Induction of apoptosis by the bis-Pt(III) complex [Pt-2(2-mercaptopyrimidine)(4)Cl-2]

We analyzed both the cytotoxicity and the type of cell death produced by th e novel binuclear Pt(III) compound Pt-Spym ([Pt-2(2-mercaptopyrimidine)(4)C l-2]) in kidney human fibroblasts and in human tumor cell lines (HeLa, CH1, CH1cisR and HL-60). The data showed that Pt-Spym displayed higher cytotoxi city against these tumor cells than cisplatin. In contrast, Pt-Spym had low toxicity against normal human fibroblasts. Interestingly, Pt-Spym circumve nted cisplatin resistance in CH1cisR cells. We also observed that Pt-Spym i nduced the characteristic changes attributed to apoptosis in cells with nor mal levels of p53 protein (CH1 and CH1cisR) and with low levels of p53 prot ein (HeLa), but not in cells lacking p53 (HL-60). Interestingly, Western bl ot data indicated that apoptosis induction by Pt-Spym in HeLa, CH1, and CH1 cisR cells was not associated with drastic changes in p53 levels. However, cis-DDP strongly decreased p53 levels in CH1 and CH1cisR cells and abolish p53 protein in HeLa cells. Altogether, these results suggest that induction of apoptosis by Pt-Spym requires the presence of p53 protein. BIOCHEM PHAR MACOL 60;3:371-379, 2000. (C) 2000 Elsevier Science Inc.