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 intracellular distributions of the cation-independent mannose 6-phosphate receptor (MPR) and a 120-kD lysosomal membrane glycoprotein (lgp120) were studied in rat hepatoma cells. Using quantitative immunogold cytochemistry we found 10% of the cell's MPR located at the cell surface. In contrast, lgp120 was not detectable at the plasma membrane. Intracellularly, MPR mainly occurred in the trans-Golgi reticulum (TGR) and endosomes. lgp120, on the other hand, was confined to endosomes and lysosomes. MPR was present in both endosomal tubules and vacuoles, whereas lgp120 was confined to the endosomal vacuoles. In cells incubated for 5-60 min with the endocytic tracer cationized ferritin, four categories of endocytic vacuoles could be discerned, i.e., vacuoles designated MPR+/lgp120-, MPR+/lgp120+, MPR-/lgp120+, and vacuoles nonimmunolabeled for MPR and lgp120. Tracer first reached MPR+/lgp120-, then MPR+/lgp120+, and finally MPR-/lgp120+ vacuoles, which are assumed to represent lysosomes. To study the kinetics of appearance of endocytic tracers in MPR-and/or lgp120-containing pools in greater detail, cells were allowed to endocytose horse-radish peroxidase (HRP) for 5-90 min. The reduction in detectability of MPR and lgp120 antigenicity on Western blots, due to treatment of cell homogenates with 3'3-diaminobenzidine, was followed in time. We found that HRP reached the entire accessible pool of MPR almost immediately after internalization of the tracer, while prolonged periods of time were required for HRP to maximally access lgp120. The combined data suggest that MPR+/lgp120+ vacuoles are endocytic vacuoles, intermediate between MPR+/lgp120-endosomes and MPR-/lgp120+ lysosomes, and represent the site where MPR is sorted from lgp120 destined for lysosomes. We propose that MPR is sorted from lgp120 by selective lateral distribution of the receptor into the tubules of this compartment, resulting in the retention of lgp120 in the vacuoles and the net transport of lgp120 to lysosomes.
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PMID:Sorting of mannose 6-phosphate receptors and lysosomal membrane proteins in endocytic vesicles. 284 7

Liver cell dysplasia (LCD) was found in 28 (60%) of 47 patients with hepatocellular carcinoma (HCC); 22 (79%) of them had associated liver cirrhosis. LCD was more frequently observed in posthepatitic cirrhosis (82%) than in the other forms. Carcinoembryonic antigen (CEA), alpha-1-antitrypsin (AAT) and alpha-fetoprotein (AFP), as demonstrated by the peroxidase-antiperoxidase method, were similarly expressed both in normal and in dysplastic cells. Hepatitis B surface antigen was found in eight cases (17%), six of which were associated with LCD. HBsAg was rarely found in dysplastic cells and frequently displayed a peculiar perinuclear pattern. The possible preneoplastic role of LCD is stressed.
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PMID:Liver cell dysplasia and hepatocellular carcinoma: a histological and immunohistochemical study. 298 89

Catalase (CAT), glutathione-peroxidase (GSH-Px) activity and reduced glutathione content (GSH) were measured in patients who had hepatocellular carcinoma, and values compared with those of normal liver and liver adjacent to neoplastic tissue. The results showed a remarkable reduction of CAT in tumor and corresponding tumor-free tissue (P less than 0.001 and P less than 0.02, respectively). All neoplastic samples had a significant lower activity of CAT than the corresponding adjacent tumor-free tissue (P less than 0.05). The GSH-Px activity of tumor tissue also was lower than normal (P less than 0.001) but similar to that of adjacent tissue. No correlation was noted between the two enzyme activities. Glutathione content was extremely low in tumor (P less than 0.001) and even in tumor-free tissue (P less than 0.05) when compared with normal liver. In all cases the content of GSH in neoplastic tissue was lower than that of the corresponding tumor-free tissue (P less than 0.05). Whereas in normal liver the activity of GSH-Px was positively correlated with the content of GSH, in the neoplastic tissue such a relationship disappeared. All these findings suggest that the antioxidant system of hepatocellular carcinoma cell is severely impaired.
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PMID:Severe impairment of antioxidant system in human hepatoma. 301 7

