Unravelling the role of ferroptosis in mediating radiation injury and its cross-talk with Nrf2 signaling

Ionizing radiation (IR) exposure, whether accidental or intentional, severely compromises normal cellular functions. Ferroptosis, a non-apoptotic cell death process regulated by enhanced cellular iron-pool and lipid peroxidation, is increasingly been recognized as a pivotal mechanism contributing to tissue injury in response to IR. To comprehensively understand the role of ferroptosis in IR mediated injury, a meta-analysis was undertaken to integrate multiple microarray datasets to identify key ferroptosis mediators in response to radiation. Different microarray datasets from Gene Expression Omnibus (GEO) database were retrieved and analysed for identification of differentially expressed radio-responsive genes in blood and intestine. Pathway analysis using KEGG and Gene ontology suggested ferroptosis as one of the predominant pathways in all datasets. Protein-protein interaction network and hub gene network constructed using STRING database and CytoScape respectively revealed hub genes associated to ferroptosis pathway. Complementing the meta-analysis, an in-vivo study was performed for validation of hub genes in C57BL/6 male mice exposed to IR. Quantitative real-time PCR (qRT-PCR) of the hub genes related to ferroptosis was performed revealing an upregulation of promoter genes and downregulation of suppressor genes in response to radiation. The induction of ferroptosis was correlated with iron content and presence of lipid peroxidation by products as a hallmark of ferroptosis induction. IR caused extensive accumulation of lipid peroxide byproducts, MDA, HNE and 8 iso-prostanes, whereas the levels of their detoxifying enzyme, glutathione peroxidise was low in irradiated samples, confirming that ferroptosis is activated in response to radiation. The role of glutathione in regulation of ferroptosis was also evaluated in these samples. Concurrently, western blotting was conducted to evaluate protein expression of key ferroptotic markers. The possible correlation of regulation of ferroptotic mediators with Nrf2 signaling was also established. Overall, this study contributes to the understanding of the regulation of ferroptosis in response to radiation. The findings have implications for developing therapeutic strategies to mitigate the harmful effects of radiation exposure. (author)