UMLS:C0019204 - FACTA Search

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

Two newly described human hepatoma derived cell lines, Hep G2 and Hep 3B [Knowles, B. B., Howe, C. C., & Aden, D. P. (1980) Science (Washington, D.C.) 209, 497-499], synthesize and secrete into the culture medium most of the major plasma apoproteins (apoA-I, apoA-II, apoB, apoC-II, apoC-III, and apoE). The synthesized apoproteins were identified by direct two-dimensional gel analysis of the culture medium or by two-dimensional analysis following purification of the apoproteins by ultracentrifugation or immunoprecipitation. We found that the apoA-I synthesized by both of the hepatoma cell lines consists of two isoproteins designated 2 and 3 which are more basic than the major plasma apoA-I isoproteins designated 4 and 5. The apoE synthesized by both cell lines is composed mainly of an array of isoproteins with increasingly higher molecular weights and lower isoelectric points as compared to those of the major apoE isoproteins found in plasma. These precursors of apoE are converted to the major apoE isoproteins upon treatment with Clostridium perfringens neuraminidase and represent sialo apoE isoproteins. ApoA-II, apoC-II, apoC-III-1, and apoC-III-2 correspond to the protein forms present in plasma. The human hepatoma cell lines (Hep G2 and Hep 3B) provide a unique model for studies of the regulation of human apoprotein and lipoprotein synthesis and catabolism.
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PMID:Characterization of the major apolipoproteins secreted by two human hepatoma cell lines. 627 88

Two enzyme forms of alkaline phosphatase have been partially purified from the medium spent for the culture of HUH-6 clone 5 cells, which were originally derived from hepatoblastoma tissue. The purification methods used are ammonium sulfate precipitation, ethanol precipitation, diethylaminoethyl cellulose chromatography, Affi-Gel Blue chromatography, and Sephadex G-200 gel filtration. These alkaline phosphatases have been characterized by thermostability, inhibition, and immunological and electrophoretic studies. Both are L-phenylalanine and L-tryptophan sensitive and L-homoarginine and L-leucylglycylglycine insensitive, and both react with an antiserum against intestinal alkaline phosphatase. The major enzyme form is a neuraminidase-cleavable, moderately thermostable isoenzyme which on polyacrylamide gel shows an electrophoretic mobility similar to that of liver alkaline phosphatase. The minor enzyme form is a neuraminidase-uncleavable, thermolabile isoenzyme which shows an intermediate electrophoretic mobility between liver and hepatoma alkaline phosphatases. The molecular weights of the major and minor enzymes have been estimated by gel filtration to be 170,000 and 110,000, respectively. These results support the conclusion that the two enzyme forms of HUH-6 alkaline phosphatase are intestinal in type, with the major enzyme form closely resembling hepatoma and oncoamnionic alkaline phosphatases, and the minor enzyme form resembling "intestine-like liver alkaline phosphatase." HUH-6 clone 5 cell line may be a useful in vitro model to study the regulatory mechanism for phenotypic expression of intestinal-type alkaline phosphatase isoenzymes in liver cancer cells.
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PMID:Intestinal-type alkaline phosphatase produced by human hepatoblastoma cell line HUH-6 clone 5. 631 71

Immunochemical and immunocytochemical techniques have been used to characterize viral glycoproteins and endogenous rat leukaemia viruses (RaLV) produced both by Novikoff hepatocellular carcinoma cells and spontaneously transformed Wistar rat embryo cells (WRC). Results from immunocytochemical analysis demonstrated that RaLV produced by Novikoff and WRC cells could be distinguished by their unique patterns of reactivity with xenoantisera raised against virus particles or viral glycoproteins. This differential labelling was unexpected since all the antisera tested had been shown by immunoprecipitation and immunodepletion analysis to be reactive with viral glycoproteins expressed on the cell surface. Since no significant differences in cell surface-associated viral glycoproteins and those shed from the cell surface were detected by pulse iodination analysis, it was concluded that the apparent discrepancy between immunoferritin labelling and immunoprecipitation analysis resulted from differences in antigen accessibility on intact virions caused by structural differences in the viral glycoproteins expressed on Novikoff and WRC cells. This conclusion was supported by results from ferritin-lectin labelling, affinity chromatography and neuraminidase digestion studies which demonstrated differences in the saccharide moieties on both virion and cell surface-associated viral glycoproteins. Further evidence of structural differences was provided by limited digestion with trypsin and V8 protease of the Mr 64 000 (Nov gp64) and Mr 68 000 (WRC gp68) viral glycoproteins immunoprecipitated from Novikoff and WRC cells, respectively, with either monospecific anti-Rauscher murine leukaemia virus anti-gp70 serum or monospecific antiserum against Nov gp64 (anti-gp64). Results from digestion studies showed that all the major cleavage fragments from WRC gp68 were of higher molecular weight than their Nov gp64-derived counterparts. Evidence that Nov gp64 and WRC gp68 both share structural homology with other murine viral gp70s was suggested by results from immunoprecipitation analysis with anti-gp70 and anti-gp64 sera under reducing and non-reducing conditions which demonstrated the presence of an interchain disulphide bond in both glycoproteins and showed that at least some of these molecules exist on the cell surface as disulphide-linked heterodimers of Mr 78 000 and 82 000.
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PMID:Structural differences in envelope glycoproteins associated with rat leukaemia virus produced by Novikoff hepatocellular carcinoma and spontaneously transformed Wistar rat embryo cells. 636 46

