Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to elucidate some of the factors that determine the characteristic expression of gangliosides in malignant melanoma and neuroblastoma the levels of ganglioside synthases (glycosyltransferases) were determined in a panel of cell lines from those tumors that exhibited a wide range of ganglioside composition. Sialyltransferases (GM3, GD3, GD1a, and GT1b synthases), N-acetylgalactosaminyltransferases (GM2 and GD2 synthases), and galactosyltransferase (GM1 and GD1b synthases) were analyzed in crude membrane preparations from these cells. The results confirmed the importance of GM3 and GD3 synthases in determining the prominence of the a (GM3 to GT1a) or b (GD3 to GQ1b) biosynthetic pathways. The overall ganglioside composition in cells was found to be dependent on the relative levels of specific enzymes acting sequentially or in competing pathways. In general, the pattern and levels of transferases correlated with the actual ganglioside content of the cell line, although several important discrepancies were noted. For example, in cell lines containing high amounts of GD2 ganglioside, the level of the preceding enzyme in the pathway (GD3 synthase) was unexpectedly low. Thus, the high GD2:GD3 ratios characteristic of most neuroblastomas result from low levels of GD3 synthase as well as high levels of GD2 synthase. In other cell lines, GD3 synthase was completely absent, resulting in the synthesis of GM2, but not GD2, by N-acetylgalactosaminyltransferase I, as would be expected. It was concluded that different glycosyltransferases play key roles in determining glycolipid expression in different cell types.
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PMID:Glycosylation pathways in the biosynthesis of gangliosides in melanoma and neuroblastoma cells: relative glycosyltransferase levels determine ganglioside patterns. 139 96

Human melanoma cells express high levels of GM3 and GD3 gangliosides whereas normal melanocytes have only low levels of GD3 but maintain their expression of GM3. In order to understand the basis for this difference, the levels of the sialyltransferase that converts GM3 to GD3 (CMP-N-acetylneuraminic acid:GM3 sialyltransferase or GD3 synthase, EC 2.4.99.8) were analyzed in melanoma and other cell lines. Enzyme levels were determined in vitro using membrane preparations and measuring the addition of [14C]-N-acetylneuraminic acid from CMP-[14C]-N-acetylneuraminic acid to GM3 in the presence of Triton CF-54. Sialyltransferase levels in 44 human cancer cell lines (including melanoma, neuroblastoma, astrocytoma, various carcinomas, and leukemias) and cultures of normal melanocytes and kidney epithelial cells were compared, and the products were identified by thin layer chromatography and fluorography. Melanoma cell lines exhibited the highest levels of incorporation and GD3 was found to be the major product. GM3 was also formed, apparently from endogenous lactosylceramide. Very low levels of GD3 synthase were found in normal melanocytes. Neuroblastoma and some astrocytoma cell lines also had significant levels of GD3 synthase. Some other cell lines incorporated high levels of radioactivity but the products did not correspond to GD3 and the major product was usually GM3. In general the levels of GD3 synthase correlated with the expression of GD3 in the various cell types. These results point to higher levels of GD3 synthase being directly responsible for the enhanced expression of GD3 in melanoma.
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PMID:Sialyltransferase levels and ganglioside expression in melanoma and other cultured human cancer cells. 280 71

For the isolation of ganglioside GD3 synthase (EC 2.4.99.8) cDNA, we developed an expression cloning approach that used an anti-GD2 monoclonal antibody for selection. A host recipient cell line that we have named KF3027-Hyg5 was also utilized. This cell line expresses high levels of GM2 as well as GM3 but no GD3 or GD2 and was constructed from mouse B16 melanoma cells transfected with the polyoma large tumor antigen gene (KF3027) and the previously cloned beta-1,4-N-acetylgalactosaminyltransferase (EC 2.4.1.92) cDNA. Four rounds of transfection, monoclonal antibody 3F8 panning, and Hirt extraction resulted in the isolation of two cDNA clones, transfection of which directed the expression of GD3 in KF3027 and B16 melanoma cells and GD3 and GD2 in KF3027-Hyg5 cells. The cDNA contained a 1650-bp insert and a single open reading frame. The deduced amino acid predicted a type II membrane topology consisting of cytoplasmic (14 aa), transmembrane (18 aa), and catalytic (309 aa) domains. The sequence also predicted the presence of a sialyl motif similar to that found in the other sialyltransferases cloned so far. As expected, mRNA of this gene (2.6 kb) was strongly expressed in human melanoma lines.
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PMID:Isolation of GD3 synthase gene by expression cloning of GM3 alpha-2,8-sialyltransferase cDNA using anti-GD2 monoclonal antibody. 793 74

