RESUMO
<p><b>OBJECTIVES</b>To explore the mechanism of development and aggressiveness in gastric carcinomas by investigating the expression and role of CD97 and its cellular ligand CD55 in gastric carcinomas.</p><p><b>METHODS</b>Tumor and corresponding normal mucosal tissue, collected from 39 gastric carcinoma patients, were examined by immunohistochemistry and RT-PCR for the expression of CD97 and CD55.</p><p><b>RESULTS</b>CD97(stalk) was strongly stained on scattered tumor cells or small tumor cell clusters at the invasion front of gastric carcinomas. The expression of CD97(stalk) was frequently observed in tumors of stage I and T1 gastric carcinoma patients. The expression of CD97(stalk) between Stage I and Stage II, III, IV specimens showed significant difference (P<0.05), between T1 and T2, T3, T4 specimens also showed significant difference (P<0.05). Specimens with tumor invasion depth limited in mucosa of T1 specimens showed higher positive CD55 expression than specimens with the same tumor invasion depth in T2, T3, T4 specimens, the expression of CD55 between T1 and T2, T3, T4 specimens was significantly different (P<0.05). There was strong correlation between the distribution patterns of CD97(stalk) and CD55 on tumor tissues (r=0.73, P<0.05). Signet ring cell carcinomas frequently contained strong CD97(stalk) and CD55-staining.</p><p><b>CONCLUSIONS</b>Our results suggest that CD97(stalk) is probably involved in the growth, invasion and aggressiveness of gastric carcinomas by binding its cellular ligand CD55. CD97(stalk) and CD55 could be useful as molecular markers for prognosis and therapy of gastric carcinoma patients.</p>