Pappas Kyrie, Ferrari Matteo, Smith Perianne, Nandakumar Subhiksha, Khan Zahra, Young Serina B, LaClair Justin, Russo Marco Vincenzo, Huang-Hobbs Emmet, Schultz Nikolaus, Abida Wassim, Karthaus Wouter, Jasin Maria, L Sawyers Charles
Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065.
Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065.
Proc Natl Acad Sci U S A. 2025 Jun 10;122(23):e2426743122. doi: 10.1073/pnas.2426743122. Epub 2025 Jun 3.
Recent approvals of polymeric adenosine diphosphate ribose (poly(ADP-ribose) polymerase inhibitors (PARPi) for BRCA-mutant metastatic castration resistant prostate cancer necessitate an understanding of the factors that shape sensitivity and resistance. Reversion mutations that restore homologous recombination (HR) repair are detected in ~50 to 80% of BRCA-mutant patients who respond but subsequently relapse, but there is currently little insight into why only ~50% of BRCA-mutant patients display upfront resistance. To address this question, we performed a genome-wide CRISPR screen to identify genomic determinants of PARPi resistance in murine prostate organoids genetically engineered in a manner that precludes the development of reversion mutations. Remarkably, we recovered multiple independent single guide RNAs (sgRNAs) targeting three different members ( and ) of the DNA prereplication complex (pre-RC), each of which independently conferred resistance to olaparib and the next-generation PARP-1 selective inhibitor AZD5305. Moreover, sensitivity to PARP inhibition was restored in , Cdc6-depleted prostate cells by knockdown of geminin, a negative regulator of Cdt1, further implicating the critical role of a functional pre-RC complex in PARPi sensitivity. Furthermore, ~50% of CRPC tumors have copy number loss of pre-RC complex genes, particularly . Mechanistically, prostate cells with impaired pre-RC activity displayed rapid resolution of olaparib-induced DNA damage as well as protection from replication fork degradation caused by Brca2 loss, providing insight into how Brca2-mutant cancer cells can escape cell death from replication stress induced by PARP inhibition in the absence of HR repair. Of note, a pharmacologic inhibitor that targets the CDT1/geminin complex (AF615) restored sensitivity to AZD5305, providing a potential translational avenue to enhance sensitivity to PARP inhibition.
近期，聚腺苷二磷酸核糖聚合酶（PARP）抑制剂已获批用于治疗携带BRCA突变的转移性去势抵抗性前列腺癌，因此有必要了解影响敏感性和耐药性的因素。在约50%至80%有反应但随后复发的BRCA突变患者中检测到恢复同源重组（HR）修复的回复突变，但目前对于为何只有约50%的BRCA突变患者表现出初始耐药性了解甚少。为了解决这个问题，我们进行了全基因组CRISPR筛选，以确定在经过基因工程改造以排除回复突变发生的小鼠前列腺类器官中PARP抑制剂耐药性的基因组决定因素。值得注意的是，我们筛选到多个独立的单向导RNA（sgRNA），它们靶向DNA复制前复合体（pre-RC）的三个不同成员（和），每个成员都独立赋予对奥拉帕利和下一代PARP-1选择性抑制剂AZD5305的耐药性。此外，通过敲低Cdt1的负调节因子geminin，在Cdc6缺失的前列腺细胞中恢复了对PARP抑制的敏感性，这进一步表明功能性pre-RC复合体在PARP抑制剂敏感性中的关键作用。此外，约50%的去势抵抗性前列腺癌（CRPC）肿瘤存在pre-RC复合体基因的拷贝数缺失，尤其是。从机制上讲，pre-RC活性受损的前列腺细胞显示奥拉帕利诱导的DNA损伤迅速修复，以及免受Brca2缺失导致的复制叉降解的影响，这为Brca2突变癌细胞如何在缺乏HR修复的情况下逃避PARP抑制诱导的复制应激导致的细胞死亡提供了见解。值得注意的是，一种靶向CDT1/geminin复合体的药物抑制剂（AF615）恢复了对AZD5305的敏感性，为增强对PARP抑制的敏感性提供了一条潜在的转化途径。
