DNA复制应激（RS）意味着在一系列阻碍准确和连续基因组复制的条件下，复制叉频繁减慢和停滞。高水平的RS会导致基因组不稳定、复制灾难以及最终的细胞死亡。RS在癌细胞中尤为常见，化疗药物将其加剧至不可持续的水平仍然是癌症治疗的核心。RS的不利后果通常由ATR和CHK1检查点激酶阻止，它们稳定受到应激的复制叉，抑制起始点的启动，并在复制受到干扰时促进细胞周期停滞。这些激酶的特定抑制剂已经被开发出来，并且在多种体外癌症模型中显示出增强RS和细胞死亡的效果。目前正在进行的临床试验正在探究它们作为单药或与主要化疗药物联合治疗对各种癌症类型的疗效。尽管作为抗癌药物宝库中有价值的补充品，但我们仍然缺乏对这些新药物的潜在致突变性的全面了解。为了研究这个问题，我们对TP53缺失的人类癌细胞进行了长期慢性治疗，使用了ATR和CHK1抑制剂（ATRi，AZD6738 / ceralasertib以及CHK1i，MK8776 / SCH-900776）。ATR或CHK1的抑制并没有显著增加细胞的突变负担，也没有产生特定的突变特征。事实上，尽管在治疗过程中诱导了与复制相关的DNA断裂，但在碱基置换、短插入/缺失和较大规模的重排数量上并没有明显变化。有趣的是，ATR抑制确实导致了间距紧密的突变略微增加，这是以前归因于经过损伤识别合成的DNA聚合酶。结果表明，ATRi和CHK1i作为独立药物在体外使用时不具有显著的突变效应。Copyright © 2023 Elsevier B.V. 版权所有。

DNA replication stress (RS) entails the frequent slow down and arrest of replication forks by a variety of conditions that hinder accurate and processive genome duplication. Elevated RS leads to genome instability, replication catastrophe and eventually cell death. RS is particularly prevalent in cancer cells and its exacerbation to unsustainable levels by chemotherapeutic agents remains a cornerstone of cancer treatments. The adverse consequences of RS are normally prevented by the ATR and CHK1 checkpoint kinases that stabilize stressed forks, suppress origin firing and promote cell cycle arrest when replication is perturbed. Specific inhibitors of these kinases have been developed and shown to potentiate RS and cell death in multiple in vitro cancer settings. Ongoing clinical trials are now probing their efficacy against various cancer types, either as single agents or in combination with mainstay chemotherapeutics. Despite their promise as valuable additions to the anti-cancer pharmacopoeia, we still lack a genome-wide view of the potential mutagenicity of these new drugs. To investigate this question, we performed chronic long-term treatments of TP53-depleted human cancer cells with ATR and CHK1 inhibitors (ATRi, AZD6738/ceralasertib and CHK1i, MK8776/SCH-900776). ATR or CHK1 inhibition did not significantly increase the mutational burden of cells, nor generate specific mutational signatures. Indeed, no notable changes in the numbers of base substitutions, short insertions/deletions and larger scale rearrangements were observed despite induction of replication-associated DNA breaks during treatments. Interestingly, ATR inhibition did induce a slight increase in closely-spaced mutations, a feature previously attributed to translesion synthesis DNA polymerases. The results suggest that ATRi and CHK1i do not have substantial mutagenic effects in vitro when used as standalone agents.Copyright © 2023 Elsevier B.V. All rights reserved.