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 nuclear Ah receptor from mouse hepatoma (Hepa-1c1c9) cells is a 176-kDa multimeric protein which is stable under conditions of up to 1 M KCl. Under denaturing conditions, the Hepa-1 nuclear receptor can be dissociated into a ligand-binding subunit of Mr approximately 91,000. The identity of subunits that compose the nuclear Ah receptor is currently unknown. We used partial proteolysis under nondenaturing conditions as an approach to study the domain organization of the nuclear form of Ah receptor from Hepa-1c1c9 cells treated with [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in culture. Low concentrations of trypsin (0.5 microgram/mg nuclear protein) generated heterogeneous fragments with the main fragment having a Stokes radius (Rs) approximately 6 nm. More discrete ligand-binding fragments of Mr approximately 84,000 (Rs approximately 4 nm/approximately 5 S) and Mr approximately 16,000 (Rs approximately 2 nm/approximately 2 S) could be generated using higher concentrations of trypsin (5 micrograms/mg nuclear protein). The relative concentration of the 84 and 16-kDa fragment was dependent on duration of protease treatment; formation of the 16-kDa fragment was accompanied by some loss in [3H]TCDD binding. Treatment of nuclear Ah receptor with alpha-chymotrypsin (1 microgram/mg nuclear protein) generated a single, apparently homogeneous ligand-binding fragment of Mr approximately 101,000 (Rs approximately 5 nm/approximately 5 S). When analyzed by DNA-cellulose chromatography, the chymotryptic fragment eluted at a significantly higher KCl concentration (462 mM) compared to native untreated nuclear Ah receptor (385 mM). Despite this increased affinity for DNA-cellulose columns, the ligand-binding fragment generated by chymotrypsin treatment was unable to interact with a dioxin responsive element in a gel retardation assay. DNA-cellulose binding ability, therefore, does not appear to be a reliable indicator of specific DNA interactions for these protease-modified fragments.
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PMID:Nuclear Ah receptor from mouse hepatoma cells: effect of partial proteolysis on relative molecular mass and DNA-binding properties. 217 30

Alpha 1-Antitrypsin (alpha 1-AT) is similar to other members of the serine protease inhibitor (serpin) supergene family in that it undergoes structural rearrangement during the formation of a covalently stabilized inhibitory complex with its cognate enzyme, neutrophil elastase. We have recently demonstrated an abundant, high-affinity cell surface receptor on human hepatoma cells and human mononuclear phagocytes which recognizes a conformation-specific domain of the alpha 1-AT-elastase complex as well as of other serpin-enzyme complexes (Perlmutter, D. H., Glover, G. I., Rivetna, M., Schasteen, C. S., and Fallon, R. J. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 3753-3757). Binding to this serpin-enzyme complex (SEC) receptor activates a signal transduction pathway for increased expression of the alpha 1-AT gene and may be responsible for clearance of serpin-enzyme complexes. In this study, we show that there is time-dependent and saturable internalization of alpha 1-AT-elastase and alpha 1-AT-trypsin complexes in human hepatoma HepG2 cells. Internalization is mediated by the SEC receptor as defined by inhibition by synthetic peptides corresponding to residues 359-374 of alpha 1-AT. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of intracellular radioactivity demonstrated that intact 75- and 66-kDa alpha 1-AT-trypsin complexes were internalized. Kinetic analysis of internalization at 37 degrees C showed that a single cohort of 125I-alpha 1-AT-trypsin complexes, prebound to cells at 4 degrees C, disappeared from the cell surface and accumulated intracellularly within 5-15 min at 37 degrees C. The intracellular concentration of radiolabeled complexes then decreased rapidly coincident with appearance of acid-soluble degradation products in the extracellular culture fluid. Intracellular degradation was inhibited by internalization at 18 degrees C or by internalization at 37 degrees C in the presence of weak bases ammonium chloride, primaquine, and chloroquine, indicating that degradation is lysosomal. These results indicate that in addition to its role in signal transduction the SEC receptor participates in internalization and delivery of alpha 1-AT-protease complexes to lysosome for degradation.
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PMID:Endocytosis and degradation of alpha 1-antitrypsin-protease complexes is mediated by the serpin-enzyme complex (SEC) receptor. 221 87

