Replicative and unscheduled DNA synthesis in adriamycin-treated myocardial cells

The effect of the potent antitumor antibiotic adriamycin (ADM) on chromosome integrity, DNA replication, and unscheduled DNA synthesis was investigated in cultured rat cardiac cells. Chromosome distribution, autoradiography, and [3H]thymidine (dThd) incorporation studies were carried out on separate cultures. A 3-hr pulse of ADM at a concentration of 1 microgram/ml was sufficient to cause chromosomal aberrations that were evident for up to 3 days post-ADM treatment. At the same ADM dosage, DNA replication was depressed for up to 6 days by as much as 90%, yet the ability of the cardiac cells to repair UV-damaged DNA was not impaired. However, cells exposed to higher concentrations of ADM failed to undergo significant UV-induced repair.