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)

To define the basis of the heterogeneity of angiotensinogen, we have characterized the immunoreactivity of high molecular weight (HMW) and low molecular weight (LMW) plasma angiotensinogen, the angiotensinogen precursor synthesized by cell-free translation, and angiotensinogen secreted by human hepatoma (Hep G2) cells. Angiotensinogen precursor synthesized by rabbit reticulocyte lysate primed with RNA prepared from liver or Hep G2 cells was compared with angiotensinogen secreted by Hep G2 cells by using immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). So as to assess the contribution of N-glycosylation of angiotensinogen, Hep G2 cells were incubated in the presence of tunicamycin. Glycosylation of secreted angiotensinogen was further characterized by using chromatography on concanavalin A-Sepharose, digestion with neuraminidase, and treatment with trifluoromethane sulfonic acid. In Sephadex G-200 column chromatography, HMW plasma angiotensinogen eluted just after the column void volume and was clearly separated from LMW angiotensinogen which eluted just before bovine serum albumin. Both HMW and LMW plasma angiotensinogen were shown to bind to monoclonal and polyclonal antibodies raised against pure LMW angiotensinogen. Only one angiotensinogen precursor (mol wt 50,000) was identified by cell-free translation which, after cleavage by renin, was reduced to mol wt 45,600. Angiotensinogen secreted by Hep G2 cells showed electrophoretic heterogeneity (mol wt 53,100-65,400). Tunicamycin-treated Hep G2 cells secreted five discrete forms of angiotensinogen, a predominant form of mol wt 46,200, with other forms (mol wt 46,800, 48,100, 49,200, and 49,600) representing 10% of secreted angiotensinogen. All five forms showed a similar reduction in molecular weight after cleavage by renin. The predominant 46,200-mol wt protein represented nonglycosylated angiotensinogen in that, after cleavage by renin, it had an electrophoretic mobility (mol wt 45,600) identical to the desangiotensin I-angiotensinogen resulting from renin cleavage of the angiotensinogen precursor. The other higher molecular weight forms of angiotensinogen secreted by tunicamycin-treated Hep G2 cells were shown to represent O-glycosylated angiotensinogen in that they were reduced to 46,200 mol wt by treatment with trifluoromethane sulfonic acid. Dexamethasone (10(-7) and 10(-6)M) stimulated angiotensinogen secretion by Hep G2 cells two- to fourfold, both in the absence and presence of tunicamycin. However, a small stimulatory effect of mestranol (10(-7) M) was evident only in the presence of tunicamycin. Neither dexamethasone nor mestranol influenced the electrophoretic pattern (SDS-PAGE) of angiotensinogen secreted by Hep G2 cells. However, when incubation media were chromatographed on Sephadex G-200 with subsequent immunoprecipitation of the column fractions, both dexamethasone and mestranol were shown to stimulate the secretion of HMW angiotensinogen (eluting just after the column void volume) which, on SDS-PAGE, migrated in a position identical to LMW angiotensinogen. From these studies, we conclude that all forms of human angiotensinogen are derived from a single precursor. The heterogeneity of secreted angiotensinogen represents differences in posttranslational processing of angiotensinogen. This processing includes both N- and O-glycosylation, and also the formation of HMW complexes (HMW angiotensinogen) through association either with other angiotensinogen molecules or with some other protein(s) whose secretion by hepatocytes is stimulated by glucocorticoids and estrogens.
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PMID:Characterization of precursor and secreted forms of human angiotensinogen. 298 36

Since the relationship between tissue ligandin and liver tumors has not been studied yet, we investigated the changes of Y protein and ligandin in human hepatoma and cholangioma by gel filtration, BSP-affinity chromatography, and SDS-gel electrophoresis. The concentration of Y protein was markedly increased in both hepatoma and cholangioma, 2.8 and 4.8 times that of control, respectively. The content of ligandin was also increased in both conditions. SDS polyacrylamide gel electrophoresis of the increased ligandin confirmed the increment of 2.3 K dalton protein, which coincided with the MW of the ligandin subunit. Although the mechanism of the ligandin increase in hepatoma tissue is not clear, one possible reason might be due to the degree of differentiation of the tumor cells. In our case, the pathological examination revealed that the tumor cell was classified as Edmondoson Type II.
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PMID:[Changes in Y-protein and ligandin in human liver tumor tissues]. 299 96

