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

Abstract

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 C5, whereas the side-chain substitution of the sialic acids of tumor glycoproteins was markedly reduced. Chemical analysis of the normal glycoproteins indicated distilled water; the extract was processed (2 1). Glycoproteins were also extracted from fresh human colonic epithelial cells (16) and fixed in formalin (21). O-acetyl groups were estimated by determining the quantity of methyl acetate produced on treatment of the lyophilized glycoprotein 0 OH 3 218 REID, CULLING, DUNN, RAMEY, MAGIL, CLAY with 0. 1 M sodium methoxide in anhydrous methanol for 2 hr at room temperature, using a miniaturized version of the assay procedures of Ludowig and Dorfman (13). The procedures and calculations used for the determination of the side-chain O-acetyl substitution pattern of the sialic acids were those used previously (I 9, 2 I). The method for determining the percentage of sialic acids substituted at C9 was however slightly modified by performing the ultrafiltration step prior to the reduction with sodium borohydride. This resulted in a considerable reduction in the color Literature Cited

Ground squirrel model for cholelithiasis: Role of epithelial glycoproteins

“…The noted reduction of sialomucin expression during the hypersecretory state by LM and TEM histochemistry was further supported by the lectin cytochemistry. This particular pattern was interesting when compared to epithelial glycoprotein secretion in other areas of the tubular gastrointestinal tract in response to disease processes (Reid et al, 1980(Reid et al, , 1985b. Many intestinal and colonic diseases present a reduction of sulphomucin and a significant increase in sialomucin synthesis and secretion.…”

Specific techniques for the identification of O‐acylated sialic acids in colonic mucins

“…(iii) Chemical correlation. Chemical studies (Reid et al, , 1978b(Reid et al, , 1979) of epithelial glycoproteins either isolated from formalin fixed colon, or from fresh colon Reid et al, 1975aReid et al, , by 1977 and post fixed, showed that the sialic acids were much more neuraminidase labile after KOH than would have been expected from the histochemical results on the same specimens; although in only a few cases was all the sialic acid removed. These data imply that there is a class of sialic acids which are not neuraminidase or KOH/ neuraminidase labile.…”

Lectin‐binding Sites in Normal, Hyperplastic, Adenomatous and Carcinomatous Human Colorectal Mucosa

“…This indicates that terminal carbohydrate structures of cellular glycoconjugates in goblet cell mucin are modified in adenomas showing mild or moderate dysplasia. Whether this is due to a different kind of sialic acid being more resistant (17,31,32) to Vibrio cholerae neuraminidase treatment, as suggested by the study of Cooper and Reuter (7), or the presence of other sugar moieties (38,39) in the non-reducing terminus of oligosaccharide chains remains unknown. In some adenomas showing mild or moderate dysplasia an apical linear staining was seen with PNA, VVA and GSA-I1 in focal areas of non-mucinous columnar cells.…”