Increased uptake of actinomycin D in Ehrlich ascites tumour cells induced by daunorubicin.

The influence of anthracyclines on the uptake of actinomycin D in Ehrlich ascites tumour cells was studied in vitro. The anthracycline daunorubicin significantly increased the [3H]actinomycin D uptake both in whole tumour cells and in isolated nuclei of tumour cells. On the other hand, actinomycin D increased daunorubicin uptake only to a very small degree. Experiments with other intercalating drugs did not influence [3H]actinomycin D binding, suggesting a specific interaction between actinomycin D and the anthracyclines. The mechanism behind this interference is discussed. The increased cellular uptake of actinomycin D in the presence of daunorubicin may have implications for antineoplastic combination chemotherapy.