DETECTION OF DNA ADDUCTS IN HL-60 CELLS TREATED WITH HYDROQUINONE AND PARA-BENZOQUINONE BY P-32 POSTLABELING

We have examined DNA adduct formation and cytotoxicity in HL-60 cells treated with either hydroquinone (HQ) or p-benzoquinone (p-BQ). Treatment of HL-60 cells with either HQ or p-BQ produced the same DNA adduct. The DNA adduct level varied from 0.05 to 10 adducts per 10(7) nucleotides as a function of treatment time and concentration for both compounds. To achieve the same DNA adduct level required higher concentrations and longer treatment times with HQ compared to p-BQ. p-BQ was also more cytotoxic to HL-60 cells than HQ. Reaction of calf thymus DNA with a p-BQ/HQ mixture produced five adducts as detected by P-32-postlabeling. Two isomers of (hydroxy)-1,N2-benzetheno-2'-deoxyguanosine-3'-phosphate were isolated from the reaction of 2'-deoxyguanosine-3'-phosphate with a p-BQ/HQ mixture and one of the isomers was identified as adduct no. 1 of the DNA reaction. The DNA adduct formed in HL-60 cells treated with HQ or p-BQ did not correspond to any of the principal adducts formed in DNA reacted with p-BQ/HQ. This result suggests that cellular mechanisms modify DNA adduct formation by HQ and p-BQ.