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

The mechanism of the cytostatic action of dimerized ribonuclease A toward cultured hepatoma cells was investigated. A decrease in mitotic index, modifications of adsorptive properties of the pericellular membrane and inhibition of the degradation of two different proteins taken up by endocytosis are the first cell functions to be affected by the dimer. This effect on protein digestion is not due to an inhibition of proteolytic enzymes. The intracellular localization of exogenous protein and of ribonuclease dimer was studied by cell fractionation. When proteins (horseradish peroxidase or rabbit immunoglobulin G) are taken up by control hepatoma cells, they are first associated with phagosomes equilibrating at a lower density than lysosomes; their density distribution gradually becomes similar to that of lysosomes. When cells are pre-exposed to ribonuclease dimer, this modification of the density distribution as a function of time no longer occurs, although these proteins are still intracellular, as indicated by fractionation by differential centrifugation. During the first hour after addition of ribonuclease dimer, kinetic studies show an increased fixation of peroxidase to the cell membrane. Protein release into the culture medium is also increased. These results can be explained either by an absence of fusion between phagosomes and lysosomes, or by an inhibition of the discharge of peroxidase adsorbed to the phagosomal membrane after fusion.
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PMID:Inhibition of the discharge of endocytosed protein from phagosomes into lysosomes in hepatoma cells exposed to dimerized ribonuclease A. 44 21

Variations of endocytic and of lysosomal functions during the cell cycle have been investigated in synchronized hepatoma cells (derived from Morris hepatoma 7288c) by following the cellular uptake of horseradish peroxidase, dextran (mol wt. 70,000), and chloroquine. Cell fractionation and cytochemistry show that in asynchronously growing cells exposed for 1 h to 5 mg/ml peroxidase, the bulk of the enzyme taken up by the cells is found in phagosomes. By using the same experimental system with synchronized HTC cells, large variations of endocytosis are observed during the cell cycle. Peroxidase uptake is lowest during mitosis, increases 5--10 times during G1 phase, reaches a plateau, and finally decreases at the end of S phase and during G2 phase. A similar evolution is observed for the uptake of dextran (0.5 or 1 mg/ml), but it is likely that a significant part of the polysaccharide is still associated with the pericellular surface after 1 h. Moreover, dextran is transferred more slowly than peroxidase to lysosomes. Cellular accumulation of chloroquine is related to intralysosomal pH or to the buffering capacity of lysosomes. Our results show that this drug is taken up more rapidly during G1 and S phases while the rate of accumulation is lowest in mitotic cells. The results are discussed in relation to the modifications of the physical properties of lysosomes during the cell cycle observed previously by cell fractionation and electron microsocopy, and to the possible role of lysosomes in the initiation of mitosis. Cyclic changes of endocytosis in actively dividing cells are demonstrated by our observations and may induce large differences in the uptake rate of extracellular substances.
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PMID:Endocytosis and chloroquine accumulation during the cell cycle of hepatoma cells in culture. 51 30

Novikoff hepatocellular carcinoma cells were radioiodinated by a cell surface-specific method using lactoperoxidase/125I. The iodinated proteins were solubilized in 0.5% Nonidet P-40 and subjected to affinity chromatography on Sepharose-conjugated lectins (Ricinus communis agglutinins I or II, soybean agglutinin, concanavalin A, or wheat germ agglutinin) and analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Almost all the iodinated proteins bound to one or more of the Sepharose-conjugated lectins, presumptive evidence that these peptides are glycosylated. Lectin affinity chromatography resolved defined subsets of iodinated glycoproteins and suggested that certain glycoproteins could be fractionated on the basis of heterogeneity of their heterosaccharide moieties. Incubation of the iodinated cells with neuraminidase resulted in increased binding of iodinated proteins to Sepharose-conjugated Ricinus communis agglutinins I and II and soybean agglutinin and decreased binding to Sepharose-conjugated wheat germ agglutinin. Binding of iodinated proteins to concanavalin A was unaffected by neuraminidase treatment of the cells. These studies demonstrate the utility of lectins for the multicomponent analysis of plasma membrane proteins.
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PMID:Lectin affinity chromatography of cell surface proteins of Novikoff tumor cells. 54 27

The cell surface proteins of AH-66 hepatoma ascites cells were examined both by fluorescent labeling with cycloheptaamylose-fluorescamine complex and by radioiodination with lactoperoxidase. The labeled proteins were analyzed by measuring the distribution of fluorescence or radioactivity in polyacrylamide gels after electrophoresis. Although the degree of fluorescent labeling with cycloheptaamylose-fluorescamine complex was substantially different from that obtained by lactoperoxidase-catalyzed iodination, proteins with molecular weights of 130,000, 90,000, 86,000, 50,000--60,000, and 37,000 were strongly labeled in common by both reagents. It is suggested that at least these proteins are exposed on the surface of the plasma membranes of AH-66 cells. One of these proteins labeled strongly by both reagents is the major glycoprotein, with an apparent molecular weight of 130,000 in 10% polyacrylamide gels.
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PMID:Proteins exposed on the outer surface of the plasma membranes of AH-66 hepatoma ascites cells. 76 41

An antigen-antibody complex of horseradish peroxidase, peroxidase-antiperoxidase (PAP), was found to selectively bind to Mallory bodies (MBs). Specific PAP binding to MBs was consistently demonstrated in liver sections from 14 patients with alcoholic cirrhosis and from one patient with hepatoma. Mallory bodies in isolated fractions also bound PAP. No structures stained with PAP in six control sections. The PAP-binding method is useful in the identification of MBs in situ and in isolated fractions. The nature of the affinity of MBs for PAP is not known, but it is postulated that nonspecific protein-immunoglobulin binding is involved.
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PMID:Peroxidase-antiperoxidase complex. Binding by Mallory bodies in unfixed tissue. 98 79

The distribution of the Lens culinaris lectin receptors on normal rat liver cells, on rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat is investigated by means of the Lens culinaris lectin-peroxidase method and by ferritin conjugated Lens culinaris lectin. The normal rat liver cells show a continuous labeling at the outer membrane surface by the lectin complexes, whereas the transformed rat liver cells exhibit a strong tendency for patchy distribution of the cell surface label. The discontinuous cell surface label in the transformed rat liver cells is obviously caused by an internalization of plasma membrane areas. The importance of these morphological findings in their relationship to Lens culinaris lectin mediated agglutination of rat liver cells and the membrane fluidity in general are discussed. In the experiments no hints to a rotation of the Lens culinaris lectin receptors from the outer membrane surface to the inner membrane surface of rat liver cells can be found.
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PMID:Lens culinaris lectin receptors in the plasma membrane of rat liver cells: comparative electron microscopic studies on normal cells, on cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells. 123 3

Comparative electron microscopic investigations were performed in living cultures of normal rat liver cells, of rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat concerning the mobility of the Concanavalin A cell surface receptors. The cells were incubated in Concanavalin A and peroxidase and subsequently washed. They were then reincubated for various periods at +37 degrees C in PBS prior to fixation. In the case of the Zajdela ascites hepatoma cells the cells were reincubated after Concanavalin A incubation followed by fixation and peroxidase incubation. The cytochemical procedure allowed us to show differences in the mobility of Concanavalin A surface receptors between normal and transformed rat liver cells. The cell surface label disappeared completely within 15 min of reincubation in the transformed cells, whereas in normal cells the same degree of loss in surface label was visible after 120 min reincubation. In both cases an internalization of labelled plasma membrane areas occurred. After complete disappearance of cell surface label in diethylnitrosamine transformed cells a complete relabelling of the cell surface occurred after 60 min reincubation caused by an exocytosis.
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PMID:Concanavalin A receptors on normal rat liver cells, on rat liver cells in vivo transformed by diethylnitrosamine and on Zajdela ascites hepatoma cells of the rat: morphokinetic analysis of cell surface dynamics. 123 15

