Targeted gold nanoparticles enhance sensitization of prostate tumors to megavoltage radiation therapy in vivo.

We report potent radiosensitization of prostate cancers in vitro and in vivo using goserelin-conjugated gold nanorods. Progressive receptor-mediated internalization of conjugated nanorods over time increases the radiation interaction cross-section of cells and contributes to the effects observed in vitro. The low concentrations of gold required, the long interval between injection of nanoparticles and radiation, and the use of megavoltage radiation to generate radiosensitization in vivo foretell the possibility of eventual clinical translation of this approach. The ability of gold nanoparticles (AuNPs) to enhance the effect of physical radiation dose on tumor cells is known. This radiosensitization effect is thought to result from an increased number of photoelectric absorption events and the increased number of electrons present in gold. The authors here sought to further increase the amount and specificity of gold accumulation in prostatic cancer cells by conjugating gold nanorods to goserelin, a synthetic luteinizing hormone releasing hormone (LHRH) analogue that would bind to the LHRH receptor overexpressed in prostate cancers. It was shown that tumour cells were more sensitive to megavoltage radiation therapy. It is hoped that there would be eventual clinical translation of this approach.