In vivo effect of cis- and trans-diamminedichloroplatinum(II) on DNA and chromatin degradation in Ehrlich ascites tumour cells.

Ehrlich ascites tumour (EAT) cell nuclei were isolated from mice treated with cis- and trans-diamminedichloroplatinum(II) (DDP). The electrophoretic analysis of DNA extracted from corresponding nuclei revealed the high level of EAT DNA stability suggesting very low DNA endonuclease activity. The DNA degradation to high molecular weight fragments was achieved by mild treatment of nuclei with exonuclease DNase I. Cis- and trans-DDP reduced the rate of EAT DNA breakdown to high molecular weight fragments. Direct gel electrophoresis of the same nuclei confirm and extend our recent finding of rat liver chromatin breakdown to large chromatin blocks of uniform size.