Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.99.6 (sialyltransferase)
 1,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sialoglycans on the cell surface of human colon cancer (HCC) cells have been implicated in cellular adhesion and metastasis. To clarify the role of N-acetylneuraminic acid (NeuAc) linked alpha2,3 to galactose (Gal) on the surface of HCC cells, we studied the intercellular adhesion of HCC cell lines expressing increasing NeuAcalpha2,3Gal-R. Our model system consisted of the HCC SW48 cell line, which inherently possesses low levels of cell surface alpha2,3 and alpha2,6 sialoglycans. To generate SW48 clonal variants with elevated cell surface NeuAcalpha2,3Gal-R linkages, we transfected the expression vector, pcDNA3, containing either rat liver cDNA encoding Galbeta1,3(4)GlcNAc alpha2,3 sialyltransferase (ST3Gal III) or human placental cDNA encoding Galbeta1,3GalNAc/Galbeta1,4GlcNAc alpha2,3 sialyltransferase (ST3Gal IV) into SW48 cells. Selection of neomycin-resistant clones (600 microgram G418/ml) having a higher percentage of cells expressing NeuAcalpha2,3Gal-R (up to 85% positive Maackia amurenis agglutinin staining compared with 30% for wild type cells) was performed. These ST3Gal III and ST3Gal IV clonal variants demonstrated increased adherence to IL-1beta-activated human umbilical vein endothelial cells (HUVEC) (up to 90% adherent cells compared with 63% for wild type cells). Interestingly, ST3Gal III and ST3Gal IV clonal variants also bound non-activated HUVEC up to 4-fold more effectively than wild type cells. Cell surface NeuAcalpha2,3Gal-R expression within the various SW48 clonal variants correlated directly with increased adhesion to HUVEC (r=0.84). Using HCC HT-29 cells, which express high levels of surface NeuAcalpha2,3Gal-R, addition of synthetic sialyl, sulfo or GalNAc Lewis X structures were found to specifically inhibit intercellular adhesion. At 1.0mM, NeuAcalpha2,3Galbeta1,3(Fucalpha1, 4)GlcNAc-OH and Galbeta1,4(Fucalpha1,3)GlcNAcbeta1,6(SE-6Galbeta1++ +, 3)GalNAcalpha1-O-methyl inhibited HT-29 cell adhesion to IL-1beta-stimulated HUVEC by 100% and 68%, respectively. GalNAcbeta1, 4(Fucalpha1,3)GlcNAcbeta1-O-methyl and GalNAcbeta1,4(Fucalpha1, 3)GlcNAcbeta1,6Manalpha1,6Manbeta1-0-C30H61, however, did not possess inhibitory activity. In conclusion, these studies demonstrated that cell surface NeuAcalpha2,3Gal-R expression is involved in HCC cellular adhesion to HUVEC. These specific carbohydrate-mediated intercellular adhesive events may play an important role in tumor angiogenesis, metastasis and growth control.
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PMID:Cell surface n-acetylneuraminic acid alpha2,3-galactoside-dependent intercellular adhesion of human colon cancer cells. 1008 Sep 50

Ganglioside GD3 is overexpressed in many types of tumors and may be associated with tumor progression and the development of metastatic potential. In our previous study (G. Zeng et al., Biochemistry, 38: 8762-8769, 1999), we established a subclone of the rat dorsal root ganglion-derived F-11 cells in which the expression of ganglioside GD3 was inhibited by stable transfection of the antisense vector against CMP-NeuAc: GM3 alpha2-8 sialyltransferase (GD3-synthase) gene. This cell line exhibits markedly reduced rate of tumor growth in vivo. Here, we further characterized the antisense-transfected cell line, and the results showed that these cells formed small, minimally vascularized tumors exhibiting extensive necrosis. In vivo Matrigel assay revealed reduced vascularization and low hemoglobin content in the antisense xenografts. Significantly fewer new vessels were found on the antisense xenografts and the skin around them than those on/around the xenografts formed by the sense-transfected and untransfected F-11 cells. The hemoglobin content of the antisense xenografts was much lower than that of the xenografts formed by the control cells. The reduced angiogenesis in the antisense xenografts was correlated with a decrease in vascular endothelial growth factor (VEGF) production. The expression of VEGF was suppressed in the antisense xenografts and the conditioned culture media of the antisense-transfected F-11 cells as determined by Western blotting analysis. This was further confirmed by immunohistochemistry of the tumors using antibodies against VEGF and platelet/endothelial cell adhesion molecule (PECAM-1). Therefore, our results demonstrate that reduced tumor growth in nude mice by suppression of GD3-synthase expression in F-11 cells results from minimal angiogenesis of the tumors through down-regulation of the VEGF expression, which indicates an important role for GD3 in tumor angiogenesis.
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PMID:Suppression of ganglioside GD3 expression in a rat F-11 tumor cell line reduces tumor growth, angiogenesis, and vascular endothelial growth factor production. 1111 51

Cancer cells undergo distinct metabolic changes to cope with their hypoxic environment. These changes are achieved at least partly by the action of transcriptional factors called hypoxia-inducible factors (HIFs). We investigated gene expression in cultured human colon cancer cells induced by hypoxic conditions with special reference to cell-adhesion molecules and carbohydrate determinants having cell-adhesive activity by using DNA-microarray and RT-PCR techniques. Hypoxic culture of colon cancer cells induced a marked increase in expression of selectin ligands, the sialyl Lewis x and sialyl Lewis a determinants at the cell surface, which led to a definite increase in cancer cell adhesion to endothelial E-selectin. The transcription of genes for fucosyltransferase VII (FUT7), sialyltransferase ST3Gal-I (ST3O), and UDP-galactose transporter-1 (UGT1), which are all known to be involved in the synthesis of the carbohydrate ligands for E-selectin, was significantly induced in cancer cells by hypoxic culture. In addition, a remarkable induction was detected in the genes for syndecan-4 (SDC4) and alpha5-integrin (ITGA5), the cell-adhesion molecules involved in the enhanced adhesion of cancer cells to fibronectin. The transcriptional induction by hypoxia was reproduced in the luciferase-reporter assays for these genes, which were significantly suppressed by the co-transfection of a dominant-negative form of HIF. These results indicate that the metabolic shifts of cancer cells partly mediated by HIFs significantly enhance their adhesion to vascular endothelial cells, through both selectin- and integrin-mediated pathways, and suggest that this enhancement further facilitates hematogenous metastasis of cancers and tumor angiogenesis.
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PMID:Hypoxia induces adhesion molecules on cancer cells: A missing link between Warburg effect and induction of selectin-ligand carbohydrates. 1514 Oct 79