Colon carcinoma glycoproteins carrying α 2,6-linked sialic acid reactive with Sambucus Nigra agglutinin are not constitutively expressed in normal human colon mucosa and are distinct from sialyl-tn antigen
✍ Scribed by Toshihiko Murayama; Christian Zuber; Walter K.F. Seelentag; Wei-Ping Li; Wolfgang Kemmner; Philipp U. Heitz; Jürgen Roth
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- French
- Weight
- 429 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
In human colon carcinoma, increased amounts of sialic acids have been found and correlated with tumor progression. Further, the degree of O-acetylation of sialic acid residues in normal mucosa is higher than in colon carcinoma. Thus, tumor-associated sialylated antigens may be constitutively expressed in O-acetylated form in normal mucosa unreactive with the respective monoclonal antibodies. We have earlier demonstrated a colon carcinoma-associated expression of a 2,6-linked sialic acid residues with the Sambucus nigra agglutinin (SNA). We report now that de-acetylation of normal and transitional colonic mucosa, in contrast to sialyl-Tn antigen, does not result in SNA binding. Further, the a 2,6-linked sialic acid recognized by SNA is distinct from that of sialyl-Tn antigen. This is confirmed by Northern blotting detecting transcripts for a 2,6 sialyltransferase of N-glycoproteins and measurement of activity for this sialyltransferase. Blot analysis by SNA of colon carcinoma cells revealed few reactive glycoproteins. Quantitative differences in lectin labeling and sialyltransferase activity were found in HCT116 colon carcinoma cell sub-lines. Our data suggest that SNA binding in human colon carcinoma is due to de novo expression of a specific sialic acid present on selected glycoproteins. Int.