Molecular Toxicology Group, Department of Biology, University of Konstanz, 78457 Konstanz, Germany.
Bundeswehr Institute of Pharmacology and Toxicology, 80937 Munich, Germany.
Cells. 2023 Oct 2;12(19):2396. doi: 10.3390/cells12192396.
Sulfur mustard (SM) and its derivatives are potent genotoxic agents, which have been shown to trigger the activation of poly (ADP-ribose) polymerases (PARPs) and the depletion of their substrate, nicotinamide adenine dinucleotide (NAD). NAD is an essential molecule involved in numerous cellular pathways, including genome integrity and DNA repair, and thus, NAD supplementation might be beneficial for mitigating mustard-induced (geno)toxicity. In this study, the role of NAD depletion and elevation in the genotoxic stress response to SM derivatives, i.e., the monofunctional agent 2-chloroethyl-ethyl sulfide (CEES) and the crosslinking agent mechlorethamine (HN2), was investigated with the use of NAD booster nicotinamide riboside (NR) and NAD synthesis inhibitor FK866. The effects were analyzed in immortalized human keratinocytes (HaCaT) or monocyte-like cell line THP-1. In HaCaT cells, NR supplementation, increased NAD levels, and elevated PAR response, however, did not affect ATP levels or DNA damage repair, nor did it attenuate long- and short-term cytotoxicities. On the other hand, the depletion of cellular NAD via FK866 sensitized HaCaT cells to genotoxic stress, particularly CEES exposure, whereas NR supplementation, by increasing cellular NAD levels, rescued the sensitizing FK866 effect. Intriguingly, in THP-1 cells, the NR-induced elevation of cellular NAD levels did attenuate toxicity of the mustard compounds, especially upon CEES exposure. Together, our results reveal that NAD is an important molecule in the pathomechanism of SM derivatives, exhibiting compound-specificity. Moreover, the cell line-dependent protective effects of NR are indicative of system-specificity of the application of this NAD booster.
硫芥（SM）及其衍生物是有效的遗传毒性剂，已被证明能触发多聚（ADP-核糖）聚合酶（PARP）的激活和其底物烟酰胺腺嘌呤二核苷酸（NAD）的耗竭。NAD 是参与包括基因组完整性和 DNA 修复在内的众多细胞途径的必需分子，因此，NAD 补充可能有益于减轻芥子气诱导的（遗传）毒性。在这项研究中，使用 NAD 增强剂烟酰胺核苷（NR）和 NAD 合成抑制剂 FK866，研究了 NAD 耗竭和升高在 SM 衍生物遗传毒性应激反应中的作用，即单功能剂 2-氯乙基乙基硫醚（CEES）和交联剂美法仑（HN2）。在永生化人角质形成细胞（HaCaT）或单核细胞样细胞系 THP-1 中分析了这些作用。在 HaCaT 细胞中，NR 补充增加了 NAD 水平并升高了 PAR 反应，但不影响 ATP 水平或 DNA 损伤修复，也不减轻长期和短期细胞毒性。另一方面，通过 FK866 耗尽细胞 NAD 会使 HaCaT 细胞对遗传毒性应激敏感，特别是 CEES 暴露，而通过增加细胞 NAD 水平的 NR 补充挽救了 FK866 的致敏作用。有趣的是，在 THP-1 细胞中，NR 诱导的细胞 NAD 水平升高确实减轻了芥子气化合物的毒性，尤其是在 CEES 暴露时。总之，我们的结果表明 NAD 是 SM 衍生物发病机制中的重要分子，表现出化合物特异性。此外，NR 在细胞系依赖性保护作用表明了该 NAD 增强剂应用的系统特异性。
