Detection of oxidative DNA damage induced by high LET radiation

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Production of 8-hydroxy-2'-deoxyguanosine (8-OHdG), an OH radical induced base damage, was examined upon irradiation with carbon, neon, silicon and iron ions over an LET range from 20 to 440keV/μm under oxic and hypoxic conditions. 8-OHdG was detected by HPLC and an electro-chemical detector after extraction of DNA from irradiated cells. The yield of 8-OHdG was decreased with increasing LET under oxic condition, and strongly depended on ion species. Under hypoxic condition the yield appeared not to decrease monotonically but to approach constant level or rather to increase in the high LET region. This observation is consistent with the oxygen-in-the-track model where oxygen molecules are supposed to be produced along ion tracks. To visualize the distribution of 8-OHdG along ion tracks we imaged 8-OHdG distribution using FITC-labeled 8-OHdG antibody. At a dose as small as 5Gy, 8-OHdG was detected for every ion.