Ultra-high dose rate irradiation induced DNA strand break in plasmid DNA
10.3760/cma.j.cn112271-20221122-00453
- VernacularTitle:超高剂量率照射诱导质粒DNA链断裂损伤的研究
- Author:
Hui LUO
1
;
Qigang YUAN
;
Phyllis ZHANG
;
Leijie MA
;
Ronghu MAO
;
Hongchang LEI
;
Yanan SUN
;
Shuai SONG
;
Xiaohui WANG
;
Hong GE
Author Information
1. 郑州大学附属肿瘤医院肿瘤放疗科，郑州 450008
- Keywords:
Ultra-high dose rate irradiation;
DNA strand breaks;
Physioxia;
Free radical;
Relative biological effectiveness
- From:
Chinese Journal of Radiological Medicine and Protection
2023;43(3):161-167
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the effects on DNA strand break induced by ultra-high dose rate (FLASH) electron beam and conventional irradiation, and investigate whether FLASH effect was correlated with a reduction of radiation response.Methods:Aqueous pBR322 plasmid was treated with FLASH (125 Gy/s) and conventional irradiation (0.05 Gy/s) under physioxia (4% O 2) and normoxia (21% O 2). Open circle DNA and linear DNA were detected by agarose gel electrophoresis, and the plasmid DNA damage was quantified with an established mathematical model to calculate the relative biological effect (RBE) of DNA damage. In some experiments, Samwirin A (SW) was applied to scavenge free radicals generated by ionizing radiation. Results:Under physioxia, the yields of DNA strand breakage induced by both FLASH and conventional irradiation had a dose-dependent manner. FLASH irradiation could significantly decrease radiation-induced linear DNA compared with conventional irradiation ( t=5.28, 5.79, 7.01, 7.66, P<0.05). However, when the aqueous plasmid was pretreated with SW, there was no difference of DNA strand breakage between FLASH and conventional irradiation ( P>0.05). Both of the yields of open circle DNA and linear DNA had no difference caused by FLASH and conventional radiotherapy at normoxia, but were significantly higher than those under physioxia. In addition, the yields of linear DNA and open circle DNA induced by FLASH irradiation per Gy were (2.78±0.03) and (1.85±0.17) times higher than those of conventional irradiation, respectively. Conclusions:FLASH irradiation attenuated radiation-induced DNA damage since a low production yield of free radical in comparison with conventional irradiation, and hence the FLASH effect was correlated with oxygen content.
