Intestinal-type Adenomas Research Articles

Different expression of Tn and sialyl-Tn antigens between normal and diseased human gastric epithelial cells.

Thomsen-Friedenreich antigen (T antigen) has been supposed to be a cancer-specific carbohydrate antigen. We have previously shown that one third of the Japanese population normally expressed T antigen in gastric surface epithelia and the other two thirds expressed fucosyl-T antigen. Their sialylation and blocked-synthesis were associated with diseased conditions. In the present study, we studied gastric surface epithelial expression of monosaccharide antigen Tn, i.e., a precursor of T antigen, and sialyl-Tn. Normal fundic and pyloric epithelia, respectively, expressed Tn supranucleally and cytoplasmically, but did not express sialyl-Tn. In the intestinal metaplasias and intestinal-type adenomas, goblet cells expressed sialyl-Tn in their vacuoles, and absorptive cells expressed Tn apically. In gastric-type adenomas, Tn, but not sialyl-Tn, was detected. Intestinal-type cancers expressed Tn and sialyl-Tn more often than the diffuse-type cancers. Five cancers did not express Tn, sialyl-Tn, or the T-related antigens. In these, four were diffuse-type cancers. We concluded that: a) normal gastric epithelial cells express Tn; b) metaplastic differentiation is associated with sialylation of Tn and c) expression of Tn and sialyl-Tn is depressed in the gastric cancers.

Differential p53 protein expression in stomach adenomas of gastric and intestinal phenotypes: possible sequences of p53 alteration in stomach carcinogenesis.

In a comparative study, the expression of p53 protein was investigated in intestinal- and gastric-type adenomas of the stomach. The former is a conventional type, which is well known to be a premalignant lesion of the stomach, but the latter is a rare, more recently noted entity. Of 28 intestinal-type adenomas, 17 (60.7%) contained more than 5% of p53 immunoreactive cells. In these adenomas, the extent of positivity for p53 protein was significantly higher in high-grade dysplasia than in low-grade dysplasia (P < 0.05), suggesting that p53 alteration plays a part in the dysplastic progression of intestinal-type adenomas. Among 18 gastric-type adenomas in which most of the tumour cells displayed gastric-type mucin, substantial expression of p53 protein was found only in the 3 tumours with high-grade dysplasia. Thus, the incidence of p53 expression was significantly higher in intestinal-type adenomas than in gastric-type adenomas (P < 0.01). These results suggest that p53 gene alteration is an earlier event in the gastric carcinogenetic sequence with the intestinal phenotype than in that with the gastric phenotype.