Synergetic Effect of Silver Nanoparticles and UVC Irradiation on H2AX Gene Expression in TK6 Cells

The Bystander Effect of Ultraviolet Radiation and Mediators

A bystander effect is biological changes in non-irradiated cells by transmitted signals from irradiated bystander cells, which causes the radiation toxic effects on the adjacent non-irradiated tissues. This phenomenon occurs by agents such as ionizing radiation, ultraviolet radiation (UVR) and chemotherapy. The bystander effect includes biological processes such as damage to DNA, cell death, chromosomal abnormalities, delay and premature mutations and micronuclei production. The most involved genes in creating this phenomenon are cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), the nuclear factor of kappa B (NFkB) and Mitogen-Activated Protein Kinases (MAPKs). Radiation generated reactive oxygen species (ROS) can damage DNA, membranes and protein buildings. Studies have shown that Vitamin C, Hesperidin, and melatonin can reduce the number of ROS and have a protective role. Silver nanoparticles (Ag NPs) are the most abundant nanoparticles produced and when they enter cells, they can create DNA damage. Studies have shown that combined treatment with UVR and silver nanoparticles could form γ-H2AX and 8-hydroxy-2'-deoxyguanosine (8-OHdG) synergistically. This article reviews the direct and the bystander effects of UVR on the nuclear DNA, the effect of radioprotectors and Ag NPs on these effects.

Impact of Silver Nanoparticles on the Ultraviolet Radiation Direct and Bystander Effects on TK6 Cell Line

PURPOSE/AIM

Ultraviolet C (UVC) radiation is harmful to cells and living organisms that cause direct and indirect DNA damage. UVC can also increase the inflammatory genes expression such as COX-2 that results in elevated oxidative stress that plays a role in radiation-induced bystander effect (BSE). Silver nanoparticles (AgNPs) have used widely in commercial and medical products and the toxicological risks of AgNPs must be determined. The aim of this study was to investigate the direct and BSEs of UVC radiation and AgNPs on TK6 cell line.

MATERIALS AND METHODS

TK6 cells were exposed to AgNPs (10 μg/ml, 1 h). Then, they were exposed to UVC and to determine the BSEs of radiation, the irradiated cells media were transferred to nonirradiated cells. Expression level of H2AX and COX-2 mRNAs were examined by quantitative real-time PCR and 8-OHdG formation was examined by ELISA. The cell viability examined by MTT assay.

RESULTS

P < 0.05 was considered as the level of significance. The results showed that the mean expression level of H2AX mRNA in the AgNPs + UVC group increased significantly in comparison with UVC group. 8-OHdG increased significantly in the BSE of UV group in comparison with sham control of BSE. COX-2 mRNA increased significantly in the BSE of AgNPs + UVC with sham control in BSE.

CONCLUSIONS

Our findings showed the induced DNA damage in TK6 cell by AgNPs and UVC radiation and also were seen BSE.