Augmentation of epirubicin cytotoxicity by cycloheximide.

The effect of cycloheximide (CH) on the cytotoxic activity of the anthracycline antibiotic epirubicin (EPI) was examined in cell cultures of murine leukemia doxorubicin (DOX)-sensitive P388 and -resistant P388 cells. The addition of CH (0.002 mu g/ml) to the growth medium markedly enhanced the EPI-induced cytotoxic effect in sensitive cells as well as that observed in resistant cells. CH, however, did not affect the intracellular content of EPI. The inhibition of DNA synthesis in leukemia cells was remarkable with the combination of EPI and CH compared with each drug alone. These results suggest that the combination of EPI and CH appears to be useful in killing mouse leukemia cells.