Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 influence of varying the amount of wheat germ agglutinin immobilized on Sepharose beads on the binding of glycoproteins to these beads was investigated. A series of wheat germ agglutinin-Sepharose gels containing between 0.10 and 10.0 mg of lectin/ml of gel was prepared, and the actual lectin content was established by acid hydrolysis of the gel followed by analysis of glycine, a major amino acid in wheat germ agglutinin. Affinity chromatography of labeled glycoproteins indicated that glycophorin bound to all the wheat germ agglutinin-Sepharose preparations. Fetuin, ovomucoid, and alpha 1-acid glycoprotein bound not at all or very poorly to gels with a low content of wheat germ agglutinin (less than 0.95 mg/ml). The specific binding of these glycoproteins increased with increasing lectin content on the gels, and on gels of high content (greater than 3 mg/ml) the binding was virtually quantitative. On chromatographing a mixture of glycophorin, alpha 1-acid glycoprotein, fetuin, and ovomucoid on wheat germ agglutinin-Sepharose, containing 0.08 mg of lectin/ml of gel, glycophorin was selectively retained on the gel. It was possible to purify glycophorin from an extract of human erythrocyte membranes in one step by chromatography on the above gel. By using the series of gels, it was demonstrated that Morris hepatoma 7777 membranes contained at least 4-fold more sialoglycoproteins which bound to low density wheat germ agglutinin-Sepharose compared to rat liver membranes. These hepatoma sialoglycoproteins were isolated, purified, and partially characterized as having a high proportion of O-linked sialyloligosaccharides. Our studies illustrate the use of low density wheat germ agglutinin-Sepharose gels both for the detection and for easy isolation of mucin-type glycoproteins from crude extracts of cells or membranes.
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PMID:Interaction of sialoglycoproteins with wheat germ agglutinin-sepharose of varying ratio of lectin to Sepharose. Use for the purification of mucin glycoproteins from membrane extracts. 371 Nov 7

Quantitative studies on the binding of concanavalin A (Con A) and wheat-germ agglutinin (WGA) to a series of rat hepatocarcinoma metastatic variants revealed a positive correlation between the amount of cell-surface-bound lectin and lung colonization potential. Scatchard analysis of Con A and WGA binding to 10 individual clones isolated from a subcutaneous (s.c.) tumor transplant and to tumor-cell isolates from 10 individual spontaneous lung metastases from the same animal showed diverse binding characteristics for these cell populations. Nevertheless, the expression of Con A receptor sites accurately predicted the lung colonization potential of 3 isolates from the lung metastases. Higher lectin binding curves were observed for the clones from the subcutaneous tumor than for the isolates from lung metastases. These data suggest that a high Con-A binding potential is indicative of a high lung colonization potential for these hepatocarcinoma cells, but that this phenotype may be rapidly lost during tumor outgrowth in the lungs. The binding of tumor cells to vascular endothelial cell monolayers was inhibited in the presence of Con A; however, no inhibition was observed with 2 other lectins. Attachment of tumor cells to endothelial cell monolayers was also inhibited by the monosaccharides methyl alpha-D-mannopyranoside and N-acetyl-D-galactosamine. Other monosaccharides tested did not alter the attachment of tumor cells to endothelial cell monolayers.
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PMID:The role of tumor-cell surface carbohydrate in experimental metastasis. 375 58

The bacterially fermented mistletoe preparation Iscador, used in cancer therapy for 30 years, and the recently prepared unfermented preparation, have been tested on rat hepatoma tissue culture (HTC) cells and human leukemia Molt 4 cells. As observed by phase-contrast microscopy, treatment of HTC cells with fermented or unfermented Iscador, at a concentration corresponding to 1 mg of fresh plant per milliliter culture, led to rapid lysis of cellular membranes. At a lower concentration, 0.1 mg/ml, unfermented Iscador led to the formation of polynucleated cells. On Molt 4 cells, fermented Iscador also produced cytolysis but after a longer time of action. Unfermented Iscador showed a much stronger cytotoxic effect on these cells than on HTC cells. Fermented Iscador was slightly more potent than unfermented Iscador in inhibiting the growth of HTC cells, but on Molt 4 cells fermented Iscador was less active than unfermented Iscador. DNA synthesis, measured by [3H]thymidine incorporation in HTC and Molt 4 cells, was inhibited by fermented and unfermented Iscador with the same type of differences of action as on cell growth. Fermented Iscador contained a low amount of lectins, approximately 100 ng/ml, while unfermented Iscador contained about 10 times more. A purified mistletoe lectin produced effects on HTC and Molt 4 cells similar to those of unfermented preparations. HTC cells were 100 times less sensitive to this lectin than Molt 4 cells. These results are discussed in relation to the known biological effects of lectins.
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PMID:Comparison of the effects of fermented and unfermented mistletoe preparations on cultured tumor cells. 380 75

