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)

Human alpha-fetoprotein has been isolated from the serum and ascitic fluid of a patient with hepatoma by a combination of immunoadsorbent column chromatography and Sephadex G-150 gel filtration. Human alpha-fetoprotein is a sialylated glycoprotein with an estimated molecular weight of 67 500, composed of a single-chain polypeptide of approximately 580 amino acid residues and 3.6% carbohydrate. It is a negatively charged protein with an acid isoelectric point (pH 4.57). In addition to the monomeric form of alpha-fetoprotein, we have identified human alpha-fetoprotein polymers, including dimeric and trimeric forms, which dissociate to the monomer only upon exposure to disulfide-reducing reagents, implying that their formation is dependent upon intermolecular disulfide bonds. These polymers are found in human alpha-fetoprotein isolated by isoelectric focusing in both the major (pI 4.57) and minor (pI 5.2) alpha-fetoprotein fractions. The first 17 residues of the NH2-terminal amino acid sequence of the hepatoma-derived human alpha-fetoprotein have been identified. Fetal alpha-fetoprotein is indistinguishable from hepatoma alpha-fetoprotein by several criteria, including immunoelectrophoresis, acryalmide gel electrophoresis, and proclivity for dimerization.
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PMID:Studies on human alpha-fetoprotein. Isolation and characterization of monomeric and polymeric forms and amino-terminal sequence analysis. 7 Feb 28

Human alpha-fetoproteins were purified from umbilical cord serum and from ascites fluid of a patient with hepatoma by affinity chromatography, and their chemical compositions and terminal sequences were compared. The amino acid compositions of these alpha-fetoproteins were similar and in good agreement with the values reported by other investigators. The COOH-terminal 5-amino acid sequence determined by carboxypeptidase digestion and the NH2-terminal 20-amino acid sequence determined by an automated sequence analyzer revealed that both alpha-fetoproteins had the same terminal sequences of amino acids. The sequence analysis showed that a part of each of the proteins lacked its NH2-terminal residues for one or three amino acids. A small difference in the carbohydrate composition of each alpha-fetoprotein was observed. It was concluded that alpha-fetoproteins from fetal serum and from ascites fluid of a patient with hepatoma had very similar structures.
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PMID:Comparative chemical structures of human alpha-fetoproteins from fetal serum and from ascites fluid of a patient with hepatoma. 7 Nov 98

A method for the purification of human alpha1-fetoprotein from the ascites fluid of a hepatoma-bearing patient is described that is capable of yielding large quantities of pure alpha1-fetoprotein within a relatively short period of time. The technique is based entirely on the physicochemical properties of the alpha1-fetoprotein molecule and uses sequential purification steps: ion-exchange chromatography on DEAE-Sephadex A-50, molecular-sieve chromatography on Sephadex G-200, negative-affinity chromatography on Sepharose-Blue Dextran, positivepaffinity chromatography on concanavalin A-Sepharose and, finally, molecular-sieve chromatography on Sephadex G-100. The efficiency of the entire procedure in its present form is 15% of the alpha1-fetoprotein activity of the starting preparation from ascites fluid. The purity of the final product was shown by polyacrylamide gel electrophoresis, radioimmunoelectrophoresis, and determinations of the NH2-terminal and COOH-terminal amino acid residues of the alphs1-fetoprotein isolated. Amino acid analysis of the final product revealed a composition very similar to those reported for alpha-fetoprotein preparations that have been previously isolated by the use of immunochemical technology.
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PMID:Physicochemical approach to the purification of human alpha1-fetoprotein from the ascites fluid of a hepatoma-bearing patient. 7 14