The inner mitochondrial membranes from bovine heart, rat liver, and Morris hepatoma 7777 all bound the mitochondrial isozymes of aspartate aminotransferase and malate dehydrogenase with comparable affinities and binding ratios (mg of enzyme bound per mg of membrane protein). A low molecular weight fraction separated from a detergent extract of the heart membrane by chromatography on Sephacryl S-300 contained most of the binding activity of the extract for the aminotransferase and had a dissociation constant for the aminotransferase of 0.2 microM. The protein component of the membrane binding sites for the aminotransferase was apparently present in this fraction because binding activity was largely eliminated by proteolysis with trypsin. When this fraction was chromatographed on an aminotransferase affinity column, only the portion that was bound and eluted by 0.25 M KCl associated with added aminotransferase. Unlike the membrane, which was markedly inhibited by the non-ionic detergent Genapol but was inhibited only 20% by trypsin, the binding activity of this subfraction was completely inhibited by trypsin but not by Genapol. This suggests, on the membrane, that the aminotransferase binds to the binding protein and is then transferred to lipids specifically associated with the binding protein. These putative lipids are presumably removed on the affinity column. Although the yield of the binding protein was low, there is probably ample binding protein in mitochondria to accommodate the aminotransferase. In every case, binding of the aminotransferase to the membrane inactivated the malate dehydrogenase binding site whereas malate dehydrogenase had little effect on the binding of the aminotransferase and only associated with the higher molecular weight fractions from the Sephacryl column that contained Complex I activity. Inactivation of the malate dehydrogenase site by the aminotransferase, but not vice versa, could result from aminotransferase associating with the binding protein and malate dehydrogenase with Complex I followed by association of the enzymes with lipids located in the same region of the membrane. However, since aminotransferase is more cationic, it is not displaced readily from the lipids by malate dehydrogenase. The relevance of these interactions to the organization of the enzymes is discussed.
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PMID:Interactions among mitochondrial aspartate aminotransferase, malate dehydrogenase, and the inner mitochondrial membrane from heart, hepatoma, and liver. 224 39

When human HepG2 hepatoma cells were pulsed with 125I-labeled high density lipoproteins (HDL) and chased in fresh medium, up to 65% of the radioactivity released was precipitable with trichloroacetic acid. Cell-internalized 125I-HDL contributed to the release of acid-precipitable material; when cells were treated with trypsin before the chase to remove 125I-HDL bound to the outer cell membrane, 50% of the released material was still acid-precipitable. Characterization of the radioactive material resecreted by trypsinized cells revealed the presence of particles that were similar in size and density to mature HDL and contained intact apolipoproteins (apo) A-I and A-II. The release of internalized label occurred at 37 degrees C but not at 4 degrees C. Monensin, which inhibits endosomal recycling of receptors, decreased the binding of 125I-HDL to cells by 75%, inhibited the release of internalized radioactivity as acid-precipitable material by 80%, and increased the release of acid-soluble material by 90%. In contrast, the lysosomal inhibitor chloroquine increased the association of 125I-HDL to cells by 25%, inhibited the release of precipitable material by 10%, and inhibited the release of acid-soluble radioactivity by 80%. Pre-incubation with cholesterol caused a 50% increase in the specific binding, internalization, and resecretion of HDL label. Cholesterol affected the release of acid-precipitable label much more (+90%) than that of acid-soluble material (+20%). Taken together, these findings suggest that HepG2 cells can bind, internalize, and resecrete HDL by a retroendocytotic process. Furthermore, the results with cholesterol and monensin indicate that a regulated, recycling, receptor-like molecule is involved in the binding and intracellular routing of HDL.
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PMID:Retroendocytosis of high density lipoproteins by the human hepatoma cell line, HepG2. 236 67

A human hepatocellular carcinoma (HCC) cell line (KYN-1) has been established from a resected HCC of a 58-yr-old Japanese, male patient with HCC. Original resected HCC was moderately differentiated and proliferated in a solid pattern with vague trabecular structure in part. This cell line has been maintained for 10 mo. through 50 passages. Morphological features of KYN-1 cells demonstrated one or more large, round-to-oval nuclei with prominent nucleoli and eosinophilic polygonal-to-spindle abundant cytoplasm. In addition, some of these cells contained mucicarmin-positive materials in the cytoplasm. The cells exhibited a typical epithelial feature with pavementlike cell arrangement, and lacked contact inhibition. The doubling times of the cells grown in a serum-containing and a serum-free medium were about 31 h and 10 to 11 d, respectively. Functionally, KYN-1 cells produced albumin, alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), ferritin, beta 2-microglobulin (BMG), and alpha 1-anti-trypsin (AAT). Positive reactions for albumin, AFP, CEA, and ferritin were identified in the cells by immunohistochemical techniques. Chromosome study revealed the chromosome number in a range from 61 to 74 without mode. The tumorigenicity of KYN-1 cells was identified by the tumor formation after subcutaneous inoculation of the cells into nude mice. The developed tumor showed compact growth of the tumor cells with gland formations containing mucicarmin-positive materials. Features of adenocarcinoma were identified by electron microscopy. The tumor cells were also identified to contain albumin, AFP, CEA, ferritin, and AAT by immunohistochemical techniques. AFP, CEA, and BMG were detected in the sera of nude mice. Thus, KYN-1 cells represented the morphologic features of adenocarcinoma, retaining some characteristics of original HCC. These findings suggest that KYN-1 is a new human HCC cell line with transformation to adenocarcinoma, which will provide useful information to clarify the histogenesis of combined hepatocellular and cholangiocellular carcinoma.
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PMID:A new human hepatocellular carcinoma cell line (KYN-1) with a transformation to adenocarcinoma. 243 Sep 33

