Increased apoptosis associated with depressed type of early intestinal gastric cancer

Early gastric cancer can be macroscopically classified into elevated and de pressed types. To clarify the relationship between macroscopic appearance o f early gastric cancer and apoptosis or cell proliferation. formalin-fixed paraffin-embedded tissue specimens of 44 intestinal-type early gastric canc ers were investigated by the TUNEL method and immunohistochemical technique s. Diffuse type as excluded in this study. When tissue sections of gastric cancer were vertically classified into the 3 compartments or luminar, inter mediate and basal, the apoptosis index (%) was significantly higher in the basal compartment of depressed type (1.76 +/-2.04, mean +/- SD) than in the basal compartment of elevated type (0.63 +/-0.81, P=0.01). In depressed ty pe, the apoptosis index (%) was significantly higher in the basal compartme nt than in the luminar compartment (0.76 +/-0.85. P=0.03). Apoptosis-induci ng protein. Bax, was expressed more in each of the compartments of depresse d type than in those or elevated type, while there were no significant diff erences in expression of anti-apoptotic protein, Bcl-2, bet;cen the two typ es. Moreover, the apoptosis index (%) of Bax-positive gastric cancer was si gnificantly higher in the basal compartment (P=0.03), compared to that of B ax-negative gastric cancer, awhile there were no significant differences in apoptosis index (%) in any compartment between Bcl-2-positive and Bcl-2-ne gative gastric cancers. There were no significant differences in Ki-67 expr ession, either between the two types, or among the compartments of depresse d type. These results indicate that increased apoptosis with excessive expr ession of Bax in the basal compartment is involved in the morphogenesis of the depressed type in intestinal-type early gastric cancer.