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)

A protein preparation that specifically binds insulin-like growth factors (IGFs) I and II was purified from medium conditioned by rat liver BRL-3A cells using molecular sieve chromatography in 1 M acetic acid followed by affinity chromatography on IGF-II-agarose. The affinity-purified IGF-binding protein exhibits a single major band with apparent Mr = 36,300 under reducing conditions on sodium dodecyl sulfate-polyacrylamide gels. The IGF-binding protein is efficiently and specifically cross-linked to either 125I-IGF-I (human) or 125I-IGF-II (rat) using disuccinimidyl suberate. An IGF-binding protein of similar apparent molecular weight was also affinity purified from rat hepatoma H-35 cell conditioned medium and found to differ from the BRL-3A protein such that potent polyclonal antisera prepared in rabbits against the purified BRL-3A IGF-binding protein exhibited a much lower titer for the H-35 protein in an enzyme-linked immunosorbent assay and upon immunoblotting. In order to determine whether a single BRL-3A IGF-binding protein is present in the affinity-purified preparation, the protein was prepared for sequencing on a Sephacryl S-300 column in 6 M guanidine HCl after reduction and alkylation. The amino acid composition (expressed in percentages) of this IGF-binding protein was determined to be: Cys = 5.5, Lys = 4.8, His = 2.8, Arg = 7.8, Asx = 10.2, Thr = 5.1, Ser = 3.9, Glx = 15.7, Gly = 17.4, Ala = 7.3, Val = 4.6, Met = 1.4, Ile = 2.4, Leu = 8.3, Tyr = 1.0, Phe = 1.9. Sequencing of the NH2-terminal portion of this protein led to the identification of 31 amino acids in the following order: Phe-Arg-Cys-Pro-Pro-Cys-Thr-Pro-Glu-Arg-Leu-Ala-Ala-Cys-Gly-Pro-Pro-Pro- Asp-Ala-Pro-Cys-Ala-Glu-Leu-Val-Arg-Glu-Pro-Gly-Cys. We conclude that rat liver BRL-3A cells secrete a single major IGF-binding protein capable of binding both IGF-I and IGF-II.
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PMID:Purification and amino-terminal sequence of an insulin-like growth factor-binding protein secreted by rat liver BRL-3A cells. 242 67

A synthetic peptide corresponding to the seven carboxy-terminal amino acids of tyrosine aminotransferase was coupled to ovalbumin or keyhole limpet haemocyanin, and the resulting conjugates were used to raise anti-peptide antibodies by immunization of rabbits. The crude sera were purified and tested for recognition of the whole enzyme by enzyme-linked immunosorbent assay and immunoprecipitation in extracts from [35S] methionine labeled hepatoma cells. Our results support the existence of an intact C-terminus. If processing takes place, it will rather occur at the N-terminus of this hepatic enzyme.
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PMID:Integrity of the C-terminal part of tyrosine aminotransferase revealed by an anti-peptide serum. 243 20

alpha 1-Microglobulin (alpha 1m) was determined by radio-immunoassay in the supernatants of five human hepatoma cell lines. High amounts of alpha 1m were produced by PLC/PRF/5, intermediate ones by Hep G2 and Hep 3B and very low ones by Malhavu and SK Hepl. alpha 1m isolated from hepatoma cell lines PLC/PRF/5 or Hep G2 supernatants displayed the same physicochemical properties as that purified from human urines: the apparent molecular mass was 26 kDa and the pI from 5.6 to 6.4 as measured after two-dimensional polyacrylamide gel electrophoresis in denaturating conditions; for the native molecule the pI was estimated to be 4.0-4.9. Both urinary and hepatoma alpha 1m migrate as a diffuse band in the alpha zone in agarose gel at pH 8.6 in non-denaturing conditions and present a brown chromophore covalently associated with the molecule. After biosynthetic labelling with [35S]methionine, proteins extracted from hepatoma cell line PLC/PRF/5 and from isolated hepatocytes of human liver were separated by two-dimensional PAGE and transferred to a nitrocellulose membrane. alpha 1m was identified and found to be identical in both cases. However, when compared with the alpha 1m isolated from cell supernatants, less charge heterogeneity but also minor additional spots of higher molecular mass were observed.
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PMID:Purification of alpha 1-microglobulin produced by human hepatoma cell lines. Biochemical characterization and comparison with alpha 1-microglobulin synthesized by human hepatocytes. 243 35

