Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, United States.
McKetta Department of Chemical Engineering, Cockrell School of Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.
J Am Chem Soc. 2021 Nov 17;143(45):18960-18976. doi: 10.1021/jacs.1c07234. Epub 2021 Nov 2.
DNA interstrand cross-links (ICLs) are extremely deleterious and structurally diverse, driving the evolution of ICL repair pathways. Discovering ICL-inducing agents is, thus, crucial for the characterization of ICL repair pathways and Fanconi anemia, a genetic disease caused by mutations in ICL repair genes. Although several studies point to oxidative stress as a cause of ICLs, oxidative stress-induced cross-linking events remain poorly characterized. Also, polycyclic aromatic amines, potent environmental carcinogens, have been implicated in producing ICLs, but their identities and sequences are unknown. To close this knowledge gap, we tested whether ICLs arise by the oxidation of 8-arylamino-2'-deoxyadenosine (ArNHdA) lesions, adducts produced by arylamino carcinogens. Herein, we report that ArNHdA acts as a latent cross-linking agent to generate ICLs under oxidative conditions. The formation of an ICL from 8-aminoadenine, but not from 8-aminoguanine, highlights the specificity of 8-aminopurine-mediated ICL production. Under the influence of the reactive oxygen species (ROS) nitrosoperoxycarbonate, ArNHdA (Ar = biphenyl, fluorenyl) lesions were selectively oxidized to generate ICLs. The cross-linking reaction may occur between the C2-ArNHdA and N2-dG, presumably via oxidation of ArNHdA into a reactive diiminoadenine intermediate followed by the nucleophilic attack of the N2-dG on the diiminoadenine. Overall, ArNHdA-mediated ICLs represent rare examples of ROS-induced ICLs and polycyclic aromatic amine-mediated ICLs. These results reveal novel cross-linking chemistry and the genotoxic effects of arylamino carcinogens and support the hypothesis that C8-modified adenines with low redox potential can cause ICLs in oxidative stress.
DNA 链间交联（ICLs）是极其有害且结构多样的，它们推动了 ICL 修复途径的进化。因此，发现诱导 ICL 的试剂对于 ICL 修复途径和范可尼贫血（一种由 ICL 修复基因突变引起的遗传疾病）的特征至关重要。尽管有几项研究指出氧化应激是 ICL 产生的原因，但氧化应激诱导的交联事件仍未得到充分描述。此外，多环芳烃是一种强效的环境致癌物质，已被牵连到产生 ICL，但它们的身份和序列尚不清楚。为了填补这一知识空白，我们测试了 ICL 是否是由芳基氨基致癌物产生的 8-芳基氨基-2'-脱氧腺苷（ArNHdA）损伤的氧化引起的。在此，我们报告 ArNHdA 在氧化条件下作为潜伏交联剂生成 ICL。8-氨基腺嘌呤而不是 8-氨基鸟嘌呤形成 ICL，突出了 8-氨基嘌呤介导的 ICL 产生的特异性。在活性氧（ROS）亚硝酰过氧碳酸盐的影响下，ArNHdA（Ar = 联苯，芴基）损伤被选择性氧化生成 ICL。交联反应可能发生在 C2-ArNHdA 和 N2-dG 之间，推测是通过将 ArNHdA 氧化成活性二亚氨基腺嘌呤中间体，然后 N2-dG 对二亚氨基腺嘌呤进行亲核攻击。总的来说，ArNHdA 介导的 ICL 代表了 ROS 诱导的 ICL 和多环芳烃介导的 ICL 的罕见例子。这些结果揭示了芳基氨基致癌物质的新型交联化学和遗传毒性作用，并支持了低氧化还原电位的 C8 修饰腺嘌呤可在氧化应激中引起 ICL 的假说。
