Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When 7721 human hepatocarcinoma cells were treated with 100 nM phorbol-12-myristate-13-acetate (PMA), the activity of N-acetylglucosaminyltransferase V(GnT-V) in the cells varied in accordance with the activity of membranous protein kinase C (PKC), but not with that of cytosolic PKC. Quercetin, a non-specific inhibitor of Ser/Thr protein kinase, and D-sphingosine and staurosporine, two specific inhibitors of PKC, blocked the activation of membranous PKC and GnT-V by PMA. Among the three inhibitors, quercetin was least effective. The inhibitory rates of quercetin and staurosporine toward membranous PKC and GnTV were proportional to the concentrations of the two inhibitors. The activities of GnTV and membranous protein kinase A (PKA) were also induced in parallel by dibutyryl cAMP (db-cAMP) and this induction was blocked by a specific PKA inhibitor. When cell free preparations of 7721 cells and human kidney were treated with alkaline phosphatase (ALP) to remove the phosphate groups, the GnTV activities were decreased. These results suggest that GnTV may be activated by membranous PKC or PKA, indirectly or directly, via phosphorylation of Ser/Thr residues.
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PMID:Regulation of N-acetylglucosaminyltransferase V by protein kinases. 874 53

When quiescent rat hepatocellular carcinoma 7919 cells were treated with epidermal growth factor (EGF) or insulin (stimulators of receptor tyrosine kinase activity), the activity of N-acetylglucosaminyltransferase V was increased. The effect of EGF reached a maximum after 10 min and remained high for 30 min, while the effect of insulin reached a maximum after 5 min and decreased after 15 min. Preincubation of the cells with 1-O-octadecyl-2-O-methylglycerophosphocholine (Et18-OH3), which blocked the activation of mitogen-activated protein kinase by EGF, also blocked the activation of N-acetylglucosamyltransferase V by this hormone, whereas the activation of N-acetylglucosamyltransferase V by insulin could not be blocked by Et18-OH3. Our results suggest that N-acetylglucosamyltransferase V may be regulated by different receptor protein tyrosine kinase pathways.
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PMID:Effects of epidermal growth factor and insulin on the activity of N-acetylglucosaminyltransferase V. 918 16

Cell-surface glycoproteins are regarded as candidates for involvement in the spread of tumor cells. N-linked beta1-6 branched oligosaccharides may contribute directly to the malignant or metastatic phenotypes of tumor cells. Increased beta1-6 branching has been associated with an increased level of N-acetylglucosaminyltransferase V (GlcNAc transferase V), the glycosyltransferase that initiates the beta1-6 branching. In this report, 33 pathologically verified hepatocellular carcinoma (HCC) specimens, six non-cancerous tissues surrounding HCC and five normal liver specimens have been studied. We have quantified N-linked beta1-6 branched oligosaccharides indirectly by measuring GlcNac transferase V activity. The average GlcNac transferase V activities in hepatocellular carcinoma (HCC), noncancerous tissues surrounding HCC and normal liver tissues were 324.2 +/- 269.8, 84.8 +/- 20.7 and 7.0 +/- 6.2 pmol product h(-1) mg protein(-1) (P < 0.05) respectively. In addition, the activity was correlated with the TNM classification of HCC. The average activities of GlcNAc transferase V in stages T1, T2-3 and T4 were 77.6 +/- 57.8, 369.0 +/- 294.7 and 329.9 +/- 205.9 pmol product h(-1) mg protein h(-1) respectively (P < 0.05), showing that the activity of the enzyme in advanced HCC was higher than that in early HCC. Our preliminary results indicated that GlcNAc transferase V activity increased in human HCC and was correlated with its progression.
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PMID:Elevated activity of N-acetylglucosaminyltransferase V in human hepatocellular carcinoma. 949 31