The effect of culture conditions on the glutamylation of methotrexate by intact H35 hepatoma cells and folylpolyglutamate synthetase (FPGS) activity in the corresponding crude extracts has been examined. The rate of cellular glutamylation of methotrexate observed in rapidly dividing cultures was 4-fold higher than confluent cultures, and was accompanied by an increase in extract FPGS activity (2.2-fold). The depletion of cellular folates produced comparable increases in both cellular methotrexate glutamylation and extract FPGS activity (approximately 1.8-fold). Near-quantitative reductions in cellular methotrexate glutamylation were caused by media additions of reduced folates and methotrexate to confluent cultures of wild-type and folate-depleted H35 cells. However, these produced relatively modest reductions in FPGS activity in the corresponding crude extracts (approximately 50%). Methionine exclusion resulted in a greater than 50% decrease in FPGS activity in crude extracts of these cells compared to extracts of control cultures. The combination of methionine exclusion and folinic acid addition lowered the FPGS activity to less than 25% that of control. The data suggest that the changes in the glutamylation rate of methotrexate in whole cells due to culture conditions such as folate restriction, reduced folate addition, methionine exclusion, and growth state are at least in part a consequence of alterations in FPGS activity. This conclusion is consistent with the proposition that the metabolism of slow-acting substrates for FPGS (such as 4-amino antifolates and their corresponding polyglutamates) may be sensitive to changes in enzyme levels or activity (Cook et al., Biochemistry, 26: 530-539, 1987). Analysis of the products formed by FPGS from extracts using methotrexate as the substrate revealed no significant amounts of polyglutamate species higher than 4-NH2-10-CH3-PteGlu3. In contrast, when using the thymidylate synthase inhibitor N10-propargyl-5,8-dideazafolic acid as the starting substrate under identical assay conditions, FPGS from extracts catalyzed the formation of predominantly long chain polyglutamate derivatives (Glu4 and higher). These results reflect the relative efficacy of methotrexate and N10-propargyl-5,8-dideazafolic acid, as well as their polyglutamate derivatives, as substrates for FPGS.
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PMID:Role of folylpolyglutamate synthetase in the regulation of methotrexate polyglutamate formation in H35 hepatoma cells. 245 60

Two different insulin-like growth-factor (IGF)-binding proteins have been found in human blood, one of high molecular mass and dependent on growth hormone for synthesis, the other of low molecular mass and independent of growth hormone. The small IGF-binding protein is abundant in human amniotic fluid. Its amino acid sequence has now been determined by direct analysis of the protein and its proteolytic fragments. Also, by immunoscreening a partial cDNA clone was isolated from a human hepatoma cell line. The mature protein consists of 234 amino acids and is coded for by an mRNA of approximately 1700 nucleotides in length. The primary structure of the protein reveals 18 Cys residues in N-terminal and C-terminal clusters and an Arg-Gly-Asp peptide sequence, common to extracellular proteins binding to receptors of the integrin family. A protein-sequence polymorphism was detected at position Ile/Met-228, indicating possible allelic variation. The 3'-untranslated mRNA sequence has a high A + T content and shows five copies of an ATTTA sequence, which has been shown to be involved in the regulation of the stability of certain mRNAs coding for growth-regulating proteins.
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PMID:Human insulin-like growth-factor-binding protein. Low-molecular-mass form: protein sequence and cDNA cloning. 246 65

