Induction of genotoxic and cytotoxic damage by aclarubicin, a dual topoisomerase inhibitor

The anthracycline aclarubicin (ACLA) is an intercalative Antibiotic and antineoplastic agent that efficiently binds to DNA, leading to a secondary inhibition of the catalytic activity of Topoisomerase II (Topo II) on DNA. Besides this activity, ACLA has been reported to exert a concomitant poisoning effect on Topo I, in a fashion similar to that of the antitumor drug camptothecin and its derivatives. As a consequence of this dual (Topo II catalytic inhibiting/Topo I poisoning) activity of ACLA, the picture is somewhat confusing with regards to DNA damage and cytotoxicity. We studied the capacity of ACLA to induce catalytic inhibition of Topo II as well as cytotoxic effects and DNA damage in cultured Chinese hamster V79 cells and their radiosensitive counterparts irs-2. The ultimate purpose was to find out whether differences could be observed between the two cell lines in their response to ACLA, as has been widely reported for radiosensitive cells treated with topo poisons. Our results seem to agree with the view that the radiosensitive irs-2 cells appear as hypersensitive ACLA as compared with radiation repair-proficient V79 cells. The recovery after ACLA treatment was also followed-up, and the irs-2 mutant was found to be less proficient than V79 to repair DNA strand breaks induced by ACLA.