, EC 5.3.1.9), known to map on chromosome 7, this entire chromosome could be excluded as a possible carrier of the Glc-6-Pase structural gene. In addition, the structural genes for Glc-6-Pase and for tyrosine aminotransferase (TyrATase; L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5), another enzyme deficient in lethal deletion homozygotes, were shown to map on two different chromosomes. Together with our previous studies of TyrATase gene regulation, the present experiments suggest that the region of the mouse genome defined by the deletions includes one or more genes regulating the expression of several structural genes that map on different chromosomes and that encode liver-cell-type specific traits.
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PMID:Correction of a genetically caused enzyme defect by somatic cell hybridization. 657 48

The highly glucolytic hepatoma cell line H-91 is characterized by a high hexokinase activity to rat liver; 50% of this activity is associated with the mitochondrial fraction [Bustamante, E., & Pederson, P.L. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 3735--3739]. Treatment of mitochondria from this cell line with adenosine 5'=triphosphate (ATP) or glucose 6-phosphate solubilizes bound hexokinase activity. Solubilization of the enzyme by ATP results in a six- to sevenfold purification. Free ATP, unchelated by Mg ions, induces the release of the enzyme from the membrane, whereas the MgATP complex is ineffective. Ethylenediaminetetraacetic acid (EDTA) fails to release mitochondrial hexokinase indicating that the enzyme is not attached to the membrane by divalent cations. Energization of mitochondria is not required for ATP to induce solubilization of bound hexokinase. This is evidenced by (a) the ability of the nonhydrolyzable ATP analogue adenylyl imidodiphosphate to solubilize the enzyme, (b) the inability of uncouplers and inhibitors of oxidative phosphorylation to either solubilize or prevent the release of mitochondrial hexokinase, and (c) the inability of atractyloside to solubilize or prevent the release of bound hexokinase. The bound and the ATP-solubilized forms of mitochondrial hexokinase from H-91 hepatoma cells are kinetically different. When membrane bound, the enzyme has a significantly higher apparent affinity (Km = 0.25 mM) for its substrate MgATP than when solubilized (Km = 1.2 mM). Free ATP acts as a competitive inhibitor of mitochondrial hexokinase. Both the membrane-bound and the solubilized forms of mitochondrial hexokinase have about the same apparent affinity for glucose (Km = 56 and 83 microM, respectively). The experiments reported here provide the first description of the properties and the nature of binding of mitochondrial hexokinase from a tumor cell line growing in tissue culture.
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PMID:Mitochondrial hexokinase of rat hepatoma cells in culture: solubilization and kinetic properties. 677 59

The membrane-bound UDP-GalNAc:polypeptide N-acetylgalactosamine transferase from an ascites hepatoma, AH 66, has been purified 48,100-fold, mainly by affinity chromatography in aqueous Triton X-100 on apomucin (deglycosylated bovine submaxillary mucin) coupled to Sepharose. The purified preparation behaved homogeneously on gel filtration on Sephadex G-150 in aqueous Triton X-100 and on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with an apparent molecular weight of about 55,000. The enzyme requires Mn2+, and only UDP-GalNAc served as a sugar donor. Apomucin, A1 protein, kappa-casein, apofetuin, and apoantifreeze glycoproteins served as acceptors, but the rate and amount of the transfer varied considerably from one acceptor to another. The transfer reaction terminated at the level of glycosylation of from only a few to at most about 40% of the serine plus threonine residues from which mucin-type oligosaccharides had been removed. This indicates that the transferase requires a certain conformation surrounding the acceptor site, but suggests also that a special mechanism may be functioning in vivo for frequent glycosylation of the abundant serine plus threonine residues of mucins. Lacto-N-fucopentaose I, ceramide di- and trihexosides, and globoside were not acceptors.
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PMID:Purification and characterization of UDP-GalNAc:polypeptide N-acetylgalactosamine transferase from an ascites hepatoma, AH 66. 680 38

In eukaryotic cells, secretory proteins and glycoproteins migrate from the rough endoplasmic reticulum, their site of synthesis, through Golgi vesicles before being released from the cell. Cellular and viral integral plasma membrane glycoproteins are co-translationally inserted into the rough endoplasmic reticulum membrane and follow a similar pathway to the cell surface. Previous studies using endoglycosidase H (Endo H) suggested that in rat hepatoma cells the vesicular stomatitis virus (VSV) G protein, albumin and transferrin migrate from the rough endoplasmic reticulum to the Golgi apparatus at different rates. Here we show directly that in human hepatoma HepG2 cells, five secreted proteins mature from the rough endoplasmic reticulum to Golgi vesicles at characteristic rates which differ at least threefold. The results are incompatible with bulk-phase movement of the luminal contents of the endoplasmic reticulum, and suggest that there is a membrane-bound receptor that selectively mediates the transport of secretory proteins from the rough endoplasmic reticulum to the Golgi.
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PMID:Hepatoma secretory proteins migrate from rough endoplasmic reticulum to Golgi at characteristic rates. 686 94


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