Using an expression cloning approach, we have isolated a cDNA encoding GD3 synthase (CMP-NeuAc:NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer alpha 2,8-sialyltransferase, EC 2.4.99.8), which is a key regulatory enzyme determining the prominence of the ganglioside biosynthesis pathway. The cloned cDNA encodes a 341-amino acid protein containing a single transmembrane domain at its N-terminal region, suggesting that the protein has a type II transmembrane topology. The sequence of alpha 2,8-sialyltransferase showed a high level of similarity with other sialyltransferases at two conserved regions typical in the sialyltransferase family. Transfected cells containing the cloned cDNA expressed GD3 ganglioside on the cell surface, which was detectable with specific anti-GD3 antibody by immunofluorescence and immunostaining after separation of isolated glycolipids on thin-layer chromatography. The cDNA hybridized to a single mRNA species of 2.4 kb in melanoma cells. This sialyltransferase is distinctive in catalyzing the formation of the alpha 2-8 linkage of sialic acids.
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PMID:Expression cloning of a CMP-NeuAc:NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer alpha 2,8-sialyltransferase (GD3 synthase) from human melanoma cells. 805 40

A cDNA encoding a GM3-specific alpha-2,8-sialyltransferase (GD3 synthase) was obtained from an expression cDNA library of human melanoma cell line WM266-4 by enrichment of Namalwa KJM-1 cells highly expressing GD3 using an anti-GD3 antibody and a fluorescence-activated cell sorter. Selection of B-cell line Namalwa cells expressing transfected cDNAs in the presence of anti-GD3 monoclonal antibody KM641 gave a cDNA (pAMo-GD3) encoding a protein with a type II transmembrane topology as found for mammalian glycosyltransferases. The following evidence confirms that the cDNA encodes an alpha-2,8-sialyltransferase, which specifically converts GM3 to GD3. (i) Transfection of pAMo-GD3 into Namalwa KJM-1 cells leads to the appearance of GD3 and a GD3 synthase activity. (ii) Northern blot analysis revealed a correlation between the expression of this gene and GD3 in several cell lines. (iii) The putative COOH-terminal active domain of this cloned enzyme fused with protein A has been purified with IgG-Sepharose beads and has been shown to possess GD3-synthesizing activity, excluding the possibility that the cloned cDNA encodes a transacting factor inducing a GD3 synthase. The deduced primary sequence also contains the "sialyl motif" conserved among all the sialyltransferases cloned to date. The polymerase chain reaction analysis reveals that this gene is located on chromosome 12.
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PMID:Expression cloning of a GM3-specific alpha-2,8-sialyltransferase (GD3 synthase). 819 50

To address the role of alpha2,8-sialyltransferase (GD3 synthase) in the biosynthesis of gangliosides, we examined the substrate specificity of the enzyme. In the ganglioside synthesis pathway, it has been generally accepted that sialyltransferase II (SAT II) catalyzes the production of GD3 from GM3, and sialyltransferase V (SAT V) catalyzes the production of GD1c/GT1a/GQ1b from GM1h/GD1a/GT1b. However, acceptor specificity of the clones GD3 synthase that was isolated from human melanoma cells [Nara, K., Watanabe, Y., Maruyama, K., Kasahara, K., Nagai. Y. & Sanai, Y. (1994) Proc. Natl Acad. Sci. USA 91, 7952-7956] has revealed that this enzyme utilized the gangliosides containing the terminal Sia(alpha2-3)Gas structure of the carbohydrate moiety, which includes GM3, GM1b, GD1a and GT1B as exogenous substrates. Kinetic data also showed that the enzyme was able to utilize both GM3 and GM1b/GD1a/GT1b as acceptor substrates. These data indicate that the enzyme catalyzes the formation of not only GD3 but also GD1c, GT1a, and GQ1B in vitro. Furthermore, by transfection of the cloned human alpha2,8-sialyltransferase cDNA, transient and stable expression of GT1a and GQ1b wa also observed in COS-7 cells and Swiss 3T3 cells that originally lacked SAT II and SAT V activities. These observations indicate that the enzyme has both SAT II and SAT V activities in vivo.
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PMID:Acceptor substrate specificity of a cloned GD3 synthase that catalyzes the biosynthesis of both GD3 and GD1c/GT1a/GQ1b. 870 63

GD3 Synthase (alpha 2,8sialyltransferase) (EC 2.4.99.8) cDNA has been cloned by eukaryotic cell expression cloning. Using this cDNA as a probe, the expression level of the gene in human cancer cell lines was analysed by Northern blotting and RT-PCR, then correlated with the ganglioside expression and enzyme activity. Melanoma cell lines showed extremely strong bands in Northern blot and RT-PCR/Southern analysis. The enzyme activity was also very high in melanomas as expected. Neuroblastoma and astrocytoma lines showed relatively low levels of the gene expression, whereas they expressed high levels of GD2. Although the mRNA level of the GD3 synthase gene and enzyme activity in individual cell lines correlated positively, some cell lines showed much higher activity than expected from the mRNA level. Among leukaemia lines, adult T cell leukaemia-associated (HTLV-I+) lines showed fairly high levels of the mRNA. On the other hand, T-ALL lines showed very low levels. In addition, GD3 and GD2 expression and mRNA level of the gene during T lymphocyte activation were analysed. Only GD3 expression was induced by any of the stimulatory reagents used, and corresponding up-regulation of the GD3 synthase gene was shown in RT-PCR/Southern analysis.
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PMID:Expression of alpha 2,8-sialyltransferase (GD3 synthase) gene in human cancer cell lines: high level expression in melanomas and up-regulation in activated T lymphocytes. 874 67