The reactivity of sera in liver diseases was investigated by an immunoradiometric assay for antibody to liver membrane antigens (LMAg). Serum reactivity was similar using glutaraldehyde treated hepatocytes from man and several animals, but the reactivity with human hepatocellular carcinoma cell lines was weak and irregular. F(ab)2 fragments from reactive sera were used in competitive inhibition experiments to ascertain whether anti-LMAg from different liver diseases reacted with the same or different antigenic determinants of the liver membrane. Sera from different patients with autoimmune CAH reacted predominantly with the same membrane components, as did sera from hepatitis B virus associated CAH (CAH-B); however sera from acute viral hepatitis A did not and, since such sera were reactive to LMAg in the assay, other membrane antigens are presumably involved. Enzymatic treatment of viable hepatocytes was performed to determine the nature of the reactive antigen(s): proteases or periodate resulted in reduced binding of reactive sera, but neuraminidase did not, suggesting that the LMAg recognized by CAH sera comprises species non-specific membrane glycoproteins. We conclude, on the basis of quantitative data from a immunoradiometric assay, that antibody to LMAg is more probably reactive than pathogenic, and that assessment of the antigenicity of specific membrane components is necessary.
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PMID:Antibodies to liver cell membrane antigens in chronic active hepatitis (CAH). III. Partial characterization of the liver cell membrane antigens and comparison of reactivities in sera from patients with various liver diseases. 643 84

Insulin receptors from rat hepatoma cells (Fao) and human placenta were partially purified by detergent solubilization and lectin purification. The insulin receptor preparations were subjected to sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis under reducing or nonreducing conditions. The proteins were transferred to nitrocellulose paper and the electrophoretic blots were treated with human anti-receptor autoantibodies, rabbit antibody to purified insulin receptor, or a monoclonal antibody to human insulin receptor. The nitrocellulose paper was then treated with 125I protein A or 125I second antibody followed by autoradiography. The rabbit polyclonal antiserum and one of the human autoantibodies recognized both the alpha (Mr = 135,000) and beta (Mr = 95,000) subunits after transfer from a SDS gel to nitrocellulose paper. On transfers from nonreduced gels, several high-molecular species were labeled ranging from Mr = 200,000 to Mr = 330,000. Similar high-molecular bands of the receptor were seen if highly purified human placental receptor, as well as partially purified receptor from rat or human origin, were used. As little as 0.1-0.5 microgram of pure receptor could be detected by this technique. Treatment of the receptor with neuraminidase (50 mU/ml) before gel electrophoresis resulted in a 50% increase in intensity of intact receptor and about a 70% increase in the labeling of the alpha-subunit of the receptor, but no change in labeling of the beta-subunit. The monoclonal antibody used, as well as two other human autoantibodies, did not recognize the receptor after transfer to nitrocellulose paper.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Visualization of the insulin receptor by immunoblotting. 647 60

The addition of excess sodium citrate to plasma was found to inhibit fibrin polymerisation (clot opacity) from patients with cirrhosis, hepatitis and hepatoma but not from normal controls. Abnormal clot opacity in plasma from patients with liver disease could be partly or completely abolished by removal of citrate ions by dialysis against citrate-free buffer, but not by dialysis against buffer containing citrate. Similar results were observed in plasma freed of calcium ions by treatment with EGTA. Treatment of plasma with neuraminidase largely abolished the inhibitory effect of excess citrate, and the thrombin times and clot opacity of asialofibrinogen were less affected by citrate than native fibrinogen. In addition, the effects of citrate on the clotting of purified, calcium-free fibrinogen from cirrhotic patients correlated with the sialic acid content. It is concluded that binding of citrate ions to fibrinogen renders the molecule acutely more sensitive to elevations in the sialic acid content, and that a simple plasma clot opacity test in the presence of excess citrate may be a useful aid in the differential diagnosis of liver disease. These findings may also explain why defects in fibrin polymerisation observed in plasma are not always reproduced in purified fibrinogen or fibrin monomer preparations.
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PMID:The role of sodium citrate in the dysfibrinogenaemia of liver disease. 672 77

Asialofetuin sialyltransferase from Triton X-100 extracts of rat liver was resolved by phosphocellulose chromatography into two fractions, designated I and II in order of elution. When previously treated with Arthrobacter ureafaciens neuraminidase, fraction I eluted at about the same position as II while no alteration occurred in II. Primary rat hepatomas contained only a single asialofetuin sialyltransferase, identical to fraction I in chromatographic behavior. Transferases I and II were purified to near homogeneity. Transferase II, as well as neuraminidase-treated I, could be sialylated auto-catalytically, indicating that the lack of sialic acid in II is not due to the lack of a sialic-acid-accepting site. Both enzymes formed an (alpha 2 leads to 6)sialylgalactoside linkage with asialo-glycoproteins of the glycosylamine-type and with lactose, and were indistinguishable immunologically. Nevertheless, the transferases exhibited different molecular weights of 37000 (I) and 43000 (II). When heated at 50 degrees C, transferase I lost half its original activity within 20 min while II was scarcely inactivated. Kinetically, transferase I showed three-times higher affinity than II for CMP-N-acetylneuraminic acid and for desialylated plasma membrane. Asialofetuin sialyltransferase was also purified from primary rat hepatoma. The purified enzyme was identical to transferase I in every respect examined. We conclude that hepatomas contain transferase I but lack transferase II.
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PMID:Purification and characterization of beta-galactoside (alpha 2 leads to 6)sialyltransferase from rat liver and hepatomas. 675 21

Alkaline phosphatase was purified from plasma membrane of rat ascites hepatoma AH-130 cells by chromatographies on DEAE-cellulose and Affi-Gel Blue and preparative polyacrylamide gel electrophoresis. The yield of the purified enzyme, finally as the denatured subunits, was about three times better than that obtained previously [J. Biochem. (1978) 83, 1471-1483]. The purified enzyme, a glycoprotein, was analyzed for amino acid and carbohydrate compositions. The composition of the carbohydrate moiety, which amounted to about 18% by weight, indicated that both N- and O-glycosidic sugar chains were contained in the protein. The purified alkaline phosphatase (as the denatured subunits) was used to produce monospecific antibody, which was found to have the same immunological reaction with the native antigen as the antibody raised against the partially purified native enzyme. Immunological analysis by Ouchterlony double gel diffusion and quantitative immunoprecipitation demonstrated that the hepatoma enzyme was identical with that of the liver. In standard polyacrylamide gel electrophoresis at pH 8.9, the hepatoma alkaline phosphatase migrated a little more slowly than the liver enzyme. Both enzymes, however, showed identical mobility after complete removal of sialic acid from them with neuraminidase. These results suggest that the only difference between the two enzymes was in the carbohydrate moiety, especially in the sialic acid content.
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PMID:Chemical and immunological characterization of rat ascites hepatoma alkaline phosphatase: a comparison with the liver enzyme. 706 59

Using the principle of relief of self-quenching of carboxyfluorescein [Weinstein, J. N., Yoshikami, S., Henkart, P., Blumenthal, R., & Hagins, W. A. (1977) Science 195, 489-492] upon leakage of the dye from the interior of lipid vesicles, we investigated the integrity of sonicated small unilamellar vesicles in the presence of isolated hepatocytes, Zajdela ascites hepatoma cells, and plasma membranes of either cell type. We observed that cells as well as plasma membranes induce leakage of carboxyfluorescein from vesicles. Two parameters (initial rate and maximal level of induced leakage) were determined to quantitate the leakage events and were found to depend on cell density, vesicle concentration, and vesicle lipid composition. The magnitude of both parameters is shown to increase with cell density and to decrease with increasing vesicle lipid concentration and seems to be proportional to the number of vesicles found in close contact with the cell. For vesicles made of phosphatidylcholine and cholesterol, the degree of induced leakage increases steeply with cholesterol contents increasing from 30 to 40 mol %. In the case of simultaneous presence of 10 mol % phosphatidylserine, induced leakage can be observed at cholesterol contents exceeding 20 mol %. We show that leak-inducing activity resides in the plasma membrane and that it can be considerably reduced by treatment of the plasma membranes with neuraminidase or trypsin, suggesting the involvement of cell-surface glycoprotein(s). Release of activity from intact cells and isolated plasma membranes into the medium occurs spontaneously (at a slow rate) but can be facilitated by freezing and thawing; the activity can subsequently be recovered in a soluble form from the medium.
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PMID:Cell-induced leakage of liposome contents. 721 93

The [3H]hydrocortisone transfer into intact target cells and into non-target cells, e. g. isolated hepatocytes, hormone-sensitive Morris hepatoma 7777 cells, hormone-resistant Zajdela ascite hepatoma cells, was studied. In target cells the glucocorticoid transfer is temperature-dependent, i. e. the curve for hormone binding by the cells at increasing concentrations shows a plateau Phospholipase A2 and neuraminidase decrease the ability of the cells to incorporate the labelled hormone. The experimental data differ significantly from those obtained for target cell cytosol and for intact Zajdela hepatoma cells. It was assumed that in target cells the crucial role in hormone transfer into the cells belongs to plasma membranes, while in non-target cells the hormone penetrates inside the cells by passive diffusion.
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PMID:[Role of plasma membranes in the glucocorticoid transfer into target cells]. 723 83

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