Isolation of a sulfated glycopeptidic antigen from human gastric tumors: Its localization in normal and cancerous gastrointestinal tissues

Abstract

A sulfated glycopeptidic antigen (SGA) was purified from papain-digested cancerous human gastric mucosa. The amino acid composition of this antigen was characterized by a high percentage of threonine and proline. Serine was present in small quantities and aromatic amino acids were absent. The amount of sulfate present was evaluated at 7.5%. Fucose, galactose, N-acetyl glucosamine, N-acetyl galactosamine and sialic acid were found to be present in the molar ratio 1:4.6:3.0:6.2:5.0. With immunofluorescence techniques, a rabbit antiserum against the sulfated glycopeptide stained adult gastric mucosa when this tissue had intestinal metaplasia and stained the goblet cells of the intestinal tract (small and large intestines). About 50% of colonic carcinomas and some gastric carcinomas contained SGA. This sulfated antigen was present in well-differentiated tumors and there was a good correlation between tumoral acid mucous secretory activity and the SGA positivity.

Antigens of gastric and intestinal mucous cells in human colonic tumours

“…Tissue and cell localization of M3 antigen were reported in a previous work (Bara et al, 1978). It was found that anti-M3 serum did not stain normal gastric mucosa on frozen sections.…”

“…(b) Anti-sulphoglycopeptidic antigen (SGA) serum was obtained as described previously (Bara et al, 1978). Briefly, 1 mg of SGA (purified from gastric tumours) was emulsified in complete Freund's adjuvant (Difco) and injected in the footpads.…”

“…IN A RECENT WORK (Bara et al, 1978) we described an antigen (SGA, now termed M3) that was associated with goblet cells in normal intestinal mucosa but not in normal stomach, and which appeared as an aberrant antigen in certain gastric tumours.…”

Differences in the expression of mucus-associated antigens between proximal and distal human colon adenocarcinomas

“…The first ones, called Ml are isolated as fucomucin (Bara et al, 1983a) common to gastric surface epithelium and ovarian mucinous cyst fluid (Bara et al, 1977) of pure endocervical type (Bara et al, 1979) mucosa. In contrast, another one, called M3 (Bara et al, 1978 was described in association with sulfomucins or sialomucins and found in goblet cells of the normal colonic but not in gastric mucosa. No regional difference between proximal and distal colonic mucosa can be shown using such antigens.…”

Another oncofoetal antigen in colonic carcinoma

“…Thus its occurrence in colonic carcinoma, though absent from normal adult colon, provides a new example of a re-emergent oncofoetal antigen. From a comparison of antigenic and biochemical properties and gastrointestinal distribution, it appears to be distinct from previously reported antigens of normal and malignant gastrointestinal tissues (Goldenberg et al, 1976;Bara et al, 1978;Pant et al, 1978).…”