In vitro irradiation of doxorubicin with 18F-FDG Cerenkov radiation and its potential application as a theragnostic system

Abstract

Doxorubicin (DOX), an effective chemotherapeutic agent, has a wide excitation band centred at 480 nm. Cerenkov radiation (CR) is considered an internal light source in photodynamic therapy (PDT). DOX could be photoactivated by CR and thus, enhancing its cytotoxicity. In this work, ¹⁸F-FDG was used to evaluate the effect of Cerenkov radiation on DOX, in comparison to irradiation with a 450-nm laser beam, in terms of ROS production. The production of ¹O₂ and O₂^⁎- reactive species during DOX irradiation was detected indirectly by ABMA and DCPIP bleaching, respectively. The cytotoxic effect of the DOX / ¹⁸F-FDG CR system was evaluated in the T47D breast cancer cell line. The irradiation of DOX produced ¹O₂ and O₂^⁎- species using both ¹⁸F-FDG CR and a 450-nm laser beam. The majority reactive species produced in both cases was ¹O₂; a favourable result, given the greater cytotoxicity of this species. The viability of T47D cells in presence of DOX (5 nM), ¹⁸F-FDG (37.5 μCi) and DOX (5 nM)/¹⁸F-FDG (37.5 μCi) was (86 ± 9)%, (84 ± 8)% and (64 ± 5)%, respectively; these results suggest a synergistic cytotoxic effect derived from the cytotoxic activity of DOX and its photoactivation by ¹⁸F-FDG CR. It is worth noting that the system could be optimized in terms of DOX concentration and ¹⁸F-FDG activity for better results. Due to the fact that ¹⁸F-FDG is widely used in nuclear imaging, the DOX/¹⁸F-FDG system also possesses theragnostic characteristics. Thus, in this work, it is demonstrated that DOX can be used in a dual therapy system based on chemotherapy-PDT when ¹⁸F-FDG CR is used as a DOX excitation source.

Keywords: (18)F-FDG; Cerenkov radiation; Chemotherapy-PDT system; Doxorubicine∙HCl; Photodynamic therapy; Synergetic effect.