The aim of the present study was to examine the expression of pS2 protein in gastric carcinomas and normal gastric mucosa. Ninety cases of gastric carcinoma surgically removed by total or partial gastrectomy from 48 males and 42 females, 37-86 years old, were included in this study. Detection of pS2 protein was performed immunohistochemically by the use of monoclonal antibody and the staining was scored by an Histoscore system from 0 to 12 grades. Cytoplasmic immunostaining was detected in 55 cases (61%) of gastric carcinoma and in all examined cases of normal gastric mucosa near the tumors. In normal gastric mucosa the immunoreaction was localized in subnuclear and perinuclear region of the superficial epithelium and the upper two thirds of the foveolae, as well as in luminal secretions, whereas the deeper glands were negative. In the regions of epithelial dysplasia or intestinal metaplasia which were coexistent with the tumors, the staining was weaker than in normal epithelium or negative. In carcinomas the staining was positive in 26 out of 45 (57,8%) intestinal, 13 out of 25 (52%) diffuse, 12 out of 13 (92,3%) mixed and 4 out of 7(57,2%) mucinous type. Significantly higher H-score for pS2 protein was observed in carcinomas stage III and in those with more than 3 metastatic lymph nodes (P=0.05). There was no significant correlation of pS2 expression with clinical and pathological parameters such as patient age or sex, tumor grade, size and location. In conclusion, our findings indicate that: a. pS2 protein has constant expression and disrtibution in the gastric epithelium which is probably related to its putative physiological role in the cell renewal of gastric mucosa, and b. high pS2 expression in gastric carcinomas may be related to more aggressive biological behavior.

Key words: Gastric carcinoma, pS2, immunohistochemistry.

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