Fetal rat liver cells derived from 19-day gestation rats were exposed in culture to the carcinogen, 3'-methyl-4-dimethyl-aminoazobenzene (MDAB) for 3 days and then maintained in medium supplemented with the tumor promoter, phenobarbital (PB). Tumors developed in immunodeficient mice inoculated with cells derived from cultures which had been maintained for more than 8 weeks. Histologically, three types of tumors could be distinguished. One contained epithelial-like cells, which resembled what has previously been described as 'clear' epithelial cells. The second contained cells which were more basophilic, with prominent nuclei and closely resembled the hepatoma cell line Mc-A-R-777. The third group of tumors possessed cells of both varieties. Cell lines derived from these tumors were then characterized by determining their capacity to synthesize and secrete alpha-fetoprotein, albumin and transferrin by measuring the incorporation of 35S-methionine into immunoprecipitates obtained by reaction with the respective specific antibodies and the content of the respective mRNAs were determined by hybridization to cDNAs. The activity of gamma-glutamyl-transpeptidase (GGT) and the liver specific enzyme tyrosine aminotransferase (TAT), as well as the induction of TAT by dexamethasone was also evaluated. The presence of these markers in some of the cell lines strongly suggests that they are derived from parenchymal cells. In contrast, other cell lines which morphologically resemble 'clear' epithelial cells are negative, suggesting that they may be derived from non-parenchymal epithelial cells which exist in the original culture. However, some epithelial-like cell lines derived from tumors of mixed morphology appear different to those established from tumors which contained only epithelial-like cells. These express low levels of transferrin and tyrosine aminotransferase suggesting that they may be more closely related to hepatocytes than those cells which are derived from tumors which originally comprised only epithelial cells. The absence or presence of liver markers correlates with the morphology of the respective cell lines since transferrin and TAT are only present in significant levels in those lines which comprise cells with a morphology resembling hepatoma cell lines. In cell lines which show mixed morphology, immunocytochemistry reveals that significant amounts of transferrin are only present in the parenchymal-like population. Growth rate measurements show that the faster growing cell lines generally possessed lower levels of transferrin and TAT expression. It can be concluded from these studies that it is possible to transform cells derived from fetal rat liver in culture using a hepatocarcinogen.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Transformation of cultured fetal rat liver cells by MDAB and phenobarbital. Morphological, biochemical and immunocytochemical characterization of cell lines. 247 May 26

Human S-protein (vitronectin) and hemopexin, two structurally related plasma proteins of similar molecular mass and abundance, were analyzed for tyrosine sulfation. Both proteins were synthesized and secreted by the human hepatoma-derived cell line Hep G2, as shown by immunoprecipitation from the culture medium of [35S]methionine-labelled cells. When Hep G2 cells were labelled with [35S]sulfate, S-protein, but not hemopexin, was found to be sulfated. Half of the [35S]sulfate incorporated into S-protein was recovered as tyrosine sulfate. The stoichiometry of tyrosine sulfation was approximately two mol tyrosine sulfate/mol S-protein. Examination of the S-protein sequence for the presence of the known consensus features for tyrosine sulfation revealed three potential sulfation sites at positions 56, 59 and 401. Tyrosine 56 is the most probable site for stoichiometric sulfation, followed by tyrosine 59 which appears more likely to become sulfated than tyrosine 401. Tyrosines 56 and 59 are located in the anionic region of S-protein which has no homologous counterpart in hemopexin. We discuss the possibility that tyrosine sulfation of the anionic region of S-protein may stabilize the conformation of S-protein in the absence of thrombin-antithrombin III complexes and may play a role in its binding to thrombin-antithrombin III complexes during coagulation.
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PMID:Sulfation of two tyrosine-residues in human complement S-protein (vitronectin). 247 56

