EXPRESSION OF BCL-2 AND P53 CORRELATES WITH THE MORPHOLOGY OF GASTRICNEOPLASIA

The growth of a tumour can be determined by an interplay between cell proliferation and loss. The expression of apoptosis-related proteins ( Bcl-2 and p53), cell proliferation (Ki-67), and apoptotic cell death w ere investigated using immunohistochemistry and terminal deoxynucleoti dyl transferase-mediated dUTP-biotin nick end labelling in gastric neo plasm, to evaluate whether they correlate with the morphology of the t umour. The materials included ten cases of gastric adenoma and 40 case s of early gastric carcinoma consisting of differentiated adenocarcino mas (n=20) and undifferentiated carcinomas (n=20). All cases of adenom a and eight cases of differentiated adenocarcinoma were of the elevate d type, while 12 differentiated adenocarcinomas and all of the undiffe rentiated carcinomas were of the depressed type. The diffuse expressio n of Bcl-2 was observed in all cases of adenoma and seven out of eight (88 per cent) of elevated-type differentiated adenocarcinoma. In cont rast, Bcl-2 expression was absent or focal in the depressed type of ca rcinoma. Overexpression of p53 was found exclusively in the depressed type of carcinoma. Thus, Bcl-2 and p53 expression was associated with tumour morphology. It seemed unlikely that Bcl-2 and p53 expression wa s involved in the morphogenesis of the gastric tumours through inhibit ing apoptotic cell death, since the degree of apoptosis in Bcl-2-posit ive gastric tumours was rather higher than that in Bcl-2-negative ones and it did not differ significantly between p53-positive and p53-nega tive tumours. Instead, the diffuse distribution of Bcl-2 correlated wi th the superficial distribution of Ki-6-positive proliferating cells, and the overexpression of p53 had a tendency to correlate with the dif fuse distribution of proliferating cells. These results suggest that d iffuse Bcl-2 expression and a superficial distribution of proliferatin g cells may contribute to the elevated configuration, and that overexp ression of p53 and a diffuse distribution of proliferating cells may r esult in the depressed configuration in the relatively early stages of gastric tumourigenesis. (C) 1998 John Wiley & Sons, Ltd.