LACK OF CORRELATION BETWEEN CISPLATIN-INDUCED APOPTOSIS, P53 STATUS AND EXPRESSION OF BCL-2 FAMILY PROTEINS IN TESTICULAR GERM-CELL TUMOR-CELL LINES

We investigated the role of p53 and of the Bcl-2 family proteins in th e apoptotic response of a panel of testicular tumour cell lines (NT2, NCCIT, S2 and 2102 EP). The p53 gene status and the capacity of the p5 3 protein to transactivate the P21/WAF/CIP gene were determined, and w e examined the correlation between p53 status and the susceptibility t o cisplatin-induced apoptosis. In contrast to wild-type p53-containing NT2 and 2102 EP cells, NCCIT (mutant p53) and S2 (no p53 protein) cel ls were shown to be p53-transactivation defective. However, NCCIT and SZ cells with nonfunctional p53 were readily triggered into apoptosis by cisplatin, whereas p53-transactivation competent 2102 EP cells fail ed to undergo cisplatin-induced apoptosis. The defective apoptotic pat hway in 2102 EP cells was reflected by a 4-fold decreased sensitivity to cisplatin in the MTT assay. We further demonstrated that the p53-in dependent differential cisplatin sensitivity among the testicular germ cell tumour (TGCT) cell lines was not due to differences in cellular cisplatin accumulation or DNA platination. The pattern of endogenous e xpression levels of Bar, Bcl-2, Bcl-x and Bak, which was not modulated by cisplatin treatment, demonstrated that these Bcl-2 family proteins are not involved in drug-induced apoptosis in the TOOT cell lines. Ou r results suggest a lack of correlation between cisplatin induced apop tosis, p53 status and expression of Bcl-2 family proteins in our panel of TGCT cell lines. We conclude that the cisplatin-induced apoptotic pathway in TGCT cell lines might be p53-independent and is probably no t associated with differences in the Bcl-2/Bax rheostat. (C) 1997 Wile y-Liss, Inc.