Zohreh Eftekhari - Student research committee, Shiraz University of Medical Sciences, Shiraz, IRAN Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, IRAN
Reza Fardid - Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, IRAN Ionizing and Non-Ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, IRAN
Abbas Behzad Behbahani - Diagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, IRAN

Introduction: The radiation induced bystander effect (BSE) is the induction of biological changes in unexposed cells, by signals transmitted from bystander cells that cause the spread of radiation toxicity to adjacent or far tissues. In addition, reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as cytokines are involved in mediating mechanisms in bystander effect through unknown factors. Bystander effects occur due to stressors, such as ionizing radiation, Ultra violet Radiation (UVR) and chemotherapy drugs, which include a wide range of biological processes, such as DNA damage, cell death, apoptosis, cell survival reduction, delayed and premature mutations, and Micronuclei formation. Silver nanoparticles (Ag NPs) are widely used in electronics, bio-sensing, food industry, paints, sunscreens and medical devices. Due to the widespread use of these particles, the toxicological risks of Ag NPs must be determined for effective and safe use. The aim of this study was to investigate the possibility of increasing bystander effect on TK۶ human lymphoblastoid cell line, which were exposed to UVC and Ag NPs. Materials and Methods: The studied groups included Control, UVR, Ag NPs, UVR+ Ag NPs, BSE of UVR, BSE of UVR + Ag NPs. TK۶ cells were cultured in ۲۴-well plates. After ۲۴hrs Cells were exposed to Ag NPs (۱۰μg/ml) for ۱hr. Then they were exposed to UVR and after irradiation to determining the bystander effect, the irradiated cells medium was transferred to non-irradiated cells. Expression level of H۲AX mRNAs were examined by relative quantitative real-time polymerase chain reaction (PCR). Results: The results showed that there was a significant difference in the mean expression level of H۲AX genes of the UV group compared to the control group, control with Ag NPs, BSE of UV with BSE of UV + Ag Nps. There were not differences between control and BSE of UV. Conclusion: Our findings demonstrate the gene expression of H۲AX increased in UVR, Ag NPs, UVR + Ag NPs, groups significantly. In bystander groups UVR + Ag NPs decreased the H۲AX gene expression in comparison to control group.

UV Radiation, Bystander Effect, Ag nanoparticle, H۲ax gene