DNA repair pathway inhibitors are a new class of anticancer drugs that are advancing in clinical trials. Peposertib is an inhibitor of DNA-dependent protein kinase (DNA-PK), which is a key driver of nonhomologous end-joining (NHEJ). To identify regulators of response to peposertib, we performed a genome-wide CRISPR knockout screen and found that loss of POLQ (polymerase theta, POLθ) and other genes in the microhomology-mediated end-joining (MMEJ) pathway are key predictors of sensitivity to DNA-PK inhibition. Simultaneous disruption of two DNA repair pathways via combined treatment with peposertib plus a POLθ inhibitor novobiocin exhibited synergistic synthetic lethality resulting from accumulation of toxic levels of DNA double-strand break end resection. TP53-mutant tumor cells were resistant to peposertib but maintained elevated expression of POLQ and increased sensitivity to novobiocin. Consequently, the combination of peposertib plus novobiocin resulted in synthetic lethality in TP53-deficient tumor cell lines, organoid cultures, and patient-derived xenograft models. Thus, the combination of a targeted DNA-PK/NHEJ inhibitor with a targeted POLθ/MMEJ inhibitor may provide a rational treatment strategy for TP53-mutant solid tumors. Significance: Combined inhibition of NHEJ and MMEJ using two nontoxic, targeted DNA repair inhibitors can effectively induce toxic DNA damage to treat TP53-deficient cancers.

中文翻译：

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靶向 DNA 修复并联合抑制 NHEJ 和 MMEJ 可诱导 TP53 突变癌症的综合致死性

DNA修复途径抑制剂是一类正在临床试验中取得进展的新型抗癌药物。Peposertib 是 DNA 依赖性蛋白激酶 (DNA-PK) 的抑制剂，DNA-PK 是非同源末端连接 (NHEJ) 的关键驱动因素。为了确定对peposertib反应的调节因子，我们进行了全基因组CRISPR敲除筛选，发现POLQ（聚合酶theta，POLθ）和微同源介导的末端连接（MMEJ）途径中其他基因的丢失是对peposertib敏感性的关键预测因素DNA-PK 抑制。通过使用peposertib加POLθ抑制剂新生霉素联合治疗同时破坏两条DNA修复途径，表现出协同合成致死性，这是由于DNA双链断裂末端切除毒性水平的积累所致。TP53 突变肿瘤细胞对 peposertib 具有耐药性，但 POLQ 表达保持升高，并且对新生霉素的敏感性增加。因此，peposertib 与新生霉素的组合在 TP53 缺陷的肿瘤细胞系、类器官培养物和患者来源的异种移植模型中产生了合成致死性。因此，靶向DNA-PK/NHEJ抑制剂与靶向POLθ/MMEJ抑制剂的组合可能为TP53突变实体瘤提供合理的治疗策略。意义：使用两种无毒的靶向 DNA 修复抑制剂联合抑制 NHEJ 和 MMEJ，可以有效诱导毒性 DNA 损伤，从而治疗 TP53 缺陷的癌症。和患者来源的异种移植模型。因此，靶向DNA-PK/NHEJ抑制剂与靶向POLθ/MMEJ抑制剂的组合可能为TP53突变实体瘤提供合理的治疗策略。意义：使用两种无毒的靶向 DNA 修复抑制剂联合抑制 NHEJ 和 MMEJ，可以有效诱导毒性 DNA 损伤，从而治疗 TP53 缺陷的癌症。和患者来源的异种移植模型。因此，靶向DNA-PK/NHEJ抑制剂与靶向POLθ/MMEJ抑制剂的组合可能为TP53突变实体瘤提供合理的治疗策略。意义：使用两种无毒的靶向 DNA 修复抑制剂联合抑制 NHEJ 和 MMEJ，可以有效诱导毒性 DNA 损伤，从而治疗 TP53 缺陷的癌症。