Oxidative damage and direct adducts in calf thymus DNA induced by the pentachlorophenol metabolites, tetrachlorohydroquinone and tetrachloro-1,4-benzoquinone
Oxidative damage and direct adducts in calf thymus DNA induced by the pentachlorophenol metabolites, tetrachlorohydroquinone and tetrachloro-1,4-benzoquinone
复制标题
DOI：
10.1093/carcin/22.4.627
复制
发表时间：
2001-04-01
期刊：
影响因子：
4.7
通讯作者：
Swenberg, JA
中科院分区：
文献类型：
--
作者：
Lin, PH;Nakamura, J;Swenberg, JA
研究了五氯酚（PCP）醌类代谢物，即四氯-1,4-苯醌（Cl(4)BQ）和四氯对苯二酚（Cl(4)HQ）在小牛胸腺DNA中引起的DNA损伤。p -32标记后分析发现，经Cl(4)BQ （5 mM）处理的小牛胸腺DNA中产生了四种主要加合物和几种次要加合物（每10(5)个总核苷酸中有3.5个加合物）。这些DNA加合物即使在诱导热去嘌呤化的条件下也具有化学稳定性，并且不太可能发生去嘌呤化/去嘧啶化以形成无嘌呤/无嘧啶（AP）位点。此外，在Cl(4)BQ修饰的小牛胸腺DNA中，8-羟基脱氧鸟苷（8-HO-dG）（每105个核苷酸中有5个8-HO-dG）和Ar位点（每105个核苷酸中有0.5个AP位点）增加。进一步的研究表明，在Cu（II）和NADPH存在的情况下，低浓度Cl(4)BQ （1 muM）诱导8-HO-dG（每105个核苷酸中有10个8-HO-dG）翻倍，AP位点（每105个核苷酸中有20个AP位点）急剧增加，DNA单链断裂。Cl(4)HQ + Cu（II）诱导的DNA损伤类型与Cl(4)BQ + Cu（II）和NADPH诱导的DNA损伤类型相似，但过氧化氢酶抑制DNA损伤的形成。这些数据表明，氧化损伤与AP位点的形成有因果关系，Cl(4)HQ + Cu（II）和Cl(4)BQ + Cu（II）和NADPH诱导的8-HO-dG浓度依赖性增加与AP位点的形成相关（r(2) = 0.977）， 8-HO-dG与Ar位点的比例为1:6 .6，AP位点裂解实验证实，与Cl(4)HQ和Cu（II）诱导的Ar位点相似，85%的AP位点被检测到5 ' -裂解。由于过氧化氢单独引起类似的DNA损伤，这些结果表明Cu（II）和过氧化氢参与了Cl(4)HQ/Cl(4)BQ诱导DNA氧化损伤。这些数据表明，PCP醌和对苯二酚可诱导基因组DNA中直接和氧化碱基修饰以及5 ' -cleaved Ar位点的形成，这些病变可能对PCP的致裂性和致癌性具有重要意义。
DNA damage induced by quinoid metabolites of pentachlorophenol (PCP), i.e, tetrachloro-1,4-benzoquinone (Cl(4)BQ) and tetrachlorohydroquinone (Cl(4)HQ), was investigated in calf thymus DNA, The P-32-post-labeling assay revealed four major and several minor adducts (3.5 adducts per 10(5) total nucleotides) that were produced in calf thymus DNA treated with Cl(4)BQ (5 mM), These DNA adducts were chemically stable even after conditions that induce thermal depurination and are unlikely to undergo depurination/depyrimidination to form apurinic/ apyrimidinic (AP) sites. In addition, increases in 8-hydroxy-deoxyguanosine (8-HO-dG) (5 8-HO-dG per 105 nucleotides) and Ar sites (0.5 AP sites per 105 nucleotides) were observed in Cl(4)BQ-modified calf thymus DNA, Further investigation indicated that in the presence of Cu(II) and NADPH, low concentrations of Cl(4)BQ (1 muM) induced a doubling of 8-HO-dG (10 8-HO-dG per 105 nucleotides) and dramatic increases in AP sites (20 AP sites per 105 nucleotides) and DNA single-strand breaks. The types of DNA damage induced by Cl(4)HQ plus Cu(II) were similar to those by Cl(4)BQ plus Cu(II) and NADPH, whereas catalase inhibited the formation of DNA damage. These data suggest that oxidative damage is causally involved in the formation of AP sites, Concentration-dependent increases in 8-HO-dG induced by Cl(4)HQ plus Cu(II) and Cl(4)BQ plus Cu(II) and NADPH were correlated with the formation of AP sites (r(2) = 0.977) with a ratio of 8-HO-dG to Ar sites at 1:1.6, The AP site-cleavage assay confirmed that similar to 85% of the Ar sites induced by Cl(4)HQ and Cu(II) were detected as 5 ' -cleaved AP sites. Since hydrogen peroxide alone causes similar DNA damage, these results suggest the involvement of Cu(II) and hydrogen peroxide in the induction of oxidative DNA damage by Cl(4)HQ/Cl(4)BQ. The data demonstrate that PCP quinone and hydroquinone induce direct and oxidative base modifications as well as the formation of 5 ' -cleaved Ar sites in genomic DNA, These lesions may have important implications for PCP clastogenicity and carcinogenicity.