UDP-N-acetylglucosamine:alpha-6-d-mannoside beta-1, 6-N-acetylglucosaminyltransferase V (GlcNAcT-V) has been purified from cell extracts of the human hepatoma cell line, Hep3B, with 8.7% recovery. The purified enzymes had molecular masses of about 67 and 65 kDa on denaturated and natural conditions, respectively. The values of pI was 5.9. The GlcNAcT-V, when resolved by SDS-PAGE, was positive for Schiff staining, suggesting that the enzyme is glycoprotein. When GlcN,GlcN-biant-PA and UDP-GlcNAc were used as substrates, the enzyme displayed a temperature optimum of around 50 degrees C and optimum an pH of 6.5. The enzyme was stable in response to incubation from pH 4.5 to pH 10.5 at 4 degrees C for 24 h. The presence of UDP-GlcNAc and GlcN,GlcN-bi-PA protected the enzyme from heat inactivation, the extent depending upon the substrate concentration. The activity of the enzyme was stimulated by Mn2+ ion; however, it was inhibited by Fe3+. The enzyme activity was inhibited by another series of NDP-sugars including ADP-, CDP-, GDP-, and TDP-GlcNAc. Studies on the activity of the enzyme toward a variety of pyridylaminated sugars showed that the enzyme is most active toward biantennary (GlcN,GlcN-bi-PA) sugars. The enzymes had apparent Km values of 1.28 and 5.8 mM for GlcN,GlcN-bi-PA and UDP-GlcNAc, respectively. In order to isolate the GlcNAcT-V gene, PCR primers of GNN-1 and GNN-8 were designed and the amplified PCR product carrying the gene was cloned and sequenced. Nucleotide sequence analysis showed a 2220-bp open reading frame encoding a 740-amino-acid protein. This was almost same as the previously reported human sequences, except for some sequence differences in three amino acids. The three amino acid changes were as follows: 375V --> L, 555T --> R, and 592A --> G. These studies represent the detailed characterization of a purified GlcNAcT-V from human hepatoma cell Hep3B.
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PMID:Characterization of UDP-N-acetylglucosamine:alpha-6-d-mannoside beta-1,6-N-acetylglucosaminyltransferase V from a human hepatoma cell line Hep3B. 1039 45

The antisense cDNA of N-acetylglucosaminyltransferase V (GnT-V, EC 2. 4.1.155) was constructed as pcDNA3/GnT-V-AS plasmid and transfected into 7721 cells, a human hepatocarcinoma cell line. The transfection was confirmed with Northern blot. By using HPLC and HRP-lectin staining, it was found that the cells transfected with pcDNA3/GnT-V-AS (GnT-V-AS/7721) expressed less GnT-V activity and beta-1,6-GlcNAc branching in the cell glycoproteins compared with the cells mock-transfected with the vector pcDNA3 (pcDNA3/7721). The growth rate of GnT-V-AS/7721 was decreased in serum-containing medium, while the cell death was accelerated in serum-free medium. The GnT-V-AS/7721 cells were more susceptible to the apoptosis induced by ATRA than the mock-transfected cells. This was evidenced by the obvious appearance of a hypoploid sub-G(1) fraction in the DNA histogram using FCM analysis, the more condensed new moon-type nuclei under morphological observation, and the more intensive TUNEL reaction for assaying the fragmented DNA. At the same time as GnT-V down-regulation by GnT-V-AS, an increase of another N-aceylglusaminyltransferase, GnT-III (EC 2.4.1.144), was observed, and the biological significance of this finding was discussed.
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PMID:Increased susceptibility to apoptosis of human hepatocarcinoma cells transfected with antisense N-acetylglucosaminyltransferase V cDNA. 1052 94

