Glucose-regulated protein 75 overexpression attenuates ionizing radiation-mediated injury in PC12 cells by inducing the expression of topoisomerase IIα.

Glucose-regulated protein 75 (Grp75), also known as mortalin/mthsp70/PBP74, is a member of the heat-shock protein 70 (HSP70) family. Grp75 is known to protect cells from stress-induced injury. Previous studies have shown that the expression of Grp75 is upregulated by a low dose of ionizing radiation (IR). To evaluate the protective role of Grp75 on cell proliferation in response to IR, Grp75 was overexpressed in a rat adrenal pheochromocytoma cell line (PC12). It was revealed that Grp75 overexpression desensitized PC12 cells to IR-mediated cell injury. In addition, the expression of topoisomerase IIα (Topo IIα) was downregulated in PC12 cells following γ-ray IR. The effect of Grp75 overexpression on Topo IIα expression was examined. It was revealed that Grp75 overexpression reversed the inhibitory effect of IR on Topo IIα expression. In conclusion, the data indicated that Grp75 overexpression attenuates IR-induced injury in PC12 cells by maintaining the expression of Topo IIα.