Lin P H, Nakamura J, Yamaguchi S, La D K, Upton P B, Swenberg J A
Department of Environmental Sciences and Engineering, The University of North Carolina, Chapel Hill, NC 27599-7400, USA.
Carcinogenesis. 2001 Apr;22(4):635-9. doi: 10.1093/carcin/22.4.635.
DNA damage induced by tetrachlorohydroquinone (Cl(4)HQ), the quinonoid metabolite of pentachlorophenol (PCP), was investigated in human HeLa S3 tumor cells. Formation of one major and two minor DNA adducts in cells treated with Cl(4)HQ (50-300 microM) was detected by (32)P-post-labeling assay and the adducts accumulated over the course of the experiment (0.5-2 h), with total adduct levels estimated to be 3-6 per 10(8) nucleotides. These adducts did not correspond to those derived from calf thymus DNA treated with tetrachloro-1,4-benzoquinone. Results from the apurinic/apyrimidinic (AP) sites assay indicated that the number of AP sites was 2-fold greater in cells exposed to Cl(4)HQ (300 microM) than the corresponding control. Further characterization of the AP sites confirmed that Cl(4)HQ induced predominantly (75%) putrescine-excisable AP sites in HeLa S3 cells. In parallel, the concentration of 8-hydroxy-2'-deoxyguanosine (8-HO-dG) in cells treated with Cl(4)HQ for 0.5 and 2 h was increased 2- and 5-fold, respectively, compared with the control. The extent of oxidative DNA damage induced by Cl(4)HQ was approximately two orders of magnitude greater than those of direct DNA adducts. Overall, it appears that reactive oxygen species mediate the parallel formation of AP sites and 8-HO-dG in HeLa S3 cells following treatment with Cl(4)HQ and that the contribution of depurination/depyrimidination of direct DNA adducts is relatively insignificant compared with the formation of oxidized AP sites. We conclude that putrescine-excisable AP sites represent a major type of ROS-mediated oxidative DNA damage in cellular DNA induced by Cl(4)HQ and may play a role in PCP-induced clastogenicity in mammalian cells.
研究了五氯苯酚（PCP）的醌类代谢物四氯对苯二酚（Cl(4)HQ）在人HeLa S3肿瘤细胞中诱导的DNA损伤。通过³²P后标记分析法检测到用Cl(4)HQ（50 - 300 microM）处理的细胞中形成了一种主要的和两种次要的DNA加合物，并且这些加合物在实验过程（0.5 - 2小时）中积累，估计每10⁸个核苷酸的总加合物水平为3 - 6个。这些加合物与用四氯 - 1,4 - 苯醌处理的小牛胸腺DNA衍生的加合物不同。脱嘌呤/脱嘧啶（AP）位点分析结果表明，暴露于Cl(4)HQ（300 microM）的细胞中的AP位点数量比相应对照高2倍。对AP位点的进一步表征证实，Cl(4)HQ在HeLa S3细胞中主要诱导（75%）腐胺可切除的AP位点。同时，与对照相比，用Cl(4)HQ处理0.5小时和2小时的细胞中8 - 羟基 - 2'-脱氧鸟苷（8 - HO - dG）的浓度分别增加了2倍和5倍。Cl(4)HQ诱导的氧化性DNA损伤程度比直接DNA加合物大约高两个数量级。总体而言，似乎活性氧介导了Cl(4)HQ处理后HeLa S3细胞中AP位点和8 - HO - dG的平行形成，并且与氧化AP位点的形成相比，直接DNA加合物的脱嘌呤/脱嘧啶作用相对较小。我们得出结论，腐胺可切除的AP位点代表了Cl(4)HQ诱导的细胞DNA中活性氧介导的氧化性DNA损伤的主要类型，并且可能在PCP诱导的哺乳动物细胞致染色体断裂性中起作用。