DNA was isolated from livers of the rats treated with DAB during various steps of hepatoma development. After histological examination the tumor tissue was separated from the normal liver tissue and used as the source of DNA. Chromatographic fractionation on DEAE and Ecteola celluloses shows characteristic patterns for DNA isolated at various steps of hepatoma development. The largest differences in hepatoma DNA as compared to normal liver DNA were demonstrated in the DNA fraction eluated with 2.0 M-NaCl and NH3, gradient 0.1--1.0 M (m. w. 2--9 x 10(6)), and an increase in the first DNA fraction (m. w. less than 1 x 10(6)) was observed. Differences in the chromatographic patterns are discussed in terms of direct DAB action on DNA.
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PMID:Chromatographic pattern of DNA isolated from liver tissue during hepatoma development. 11 86

Macromomycin (MCR), a polypeptide antibiotic previously shown to have antitumor activity in experimental tumors, has been purified into an electrophoretically homogeneous component with an approximate molecular weight of 12,500. MCR has alanine as an NH2-terminal amino acid, 4 cysteine residues, and no arginine or methionine residues. With a fluorescence assay and agarose gel electrophoresis, MCR was shown to induce strand breaks in PM2 DNA in vitro. 2-Mercaptoethanol inhibited the DNA cleavage activity of MCR. When incubated with Novikoff hepatoma ascites cells in tissue culture, MCR caused Novikoff hepatoma ascites cell DNA degradation as observed by the slower sedimentation of DNA on alkaline sucrose density gradient centrifugation when compared to untreated cell DNA. DNA synthesis in Novikoff hepatoma ascites cells was inhibited by 80% after a two-hr treatment with MCR (0.03 microgram/ml). RNA and protein syntheses were inhibited by 25 and less than 10%, respectively, at this concentration of drug. At a concentration of MCR (1.0 microgram/ml), syntheses of DNA and RNA in Novikoff hepatoma ascites cells were totally inhibited. The results of this study suggest that MCR may inhibit tumor cell growth by causing DNA breakage with subsequent inhibition of DNA and other macromolecule syntheses.
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PMID:Purification and mechanism of action of macromomycin. 42 Dec 1

A Glycoprotein, particularly high in tumors, has been extracted from Morris 5123C rat hepatomas and purified. The compound constitutes a major binding component for 67Ga in this hepatoma. It has a molecular weight of approximately 45,000. Its molecular weight was determined by sodium dodecyl sulfate:polyacrylamide gel electrophoresis and by Sephadex G-200 superfine gel filtration. The steps involved in its extraction and purification include ultrafiltration, gel filtration through Sephadex G-200 superfine, ion-exchange chromatography on diethylaminoethyl Sephadex A-50, and hydroxylapatite chromatography. The homogeneity of the compound was established by gel electrophoresis. The NH2-terminal residue, the percentage of nitrogen, the nonamino carbohydrate content, and the amino acid composition are reported.
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PMID:Isolation and partial characterization of a 67Ga-binding glycoprotein from Morris 5123C rat hepatoma. 71 29

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

Amino acid sequence information was obtained for the NH2 terminus, and for endogenous peptides generated by trypsin digestion, of a purified, truncated form of rat hepatic squalene synthase (RSS, EC 2.5.1.21) (Shechter, I., Klinger, E., Rucker, M. L., Engstrom, R. G., Spirito, J. A., Islam, M. A., Boettcher, B. R., and Weinstein, D. B. (1992) J. Biol. Chem. 267, 8628-8635). Degenerate primers, based on the amino acid sequences, were synthesized and used for the amplification and sequencing of a 1708-base pair (bp) cDNA for RSS from the rat hepatoma cell line H35. An open reading frame of 1248 bp encoding 416 amino acids (M(r) = 48,103) was detected for RSS. We have constructed a pRSS1327 expression vector by molecular cloning of a 1327-bp cDNA, which includes sequences of the entire coding region for RSS, into pBluescript. Expression in Escherichia coli of a functional, full-length RSS was confirmed by immunoblot analysis and enzymatic activity. We present and evaluate a model for the secondary structure of RSS and its possible membrane orientation. The model predicts a 315-residue domain at the center of the protein that contains the catalytic site and is released in a soluble form by partial proteolysis. The 33-residue NH2-terminal and 98-residue COOH-terminal sections are not involved in catalysis. Sequence analysis of the catalytic domain of RSS indicate three regions with high homology to sequences in a number of functionally distinct proteins that utilize polyprenyl diphosphate substrates.
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PMID:Molecular cloning, expression, and characterization of the cDNA for the rat hepatic squalene synthase. 140 Apr 48