A 57-year-old man had upper gastrointestinal signs and symptoms associated with testicular swelling and elevation of the serum alpha-fetoprotein level. Abdominal exploration revealed a large solitary liver mass and massively enlarged retroperitoneal lymph nodes, and a right scrotal exploration revealed a 4-cm testicular tumor. An orchidectomy and retroperitoneal biopsy were performed. The tumor was composed of nests, sheets, trabeculae, and clusters of polyhedral cells with eosinophilic cytoplasm and nuclei with prominent nucleoli. The tumor cells stained strongly for alpha-fetoprotein, alpha 1-anti-trypsin, and albumin by the immunoperoxidase technic. The clinical, light microscopic, and immunocytochemical features indicate that the testicular tumor was a metastatic hepatocellular carcinoma, only the second reported case of this type.
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PMID:Hepatocellular carcinoma metastatic to the testis. 243 71

Sulfation of human alpha 2-antiplasmin, the major plasma inhibitor of fibrinolysis, was examined using both protein isolated from human plasma and protein synthesized and biosynthetically labeled with [35S]sulfate by a human hepatoma-derived cell line. Linkage of sulfate to tyrosine was demonstrated by recovery of labeled tyrosine sulfate after base hydrolysis of sulfate-labeled alpha 2-antiplasmin. Analysis by reverse-phase high performance liquid chromatography of peptides released from alpha 2-antiplasmin by cleavage with trypsin or cyanogen bromide indicated that sulfate is linked to a single segment of the protein. A cyanogen bromide peptide corresponding to the sulfate-labeled peptide was prepared from alpha 2-antiplasmin isolated from human plasma. Consistent with the presence of tyrosine sulfate in this peptide, its chromatographic elution was altered by treatment with acid under conditions which release sulfate from a tyrosine residue. No peptide in the total digest of alpha 2-antiplasmin by cyanogen bromide eluted at the position of the peptide following desulfation, suggesting that all of the protein is in a sulfated form. The sequence of the sulfate-containing cyanogen bromide peptide as determined by sequential Edman degradation, amino acid composition, and fast atom-bombardment-mass spectrometry was: Glu-Glu-Asp-Tyr(SO4)-Pro-Gln-Phe-Gly-Ser-Pro-Lys-COOH. This peptide is a segment of the previously identified plasmin-binding domain of alpha 2-antiplasmin.
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PMID:Sulfation of a tyrosine residue in the plasmin-binding domain of alpha 2-antiplasmin. 243 96

We identified the major autophosphorylation sites in the insulin receptor and correlated their phosphorylation with the phosphotransferase activity of the receptor on synthetic peptides. The receptor, purified from Fao hepatoma cells on immobilized wheat germ agglutinin, undergoes autophosphorylation at several tyrosine residues in its beta-subunit; however, anti-phosphotyrosine antibody (alpha-PY) inhibited most of the phosphorylation by trapping the initial sites in an inactive complex. Exhaustive trypsin digestion of the inhibited beta-subunit yielded two peptides derived from the Tyr-1150 domain (Ullrich, A, Bell, J. R., Chen, E. Y., Herrera, R., Petruzzelli, L. M., Dull, T. J., Gray, A., Coussens, L., Liao, Y.-C., Tsubokawa, M., Mason, A., Seeburg, P. H., Grunfeld, C., Rosen, O. M., and Ramachandran, J. (1985) Nature 313, 756-761) called pY4 and pY5. Both peptides contained 2 phosphotyrosyl residues (2Tyr(P], one corresponding to Tyr-1146 and the other to Tyr-1150 or Tyr-1151. In the absence of the alpha-PY additional sites were phosphorylated. The C-terminal domain of the beta-subunit contained phosphotyrosine at Tyr-1316 and Tyr-1322. Removal of the C-terminal domain by mild trypsinolysis did not affect the phosphotransferase activity of the beta-subunit suggesting that these sites did not play a regulatory role. Full activation of the insulin receptor during in vitro assay correlated with the appearance of two phosphopeptides in the tryptic digest of the beta-subunit, pY1 and pY1a, that were inhibited by the alpha-PY. Structural analysis suggested that pY1 and pY1a were derived from the Tyr-1150 domain and contained 3 phosphotyrosyl residues (3Tyr(P] corresponding to Tyr-1146, Tyr-1150, and Tyr-1151. The phosphotransferase of the receptor that was phosphorylated in the presence of alpha-PY at 2 tyrosyl residues in the Tyr-1150 domain was not fully activated during kinase assays carried out with saturating substrate concentrations which inhibited further autophosphorylation. During insulin stimulation of the intact cell, the 3Tyr(P) form of the Tyr-1150 domain was barely detected, whereas the 2Tyr(P) form predominated. We conclude that 1) autophosphorylation of the insulin receptor begins by phosphorylation of Tyr-1146 and either Tyr-1150 or Tyr-1151; 2) progression of the cascade to phosphorylation of the third tyrosyl residue fully activates the phosphotransferase during in vitro assay; 3) in vivo, the 2Tyr(P) form predominates, suggesting that progression of the autophosphorylation cascade to the 3Tyr(P) form is regulated during insulin stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A cascade of tyrosine autophosphorylation in the beta-subunit activates the phosphotransferase of the insulin receptor. 244 32

