title: Transfection of 2,6 and 2,3-sialyltransferase genes and GlcNAc-transferase genes into human glioma cell line U-373 MG affects glycoconjugate expression and enhances cell death.
abstract: Human glioma cell line U-373 MG expresses CMP-NeuAc : Galbeta1,3GlcNAc alpha2,3-sialyltransferase [EC No. 2.4.99.6] (alpha2,3ST), UDP-GlcNAc : beta-d-mannoside beta1,6-N-acetylglucosaminyltransferase V [EC 2.4.1.155] (GnT-V) and UDP-GlcNAc3: beta-d-mannoside beta1,4-N-acetylglucosaminyltransferase III [EC 2.4.1.144] (GnT-III) but not CMP-NeuAc : Galbeta1,4GlcNAc alpha2,6-sialyltransferase [EC 2.4.99.1] (alpha2,6ST) under normal culture conditions. We have previously shown that transfection of the alpha2,6ST gene into U-373 cells replaced alpha2,3-linked sialic acids with alpha2,6 sialic acids, resulting in a marked inhibition of glioma cell invasivity and a significant reduction in adhesivity. We now show that U-373 cells, which are typically highly resistant to cell death induced by chemotherapeutic agents (< 10% death in 18 h), become more sensitive to apoptosis following overexpression of these four glycoprotein glycosyltransferases. U-373 cell viability showed a three-fold decrease (from 20 to 60% cell death) following treatment with staurosporine, C2-ceramide or etoposide, when either alpha2,6ST and GnT-V genes were stably overexpressed. Even glycosyltransferases typically raised in cancer cells, such as alpha2,3ST and GnT-III, were able to decrease viability two-fold (from 20 to 40% cell death) following stable overexpression. The increased susceptibility of glycosyltransferase-transfected U-373 cells to pro-apoptotic drugs was associated with increased ceramide levels in Rafts, increased caspase-3 activity and increased DNA fragmentation. In contrast, the same glycosyltransferase overexpression protected U-373 cells against a different class of apoptotic drugs, namely the phosphatidylinositol 3-kinase inhibitor LY294002. Thus altered surface protein glycosylation of a human glioblastoma cell line can lead to lowered resistance to chemotherapeutic agents.
authors.affiliation: Department of Pediatrics MC 4068, University of Chicago School of Medicine, 5841 S. Maryland Avenue, Chicago, IL 60637, USA. dawg@midway.uchicago.edu
authors.forename: G
authors.initials: G
authors.lastname: Dawson
authors.forename: J R
authors.initials: JR
authors.lastname: Moskal
authors.forename: S A
authors.initials: SA
authors.lastname: Dawson
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000235:genetics; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D005910:Glioma / Q000201:enzymology* / Q000235:genetics; D006001:Glycoconjugates / Q000096:biosynthesis*; D006031:Glycosylation; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics* / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics* / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D014162:Transfection; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D004791:Enzyme Inhibitors; D006001:Glycoconjugates; D009025:Morpholines; C064769:N-acetylsphingosine; D009844:Oligosaccharides; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D005047:Etoposide; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D012799:Sialyltransferases; C029156:N-acetyllactosaminide alpha-2,3-sialyltransferase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D019311:Staurosporine; D013110:Sphingosine; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase