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Sulfated mucus glycoprotein biosynthesis by human gastric mucosal biopsies was studied. Human gastric healthy specimens and cancer specimens were obtained from antral and corpus normal mucosal areas by biopsy. A comparison was made of the biosynthesized sulfated mucus glycoproteins assessed by the incorporation of ³⁵S-sulfate and ¹⁴C-glucosamine into the specimens using an organ culture technique. A significant uptake of ³⁵S-sulfate or ¹⁴C-glucosamine into the mucus glycoproteins was demonstrated in all specimens. ¹⁴C-glucosamine incorporation into the glycoproteins was almost the same for all biopsies. The synthesis of sulfated glycoprotein in healthy antral mucosa was about four times that in corpus mucosa. Significantly raised levels in sulfated glycoprotein biosynthesis were found in cancer specimens, being about 30 and 13 times higher in antrum and corpus mucosa than that of healthy specimens, respectively.

Radiolabeled glycoconjugates were prepared by incorporation of [³⁵S]sulfate and [³H]glucosamine into the gastric mucosa of human gastric resection specimens, using organ culture techniques. Specimens which incorporated higher amounts of [³⁵S]sulfate into high molecular glycoconjugates (Fr-1) were designated as group I. The average specific activity in Fr-1 of group I was 30 times that of group II, but the glucosamine uptake remained about the same in all cases. All specimens in group I were positive to intestinal metaplasia in their adjacent mucosal area. The sulfated glycoproteins in Fr-1 of group I were found to incorporate 80% of the ³⁵S and the remaining 20% by sulfated glycosaminoglycans. But the glycoconjugates constituting all the Fr-1 of group II were identified as glycoproteins and incorporating ³⁵S only to a small extent were identified as sulfated glycoproteins. The susceptibility of the glycoproteins from group I mucosa to pronase digestion was different from that of group II. The glycoproteins synthesized in group I mucosa were as sulfated glycoproteins as well as nonsulfated glycoproteins and glycosaminoglycans, while the group II glycoproteins consisted primarily of nonsulfated glycoproteins.

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