Expression of alpha 2,6-sialylated sugar chains in normal and neoplastic colon tissues. Detection by digoxigenin-conjugated Sambucus nigra agglutinin.
It has previously been reported that about 90% of human colon carcinomas express increased levels of the sialyltransferase which adds sialic acid in alpha 2,6 linkage to galactose residues on N-linked chains of glycoproteins. To ascertain whether colon cancer tissues actually express increased amounts of alpha 2,6-sialylated sugar chains on their glycoconjugates, we screened tissue sections of normal colon, benign and malignant colon tumors with digoxigenin-conjugated Sambucus nigra agglutinin (SNA), a NeuAc alpha 2,6Gal/GalNAc-specific lectin. At the concentration of lectin used, epithelial cells of all the 13 normal colon specimens examined were unreactive; 3 out of 8 benign lesions showed a weak reactivity being the remainder unreactive, while 23 out of 26 carcinomas were positive at a variable degree. Qualitative differences were evident among different carcinoma specimens. In some cases a large number of intensely stained intracytoplasmatic particles was present, thus suggesting that reactivity may be associated with secretions, very likely of mucus droplets. In other specimens there was a more uniform distribution of the staining which suggest that reactivity is associated with cell membrane glycoconjugates. These data indicate that the expression of a2,6-sialylated sugar chains is remarkably increased in the majority of colon cancer specimens examined.
Dall'Olio
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Dipartimento di Patologia Sperimentale, Università di Bologna, Italy.
Trerè
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D000236:Adenoma / Q000737:chemistry; D002240:Carbohydrate Sequence; D002277:Carcinoma / Q000737:chemistry; D003106:Colon / Q000737:chemistry*; D003110:Colonic Neoplasms / Q000737:chemistry*; D003111:Colonic Polyps / Q000737:chemistry; D004076:Digoxigenin / Q000378:metabolism; D006001:Glycoconjugates / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000737:chemistry; D037102:Lectins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000378:metabolism; D037121:Plant Lectins; D054788:Ribosome Inactivating Proteins
D006001:Glycoconjugates; D037102:Lectins; D037121:Plant Lectins; C050600:Sambucus nigra lectins; D009439:Neuraminidase; D054788:Ribosome Inactivating Proteins; D004076:Digoxigenin