To determine alpha-fetoprotein (AFP) in human saliva, a highly sensitive sandwich enzyme immunoassay for saliva AFP was developed. AFP standards and saliva samples were added into the wells of a polystyrene plate coated with goat IgG antibody against human AFP. After incubation, the wells were washed and horseradish peroxidase-labelled antibody was added. The enzyme activity specifically bound to the well was assayed using 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide as substrate. The reaction was stopped by addition of 2 M sulphuric acid and the AFP concentration was determined from the absorbance at 450 nm. The minimum detectable concentration was 8 ng/L. The recovery of AFP mixed with human saliva was 91.1-102.4%. The within-assay and between-assay coefficients of variation were 6.5-8.9% and 7.6-10.8%, respectively. The assay correlated well with a radioimmunoassay for human AFP (r = 0.985, n = 13, P less than 0.001). The mean concentration of AFP in normal human saliva was 14.3 ng/L (SEM = 4.9 ng/L, n = 10) and significantly higher levels of saliva AFP were observed in hepatocellular carcinoma patients with positive serum AFP (mean 1367.8 ng/L, SEM 595.4 ng/L, n = 6; P less than 0.001). Strong correlation was observed between saliva AFP and serum AFP (r = 0.978, P less than 0.01, n = 13).
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PMID:Highly sensitive sandwich enzyme immunoassay for alpha-fetoprotein in human saliva. 128 27

Peritoneal liver biopsy specimens from eight patients with hepatitis B associated cirrhosis, complicated by hepatocellular carcinoma, were studied for identification and localisation of myofibroblasts. The avidin-biotin peroxidase complex technique was used on paraffin wax sections, using monoclonal antibodies for actin and desmin, and ultrastructural examination was performed. Myofibroblasts were found in seven of the eight cirrhotic specimens and in all eight tumour specimens. They were identified in the fibrotic areas by the immunohistochemical technique, but ultrastructural examination disclosed their presence in the perisinusoidal space and between tumour cells.
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PMID:Myofibroblasts in hepatitis B related cirrhosis and hepatocellular carcinoma. 131 87

Immunohistochemical evaluation of Cu, Zn- and Mn-superoxide dismutase (SOD) activity in various viral liver diseases was performed by the peroxidase-conjugated antibody indirect method. Anti-human Cu, Zn-SOD (rabbit) and anti-human Mn-SOD (guinea-pig) derived and purified from SOD of human erythrocytes and placentas were used to determine SOD distribution in liver tissues. SOD in the liver tissues was detected in 68 inpatients of our unit. They consisted of 23 cases with chronic hepatitis caused by hepatitis B virus (13) and hepatitis C virus (10), 24 with liver cirrhosis caused by hepatitis B virus (5) and hepatitis C virus (19) (15: compensatory, 9: decompensatory) and 21 with hepatocellular carcinoma caused by hepatitis B virus (2) and hepatitis C virus (18) complicated of liver cirrhosis. In viral liver diseases, SODs in the liver tissues were distributed to hepatocytes mainly in the pattern of cytoplasmic diffusion. The incidence of immunohistochemical Cu, Zn-SOD and Mn-SOD were 47.8% and 56.5% in chronic hepatitis, 93.3% and 86.7% in compensated liver cirrhosis, 11.1% and 22.2% in decompensated liver cirrhosis, respectively. The aggression of viral liver disease was accompanied with the decrease of SOD concentration in the liver tissues. Hepatocellular carcinoma cells were negative for Mn-SOD in all cases, and weakly positive for Cu, Zn-SOD in 2 out of 21 cases. Comparatively strongly positive SOD findings were obtained from normal regions neighboring carcinomas. A close relationship between the depletion of SOD in liver tissues and carcinogenesis in viral liver diseases was observed.
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PMID:Relationship between superoxide dismutase (SOD) and viral liver diseases. 132 May 79


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