Expression of blood group ABH, Lewis, and sialylated-Lea antigens in human hepatocellular carcinomas and the adjacent nontumorous liver tissues was investigated with the use of seven monoclonal antibodies against these carbohydrate determinants. Chromatogram antibody-binding assay and solid-phase enzyme immunoassay of the upper-phase neutral glycolipids revealed the tumor-associated expression of blood group A-active glycolipids incompatible with blood-type status of the patients, a blood group A-active glycolipid with mobility on thin-layer chromatography between the known 6- and 8-sugar blood group A-active glycolipids in human erythrocytes, blood group H-active glycolipids, and blocked synthesis of Lea-active glycolipids with or without concomitant accumulation of Leb-active glycolipids. Immunohistochemical analysis of the fixed tissues with the use of an avidin-biotin-peroxidase complex method revealed blood group antigens in biliary epithelial cells but not in parenchymal liver cells. However, hepatocellular carcinoma cells in some cases expressed H and Leb antigens. Although only type 1 chain H antigen was detected in biliary epithelial cells, both type 1 and type 2 chain H antigens were found in hepatocellular carcinoma cells.
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PMID:Neoexpression of ABH and Lewis blood group antigens in human hepatocellular carcinomas. 302 3

We have isolated a heme protein from canine midbrains that possesses potent peroxidase activity. This enzyme catalyzes the oxidation of dopamine to neuromelanin in the presence of H2O2. We have further shown that the isolated peroxidase possesses potent cytotoxic activity in the presence of superoxide or H2O2 and Cl-. The enzyme possesses an endogenous NAD(P)H oxidase activity that can promote the cytotoxic activity by virtue of its production of superoxide. Other enzymes such as dihydroorotate dehydrogenase and galactose oxidase, which produce O2- and H2O2, respectively, are also effective in promoting the cytotoxic activity of the brainstem peroxidase. Although rat erythrocytes were routinely used as the target cell, other cell types, including rat hepatoma and mouse neuroblastoma cells, are also susceptible to the toxic action of the peroxidase. The cytotoxic action of the brainstem peroxidase is dramatically enhanced by kainic acid and is significantly enhanced by Mn2+, whereas dopamine was found to be a potent inhibitor of the cytotoxic activity. Based on these findings, we postulate a central role for the brainstem peroxidase in dopamine metabolism as well as in the biochemical and anatomical changes associated with Parkinson's disease.
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PMID:Neuromelanogenic and cytotoxic properties of canine brainstem peroxidase. 302 61

Expression of ABH, Lewis, and sialyl Lea antigens was studied in five combined hepatocellular-cholangiocarcinomas. Formalin-fixed liver tissues were immunostained for those antigens using well-characterized monoclonal antibodies and an avidin-biotin-peroxidase complex (ABC) method. Results were compared with those obtained in normal liver tissues and cholangiocarcinomas, and also with the previous observations of the authors on hepatocellular carcinomas. Although not detected in normal parenchymal liver cells, A, H, Lewis, and sialyl Lea antigens were found in combined hepatocellular-cholangiocarcinoma cells. Incompatible A antigen also was detected in one blood type O patient. Distribution and intensity of the antigens were similar to those in hepatocellular carcinomas and different from those in cholangiocarcinomas. No preferential accumulation of blood-group antigens could be found in the area of cholangiocarcinoma-like differentiation of the combined hepatocellular-cholangiocarcinoma. The observations suggested that Regional morphological differentiation of the hepatocellular-cholangiocarcinoma might not be always associated with the change in the expression of the blood group antigens. Moreover, the expression was essentially the same between the hepatocellular-cholangiocarcinoma and the typical hepatocellular carcinoma. The hepatocellular-cholangiocarcinoma, therefore could be a variant of the hepatocellular carcinoma.
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PMID:Expression of ABH and Lewis blood group antigens in combined hepatocellular-cholangiocarcinoma. Possible evidence for the hepatocellular origin of combined hepatocellular-cholangiocarcinoma. 303 28

The cation-independent mannose-6-phosphate (Man-6-P) receptor is involved in the targeting of newly synthesized lysosomal hydrolases. To investigate the intracellular distribution of this receptor, a conjugate of lactoperoxidase coupled to asialoorosomucoid was used to catalyze its iodination within the endosomes of human hepatoma (HepG2) cells. The 215-kD, cation-independent Man-6-P receptor was iodinated by this procedure as shown by pentamannosyl-6-phosphate-Sepharose affinity chromatography and by immunoprecipitation of labeled cell extracts. The amount of this receptor detected in endosomes was found to be unchanged after inhibition of protein synthesis with cycloheximide. If the Man-6-P receptor accumulates in the Golgi apparatus in the absence of lysosomal hydrolase synthesis, it should have been correspondingly depleted from endosomes after a period of cycloheximide treatment, because these pools of receptor are in rapid equilibrium. Therefore, these data suggest that newly synthesized ligands are not required for the transport of the cation-independent Man-6-P receptor from the Golgi apparatus to endosomes.
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PMID:The endosomal concentration of a mannose 6-phosphate receptor is unchanged in the absence of ligand synthesis. 303 25

