Differences between the O-acetylated sialic acids of the epithelial mucins of human colonic tumors and normal controls: a correlative chemical and histochemical study.

Chemical analyses, together with histochemical assessments, were carried out on specimens of adenocarcinoma of the colon and histologically normal colonic epithelium (from resection margins from cases of carcinoma of the colon). In the epithelial glycoproteins of the normal tissue, both chemical and histochemical investigations indicated that the great majority of the sialic acids contained a side-chain O-acyl substituent located at position C8, whereas the side-chain substitution of the sialic acids of tumor glycoproteins was markedly reduced. Chemical analysis of the normal glycoproteins indicated that the great majority of the sialic acids were resistant to digestion with Vibrio cholerae neuraminidase, presumably due to an ester substituent at C4. The sialic acids of the tumor glycoproteins were significantly different from normal, in that they were less resistant to digestion with neuraminidase (p greater than 0.01), and therefore had a lower percentage of substitution at C4 (p greater than 0.01).