Naringin inhibits gamma radiation-induced oxidative DNA damage and inflammation, by modulating p53 and NF-κB signaling pathways in murine splenocytes

Abstract

The adverse effects of ionizing radiation occur due to the generation of reactive oxygen species (ROS). The aim of this study was to identify the protective effects of naringin (NG), a citrus flavonoid, on ionizing radiation (IR)-induced differential stress response, with an exploration of the mechanisms involved in this process. Isolated murine splenocytes were incubated in the presence and in the absence of different concentrations of NG (50 and 100 μM) for 1 h prior to 6 Gy γ-irradiation, and the molecular mechanisms of action were determined through biochemical, immunoblot, flow cytometric, and immunofluorescence studies. Pretreatment with NG significantly prevented IR-induced intracellular ROS generation, thereby preventing the formation of cellular TBARS and the development of cellular nitrite. NG significantly reduced nuclear DNA damage with respect to the irradiated splenocytes, through the inhibition of DNA-PKcs and p-γH2AX. The reduced cell viability as a result of irradiation was recovered by NG through modulation of the redox-regulated cell signaling system. NG pretreatment resulted in significant inhibition of IR-induced G1/S phase cell cycle arrest through the modulation of p53-dependent p21/WAF1, cyclin E, and CDK2 activation. The results also demonstrated that NG blocked the IR-induced p38 function and reversed IR-mediated differential stress response through inhibition of the NF-κB pathway. Thus, the p38/NF-κB pathway participated in the IR-induced inflammatory development, leading to upregulation of CRP, MCP-1, and iNOS2 gene expression. However, NG pretreatment reversed the inflammatory development through downregulation of NF-κB, and regulated the expression of CRP, MCP-1, and iNOS2. The above results provide a theoretical basis for the preventive use of NG against radiation-induced multiple cellular anomalies.

Keywords::

• reactive oxygen species
• DNA damage
• cell cycle arrest
• inflammation
• immune suppression

Acknowledgments

The authors are thankful to Dr. Abhijit Saha (Division of Radiation Chemistry, UGC-DAE CSR, Kolkata Centre, India) for providing the necessary irradiation facilities. The authors are also thankful to Dr. Debashis Bandyopadhyay for editorial assistance. The authors gratefully acknowledge CRNN and DBT-IPLS, University of Calcutta, for providing research facilities.

Declaration of interest

The authors have declared no conflict of interest. The authors acknowledge the Council of Scientific and Industrial Research (CSIR) for major funding support [23(0024)/12/EMRII]. KM is the recipient of CSIR SRF and UD is a JRF of the Life Science Research Board (LSRB).