We describe the simple and rapid enzyme immunoassay of protein C in human plasma with use of a Cobas Fara centrifugal analyzer. The antibody, labeled with horseradish peroxidase, is reacted with antigen (protein C) for 15 min. The peroxidase activity of the resulting antigen-antibody conjugate is measured at 500 nm for 5 min in the presence of excess H2O2, phenol, and 4-aminoantipyrine, as compared with that of free conjugates. Results are calculated from a stored standard curve and expressed as a percentage of the value determined for a pooled specimen of normal adult plasma. The standard curve is linear from 0% to 200%. The CV is generally less than 4% for different concentrations of protein C. In liver cirrhosis, hepatocellular carcinoma, therapy with warfarin, thrombosis, and disseminated intravascular coagulation, protein C concentrations are about 40-70% of normal. Results obtained with the present homogeneous enzyme immunoassay correlated well with those by enzyme-labeled immunosorbent assay (r = 0.97).
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PMID:Protein C in human plasma determined by homogeneous enzyme immunoassay with use of a centrifugal analyzer. 304 78

Immunolocalization of type III collagen and procollagen in cirrhotic human liver was studied using monoclonal antibody specific for the helical determinant of type III collagen extracted from human placenta. Deparaffinized, trypsin-treated cirrhotic liver sections from 8 autopsy cases were examined by the unlabeled peroxidase-antiperoxidase and immunofluorescence techniques. These techniques revealed the localization of this epitope shared by type III collagen and procollagen not only in the extracellular matrix of hepatocytes and sinusoidal cells but also in the cytoplasm. In hepatocellular carcinoma concurrent with cirrhosis, neoplastic cells were shown to react with this antibody as well. These results are consistent with data obtained using antiserum specific for bovine type III procollagen aminopeptide which appeared in our previous report.
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PMID:Immunolocalization of type III collagen and procollagen in cirrhotic human liver using monoclonal antibodies. 308 39

We used a conjugate of transferrin and horseradish peroxidase (Tf/HRP) to label the intracellular transferrin receptor route in the human hepatoma cell line HepG2. The recycling kinetics of [125I]Tf/HRP were similar to those of unmodified [125I]Tf, implying identical routes for both ligands. 3,3'Diaminobenzidine (DAB)-cytochemistry was performed on post-nuclear supernatants of homogenates of cells which were incubated with both Tf/HRP and [125I]Tf, and caused two different effects: (a) the equilibrium density of [125I]Tf containing microsomes in a Percoll density gradient was increased, and (b) the amount of immunoprecipitable [125I]Tf from density-shifted lysed microsomes was only 20% of that of nonDAB treated microsomes. The whole biosynthetic route of alpha 1-antitrypsin (AT), a typical secretory glycoprotein in HepG2 cells, was labeled during a 60-min incubation with [35S]methionine. DAB cytochemistry was performed on post-nuclear supernatants of homogenates of cells which were also incubated with Tf/HRP. DAB cytochemistry caused approximately 40% of microsome-associated "complex" glycosylated [35S]alpha 1-antitrypsin ([35S]c-AT) to shift in a Percoll density gradient. Only part of the density shifted [35S]c-AT could be recovered by immunoprecipitation. A maximum effect was measured already after 10 min of Tf/HRP uptake. The density distribution of the "high mannose" glycosylated form of 35S-alpha 1-anti-trypsin [( 35S]hm-AT) was not affected by Tf/HRP. If in addition to Tf/HRP also an excess of non-conjugated transferrin was present in the medium, [35S]c-AT was not accessible for Tf/HRP, showing the involvement of the transferrin receptor (TfR) in the process. Furthermore, we show that if Tf/HRP and [35S]c-AT were located in different vesicles, the density distribution of [35S]c-AT was not affected by DAB-cytochemistry. Pulse-labeling with [35S]methionine was used to show that [35S]c-AT became accessible to endocytosed Tf/HRP minutes after acquirement of the complex configuration. A common intracellular localization of endocytosed Tf/HRP and secretory protein could be confirmed by immuno-electron microscopy: cryosections labeled with anti-albumin (protein A-colloidal gold) as well as DAB reaction product showed double-labeling in the trans-Golgi reticulum.
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PMID:The pathways of endocytosed transferrin and secretory protein are connected in the trans-Golgi reticulum. 326 Feb 38


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