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Abstract：
BACKGROUND: Poly(ADP-ribose) polymerase (PARP) inhibitors have emerged as promising chemotherapeutic drugs primarily against BRCA1/2-associated tumours, known as synthetic lethality. However, recent clinical trials reported patients\' survival benefits from PARP inhibitor treatments, irrelevant to homologous recombination deficiency. Therefore, revealing the therapeutic mechanism of PARP inhibitors beyond DNA damage repair is urgently needed, which can facilitate precision medicine.
METHODS: A CRISPR-based knock-in technology was used to establish stable BRCA1 mutant cancer cells. The effects of PARP inhibitors on BRCA1 mutant cancer cells were evaluated by biochemical and cell biological experiments. Finally, we validated its in vivo effects in xenograft and patient-derived xenograft (PDX) tumour mice.
RESULTS: In this study, we uncovered that the majority of clinical BRCA1 mutations in breast cancers were in and near the middle of the gene, rather than in essential regions for DNA damage repair. Representative mutations such as R1085I and E1222Q caused transient extra spindle poles during mitosis in cancer cells. PAR, which is synthesized by PARP2 but not PARP1 at mitotic centrosomes, clustered these transient extra poles, independent of DNA damage response. Common PARP inhibitors could effectively suppress PARP2-synthesized PAR and induce cell senescence by abrogating the correction of mitotic extra-pole error.
CONCLUSIONS: Our findings uncover an alternative mechanism by which PARP inhibitors efficiently suppress tumours, thereby pointing to a potential new therapeutic strategy for centrosome error-related tumours.
BACKGROUND: Funded by National Natural Science Foundation of China (NSFC) (T2225006, 82272948, 82103106), Beijing Municipal Natural Science Foundation (Key program Z220011), and the National Clinical Key Specialty Construction Program, P. R. China (2023).
METHODS: A CRISPR-based knock-in technology was used to establish stable BRCA1 mutant cancer cells. The effects of PARP inhibitors on BRCA1 mutant cancer cells were evaluated by biochemical and cell biological experiments. Finally, we validated its in vivo effects in xenograft and patient-derived xenograft (PDX) tumour mice.
RESULTS: In this study, we uncovered that the majority of clinical BRCA1 mutations in breast cancers were in and near the middle of the gene, rather than in essential regions for DNA damage repair. Representative mutations such as R1085I and E1222Q caused transient extra spindle poles during mitosis in cancer cells. PAR, which is synthesized by PARP2 but not PARP1 at mitotic centrosomes, clustered these transient extra poles, independent of DNA damage response. Common PARP inhibitors could effectively suppress PARP2-synthesized PAR and induce cell senescence by abrogating the correction of mitotic extra-pole error.
CONCLUSIONS: Our findings uncover an alternative mechanism by which PARP inhibitors efficiently suppress tumours, thereby pointing to a potential new therapeutic strategy for centrosome error-related tumours.
BACKGROUND: Funded by National Natural Science Foundation of China (NSFC) (T2225006, 82272948, 82103106), Beijing Municipal Natural Science Foundation (Key program Z220011), and the National Clinical Key Specialty Construction Program, P. R. China (2023).
摘要：
背景：聚（ADP-核糖）聚合酶（PARP）抑制剂已成为主要针对BRCA1/2相关肿瘤的有希望的化疗药物，被称为合成杀伤力。然而,最近的临床试验报道了患者从PARP抑制剂治疗中获益，与同源重组缺陷无关。因此,迫切需要揭示PARP抑制剂超越DNA损伤修复的治疗机制，这可以促进精准医疗。
方法：使用基于CRISPR的敲入技术来建立稳定的BRCA1突变癌细胞。通过生化和细胞生物学实验评价PARP抑制剂对BRCA1突变癌细胞的作用。最后,我们验证了其在异种移植和患者来源的异种移植（PDX）肿瘤小鼠中的体内作用。
结果：在这项研究中，我们发现，乳腺癌中的大多数临床BRCA1突变都在基因的中间，而不是在DNA损伤修复的必要区域。代表性突变如R1085I和E1222Q在癌细胞的有丝分裂期间引起短暂的额外纺锤体极。PAR,它是由PARP2而不是PARP1在有丝分裂中心体合成的，聚集了这些瞬态额外的极点，与DNA损伤反应无关。常见的PARP抑制剂可以有效抑制PARP2合成的PAR，并通过消除有丝分裂极外误差的纠正来诱导细胞衰老。
结论：我们的发现揭示了PARP抑制剂有效抑制肿瘤的替代机制，从而指出了中心体错误相关肿瘤的潜在新治疗策略。
背景:国家自然科学基金(国家自然科学基金)(T2225006,82272948,82103106),北京市自然科学基金重点项目Z220011,国家临床重点专科建设计划,P.R.中国（2023年）。
方法：使用基于CRISPR的敲入技术来建立稳定的BRCA1突变癌细胞。通过生化和细胞生物学实验评价PARP抑制剂对BRCA1突变癌细胞的作用。最后,我们验证了其在异种移植和患者来源的异种移植（PDX）肿瘤小鼠中的体内作用。
结果：在这项研究中，我们发现，乳腺癌中的大多数临床BRCA1突变都在基因的中间，而不是在DNA损伤修复的必要区域。代表性突变如R1085I和E1222Q在癌细胞的有丝分裂期间引起短暂的额外纺锤体极。PAR,它是由PARP2而不是PARP1在有丝分裂中心体合成的，聚集了这些瞬态额外的极点，与DNA损伤反应无关。常见的PARP抑制剂可以有效抑制PARP2合成的PAR，并通过消除有丝分裂极外误差的纠正来诱导细胞衰老。
结论：我们的发现揭示了PARP抑制剂有效抑制肿瘤的替代机制，从而指出了中心体错误相关肿瘤的潜在新治疗策略。
背景:国家自然科学基金(国家自然科学基金)(T2225006,82272948,82103106),北京市自然科学基金重点项目Z220011,国家临床重点专科建设计划,P.R.中国（2023年）。
