Influence of bismuth oxide nanoparticles on bystander effects in MCF-7 and hFOB 1.19 cells under 10 MV photon beam irradiation

Abstract

BackgroundNanomaterials have been applied as radiosensitizer in an effort to improve the effectiveness of radiotherapy in killing cancer cells while simultaneously sparing the healthy normal tissue. Increase in radiotoxicity to the cancerous region might also influence the non-targeted cells through radiation-induced bystander effect (RIBE) mechanism. In this study, we implemented Bi2O3 NPs as radiosensitizer in combination with megavoltage radiotherapy and probe into the RIBE consequences in the non-targeted cells. AimTo investigate the effects of bismuth oxide nanoparticles (Bi2O3 NPs) on RIBE triggered in MCF-7 and hFOB 1.19 after irradiation with 10 MV clinical photon beam. Materials and methodsThe MCF-7 (human breast cancer) and hFOB 1.19 (human fetal osteoblast) cell lines were incubated with and without Bi2O3 NPs prior to irradiation. The treated cells were irradiated with radiation doses of 0 to 12 Gy using 10 MV photon beam in a single exposure. The irradiated-cell conditioned medium (ICCM) were collected from the targeted cells and transferred into the non-targeted cells. Reactive oxygen species (ROS), cell viability and colony forming assay was employed to evaluate the effect. ResultsThe present study demonstrated that the MCF-7 and hFOB 1.19 bystander cells are able to maintain their cell viability for more than 80% after 48 h incubation with ICCM treated with Bi2O3 NPs at 2 Gy radiation dose. The percentage of cell survival fraction of hFOB 1.19 cells which received ICCM with Bi2O3 NPs decreased to 86.8%, in contrast to MCF-7 bystander cells which show an increment in their cells survival after treatment with Bi2O3 NPs. Our results show that the ROS level was increased in the bystander cells, but the addition of Bi2O3 NPs did not significantly increase the ROS level. ConclusionsThe application of nanoparticles for radiosensitization during radiotherapy must also considered the RIBE responses in the non-irradiated cells. These findings provide evidence that the use Bi2O3 NPs as radiosensitizer in radiotherapy is safe and do not significantly increase the RIBE responses in non-targeted cells.