Apoptosis induction and inhibition of H-ras overexpression by novel trans-[PtCl2(isopropylamine)(amine')] complexes

Hitherto, it has been generally accepted as a paradigm of the biochemical pharmacology of platinum antitumor drugs that a cis configuration of the leaving groups is necessary for antitumor activity of platinum compounds. However, it has been recently observed that certain trans-platinum complexes have both in vitro and in vivo antitumor activity. We previously reported the synthesis, characterization and cytotoxic activity against ras-transformed cells of several trans-[PtCl2LL'] complexes where L and L' are asymmetric aliphatic amines (L = dimethylamine and butylamine, L' = isopropylamine). The results reported in this paper show that the compounds trans-[PtCl2(isopropylamine)(dimethylamine)] and trans-[PtCl2(isopropylamine)(butylamine)] kill Pam 212-ras cisplatin resistant cells through apoptosis induction. Moreover, Western blot data show that both compounds inhibit overexpression of H-ras oncogene in Pam 212-ras cells. Altogether, these data indicate that, in contrast with cis-DDP, the apoptotic activity of these novel trans-Pt(II) compounds in ras-transformed cells is associated with their ability to abolish ras-overexpression.