Enhancing Targeted Cancer Treatment by Combining Hyperthermia and Radiotherapy Using Mn–Zn Ferrite Magnetic Nanoparticles

Radiotherapy (RT) is a major treatment method for non-small-cell lung cancer (NSCLC), and development of new treatment modality is now critical to amplify the negative effects of RT on tumors. In this study, we demonstrated a nanoparticle-loaded block copolymer micellar system for cancer hyperthermia treatment (HT) that can be used for synergistic therapy under alternating magnetic field (AMF) and radiation field. Block copolymer micelles (polyethylene glycol-block-polycaprolactone, or PEG-PCL) containing hyaluronic acid (HA) and Mn-Zn ferrite magnetic nanoparticles (MZF) were fabricated via a two-step preparation. HA-modified Mn-Zn ferrite magnetic nanoparticles (MZF-HA) can be enriched in CD44 highly expressing tumor cells, such as A549 (human lung adenocarcinoma cell line), through an active targeting mechanism via receptor-ligand binding of HA and CD44 (HA receptor). MZF can generate thermal energy under an AMF, leading to a local temperature increase to approximately 43 °C at tumor sites for mild HT, and the increased tumor oxygenation can enhance the therapeutic effect of RT. In vitro experiments show that MZF-HA is able to achieve excellent specific targeting performance toward A549 cells with excellent biocompatibility as well as enhanced therapy performance under HT and RT in vitro by apoptosis flow cytometry. In the A549 subcutaneous tumor xenografts model, MRI confirms the enrichment of MZF-HA in tumor, and hypoxia immunohistochemistry analysis (IHC) proved the increased tumor oxygenation after HT. Furthermore, the tumor volume decreases to 49.6% through the combination of HT and RT in comparison with the 58.8% increase of the untreated group. These results suggest that the application of MZF-HA is able to increase the therapeutic effect of RT on A549 and can be used for further clinical NSCLC treatment evaluation.