Human plasma heparin cofactor II (HCII) inhibits thrombin by rapidly forming a stable, equimolar complex in the presence of heparin or dermatan sulfate. Cultured human hepatoma-derived cells (PLC/PRF-5) secreted (approximately equal to 200 ng/ml in 3 days) a protein of MW - 72 kD that was immunoisolated and immunoblotted with anti-HCII, co-migrated on SDS-PAGE with human plasma HCII, and formed covalent complexes with thrombin (MW - 101 kD) in the presence but not absence of heparin or dermatan sulfate; these complexes co-migrated with those obtained by incubating thrombin with human plasma under the same conditions. HCII was not detectable (less than 0.13 ng/ml) in post-culture medium from cultured human umbilical vein endothelial cells or human foreskin fibroblasts.
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PMID:Biosynthesis of functionally active heparin cofactor II by a human hepatoma-derived cell line. 299 59

DNA was extracted from NIH 3T3 cells transformed with DNAs from human primary hepatic cancer (PHC) and Hepatoma 7402 cell line. The transformant DNA was analyzed by Southern transfer and hybridization with 32P-labeled probes of various oncogenes. The EcoRI 7.2 and 9.0 kb bands characteristic of human N-ras gene were identified in transformed NIH 3T3 cells derived both from PHC and 7402 DNA. The BamHI 6.6 kb band characteristic of human c-Ha-ras I was present only in 7402 transformants, but not in PHC transformants. Using 35S-methionine incorporation, immunoprecipitation with anti-p21 monoclonal antibodies, SDS-PAGE and autoradiography, it was demonstrated that p21 synthesis was remarkably enhanced in 7402 cells as well as in transformed cells derived from both 7402 and PHC DNA. Taking the data together, it strongly implies that N-ras is one of the transforming genes for human liver cancer.
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PMID:Identification of human N-ras as the common oncogene in NIH 3T3 cells transformed with DNAs from human primary hepatic cancer and hepatoma 7402 line. 301 22

Human hepatoma cell (HepG2) or rabbit hepatocyte monolayers were incubated with [35S]methionine in presence or absence of tunicamycin, a potent inhibitor of asparagine-linked glycosylation. The 35S-labeled nonglycosylated and control fibrinogens purified from the media were used to evaluate the influence of the oligosaccharide on the catabolic properties of this glycoprotein. Plasmin, pronase, cathepsin D or cathepsin B each degraded the nonglycosylated and control fibrinogens similarly, as evidenced by the release of trichloroacetic acid-soluble radioactivity and by SDS-polyacrylamide gel electrophoresis and autoradiography of plasmic digests. Nonglycosylated and control fibrin clots also showed no differences in susceptibility to plasmic digestion. The two forms of fibrinogen demonstrated the same plasma half-life in rabbits. These data indicate that the oligosaccharide does not influence the proteolytic stability or the in vivo plasma survival of fibrinogen, and suggest that other biochemical determinants may influence the catabolic properties of this molecule.
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PMID:Catabolic properties of aglycofibrinogen synthesized by tunicamycin-treated human hepatoma (HepG2) cells and rabbit hepatocytes. 301 19

The biosynthesis of the ectoenzyme 5'-nucleotidase in the rat hepatoma cell line H4S has been studied by pulse-labeling with [35S]methionine and subsequent immunoprecipitation of the cell lysate. 5'-Nucleotidase is a membrane glycoprotein with an apparent molecular mass on SDS-gels of 72 kDa. The enzyme is initially synthesized as a 68-kDa precursor which is converted to the mature 72-kDa form in 15-60 min (t1/2 = 25 min). The molecular mass of the unglycosylated enzyme is approximately 58 kDa. Culturing the cells in the presence of varying concentrations of tunicamycin, an inhibitor of N-glycosylation, revealed six species of 5'-nucleotidase after sodium dodecyl sulfate/polyacrylamide electrophoresis. This indicates the presence of five N-linked oligosaccharide chains accounting for the difference between the 58-kDa polypeptide backbone and the 68-kDa species. The 68-kDa precursor is susceptible to cleavage by endo-beta-N-acetylglycosaminidase H; the 72-kDa mature protein is converted to several bands upon this treatment. This result indicates that part of 5'-nucleotidase keeps one or two high-mannose or hybrid chains in the mature form, even after prolonged pulse-chase labeling. The newly synthesized mature enzyme reaches the cell surface after 20-30 min. The half-life of 5'-nucleotidase is about 30 h in H4S cells. No immunoprecipitable 5'-nucleosidase is released into the culture medium.
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PMID:Transport and metabolism of 5'-nucleotidase in a rat hepatoma cell line. 302 51

