TiO2 Nanoparticle as a Sensitizer Drug in Radiotherapy: in Vitro Study

Background: Radiosensitizer drugs are used to enhance the efficiency of radiotherapy. Some nanoparticles can be considered as radiosensitizers, because they enhance cytotoxicity due to oxidative stress and increase free radical yield, especially ROS, within cells resulting to cell death.

Methods: In this study, synergistic effect of TiO2 nanoparticles was evaluated in presence of 60Co gamma rays on human breast cancer (MCF-7) and gastric cancer (MKN-45) cell lines. After cell culture, cells were exposed to several doses of gamma rays and a dose of 2Gy was selected due to survival analysis. Next, several doses of nanoparticle from each type was applied and cell survival was analyzed from which a dose of 30µg/ml was selected for the remainder of study. Finally, synergistic effect of gamma rays and nanoparticles was evaluated in two time delay groups using MTT assay.

Results: Viability of cells in presence of gamma radiation and nanoparticles, significantly reduced compared to viability of cells exposed only to radiation or nanoparticle, alone (P-value≤0.05). The effect was dependent on nanoparticle type, time between addition of nanoparticle to cells and exposure to gamma rays and also cell dependent.

Conclusion: TiO2 increased sensitivity of cancer cells to gamma radiation, due to an increase in ROS production and cytotoxicity. Anatase crystals have more severe effects than Rutile crystal because of having a larger surface area and creation of more free radicals. Therefore, this nanoparticle has the potential to be used as a radiosensitizer and further studies should be considered on other cell lines and in vivo.