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

High levels of a novel vitamin B12-binding protein (hepatoma B12 BP) have been observed recently in plasma obtained from three adolescent patients with hepatocellular carcinoma. This protein has now been isolated in homogeneous form from the plasma and pleural fluid of two of these patients by the use of affinity chromatography with vitamin B12-Sepharose. The hepatoma B12 BP belongs to the R-type group of B12-binding proteins and is essentially indistinguishable from the recently isolated human milk and saliva R-type proteins in terms of: (a) immunologic properties based on immunodiffusion and immunoprecipitation assays; (b) amino acid composition; (c) molecular weight based on amino acid and carbohydrate content; and (d) absorption spectra. Both hepatoma B12 BPs contain more sialic acid and less fucose than the milk and saliva B12 BPs. All four proteins contain similar amounts of galactose, mannose, galactosamine, and glucosamine. Differences in sialic acid content appear to account for the differences in electrophoretic mobility that were observed among the four proteins. Differences in total carbohydrate content appear to account for the differences in apparent molecular weight that were observed with both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Tumor tissue from one of the patients contained 10 times as much R-type protein as did normal liver tissue from the same patient. This suggests, although it does not prove, that synthesis by the tumor is the cause of the high levels of R-type protein found in the plasma of certain patients with hepatocellular carcinoma. Plasma survival studies performed with rabbits indicate that the hepatoma B12 BP has a prolonged plasma survival and suggests that his parameter is also of importance.
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PMID:Isolation and characterization of a novel vitamin B12-binding protein associated with hepatocellular carcinoma. 17 Dec 83

Plasma membranes were isolated from an ascites hepatoma, AH 130, by the fluorescein mercuric acetate (FMA) method. Glycopeptides and mucopolysaccharides were prepared by digesting the membranes with pronase, then by fractionating the digest chromatographically and electrophoretically. Isolated fractions were analyzed for their amino acid and carbohydrate compositions. Results were compared with those for corresponding fractions from AH 66 (J. Biochem. 76, 319-333 (1974)). Mucopolysaccharides and a series of glycopeptides were isolated from the fraction excluded from Sephadex G-50. The mucopolysaccharides were identified as a family of heparan sulfates with different electrophoretic mobilities. The glycopeptides contained serine, threonine, galactose, galactosamine, glucosamine, and sialic acid as the major constituents as aspartic acid and mannose as minor ones. This suggests that most of the carbohydrate moieties are linked to serine or threonine (O-glycosidic), and that some are linked to asparagine (N-glycosidic). No nearly purely O-glycosidic glycopeptides were found in this fraction from AH 130, through they were the major glycopeptides from the AH 66 plasma membranes. In the fraction included in the gel, glycopeptides containing fucose, galactose, mannose, glucosamine, glaactosamine, and sialic acid were found. The presence of galactosamine suggests that some of the glycopeptides are O-glycosidic though most are N-glycosidic. In the corresponding fraction from AH 66, nearly purely N-glycosidic glycopeptides were found.
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PMID:The isolation and characterization of glycopeptides and mucopolysaccharides from plasma membranes of an ascites hepatoma, AH 130. 17 52

Membrane glycoprotein biosynthesis of ascites hepatoma cells is followed by [14C]glucosamine and [3H]leucine incorporation into cells in culture. The rate of incorporation is strongly increased by the addition of Robinia lectin in culture medium. Labeled glycoproteins are released from lectin stimulated and non-stimulated cells by trypsin digestion. Studies of labeled trypsinates on sodium dodecyl sulfate gel electrophoresis and Sephadex G-200 filtration exhibit two fractions both labeled with [14C]glucosamine and [3H]leucine and having different molecular weights, one over 200000 and the other about 2000. Identical results are obtained when external membrane glycoproteins are solubilized by sodium deoxycholate. Comparison of surface glycoproteins isolated by trypsinization from control cells labeled with [3H]-glucosamine and from lectin stimulated cells labeled with [14C]glucosamine displays no significant qualitative differences between glycoprotein fractions released from both cell groups.
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PMID:Stimulation of the biosynthesis of membrane glycoproteins from Zajdela ascites hepatoma cells by Robinia lectin. 18 23

