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

Abstract

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-<i>block</i>-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. <i>In vitro</i> 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 <i>in vitro</i> 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.