The role of glycosylation on the secretion and the stability of human corticosteroid binding globulin (CBG) was studied. Cells of the human hepatoma line were labeled by [35S]methionine in presence of or absence of tunicamycin (TM). Media or cells were harvested at 0, 3, 6, and 20 h after the addition of excess unlabeled methionine. Media and cell lysates were incubated with anti-CBG serum and immune complexes were precipitated with Staphylococcus aureus protein A (Pansorbin). Immunoprecipitates were analyzed by fluorography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoprecipitation of T4-binding globulin (TBG) was also carried out with anti-TBG serum. Fluorographic analysis revealed three forms of CBG: CBG1, a glycosylated, mature, and secretory form with apparent mol wt of 70 K; CBG2, a glycosylated precursor which due to incomplete carbohydrate processing has an apparent mol wt of 54 K; and CBG3, a nonglycosylated form consisting of the 40 K core protein. In absence of TM, CBG1 was observed in media and CBG2 was detected in cell lysates. The proportion of CBG1 increased during the chase, whereas that of CBG2 decreased, indicating that CBG was secreted after processing of the oligosaccharides on CBG2. In presence of TM, CBG3 was found both in media and cell lysates. The sum of CBG3 in the medium and the cell lysate decreased during the chase, whereas that of CBG1 and CBG2 remained unchanged. Similar to CBG, TBG1 (mature form, 60 K) and TBG2 (partially processed glycosylated form, 54 K) were observed in media and cell lysates, respectively, in absence of TM. However, TBG3 (nonglycosylated, 44 K) was not detected in medium. These results indicate that glycosylation is not a key factor for the secretion of CBG but is important for its stability. On the other hand the glycosylation is indispensable for the secretion of TBG.
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PMID:Studies on the role of glycosylation for human corticosteroid-binding globulin: comparison with that for thyroxine-binding globulin. 250 69

To evaluate the level of serum thyroxine-binding globulin (TBG) in various liver diseases, TBG and T4, T3, FT4 were measured by radioimmunoassay in 29 HBsAg carriers (C), 27 patients with acute hepatitis (AH), 18 patients with inactive chronic hepatitis, 70 patients with chronic active hepatitis (CAH), 31 patients with active cirrhosis (AC), 20 patients with inactive cirrhosis (IC), 38 patients with hepatocellular carcinoma (HCC), 12 patients with metastatic Ca to the liver (Met.) and in 81 normal controls. All the patients were clinically euthyroid. The TBG as well as T4 in patients with AH, CAH, AC HCC and, Met. were significantly higher than those in controls. The T3 level was significantly elevated in CAH and AC patients. The TBG level did not correlate with serum albumin or bilirubin levels, but did correlate significantly with alanine transaminase (ALT) (r = 0.54, p less than 0.01). However, the correlation was positive in chronic active hepatitis (r = 0.40, p less than 0.01) but negative in hepatocellular carcinoma (r = -0.32, p less than 0.05). The data suggested: (1) Significant TBG and T4 elevation was found in all active liver diseases and HCC. (2) In the presence of high T4 in patients with liver disease, normal FT4 excluded the diagnosis of hyperthyroidism. (3) The elevation of TBG levels in chronic hepatitis appeared to parallel the severity of hepatocytolysis, and therefore might be the result of hepatocytolysis; while the elevation of TBG in HCC might be due to increased synthesis by the malignant cells.
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PMID:[Changes in thyroid hormone concentration in liver disease]. 250 36

Glycogen synthase was isolated from rat H4IIE hepatoma cells by the use of specific antibodies. Immunoprecipitates from cells grown in the presence of [35S]methionine contained two 35S-labeled polypeptides, designated GS1 and GS2, separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Labeling of both species was half-maximal after 3 h and remained constant up to 48 h. When cells were incubated with [32P]-phosphate, 32P was incorporated into both species with similar kinetics, half-maximal labeling occurring after 2-3 h. The steady-state ratio 32P/35S was significantly higher for the lower mobility GS2 polypeptide. Pulse-chase experiments showed that the two subunits followed similar kinetics with respect to 35S-labeling. However, the turnover of 32P on the GS2 subunit was significantly faster (t1/2 approximately 30 min) than that on the GS1 subunit (t1/2 approximately 2 h). We suggest that the two polypeptides represent different phosphorylation states of the glycogen synthase subunit and are rapidly interconverted.
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PMID:Glycogen synthase turnover and phosphorylation in rat H4IIE hepatoma cells. 251 Jun


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