Plasma membranes were isolated from an ascites hepatoma, AH 130 FN, a free-cell type subline of AH 130, by the fluorescein mercuric acetate (FMA) method. Glycopeptides and mucopolysaccharides were prepared from the membranes by pronase digestion then fractionated chromatographically and electrophoretically. Isolated fractions were analyzed for amino acid and carbohydrate compositions. The results were compared with those for corresponding fractions from AH 66 and AH 130 ((1974) J. Biochem. 76, 319-333; (1975) ibid., 78, 863-872). The fraction excluded from Sephadex G-50 contained mucopolysaccharides and a series of glycopeptides. The mucopolysaccharides were identified as chondroitin sulfate A on the basis of their chemical composition, electrophoretic behavior on cellulose acetate and digestibility with chondroitinase AC [EC 4.2.2.5]. This contrasts with previous findings that mucopolysaccharides from the corresponding fractions from AH 130 and AH 66 were heparan sulfate. The chemical composition of the glycopeptides, which showed high contents of threonine, serine, galactose, galactosamine, glucosamine, and sialic acid, indicated the presence of glycopeptides with O-glycosidic linkages. The glycopeptides also contained a small but significant amount of aspartic acid, suggesting that N-glycosidic glycopeptides were also contained in this fraction. The fraction included in Sepnadex G-50 contaoned N-glycosidic glycopeptides as major components, since the carbohydrate moieties were composed of fucose, galactose, mannose, glucosamine, sialic acid, and a smaller amount of galactosamine. The presence of galactosamine suggested that O-glycosidic glycopeptides were present as minor components. Glycopeptides with both O- and N-glycosidic linkages were isolated from AH 130, but not from AH 66.
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PMID:The isolation and characterization of glycopeptides and mucopolysaccharides from plasma membranes of an ascites hepatoma, AH 130 FN. 18 82

Ascites hepatoma cells grown in Wistar rats were incubated anaerobically in the absence of glucose or in the presence of both glucose and D(+)glucosamine, or monoiodoacetate, or NADH, which interfered with glycolysis at different steps and with different mechanisms: Under all these conditions the incorporation of amino acids into the proteins of hepatoma cells was severely reduced without any clear relationship to the degree of inhibition of glycolysis. The postmitochondrial supernatants showed defective incorporation only when obtained from cells incubated in the absence of glucose or in the presence of monolodoacetate; inhibition of glycolysis by glucosamine and NADH did not seem to affect the subcellular basis for protein synthesis. When present, the defect of the cell sap (monoiodoacetate and absence of glucose) and to disaggregation and reduced functional capacity of the polysomes (absence of glucose). The results suggested that the effects of the inhibition of glycolysis on protein synthesis and on the integrity of the protein-synthesizing machinery--which were primarily due to the depletion of the energy stores--might have been modified by the particular mechanism of action of the inhibitor and by the way low levels of ATP were reached in the cell.
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PMID:Inhibition of glycolysis and interference with protein synthesis in hepatoma cells. 19 Apr 11

In order to evaluate the role of hexosamine metabolism in tumor tissue, we studied the biodistribution of N-(F-18)-fluoroacetyl-D-glucosamine (FAGlu) in male Donryu rats bearing poorly differentiated hepatomas (AH109A and AH272). Compare with the former result of the high tumor uptake of FAGlu in C3H/He mice bearing well differentiated spontaneous hepatoma, the tumor uptakes of FAGlu in these tumors showed the lower values. This suggested that spontaneous hepatoma maintained a high activity of glucosamine metabolism, while poorly differentiated hepatoma had little activity. Metabolism of glucosamine in tumor tissue may be another marker for characterizing tumors. We also discuss the tissue distribution of new F-18 labeled hexosamines, N-(F-18)-fluoroacetyl-D-mannosamine and N-(F-18)-fluoroacetyl-D-galactosamine in tumor bearing rats.
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PMID:N-(F-18)-fluoroacetyl-D-glucosamine: a new positron labeled pharmaceutical for cancer study. 130 16