Human hepatoma HEPG2 cells were infected with recombinant vaccinia virus vectors containing cDNAs encoding both known and variant rat cytochromes P450 (CYP). CYP2B1 and CYP2B2 cytochromes were equally well expressed (110-140 pmol/mg of microsomal protein) and catalyzed metabolism of 7,12-dimethylbenz[a]anthracene (DMBA). Their regioselectivity for DMBA metabolism paralleled that of the respective purified rat liver enzymes and reproduced previously reported regioselective differences between CYP2B1 and CYP2B2 [Wilson et al. (1984) Carcinogenesis 5, 1475-1483]. CYP2A1 and CYP2A2 expressed in HEPG2 microsomes exhibited nearly equal DMBA-metabolizing activities that closely matched that of purified CYP2A1. Although purified rat liver CYP2B1 was 3 times more active than purified rat liver CYP2B2, the expressed recombinant microsomal CYP2B1 (rCYP2B1) was 20 times less active than rCYP2B2, where activity matched that of the purified cytochrome. Microsomal suppression of rCYP2B1 catalytic activity was also observed for benzo[a]pyrene. Specific amino acid substitutions at equivalent positions of the completely homologous NH2-terminal halves of rCYP2B1 and rCYP2B2 changed this suppression effect. Thus, a L58----F, I114----F double mutant exhibited 3 times the normal activity for rCYP2B1 while remaining inhibitory for rCYP2B2. The single substitutions produced very different effects. The L58----F substitution prevented expression of rCYP2B1, while the I114----F substitution was inhibitory for both rCYP2B1 and rCYP2B2 (40 and 70%). A single E282----V mutation produced a stimulation of rCYP2B1 activity comparable to that of the L58----F, I114----F double substitution.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Selective suppression of the catalytic activity of cDNA-expressed cytochrome P4502B1 toward polycyclic hydrocarbons in the microsomal membrane: modification of this effect by specific amino acid substitutions. 154 25

A protein kinase capable of phosphorylating basic fibroblast growth factor (FGF) can be localized on the outer cell surface of human hepatoma cells (SK-Hep cells). The addition of [gamma-32P]ATP, but not H3(32)PO4, results in a rapid (less than 10 min) incorporation of 32P into exogenously added basic FGF. The reaction is time and concentration dependent (apparent Km, 170 nM) and is stimulated by the addition of cAMP (EC50, 0.5 microM), but not the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate. There is also no tyrosine protein kinase detected on the cell surface. The inhibition of basic FGF binding to its low and/or high affinity sites decreases the phosphorylation of basic FGF by the ecto-protein kinase. Accordingly, pretreatment of cells with heparinase for 30 min or coincubation with heparin (0.1-10 micrograms/ml) decreases phosphorylation in a dose-dependent manner. Furthermore, the addition of a nonphosphorylatable peptide analog of basic FGF ([Val112] basic FGF-(106-146)NH2) that can compete with basic FGF binding to cells prevents the phosphorylation of basic FGF. Together, these observations suggest that 1) exogenous basic FGF must associate with its low and/or high affinity binding sites to be phosphorylated, and 2) the kinase is cAMP dependent and associated with the outer cell surface, and support the hypothesis that phosphorylation may regulate the activity and/or bioavailability of the growth factor.
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PMID:Phosphorylation of basic fibroblast growth factor by a protein kinase associated with the outer surface of a target cell. 165 31


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