N-linked beta 1-6 branched oligosaccharides may contribute directly to the malignant phenotype including metastatic potential of tumour cells. Increased beta 1-6 branching was associated with an increased level of N-acetylglucosaminyltransferase V (GnT V). In this report, the tissues from two metastatic models of human hepatocellular carcinoma (HCC) in nude mice were obtained. GnT V activity and mRNA level were determined. Results showed that GnT V activity in highly metastatic LCI-D20 models (Liver Cancer Institute, passage time: 20 days) (413.1+/-86.4U) was much higher than that in low metastatic LCI-D35 model (passage time 35 days) (155.3+/-31.9U). Northern blot showed that the mRNA level of GnT V in two models had no change. During the selection of a highly metastatic LCI-D20 model, GnT V activity increased from 301.6+/-57.3U to 413.1+/-86.4U while the highly metastatic LCI-D20 model acquired higher metastatic ability after selection. When highly metastatic LCI-D20 model tissues were implanted subcutaneously (s.c.), the GnT V activity decreased dramatically from 413.1+/-86.4U to 94.9U. This is the first report that GnT V activity increased in HCC during metastasis in vivo.
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PMID:N-acetylglucosaminyltransferase V activity in metastatic models of human hepatocellular carcinoma in nude mice. 1060 78

The effects of transfection of the metastasis suppressor gene nm23-H1 and cell-cycle related tumor-suppressor gene p16 on the activity of N-acetylglucosaminyltransferase V (GnT-V) and their relations to cancer metastatic potential were investigated. After transfection of nm23-H1 into 7721 human hepatocarcinoma cells and A549 human lung cancer cells, the activities of GnT-V were decreased by 28%-42% in the cells. In contrast, when p16 was transfected into these two cell lines, the decrease of GnT-V activity was only observed in A549 cells. This was probably to be due to the obvious expression of p16 gene in parental 7721 cells and the deletion of p16 in A549 cells. The decrease of GnT-V mRNA was only observed in nm23-H1-transfected cells, but not in p16-transfected A549 cells, suggesting that these two genes regulated GnT-V via different mechanisms. Horseradish peroxidase (HRP)-lectin staining showed that the 7721 cells transfected with nm23-H1 or the A549 cells transfected with p16 displayed a decreased intensity with HRP-leucoagglutinating phytohemagglutinin and increased intensity with HRP-concanavalin A, indicating the decline of beta1,6 N-acetylglucosamine branching structure on the asparagine-linked glycans of cell-surface and intracellular glycoproteins. The nm23-H1 transfected 7721 cells also displayed some changes in metastasis-related phenotypes, including the increase in cell adhesion to fibronectin (Fn), the decline in cell adhesion to laminin (Ln), and the decreased cell migration and invasion through matrigel. Transfection of antisense GnT-V cDNA into 7721 cells resulted in a decrease of GnT-V activity, an increase of cell adhesion to Fn or Ln, and a decrease in cell migration and invasion through matrigel. These phenotypes bore similarity to those of the 7721 cells transfected with nm23-H1. Our findings indicate that the down-regulation of GnT-V by nm23-H1 contributes to the alterations in metastasis-related phenotypes, and is an important molecular mechanism of metastasis suppression mediated by nm23-H1.
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PMID:Down-regulation of N-acetylglucosaminyltransferase V by tumorigenesis- or metastasis-suppressor gene and its relation to metastatic potential of human hepatocarcinoma cells. 1097 75

The effects of the epidermal growth factor (EGF), a stimulator of tyrosine protein kinase (TPK), and phorblol-12-myristate-13-acetate (PMA), a stimulator of protein kinase C (PKC), on the activity of N-acetylglucosaminyltransferase V (GnT-V) were studied in human hepatocarcinoma cell line 7721 in order to elucidate the regulation of TPK and PKC on GnT-V. It was found that the GnT-V activity obviously increased after treatment of the cells with EGF or PMA for 48 h. A non-specific protein kinase inhibitor, quercetin, inhibited the activities of TPK and PKC(inhibited mainly the membranous TPK and PKC)as well as GnT-V simulatanously. Moreover, quercetin completely eliminated the stimulating effect of EGF or PMA on GnT-V. When Tyrohostin-25, a specific inhibitor of TPK, or sphingosine, the specific inhibitor of PKC, was used separately to substitute for quercetin, the induction effect of EGF of PMA on GnT-V was only partially eliminated. However, when both Tyrphostin-25 and sphingosine were added to the culture medium, the elevation of GnT-V caused by EGF or PMA was entirely blocked. Cycloheximide, a well-known inhibitor of protein synthesis, showed an effect similar to the inhibition of protein kinases;it not only inhibited the basal activity of GnT-V, but also abolished the inducing stimulation of GnT-V by EGF of PMA. These results indicate that EGF or PMA regulates the activity of GnT-V via protein kinases, and GnT-V is regulated by dual mechanism of membranous TPK and PKC. Membranous TPK is more important that membranous PKC in the regulation of GnT-V.
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PMID:Dual Regulation of Tyrosine Protein Kinase and Protein Kinase C on N-acetylglucosaminyltransferase V. 1216 8

