Carbon-ion beams induce production of an immune mediator protein,high mobility group box 1,at levels comparable with X-ray irradiation

X-ray radiotherapy activates tumor antigen-specific t-cell responses,and increases in the serum levels of high mobility group box 1 (hmgb1) induced by x-ray irradiation play a pivotal role in activating anti-tumor immunity. here,we examined whether carbon-ion beams,as well as x-rays,can induce hmgb1 release from human cancer cell lines. the study examined five human cancer cell lines: te2,kyse70,a549,nci-h460 and widr. the proportion of cells surviving x- or carbon-ion beam irradiation was assessed in a clonogenic assay. the d10,the dose at which 10% of cells survive,was calculated using a linear-quadratic model. hmgb1 levels in the culture supernatants were assessed by an elisa. the d10 dose for x-rays in te2,kyse70,a549,nci-h460 and widr cells was 2.1,6.7,8.0,4.8 and 7.1 gy,respectively,whereas that for carbon-ion beams was 0.9,2.5,2.7,1.8 and 3.5 gy,respectively. x-rays and carbon-ion beams significantly increased hmgb1 levels in the culture supernatants of a549,nci-h460 and widr cells at 72 h post-irradiation with a d10 dose. furthermore,irradiation with x-rays or carbon-ion beams significantly increased hmgb1 levels in the culture supernatants of all five cell lines at 96 h post-irradiation. there was no significant difference in the amount of hmgb1 induced by x-rays and carbon-ion beams at any time-point (except at 96 h for nci-h460 cells); thus we conclude that comparable levels of hmgb1 were detected after irradiation with iso-survival doses of x-rays and carbon-ion beams. © 2015 the author.