Extent of apoptosis in relation to p53 and bcl-2 expression in germ cell tumors

This study investigates the extent of apoptosis in 53 testicular and ovarian germ cell tumors by using the in situ 3'-end DNA labeling technique on tumor sections. The tumors were also immunostained with antibodies to the p53 and bcl-2 proteins. The extent of apoptosis was highest in embryonal carcinoma (mean, 2.9%) followed by seminoma (mean, 1.1%), choriocarcinoma (mean, 0.7%) and immature teratoma (mean, 0.7%). In individual components of the mixed germ cell tumors the apoptotic index was in the same range as in the corresponding pure germ cell tumors. Mature teratomas rarely contained any apoptotic cells. Sixty-two percent of all the tumors expressed p53 protein. p53 expression was quantitatively strongest in embryonal carcinomas which also showed the highest level of apoptosis. Bcl-2 positivity could only be detected in some mesenchymal and epithelial components of the immature and mature teratomas; embryonal carcinomas, seminomas, or choriocarcinomas did not express bcl-2 at all. Our results show that the level of apoptosis in germ cell tumors associates with the histological type of the neoplastic component independent of whether it is singly present or a component of a mixed germ cell tumor. The results suggest that the quantity of p53 expression may contribute to the level of apoptosis in different tumor groups.