Transfection of sense cDNA of N-acetylglucosaminyltransferase V (GnTV) into H7721 human hepatocellular carcinoma cells resulted in the decreased expression of surface sialyl Lewis X (SLe(x)), a sialylated fucose-containing antigen. The enzymatic mechanisms were speculated to be the concomitantly decreased expression of alpha1,3-fucosyltransferase (FucT)-III, -VI, -VII and the branching enzyme of O-glycans, core 2-beta1,6-N-acetylglucosaminyltransferase (C2GnT)-I, -II. These two glycosyltransferase families were suggested to be the key enzymes in the synthesis of SLe(x). The expression of alpha2,3-sialyltransferase (ST3)-IV, but not ST3-I, -II and -III was elevated by sense GnTV. However, it did not cause the increase of SLe(x) synthesis. Transfection of antisense GnTV into H7721 cells showed entirely opposite effects on the expression of above-mentioned SLe(x) and glycosyltransferases as the sense GnTV.
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PMID:Effect of N-acetylglucosaminyltransferase V on the expressions of other glycosyltransferases. 1504 7

The relations between the structure of cell surface N-glycans to cell behaviors were studied in H7721 human hepatocarcinoma cell line, which predominantly expressed complex-type N-glycans on the surface. 1-Deoxymannojirimycin (DMJ) and swaisonine (SW), the specific inhibitor of Golgi alpha-mannosidase II or I, were selected to block the processing of N-glycans at the steps of high mannose and hybrid type respectively. All-trans retinoic acid (ATRA) and antisense cDNA of N-acetylglucosaminyltransferase-V (GnT-V) were used to suppress the expression of GnT-V and decreased the GlcNAc beta1,6-branching or tri-/tetra-antennary structure of surface N-glycans. The structural alterations of N-glycans were verified by sequential lectin affinity chromatography of [3H] mannose-labeled glycans isolated from the cell surface. The cell adhesions to fibronectin (Fn) and human umbilical vein epithelial cell (HUVEC), as well as cell migration (including chemotaxis and invasion) were selected as the parameters of cell behaviors. It was found that cell adhesion and migration were significantly decreased in SW and DMJ treated cells, suggesting that complex type N-glycan is critical for the above cell behaviors. ATRA and antisense GnTV enhanced cell adhesion to Fn but reduce cell adhesion to HUVEC and cell migration. These results reveal that cell surface complex-type N-glycans with GlcNAc beta1,6 branch are more effective than those without this branch in the cell adhesion to HUVEC and cell migration, but N-glycan without GlcNAc beta1,6-branch is the better one in mediating the cell adhesion to Fn. The integrin alpha5beta1 (receptor of Fn) on cell surface was unchanged by DMJ and SW. In contrast, ATRA up regulated alpha5, but not beta1, and antisense GnT-V decreased both alpha5 and beta1. This findings suggest that both the structure of N-glycan and the expression of integrin on cell surface are two of the important factors in the determination of cell adhesion to Fn, a complex biological process.
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PMID:Relations of the type and branch of surface N-glycans to cell adhesion, migration and integrin expressions. 1522 95


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