Adriamycin does not affect the repair of X-ray induced DNA single strand breaks

The ability of the antitumor antibiotic adriamycin (Ad) to inhibit the rejoining of DNA single strand breaks produced by X-rays was investigated in cultured cells. Chinese hamster ovary (CHO) cells were given 400 rad and were allowed to repair in the presence or absence of Ad for 60 min at 37 degrees C. The drug did not affect the ability of cells to repair DNA breaks and residual breaks found after the repair period were attributable to those induced by Ad alone.