Distribution of mono-, di, and tri-O-acetylated sialic acids in normal and neoplastic colon.

The purpose of this study was to compare the expression of O-acetylated sialic acids on normal colonic epithelial cells to that on primary and metastatic human adenocarcinoma of the colon and rectum. In 24 cases, the relative percentages of biosynthetically labeled non-, mono-, di-, and tri-O-acetylated sialic acids were measured after hydrolytic release, separation, and identification by paper chromatography. In one case, the presence of di- and tri-O-acetylated sialic acids was confirmed by fast atom bombardment-mass spectral analysis. Differences were observed in the expression of sialic acids between normal colonic epithelium, "uninvolved" colon mucosa remote to a colonic adenocarcinoma, and colonic adenocarcinoma. The levels of mono- and tri-O-acetylated sialic acids accounted for the difference in the ratios of sialic acids expressed between normal and "uninvolved" colonic mucosa, while the total amount of O-acetylation was unchanged. However, no difference was observed in the relative amounts of non- and O-acetylated sialic acids between either fresh and tissue culture-established colon carcinomas, or fresh and tissue culture-established liver metastasis derived from carcinoma of the colon. The relative expression of these O-acetylated sialic acids molecules appears to vary according to tissue type. This study suggests that individuals with adenocarcinoma of the colon express a field defect resulting in abnormal ratios of O-acetylated sialic acids.