DNA 复制是一个脆弱的细胞过程，其失调会导致基因组不稳定。在这里，我们证明了 chromobox 蛋白同源物 3 (CBX3) 结合复制蛋白 A 32-kDa 亚基 (RPA2) 并调节 RPA2 在停滞复制叉处的保留。 CBX3 被 RPA2 招募到停滞的复制叉，并抑制环指和 WD 重复结构域 3 (RFWD3) 促进的复制重启。酪蛋白激酶 2 (CK2) 激酶对 CBX3 在丝氨酸 95 处的磷酸化增强了钙粘蛋白 1 (CDH1) 介导的 CBX3 降解和停滞复制叉处的 RPA2 动力学，从而允许复制叉重新启动。基因扩增或 CK2 抑制剂治疗导致 CBX3 表达增加，使前列腺癌细胞对聚（ADP-核糖）聚合酶（PARP）抑制剂敏感，同时诱导复制应激和 DNA 损伤。我们的工作揭示了 CBX3 作为 RPA2 功能和 DNA 复制的关键调节因子，这表明 CBX3 可以作为使用 PARP 抑制剂进行癌症靶向治疗的指标。

DNA replication is a vulnerable cellular process, and its deregulation leads to genomic instability. Here, we demonstrate that chromobox protein homolog 3 (CBX3) binds replication protein A 32-kDa subunit (RPA2) and regulates RPA2 retention at stalled replication forks. CBX3 is recruited to stalled replication forks by RPA2 and inhibits ring finger and WD repeat domain 3 (RFWD3)-facilitated replication restart. Phosphorylation of CBX3 at serine-95 by casein kinase 2 (CK2) kinase augments cadherin 1 (CDH1)-mediated CBX3 degradation and RPA2 dynamics at stalled replication forks, which permits replication fork restart. Increased expression of CBX3 due to gene amplification or CK2 inhibitor treatment sensitizes prostate cancer cells to poly(ADP-ribose) polymerase (PARP) inhibitors while inducing replication stress and DNA damage. Our work reveals CBX3 as a key regulator of RPA2 function and DNA replication, suggesting that CBX3 could serve as an indicator for targeted therapy of cancer using PARP inhibitors.