Nanomaterials can enhance the delivery and treatment efficiency of anticancer drugs, but the mechanisms of the tumor-reducing activity of ferrous-ferric oxide (Fe(3)O(4)) nanoparticles (NPs) with daunorubicin (DNR) have not been established. Here we investigate the synergistic effects of Fe(3)O(4) NPs with DNR on the induction of apoptosis using K562 leukemia cells. Fe(3)O(4) NPs increased the ability of DNR to induce apoptosis in both adriamycin-sensitive and adriamycin-resistant K562 cells through the caspase 8-poly(ADP-ribose) polymerase pathway. Fe(3)O(4) NPs combined with DNR also effectively inhibited the tumor growth induced by the inoculation of K562 cells into nude mice. The increased cell apoptotic rate was closely correlated with the enhanced inhibition of tumor growth. Biodistribution studies in xenograft tumors indicated that Fe(3)O(4) NPs could be potentially excreted from the body via the gastrointestinal system. In conclusion, our study suggests that Fe(3)O(4) NPs combined with anticancer drugs could serve as a better alternative for targeted therapeutic approaches to cancer treatments.
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