Establishment and characterization of novel carbon-ion beam resistance cells

The aim of this study is to establish carbon ion beam (C-ion) resistant cancer cells and to investigate the difference in cellular characteristics between C-ion resistant and X-ray resistant cancer cells. The X-ray resistant cancer cell was already established using mouse squamous cell carcinoma cell line NRS1. The cells were repeatedly irradiated with a total dose 60 Gy of 200 kVp X-ray, and this repetitive X-ray irradiation generated the X-ray resistant cancer cell NRS1-X60. Surprisingly the result from colony formation assay after irradiation of 290 MeV/n C-ion showed that NRS1-X60 cells also acquired significant C-ion resistance, Although C-ion irradiation is known to be more effective for killing cells of X-ray resistant tumor. The survival fractions of NRS1-X60 cells at 10 Gy of X-ray or 5 Gy of C-ion is approximately 6.3- or 6.7-folds increased compared with that in NRS1 cells, respectively. DNA repair potential in NRS1-X60 cells, which is represented by the disappearance of g-H2AX foci at one day after X-ray or C-ion irradiation, is promoted by approximately 2.3-fold compared with that in NRS1 cells for both irradiations. Currently, the NRS1 cells were repeatedly irradiated with a total dose 30 Gy of C-ion, and we established NRS1-C30 cells. We will report the difference in X-ray, C-ion sensitivity, and DNA repair potential between NRS1-X60, NRS1-C30, and NRS1.Heavy Ion in Therapy and Space Radiation Symposium 2013 (HITSRS2013