Background PARP inhibitors (PARPi) have been licensed for the maintenance therapy of patients with metastatic pancreatic cancer carrying pathogenic germline BRCA1/2 mutations. However, mutations in BRCA1/2 are notably rare in pancreatic cancer. Objective There is a significant unmet clinical need to broaden the utility of PARPi. Design RNA sequencing was performed to screen potential targets for PARPi sensitivity. The synthetic lethal effects were verified in patient-derived xenograft (PDX), xenograft and patient-derived organoid models. Mechanisms were explored via LC‒MS/MS, coimmunoprecipitation, laser microirradiation, immunofluorescence, the homologous recombination (HR) or non-homologous end joining (NHEJ) reporter system, in situ proximity ligation assay and live-cell time-lapse imaging analyses. Results Targeting protein for Xenopus kinesin-like protein 2 (TPX2) is an exploitable vulnerability. TPX2 was downregulated in PDX models sensitive to PARPi, and TPX2 inhibition conferred synthetic lethality to PARPi both in vitro and in vivo . Mechanistically, TPX2 functions in a cell cycle-dependent manner. In the S/G2 phase, ATM-mediated TPX2 S634 phosphorylation promotes BRCA1 recruitment to double-strand breaks (DSBs) for HR repair, whereas non-phosphorylated TPX2 interacts with 53BP1 to recruit it for NHEJ. The balance between phosphorylated and non-phosphorylated TPX2 determines the DSB repair pathway choice. During mitosis, TPX2 phosphorylation enhances Aurora A activity, promoting mitotic progression and chromosomal stability. Targeting TPX2 S634 phosphorylation with a cell-penetrating peptide causes genomic instability and mitotic catastrophe and enhances PARPi sensitivity. Additionally, the inhibition of TPX2 or S634 phosphorylation combined with gemcitabine further sensitised pancreatic cancer to PARPi. Conclusions Our findings revealed the dual-functional significance of TPX2 in controlling DNA DSB repair pathway choice and mitotic progression, suggesting a potential therapeutic strategy involving PARPi for patients with pancreatic cancer. Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information. The transcriptome data generated by the study were deposited in the National Omics Data Encyclopedia (OER399218) (). The mass spectrometry proteomics data were deposited to the ProteomeXchange Consortium via the iProX partner repository with the dataset identifier PXD043145 (). All the relevant data that support the findings of this study are available from the corresponding author on request.

中文翻译：

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TPX2 通过赋予合成致死性，成为扩大 PARPi 在胰腺癌中效用的新靶标


背景 PARP 抑制剂 （PARPi） 已被批准用于携带致病性种系 BRCA1/2 突变的转移性胰腺癌患者的维持治疗。然而，BRCA1/2 突变在胰腺癌中非常罕见。目的 扩大 PARPi 的效用存在重大未满足的临床需求。进行设计 RNA 测序以筛选 PARPi 敏感性的潜在靶标。合成致死作用在患者来源的异种移植物 （PDX） 、异种移植物和患者来源的类器官模型中得到验证。通过 LC\MS/MS、免疫共沉淀、激光微照射、免疫荧光、同源重组 （HR） 或非同源末端连接 （NHEJ） 报告系统、原位邻位连接测定和活细胞延时成像分析探索机制。结果 非洲爪蟾驱动蛋白样蛋白 2 （TPX2） 的靶向蛋白是一个可利用的漏洞。TPX2 在对 PARPi 敏感的 PDX 模型中下调，TPX2 抑制在体外和体内都赋予 PARPi 合成致死性。从机制上讲，TPX2 以细胞周期依赖性方式发挥作用。在 S/G2 期，ATM 介导的 TPX2 S634 磷酸化促进 BRCA1 募集到双链断裂 （DSB） 以进行 HR 修复，而非磷酸化 TPX2 与 53BP1 相互作用以将其募集到 NHEJ。磷酸化和非磷酸化 TPX2 之间的平衡决定了 DSB 修复通路的选择。在有丝分裂过程中，TPX2 磷酸化增强 Aurora A 活性，促进有丝分裂进程和染色体稳定性。用细胞穿透肽靶向 TPX2 S634 磷酸化会导致基因组不稳定和有丝分裂灾难，并增强 PARPi 敏感性。 此外，抑制 TPX2 或 S634 磷酸化与吉西他滨联合使用进一步使胰腺癌对 PARPi 敏感。结论 我们的研究结果揭示了 TPX2 在控制 DNA DSB 修复途径选择和有丝分裂进展中的双重功能意义，提示胰腺癌患者具有涉及 PARPi 的潜在治疗策略。数据可根据合理要求提供。与研究相关的所有数据都包含在文章中或作为补充信息上传。该研究生成的转录组数据存放在国家组学数据百科全书 （OER399218） （） 中。质谱蛋白质组学数据通过 iProX 合作伙伴存储库存入 ProteomeXchange Consortium，数据集标识符为 PXD043145 （）。支持本研究结果的所有相关数据均可应要求从通讯作者处获得。