A comparative study of cellular and molecular pharmacology of doxorubicin and MEN 10755, a disaccharide analogue

MEN 10755 is a disaccharide anthracycline endowed with a broader spectrum o f antitumour activity than doxorubicin (DOX). To investigate the cellular a nd molecular basis of its action, cytotoxic activity, drug uptake, subcellu lar localisation, induction of DNA damage, and apoptosis were assessed in t he human A2780 ovarian carcinoma cell line. Experiments with radiolabelled anthracyclines indicated that MEN 10755 exhibited reduced cellular accumula tion and a different subcellular distribution (higher cytoplasmic/nuclear r atio) than DOX. In spite of the lower nuclear concentration, MEN 10755 was as potent as DOX in eliciting DNA single- and double-strand breaks, G2/M ce ll arrest, and apoptosis. Sequencing of drug-induced topoisomerase II cleav age sites showed a common DNA cleavage pattern for MEN 10755 and DOX. Cleav age sites were always characterised by the presence of adenine in -1 positi on. However, the extent of DNA cleavage stimulation induced by MEN 10755 wa s greater than that produced by DOX. Reversibility studies showed that MEN 10755-stimulated DNA cleavage sites were more persistent than these induced by DOX, thus suggesting a more stable interaction of the drug in the terna ry complex. As a whole, the study indicated that the cellular pharmacokinet ics of MEN 10755 substantially differs from that of DOX, showing a lower up take and a different subcellular disposition. In spite of the apparently un favourable cellular pharmacokinetics, MEN 10755 was still as potent as DOX in inducing topoisomerase-mediated DNA damage. Although the extent and pers istence of protein-associated DNA breaks may contribute to the cytotoxic ef fects, the drug's efficacy as apoptosis inducer and antitumour agent could not be adequately explained on the basis of DNA damage mediated by the know n target (i.e. topoisomerase II), thus supporting additional cellular effec ts that may be relevant in cellular response. (C) 2001 Elsevier Science Inc . All rights reserved.