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)

gamma-Glutamyltransferase (GGT, EC 2.3.2.2) is an enzyme involved in glutathione metabolism and drug and xenobiotic detoxification. Using human hepatoma Hep G2 GGT cDNA as probe, we isolated a cDNA from a human pancreatic cDNA library. Analysis of the nucleotide sequences revealed a 2244-bp insert that includes an open reading frame of 1710 bp, encoding a protein identical to the Hep G2 and human placenta GGTs. Similarly, the 5' untranslated region, though shorter, is highly homologous to that of Hep G2 cDNA. These data suggest strongly that the same gene encodes human GGT in the placenta, Hep G2 and the pancreas. We further studied the distribution of the corresponding mRNA, called type I mRNA, in different human tissues. Using a highly sensitive method associating reverse transcription with specific amplification by polymerase chain reaction, cDNA was synthesized from total RNA isolated from the tissues and GGT specific fragments were amplified. We observed the presence of a specific cDNA fragment corresponding to the type I mRNA in the human tissues and cells tested, providing the evidence for a ubiquitous expression of this GGT mRNA in human tissues.
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PMID:Gamma-glutamyltransferase: nucleotide sequence of the human pancreatic cDNA. Evidence for a ubiquitous gamma-glutamyltransferase polypeptide in human tissues. 137 36

The aim of this study was to elucidate the positive rate of serum anti-HCV in alcoholic (with negative HBsAg and without blood transfusion history) and non-alcoholic (type-B and type-NANB) patients with chronic liver diseases. The clinico-pathological difference between anti-HCV positive and negative alcoholic patients was also investigated. Anti-HCV (Chiron C-100-3) was assayed with Ortho EIA kit in 196 patients. Liver function tests and the histological findings were evaluated in 111 cases of chronic hepatitis (CH) and 39 of liver cirrhosis (LC). Following results were obtained. [1] Positive rate of serum anti-HCV in alcoholic patients was 40% in CH, 36% in LC and 100% in hepatocellular carcinoma. In non-alcoholic type-NANB group, it was 75%, 68% and 69%, respectively. [2] Serum GGT/ALT ratio was higher in anti-HCV negative patients than positive patients both in CH and LC alcoholics. In non-alcoholic group, it was higher in type-NANB patients than type-B patients. [3] Among the histological findings in CH alcoholics, lymph follicles in the portal area were characteristic in anti-HCV positive patients, while these were not seen in negative patients. [4] In LC alcoholics, regenerative nodules were irregular in size in anti-HCV positive patients, while these were even and small in negative patients. [5] Serum HCV-RNA was detected in two out of 14 anti-HCV negative patients. [6] A female alcoholic patient who showed positive serum anti-HCV and negative HCV-RNA was presented. [7] For the evaluation of the influence of HCV in alcoholics, further studies have to be continued with more sensitive HCV markers.
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PMID:[Positive rate of serum anti-HCV in various liver diseases and the clinico-pathological study of chronic liver disease in alcoholics]. 166 37

Two gamma-glutamyl transpeptidase mRNAs (mRNAI and mRNAII), with alternate 5'-untranslated regions, are expressed in the rat kidney. Oligonucleotides were designed based upon these two alternate 5' sequences and used as primers to amplify GGT genomic DNA sequences. The genomic organization of the mRNAI and mRNAII 5'-untranslated sequences reveals that the mRNAs are encoded from two separate promoters which are 2.1 kbp apart on the single GGT gene. A 2775 base pair genomic sequence, which contains the proximal GGT promoter, was cloned from two overlapping amplified fragments. S1 mapping analysis shows that the kidney GGT mRNAI is transcribed from several start sites on this promoter which displays neither a classical TATA box nor Sp1 binding sites. Chimeric plasmids, including the GGT promoter region for mRNAI, associated with the chloramphenicol acetyltransferase (CAT) reporter gene, were transiently expressed in a kidney (LLCPK) and in a hepatoma (HTC) cell line. A sequence extending 308 bases upstream from the major GGT mRNAI start site drives a promoter activity which is 5-fold higher in LLCPK than in HTC cells and is sufficient to confer cell specificity to the GGT proximal promoter.
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PMID:Organization of the 5' end of the rat gamma-glutamyl transpeptidase gene: structure of a promoter active in the kidney. 167 56

