Transport of an iron: anthracycline complex by murine leukemia cells

Cytotoxicity and transport of daunorubicin (DNR) and of a DNR: iron complex were examined, using P388 murine lymphoblasts and P388/ADR, an anthracycline-resistant sub-line. The drug: iron complex was dissociated in the presence of serum or, in serum-free medium, at the cell surface. Moreover, DNR toxicity was not promoted when the drug was provided as an iron complex. While formation of a complex with iron can markedly potentiate reactivity of anthracyclines in cell-free systems, these complexes play a role in cytotoxicity of DNR only if generated in the intracellular environment.