We have produced a monoclonal antibody (SF-25) against a human hepatoma cell line (FOCUS) that strongly reacts with an antigen shared by all six colon adenocarcinoma cell lines. This cell surface antigen was uniformly expressed in all 17 human adenocarcinomas of the colon obtained at surgery but not on the normal adjacent mucosa counterpart. Other normal tissues were negative except for a population of cells in the distal tubule of the kidney as shown by immunoperoxidase staining and direct binding to membrane preparations. Binding of this Mr 125,000 antigen to antibody is disrupted by detergents, sodium dodecyl sulfate, and paraformaldehyde fixation but not by treatment of FOCUS cells with trypsin. The SF-25 antibody when labeled with 125I shows a striking capacity by both biodistribution and nuclear imaging studies to localize human colon adenocarcinoma grown as solid tumors in nude mice. SF-25 may be useful in distinguishing between normal colon and the transformed phenotype.
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PMID:In vivo localization of human colon adenocarcinoma by monoclonal antibody binding to a highly expressed cell surface antigen. 246 Feb 25

Monoclonal antibodies against human alpha-fetoprotein (AFP) were obtained by the hybridoma technique and studied with regard to their reactivities with the human hepatoma cell lines PLC/PRF/5 and KN, and a spontaneously immortalized cell line derived from fetal liver, NuE, all of which synthesize AFP. One of the monoclonal antibodies, 19F12 (IgG2b) became bound to free AFP which was used as the immunogen with an affinity constant of 3.4 X 10(8) M-1. This value was not much higher than those of two other antibodies, 19B1 (IgG1) and 9D12 (IgG2b). However, only antibody 19F12 showed definite reactivity with AFP-producing cells in analysis using flow cytometry. Immunofluorescence microscopy showed that antibody 19F12 detected AFP over the surface of NuE and PLC/PRF/5 cells with a uniform distribution, whereas definite reactivities of antibodies 19B1 and 9D12 to these cells were not detected. These antibodies did not show the specific binding to a non-AFP-producing human lung cancer cell line, PC-9, or to human peripheral blood lymphocytes. The binding ability of 19F12 to hepatoma cells was shown in both viable and fixed cells. Addition of free AFP inhibited the binding of antibody 19F12 to PLC/PRF/5 cells in a concentration-dependent manner. The specific reactivity of 19F12 to human AFP was also confirmed by immunostaining of a tissue section of human cancer proved to be AFP positive with AFP-specific antisera. In two-dimensional polyacrylamide gel electrophoresis of the antigen (from membrane fraction of PLC/PRF/5 cells)-antibody (19F12) complex, spots derived from the antibody and a spot (pI 4.7, Mr 65,000) corresponding in pI and molecular weight to AFP were detected. Western blot analysis showed that material in the membrane fraction of PLC/PRF/5 cells recognized by antibody 19F12 has the same molecular weight as human AFP derived from placenta. In a study of reactivities to PLC/PRF/5 cells treated with various enzymes, the reactivity of this antibody decreased when cells were treated with protease and trypsin and increased when lipase was used. The binding of 19F12 to AFP was not inhibited by concanavalin A. The antibody 19F12 appeared to recognize an epitope that is considered to be part of the peptide area of AFP. These results indicate that the reactivity, the amount of bound antibodies, and the distribution of monoclonal antibodies on antigen-producing cells vary, respectively, even though these antibodies were produced using the same antigen as an immunogen.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Detection of membrane-bound alpha-fetoprotein in human hepatoma cell lines by monoclonal antibody 19F12. 246 75


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