title: Unique alpha 2, 8-polysialylated glycoproteins in breast cancer and leukemia cells.
abstract: The N-linked oligosaccharides of neural cell adhesion molecule and the rat brain voltage-dependent sodium channel alpha subunit are specifically modified by alpha 2, 8-polysialic acid chains. Until now, this carbohydrate modification has been observed only on these two proteins in mammalian cells. We have identified 180-260 kDa proteins in RBL rat basophilic leukemia cells and MCF7 human breast cancer cells that are modified by alpha 2, 8-polysialylated oligosaccharides. Immunofluorescence microscopy and Northern analysis confirmed that these proteins are neither the neural cell adhesion molecule nor the sodium channel alpha subunit. The presence of authentic alpha 2, 8-polysialic acid on the basophilic leukemia and breast cancer proteins was confirmed by the elimination of anti-polysialic acid antibody staining after treatment with the alpha 2, 8-polysialic acid-specific endo-N-acetylneuraminidase. The failure of peptide N-glycosidase F to completely remove alpha 2, 8-polysialic acid bearing oligosaccharides from the RBL protein, and the sensitivity of these oligosaccharides to beta-elimination, suggests that alpha 2, 8-polysialic acid may be found on O-linked oligosaccharides. This identification of new alpha 2, 8-polysialylated proteins in RBL basophilic leukemia and MCF7 breast cancer cells suggests that alpha 2, 8-polysialylation of glycoproteins may be more widespread than originally believed, especially in cancer cells.
authors.affiliation: Department of Biochemistry, University of Illinois College of Medicine, Chicago 60612, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Martersteck
authors.forename: N L
authors.initials: NL
authors.lastname: Kedersha
authors.forename: D A
authors.initials: DA
authors.lastname: Drapp
authors.forename: T G
authors.initials: TG
authors.lastname: Tsui
authors.forename: K J
authors.initials: KJ
authors.lastname: Colley
mesh_terms: D000581:Amidohydrolases; D000818:Animals; D001943:Breast Neoplasms / Q000737:chemistry* / Q000235:genetics; D002236:Carbohydrate Conformation; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D015471:Leukemia, Basophilic, Acute / Q000235:genetics / Q000378:metabolism; D007942:Leukemia, Experimental / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012794:Sialic Acids / Q000032:analysis; D012795:Sialoglycoproteins / Q000737:chemistry*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D019006:Neural Cell Adhesion Molecules; D012333:RNA, Messenger; D012794:Sialic Acids; D012795:Sialoglycoproteins; C021319:polysialic acid; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase