LET dependence of the production of 8-OHdG in human HL-60 cells exposed to heavy ions

Abstract

Production of 8-hydroxy-2'-deoxyguanosine (8-OHdG) was examined in human leukemia HL-60 cells irradiated with carbon, neon and silicon ions. The LETs of carbon are 20, 50 and 80 keV/μm, those of neon ions 80 and 150 keV/μm, and those of silicon ions are 150 and 250 keV/μm. Irradiated cells under the air-saturated condition were subjected to DNA extraction using isopropanol, separation of DNA strands by heat treatment, digestion into nucleosides with nuclease P1 and alkaline phosphatase. 8-OHdG was separated as a single peak on a chromatogram of ECD detector. The linearity of the peak area with irradiation dose was confirmed using X-ray irradiated specimens. For all the ions tested, 8-OHdG yield was decreased with increasing LET with a saturation tendency in the high LET region. These results are in good agreement with those of irradiated dG solution which was previously reported by us. Ion species dependence in 8-OHdG yield was not so apparent through the comparison of 1) carbon and neon ions with an LET of 80 keV/μm and 2) neon and silicon ions with an LET of 150 keV/μm.