A soluble lectin, the core-specific lectin (CSL), is synthesized and secreted by rat hepatocytes and the rat hepatoma cell line, H-4-II-E. This lectin binds mannose and N-acetylglucosamine residues in the "core" region of Asn-linked oligosaccharides. Secretion of the CSL was found to occur over an extended period of time, greater than 4 h being required for secretion of 50% of the lectin (Brownell, M. D., Colley, K. J., and Baenziger, J. U. (1984) J. Biol. Chem. 259, 3925-3932). We have determined that following synthesis in the endoplasmic reticulum, the CSL is rapidly transported to the Golgi where it is retained for an extended period of time prior to secretion. The lectin undergoes two post-translational modifications within the Golgi: an increase from Mr 24,000 to 25,000 and a progressive decrease in pI with an accompanying increase in Mr to a final value of 26,000. The lectin is also assembled into high molecular weight complexes of 150-260 X 10(3) and acquires the ability to bind carbohydrate in the Golgi. In hepatoma cells, the 24,000-25,000 modification is completed 20 min after initiation of synthesis. Assembly of the CSL subunits into high molecular weight complexes, acquisition of carbohydrate binding activity, and the 25,000-26,000 modification occur between 20 and 80 min after initiation of synthesis. These events have slower kinetics in primary hepatocytes and this allowed us to determine that the sequence of these biosynthetic events is: the 24,000-25,000 modification, complex assembly, the 25,000-26,000 modification, and acquisition of carbohydrate binding activity. The 24,000-25,000 modification occurs prior to complex assembly. Complex assembly may occur prior to, or concomitant with, the 25,000-26,000 modification. Assembly into the oligomeric form and the 25,000-26,000 modification correlate with the attainment of carbohydrate binding activity. The kinetics of CSL modification and assembly cannot account for its retention within the Golgi. Interaction with Golgi components either through carbohydrate binding or another interaction, may act to selectively retain the lectin within the Golgi.
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PMID:Biosynthesis and secretion of the rat core-specific lectin. Relationship of post-translational modification and assembly to attainment of carbohydrate binding activity. 381 49

In order to elucidate the correlation between cell surface lectin binding sites and the degree of cell adhesiveness, quantitative lectin binding assays were performed using three types of rat ascites hepatoma cell lines (free cell, mixed cell, and island-forming cell types). The lectin binding site patterns showed no remarkable differences among the intact tumor cell lines, but treatment of the cells with L-1-tosylamide-2-phenylethyl chloromethyl ketone (TPCK)-trypsin or neuraminidase induced remarkable differences in the modulation of the number of lectin binding sites. TPCK-trypsin treatment caused a marked decrease in the number of peanut agglutinin binding sites on the island-forming and mixed cell types, concomitant with disaggregation of the cells, showing that trypsin sensitive binding sites are involved in the cell-cell adhesion. Neuraminidase treatment caused a decrease in wheat germ agglutinin binding sites and an increase in castor bean agglutinin binding sites, and these effects were greater for the free cell type. These results indicated that alpha-sialyl-beta-D-galactosyl residues are more abundant on the cell surface of the free cell type than the other cell types. Therefore, it was suggested that electrostatic repulsion due to negative charges of the cell surface sialic acid contributes to the low cell adhesiveness of the free cell type.
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PMID:Lectin binding sites related with rat ascites hepatoma cell adhesion. 382 89

One of insulin's effects is to stimulate specific mRNA synthesis. Treatment of H4IIE hepatoma cells with 0.01-1.0 nM insulin results in a maximum 10-15 fold increase in the accumulation of a specific mRNA (p33-mRNA) as measured with a cloned cDNA. Concanavalin A, a lectin known to mimic many of insulin's effects, also stimulates the accumulation of p33-mRNA. The effects of both insulin and Con A were blocked by the addition of two RNA synthesis inhibitors, actinomycin D or 5,6 dichloro-1-beta-D-ribofuranosyl-benzimidazole. We therefore suggest that insulin and concanavalin A act to stimulate p33-mRNA synthesis.
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PMID:The effects of insulin and concanavalin A on the accumulation of a specific mRNA in rat hepatoma cells. 391 44

