Abstract
It is well known that incorporation of halogenated pyrimidines, such as bromo-and iodo-deoxyuridines (BrdU,IdU) incorporation into DNA to replace thymidine is sensitive to cells to ionizing radiation. However, a relation about radio-sensitization between halogenated pyrimidines and heavy-ion beams is not well known. We examined a radio-sensitization effect of cells incorporated BrdU when irradiated by carbon-and iron-ion beam. Single and double cell cycle BrdU incorporated cells were irradiated at G1-phase after synchronization. After exposure to various radiation, we tested colony formation to cell survival, DNA double strand break formation and repair by gamma-H2AX focus formation assay, and chromosome aberration formation for first post irradiation metaphase. Although two cell cycles BrdU incorporated cells presented most severe radiosensitization effects, fewer radiosensitization was observed to after higher LET radiation. Our results suggested that incorporation of halogenated pyrimidines lead to produce complex DNA damages after radiation exposure. The reason of small BrdU effects in high LET exposure may be explained that high LET radiation has already produced such damages.