The human hepatoma line Hep G2 produces an acid- and SDS-sensitive plasminogen activator inhibitor (PAI). This protein has been previously purified and used to raise polyclonal antibodies. This antiserum has been used to isolate cDNA clones from a human placental lambda gt11 cDNA library. The immunologically positive clones were screened for expression of recombinant proteins which inhibit urokinase activity and form an inhibitor-enzyme complex with 125I-urokinase. Two positives (lambda PAI 11.1 and lambda PAI 14.1) have been obtained. The cDNA insert of the longer isolate (lambda PAI 14.1) consists of 1962 base pairs encoding the entire mature Hep G2 PAI and a 3'-noncoding region of 801 base pairs. The clone apparently lacks portions of 5'- and 3'-untranslated sequences. The translated amino acid sequence matches the sequence obtained for the mature Hep G2 PAI and consists of 379 amino acids with a molecular mass of 42 770 Da. Interestingly, this PAI clone is quite different from the placental-type PAI-2 sequence as expected, but matches the sequence of the endothelial-type PAI (PAI-1) reported to be acid-insensitive and SDS-enhancible.
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PMID:cDNA cloning and expression in E. coli of a plasminogen activator inhibitor (PAI) related to a PAI produced by Hep G2 hepatoma cell. 302 37

A major glycoprotein of rat hepatoma plasma membranes was selectively released as a soluble form by incubating the membrane with phosphatidylinositol-specific phospholipase C. The soluble form corresponding to the glycoprotein was also prepared by butan-1-ol extraction of microsomal membranes at pH 5.5, whereas extraction at pH 8.5 yielded an electrophoretically different form with a hydrophobic nature. The soluble glycoprotein extracted at pH 5.5 was purified by sequential chromatography on concanavalin A-Sepharose, Sephacryl S-300 and anti-(alkaline phosphatase) IgG-Sepharose, the last step being used to remove a contaminating alkaline phosphatase. The glycoprotein thus purified was a single protein with Mr 130,000 in SDS/polyacrylamide-gel electrophoresis, although it behaved as a dimer in gel filtration on Sephacryl S-300. The glycoprotein was analysed for amino acid and carbohydrate composition. The composition of the carbohydrate moiety, which amounted to 64% by weight, suggested that the glycoprotein contained much larger numbers of N-linked oligosaccharide chains than those with O-linkage. It was confirmed that the purified glycoprotein was immunologically identical not only with that released by the phospholipase C but also with the hydrophobic form extracted with butan-1-ol at pH 8.5. The results indicate that the glycoprotein of rat hepatoma plasma membranes, which has an unusually high content of carbohydrate, is another membrane protein released by phosphatidylinositol-specific phospholipase C, as documented for alkaline phosphatase, acetylcholinesterase and Thy-1 antigen.
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PMID:Purification and characterization of a major glycoprotein in rat hepatoma plasma membranes. One of the membrane proteins released by phosphatidylinositol-specific phospholipase C. 303 62

Transfection of human hepatoma cell lines with cloned HBV DNA resulted in the secretion of large amounts of hepatitis B surface antigen (HBsAg) and core-related antigens (HBc/HBeAg) if well-differentiated cell lines were employed. Synthesis of both viral antigens was the highest in cell line HuH-7 and continued for approximately 25 days. Particles resembling hepatitis B virions (Dane particles) by morphology, density and by the presence of the preS1 surface antigen were released from the transfected HuH-7 cells into the culture medium. These particles produced in vitro were also indistinguishable from the naturally occurring hepatitis B virions in containing the virus-associated DNA polymerase and mature HBV genomes. Restriction analysis of these DNA molecules was compatible with the nucleotide sequence of the transfecting HBV DNA sequence. Viral surface antigens and core proteins present in the culture medium were fractionated and characterized by immunoprecipitation and SDS--PAGE after labeling with [35S]methionine. Antisera specific for X-gene products identified in cell extracts two hitherto unknown HBV gene products. This system thus provides a new approach to open questions regarding HBV-related gene function and HBV replication.
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PMID:Production of hepatitis B virus in vitro by transient expression of cloned HBV DNA in a hepatoma cell line. 303 5

A protein of 154 amino acids, predicted to be encoded by the X-open reading frame of the hepatitis B virus (HBV) genome, was synthesized in an in vitro translation system from SP6 transcripts containing the X-coding sequence. As characterized by SDS-PAGE and immunoprecipitation this X-protein possesses the expected molecular weight of 17 kDa and reacts specifically with rabbit antisera directed against a fusion protein from Escherichia coli that contained 145 of the 154 amino acids from the X-sequence. The X-protein, radiolabeled with [35S]methionine, provided a sensitive and specific antigen to screen for anti-X antibodies in sera from HBV patients. Positive signals were obtained preferentially in subjects suffering from HBV-induced liver cirrhosis or primary hepatocellular carcinoma (PHC), i.e., individuals that had been exposed for an extended time period to HBV gene products. Carefully controlled experiments failed to reveal the presence of X-related proteins specific to liver specimens from HBV patients.
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PMID:Synthesis of the X-protein of hepatitis B virus in vitro and detection of anti-X antibodies in human sera. 303 93


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