We reported previously that stereoisomers of 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), the D-threo and L-threo forms, exerted inhibitory and stimulatory effects on glycosphingolipid (GSL) biosynthesis in B16 melanoma cells, respectively. In the present study, the primary cultured rat neocortical explants were treated with L- or D-threo-PDMP. These isomers exhibited opposite effects on neurite outgrowth: D-PDMP was inhibitory at concentrations ranging from 5 to 20 microM, whereas L-PDMP was stimulatory over the same concentration range, and the maximal effect was observed at 10-15 microM. Rat neocortical explants were doubly labeled with [14C]serine and [3H]galactose at 15 microM L- or D-PDMP. L-PDMP increased the incorporations of both labels into sphinganine, sphingosine, ceramide, sphingomyelin, neutral GSLs, and gangliosides, whereas D-PDMP inhibited the glucosylation of ceramide resulting in a reduction of ganglioside biosynthesis and accumulation of precursors of glucosylceramide, ceramide, and sphingomyelin. To clarify the stimulatory effect of L-PDMP on GSL biosynthesis, serine palmitoyltransferase, sphingosine N-acyltransferase, glucosylceramide synthase, lactosylceramide synthase, GM3 synthase, and GD3 synthase were quantified in cell lysates of explants pretreated with this agent. Serine palmitoyltransferase was fully activated up to 150% of the control. Furthermore, marked increases in the activities of lactosylceramide synthase (200%), GM3 synthase (240%), and GD3 synthase (300%) were observed. These results suggest that the neurotrophic action of L-PDMP may be ascribable to its stimulatory effect on the biosynthesis of GSLs, especially that of gangliosides.
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PMID:Induction of ganglioside biosynthesis and neurite outgrowth of primary cultured neurons by L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol. 886 86

Using an anti-GD1b monoclonal antibody, expression cloning of a cDNA for the beta1,3-galactosyltransferase gene (EC 2.4.1.62) was performed. KF4C, mouse melanoma B16 transfected with polyoma T antigen gene, and GM2/GD2 synthase cDNA was used as a recipient cell line for the cDNA library transfection. A cDNA clone of GD3 synthase, pD3T-31 was co-transfected with a cDNA library prepared from rat brain RNA using the pcDNAI expression vector. The isolated cDNA clone pM1T-9 predicted a type II membrane protein with 4 amino acids of cytoplasmic domain, 21 amino acids of transmembrane region, and a large catalytic domain with 346 amino acids. Introduction of the cDNA clone into a mouse melanoma line B16 previously transfected with a GM2/GD2 synthase gene resulted in the neo-synthesis of GM1. Co-transfection of the cell line with pM1T-9 and a GD3 synthase cDNA resulted in the expression of GD1b as well as GM1. Moreover, introduction of pM1T-9 into L cell (lacking GM3 synthase), previously transfected with GM2/GD2 synthase gene, resulted in the definite expression of asialo-GM1. These results indicated that GD1b/GM1/GA1 synthases were identical, as previously suggested based on enzymological analysis. In Northern blots of the beta1, 3-galactosyltransferase gene with total RNA from various rat tissues, a 1.6-kilobase mRNA was strongly expressed in spleen, thymus, kidney, and testis. However, the expression level of the gene in the adult brain tissue was not especially high. On the other hand, this gene was expressed at high levels in the rat brain of embryonal day 12, and reached a peak at around birth, then fell to low level in the adult brain.
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PMID:Expression cloning of rat cDNA encoding UDP-galactose:GD2 beta1,3-galactosyltransferase that determines the expression of GD1b/GM1/GA1. 931 75

Most human neuroblastoma tumors are characterized by the high expression of GD2 (or GD2 and/or GM2) gangliosides, whereas melanomas characteristically express GD3 ganglioside. The molecular basis for these patterns was investigated by examining the relationship between ganglioside levels, glycosyltransferase (GM2/GD2 synthase and GD3 synthase) activity, and corresponding mRNA levels in a panel of human neuroblastoma and melanoma cell lines. In general, the ganglioside patterns could be explained by the levels of the transferases and their mRNA, indicating control at the level of transcription. A key role was noted for GD3 synthase. Notably, it was found that neuroblastoma cell lines with high GD2 ganglioside levels had low levels of GD3, its synthase, and mRNA for the enzyme even though this step provides the substrate for GD2 synthesis. The key role for GD3 synthase was also examined by stably transfecting GD3 synthase cDNA into a neuroblastoma cell line (SH-SY5Y) not expressing GD3 and GD2. The resulting cell line had high levels of GD2 ganglioside and altered morphology and growth characteristics.
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PMID:Relationship of glycosyltransferases and mRNA levels to ganglioside expression in neuroblastoma and melanoma cells. 993 Jul 22


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