The identification of free glycoinositol phospholipids (GPIs) following biosynthetic labeling with [3H]glucosamine in cultured cells has been reported by several laboratories. We applied this procedure to two of the cell types used in these studies, H4IIE hepatoma cells and isolated hepatocytes, but were unable to detect a [3H]glucosamine-containing lipid that met any of the criteria for GPIs, including sensitivity to phosphatidylinositol-specific phospholipase C (PIPLC) or GPI-specific phospholipase D. Part of the difficulty in radiolabeling a GPI by this procedure was the rapid metabolic conversion of [3H]glucosamine to galactosamine and neutral or anionic derivatives. A PIPLC-sensitive radiolabeled lipid was detected only after 16 h of labeling. The water-soluble fragments released from this lipid by PIPLC corresponded largely to myo-inositol 1,2-cyclic phosphate and myo-inositol 1-phosphate, products expected from PIPLC cleavage of phosphatidylinositol or lyso-phosphatidylinositol. In an alternative approach that we introduce here, free GPIs in lipid extracts from rat liver plasma membranes were labeled by reductive radiomethylation. This procedure, which radiomethylates primary and secondary amines, has been shown to label a glucosamine residue adjacent to inositol in all GPIs characterized to date. The labeled extracts were fractionated by two-dimensional thin-layer chromatography, and a cluster of polar labeled lipids were assigned as GPIs based upon the following observations. 1) They were cleaved by PIPLC, 2) after hydrolysis in 6 N HCl, both radiomethylated glucosamine and a glucosamine-inositol conjugate were identified by cation exchange chromatography, and 3) hydrolysis in 4 M trifluoroacetic acid generated a fragment consistent with glucosamine-inositol-phosphate. These results illustrate new criteria for the identification of GPIs. The labeled GPIs also contained radiomethylated ethanolamine, another component found in GPI anchors of proteins and in mature lipid precursors of GPI anchors, suggesting that the liver plasma membrane GPIs retained considerable structural homology to GPI anchors.
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PMID:Identification of glycoinositol phospholipids in rat liver by reductive radiomethylation of amines but not in H4IIE hepatoma cells or isolated hepatocytes by biosynthetic labeling with glucosamine. 132 29

In this study it could be shown that in rat the normally occurring N-acetyl neuraminic acid can be modified in its N-acyl moiety by in vivo administration of the chemically synthesized N-propanoyl precursors, N-propanoyl-D-glucosamine or N-propanoyl-D-mannosamine. It could be shown that each of these nonphysiological amino sugar analogues was incorporated into both membrane and serum glycoproteins. After treatment of rats with radiolabeled N-[acyl-1-14C]D-mannosamine, radioactivity could be removed from serum glycoprotein fractions by incubation with neuraminidase from Clostridium perfringens or from Arthrobacter ureafaciens. Mild acid hydrolysis removed 98% of the radioactivity after in vivo labeling with N-[acetyl-1-14C]D-mannosamine and 86% after labeling with N-[propanoyl-1-14C]D-mannosamine. Chromatographic analysis yielded two compounds, i.e. N-acetyl neuraminic acid and N-propanoyl neuraminic acid, the latter being identified by gas liquid chromatography/mass spectrometry studies. Measurement of protein-bound radioactivity in different rat organs revealed a different organotropy of the natural and the nonphysiological neuraminic acid precursor. Of the glucosamine derivatives, N-acetyl-D-glucosamine showed the higher rate of uptake and incorporation in most organs (except in the submandibulary gland), and especially in kidney cortex and Morris hepatoma 7777. Natural and the unphysiological mannosamine derivatives were incorporated at similar rates, except in liver, where N-acetyl-D-mannosamine was taken up and metabolized more effectively. This finding indicates that it is possible to modify the acyl group of N-acetyl neuraminic acid in vivo by the introduction of an N-propanoyl group and possibly other homologous N-acyl groups. This procedure may provide a tool for a further characterization of the biological function of sialic acids.
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PMID:Biosynthesis of a nonphysiological sialic acid in different rat organs, using N-propanoyl-D-hexosamines as precursors. 151 35

The molecular heterogeneity of alpha-fetoprotein (AFP) in yolk sac tumor (YST) was investigated. The study included 14 sera from YST, 78 sera from primary hepatocellular carcinoma (PHC), 5 fetal yolk sac (YS) culture fluids and 4 fetal liver culture fluids. The microheterogeneity of AFP was assessed by differences in reaction with AFP carbohydrate chain and lectins, and concanavalin A (Con A), Lens culinaris hemagglutinin (LCH) and phytohemagglutinin E (PHA-E) affinity crossed-line immunoelectrophoresis was used to fractionate AFP. It was found that AFP in YST or YS had similar subfraction patterns and differed clearly from AFP in PHC or fetal liver. Characteristic features of AFP subfraction in YST or YS were the presence of a LCH weakly-reactive subfraction and a high proportion of both Con A non-reactive and PHA-E strongly-reactive subfractions. The LCH weakly-reactive subfraction was specifically found in YST or YS, but was not found at all in PHC or in fetal liver. This variant is known to exist in amniotic fluid at an early stage of gestation, and is assumed to have a carbohydrate chain with both fucose and bisecting N-acetyl-glucosamine. The present findings therefore suggest that glycosylation of AFP in YST takes place by retro-genetic differentiation toward fetal yolk sac, but not toward fetal liver, and these studies confirm the suggested yolk sac origin of ovarian, as well as extragonadal, yolk sac tumor.
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PMID:[Molecular heterogeneity of alpha-fetoprotein in ovarian or extragonadal yolk sac tumor]. 171 73


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