To prepare a reference material for gamma-glutamyltransferase (GGT; EC 2.3.2.2) measurements in clinical chemistry, we constructed different vectors containing either the rat kidney or the human hepatoma Hep G2 GGT cDNA downstream from an inducible promoter for expression in Escherichia coli and Saccharomyces cerevisiae. Transformed bacterial and yeast cells were tested for GGT production by use of Western blot analysis and enzymatic activity measurements. Both rat renal and Hep G2 GGT cDNAs were expressed in E. coli, producing active and nonglycosylated enzymes localized in the periplasmic space. Recombinant Hep G2 GGT was synthesized as a single-chain protein, unlike rat renal GGT, which presented two polypeptides of 62 and 30 kDa, identified as the precursor and a GGT heavy-subunit-like peptide, respectively. Rat renal GGT was produced in S. cerevisiae as two polypeptides, 55 and 30 kDa, detected by antisera against rat renal GGT. These results suggest maturation mechanisms such as glycosylation and cleavage steps, enhancing the interest of S. cerevisiae as a useful expression system for producing active mammalian proteins as reference materials.
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PMID:Different constructs for the expression of mammalian gamma-glutamyltransferase cDNAs in Escherichia coli and in Saccharomyces cerevisiae. 167 51

gamma-Glutamyltransferase [GGT; (5-glutamyl)-peptide:amino-acid 5-glutamyltransferase, EC 2.3.2.2] is a glutathione-metabolizing enzyme, whose activity variations in serum and organs are valuable markers of preneoplastic processes, alcohol abuse, and induction by xenobiotics. To elucidate the implication of GGT in various metabolic pathways, we established a stable transgenic V79 cell line, highly producing the human GGT. A full-length cDNA, encoding the human hepatoma HepG2 GGT, was subcloned in an expression vector under the control of the simian virus 40 early promoter and was used to transfect V79 cells. We selected a cell line exhibiting a GGT activity of 2 units per mg of protein, the highest GGT expression level reported to date. As described for the human kidney and liver enzymes, the recombinant GGT purified from this cell line showed a heterodimeric structure. Its two subunits existed as sialylated and differentially glycosylated isoforms, with mean molecular masses of 80 and 29 kDa. However, catalytic features were found to be identical to those of human serum and HepG2 GGTs. The newly engineered cell line thus should be useful for the production of human GGT and as a potential alternative model for pharmacological studies.
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PMID:High-level expression of enzymatically active mature human gamma-glutamyltransferase in transgenic V79 Chinese hamster cells. 167 21

We produced monoclonal antibodies (mABs) against human integrins. Competitive enzyme-linked immunosorbent assay (ELISA) revealed that each mAB bound to different antigenic determinants. We then developed sandwich-type enzyme immunoassays (EIAs) to measure the concentration of fibronectin receptor (FNR) and vitronectin receptor (VNR). Serum immunoreactive integrin levels were measured using these EIAs in various liver and malignant diseases. In almost all cases of liver cirrhosis (LC) and hepatocellular carcinoma (HCC), serum integrin levels were significantly elevated, but were in the normal range in gastric, colon, lung cancer, and acute hepatitis (AH). The correlation between serum FNR and VNR levels was statistically significant in all cases of liver disease, and no correlation was observed between these integrin levels and conventional biochemical markers such as AST, ALT, and GGT. The serum integrin levels were demonstrated to be a potential diagnostic marker for hepatic fibrogenesis and carcinogenesis, and these sandwich EIAs could be useful for determination of these integrins in clinical laboratory tests.
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PMID:Sandwich enzyme immunoassay for serum integrins using monoclonal antibodies. 172 78

