Development of Theragnostic Hetero-nanocubes for Head and Neck Cancer Radiotherapy

Objectives: Objective of this study is to develop a nanostructure that can maximize therapeutics and diagnosis for head and neck squamous cell carcinoma (HNSCC) by enhancing its radiosensitivity while protecting normal tissues.
Methods: To synthesize FION-CeNPs FIONs coated with PEI and Bromide-activated CeO2 were covalently conjugated. Physicochemical characterization of FION-CeNP was done by TEM and Zetasizer. MR relaxivity was measured by 3T MR scanner. Radiosensitization effect was measured by using A253 cells and primary HNSCC cells. After 48hrs post 10Gy irradiation caspase 3/7 activity assay and LDH viability test were performed. Radioprotection was tested by using embyronic submandibular salivary glands (eSMG) 48hrs after 10Gy irradiation. For in vivo experiment 10mg Fe/kg FION-CeNPs were intravenously injected to A253 cell xenograft mice. MR imaging of tumor was aquired by 3T MRI scanner. Mice were irradiated 2Gy/day for 5 consecutive days. After 18days post-irradiation mice were sacrified for further analysis.
Results: Well-dispersed 20nm FION-CeNPs showed approximately 50nm hydrodynamic size with +50mV zeta potential. FION-CeNP showed high r2 relaxivity (760/mM s). FION-CeNP-pretreated irradiated confluent A253 and primary HNSCC groups showed 1.7 folds higher LDH release and 2 folds higher apoptotic rate than untreated groups. However FION-CeNP-pretreated eSMGs showed 1.5 folds higher bud number and significantly lowered apoptotic rate of c-kit/AQP-5+ pro-acinar cells and parasympathetic ganglion than untreated group. The selective protection was due to pH difference between cancer and normal cells. In xenograft model MR signal of tumor was significantly attenuated after 1hr administration of FION-CeNPs. After 18days post-irradiation FION-CeNP-pretreated mice showed 60% decreased tumor mass but salivary function was 2.3 folds higher after 50days post-irradiation.
Conclusions: FION-CeNPs successfully enhanced MR contrast in vivo with high r2 relaxivity. FION-CeNPs radio-protected salivary glands but radiosensitized HNSCC cells.