We have studied the processing of rat and human angiotensinogen precursors by microsomal membranes as a means of determining the number of asparagine-linked oligosaccharide units per angiotensinogen molecule, and thus the utilization of potential sites of N-glycosylation. Glycosylated, processed forms of angiotensinogen were isolated by chromatography on lentil lectin-Sepharose 4B. 35S-Methionine-labeled precursor and processed forms of angiotensinogen were compared with glycosylated and nonglycosylated 35S-methionine-labeled mature forms of angiotensinogen secreted by hepatoma cells, using immunoprecipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. N-Glycosylation of secreted angiotensinogen was inhibited using tunicamycin. For rat angiotensinogen, only 2 of 3 potential sites of N-glycosylation were utilized; in contrast, all 4 potential sites of N-glycosylation of human angiotensinogen were utilized. For neither rat or human angiotensinogen precursor was there any evidence for a prosequence.
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PMID:Processing of rat and human angiotensinogen precursors by microsomal membranes. 393 16

The phosphorylation characteristics of insulin receptor from control and insulin-treated rat H-35 hepatoma cells 32P-labeled to equilibrium have been documented. The 32P-labeled insulin receptor is isolated by immunoprecipitation with patient-derived insulin receptor antibodies in the presence of phosphatase and protease inhibitors to preserve the native phosphorylation and structural characteristics of the receptor. The unstimulated insulin receptor contains predominantly [32P] phosphoserine and trace amounts of [32P]phosphothreonine in its beta subunit. In response to insulin, the insulin receptor beta subunit exhibits marked tyrosine phosphorylation and a 2-fold increase in total [32P]phosphoserine contents. High pressure liquid chromatography of the tryptic hydrolysates of the 32P-labeled receptor beta subunit from quiescent cells results in the resolution of up to 9 fractions containing [32P]phosphoserine. The insulin-stimulated tyrosine phosphorylation is concentrated in two of these receptor phosphopeptide fractions, whereas the increase in [32P]phosphoserine content is scattered in low abundance over all receptor tryptic fractions. Insulin receptors affinity-purified by lectin- and insulin-agarose chromatographies from insulin-treated, 32P-labeled cells exhibit a 22-fold increase in the Vmax of receptor tyrosine kinase activity toward histone when compared to controls. The elevated kinase activity of the insulin receptor derived from insulin-treated cells is not due to the presence of hormone bound to the receptor because the receptor kinase activity is assayed while immobilized on insulin-agarose. Furthermore, the insulin-activated receptor kinase activity is reversed following dephosphorylation of the receptor beta subunit with alkaline phosphatase in vitro. The correlation between the insulin-stimulated site specific tyrosine phosphorylation on receptor beta subunit and the elevation of receptor tyrosine kinase activity strongly suggests that the insulin receptor kinase is activated by hormone-stimulated autophosphorylation on tyrosine residues in intact cells, as previously demonstrated for the purified receptor.
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PMID:Tyrosine phosphorylation of insulin receptor beta subunit activates the receptor tyrosine kinase in intact H-35 hepatoma cells. 395 14

A lectin that agglutinates human blood group B erythrocytes but not blood group A and O erythrocytes was isolated from eggs of Ayu sweet fish (Plecoglossus altivelis). The lectin also agglutinates Ehrlich ascites carcinoma cells but not rat ascites hepatoma AH109 or rat sarcoma 150 cells tested. The lectin agglutination was most effectively inhibited by monosaccharides with the first type of configuration, i.e., L-rhamnose, L-mannose and L-lyxose at a concentration of 0.03 mM. The lectin agglutination was moderately inhibited by monosaccharides with the second type of configuration, i.e., D-galactose, D-fucose and D-galacturonic acid at a concentration of 0.4 mM. However, the agglutination was not inhibited by various other monosaccharides and oligosaccharides that have other types of configuration. The basis for an apparent B-specific hemagglutination may be due to the steric similarity of the C2 and C4 of the galactosyl series, the B-specific determinant, and the L-rhamnosyl-Sepharose column and was characterized as a homogeneous low molecular weight protein (Mr 14000) with an abundance of hydrophobic amino acids and dicarboxylic amino acid.
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PMID:Blood group B-specific lectin of Plecoglossus altivelis (Ayu fish) eggs. 404 Mar 98

Numerous studies have reported the capacity of the lectin, concanavalin A, to agglutinate selected cell-types. The finding that cells transformed in culture, embryonic cells, and malignant cells are all agglutinated by this substance, may contribute to our understanding of the oncogenic process. The present study compared the response to concanavalin A of rat hepatocytes derived from livers of differing developmental and mitotic-status as well as those derived from malignant liver tumors (hepatomas). Fetal hepatocytes and hepatoma cells were highly susceptible to agglutination while hepatocytes from post-natal livers, whether dividing or quiescent, were not. Treatment with protease(s) did not make the interphase hepatocyte agglutinable. These data emphasize the importance of examining a wide variety of cells in attempting to understand the interaction of lectins on cell surfaces, and further, demonstrate the value of obtaining cells directly from tissue(s) during differing physiologic and pathologic states.
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PMID:Differential lectin agglutination of fetal, dividing-postnatal, and malignant hepatocytes. 437 8


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