Effect and mechanism of ionizing radiation on ferroptosis in mouse hepatocytes / 中华放射肿瘤学杂志

ABSTRACT

Objective:To investigate the effect and mechanism of ionizing radiation on ferroptosis in mouse hepatocytes.Methods:Twenty-four C57BL/6J mice were divided into two groups by random number table method: healthy control group (control group, n=6) and irradiation group (whole liver was irradiated with a single dose of 30 Gy X-ray, n=18). Mice were sacrificed at 6, 24 and 72 h (6 mice per time point) after irradiation to obtain liver tissue and plasma samples. The contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in plasma were measured by automatic biochemical analyzer. The prothrombin time (PT) and activated partial thromboplastin time (APTT) were measured by automatic biochemical analyzer. Pathological changes of liver tissues were observed by hematoxylin-eosin (HE) staining. The iron deposition in liver tissues was detected by Prussian blue staining. The expression levels of 4-Hydroxynonenal (4HNE) and hepcidin in the liver were determined by immunohistochemical staining, and quantitative analysis was performed. Plasma malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, total antioxidant capacity (T-AOC) and glutathione (GSH) content were determined by microplate reader analysis according to the kit instructions. The expression levels of transferrin receptor 1 (TfR1), p53, solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in the liver were measured by Western blot. Results:Compared with the control group, the plasma contents of ALT ( t=5.15, 5.47, both P<0.001) , AST at 6 and 24 h after irradiation were increased ( t=8.42, 2.50, both P<0.001), the plasma PT was prolonged ( t=3.12, P=0.011) and the APTT was shortened ( t=3.26, P=0.009) at 72 h after radiation in the irradiation group. Histopathological results showed that evident liver edema was observed at 6, 24 and 72 h after irradiation ( t=9.58, 10.09, 18.70, all P<0.001). Different degrees of iron deposition were observed ( t=8.57, 15.31, 32.11, all P<0.001). The infiltration of hepcidin positive cells was significantly increased after irradiation ( t=5.36, 13.17, 17.11, all P<0.001). The number of 4HNE positive cells was significantly increased ( t=18.86, 22.67, 9.12, all P<0.001). At the same time, ionizing radiation induced a significant increase in plasma MDA content ( t=4.36, 7.47, 8.22, all P<0.001), and a decrease in SOD ( t=4.52, 5.80, 7.60, all P<0.001), T-AOC ( t=13.24, 20.49, 24.96, all P<0.001) and GSH ( t=2.78, 6.07, 11.25, P=0.020, <0.001, <0.001), respectively. The expression level of TfR1 protein was significantly up-regulated ( t=3.46, 5.40, P=0.026, 0.006), whereas that of GPX4 protein was significantly down-regulated ( t=11.88, 30.63, both P<0.001) at 24 and 72 h after irradiation. At 6, 24 and 72 h after irradiation, the expression level of p53 protein was significantly up-regulated and maintained at a high level ( t=7.84, 4.25, 8.22, P=0.001, 0.013, 0.001), while that of SLC7A11 protein was significantly down-regulated ( t=9.29, 19.96, 9.09, all P<0.001). Conclusion:Ionizing radiation induces the ferroptosis in hepatocytes, and its mechanism may be related to the activation of p53-SLC7A11-GPX4 pathway.