The hepatoma-specific band of serum gamma-glutamyl transferase II (GGT II) and other three markers were evaluated in 77 patients with primary hepatocellular carcinoma (PHC). The positive rate of GGT II (87%) was much higher than that of the increased alpha-fetoprotein (AFP greater than or equal to 400 ng/ml, 54.5%), the increased alpha-1-antitrypsin (AAT greater than or equal to 400 mg/dl, 64.9%) and alkaline phosphatase isoenzyme I (ALP I, 13.0%). In patients with AFP less than 400 ng/ml, the positive rate of GGT II was 95.2%, higher than that of ALP I (22.8%) and AAT (60.0%). The positive rate of GGT II was positively correlated to the volume of PHC (r = 0.324, P less than 0.05), but even in patients with small PHC (less than or equal to 65 cm3), the positive rate of GGT II (78.6%) was higher than that of AFP (50.0%) and AAT (28.6%). The ALP I positivity was only seen in patients with larger PHC. Follow-up study showed that GGT II, like AFP, might occur before liver tumor could be detected by B-mode ultrasonography and computerized tomography. Therefore, GGT II is a valuable marker of PHC, especially in patients whose AFP was negative or slightly increased; GGT II may be useful for relatively early diagnosis of PHC.
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PMID:Reappraisal of diagnostic significance of a hepatoma-specific band of serum gamma-glutamyl transferase. 197 81

After screening different human hepatoma cell lines, we observed that both HepG2 and PLC/PRF/5 naturally produced large amounts of gamma-glutamyltransferase. We optimized HepG2 cell culture conditions and observed that higher cell densities were obtained when cells were cultured on microcarriers, particularly when Cytodex 3 was used and that cell growth was optimal when DMEM, the basic medium, was supplemented with 5% fetal calf serum and 6 mmol/l glutamine. These culture conditions allowed us to produce the highest amounts of GGT after about 150 h of culture. The GGT obtained from HepG2 cells was partially purified and some of its physico-chemical properties characterized. Successive Con A gel chromatography separated the activity into two peaks, suggesting that GGT from HepG2 is not uniformly glycosylated. Papain-treated HepG2 GGT showed a Mr of about 120 kDa and migrated as a single-chain protein in SDS-PAGE. Immunological and kinetic properties of the GGT were similar to other human GGTs (liver, kidney and serum). It appears that HepG2 GGT could be a source for the preparation of a human enzyme reference material.
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PMID:Gamma-glutamyltransferase from human hepatoma cell lines: purification and cell culture of HepG2 on microcarriers. 197 62

A cell line derived from H35 hepatoma cells resistant to methotrexate (MTX) as a result of a defective transport system for MTX has been examined to determine how closely the variant resembles the parent cells with regard to other biochemical properties. The capacity of extracts of resistant cells to catalyze the poly-gamma-glutamylation of MTX was approximately twice as great as that of wild-type cell extracts. Evidence of similarity between wild-type and H35 R0.3 cells was derived from the equitoxic activity to both cell lines of nonclassical antifolates and other miscellaneous antineoplastics which act by a variety of mechanisms. Two phenotypic markers of hepatic cell function, alpha-aminoisobutyric acid (AIB) transport and tyrosine aminotransferase (TAT) activity inducibility, were present in both cell types, demonstrating the maintenance of these phenotypic properties in the H35 R0.3 cells. gamma-Glutamyltransferase (GGT, EC 2.3.2.2) activity differed in that it was present in wild-type cells and barely detectable in H35 R0.3 cells. The GGT activity reappeared in the H35 cells when they regained MTX sensitivity after incubation for 14-20 weeks in MTX-free media. Although defective MTX transport appeared to be correlated with the disappearance of GGT activity in an H35 variant cell line, no functional relationship between them is apparent at this time. It is possible that a lack of GGT activity may be evidence of a more differentiated phenotype in the transport-resistant cell line.
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PMID:The absence of gamma-glutamyltransferase activity in transport-dependent methotrexate-resistant hepatoma cells. 244 22

We examined the incidence of point mutation in codons 12, 13 and 61 of c-Ki-ras and N-ras genes in human hepatocellular carcinoma (HCC) using the polymerase chain reaction and oligonucleotide hybridization techniques. Among 34 tissues specimens surgically resected from 30 patients and 5 cell lines of human HCC, only two had ras point mutations; in one case, codon 12 of c-Ki-ras was altered from GGT, coding glycine, to GTT, coding valine; in the other case, codon 61 of N-ras was altered from CAA, coding glutamine, to AAA, coding lysine. Thus, point-mutational activation of ras oncogenes is an uncommon event in human HCC.
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PMID:Low incidence of point mutation of c-Ki-ras and N-ras oncogenes in human hepatocellular carcinoma. 254 5


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