ZBP1 antagonizes MRE11-mediated DNA end resection and confers synthetic lethality to PARP inhibition in ovarian cancer.

ZBP1, a classic pattern recognition receptor (PRR), has been implicated in regulating programmed cell death and the innate immune response. However, the role of ZBP1 in the nucleus remains largely undefined. Here, we found that nuclear ZBP1 localizes to the site of DNA double-stranded breaks (DSBs) following DNA damage and impairs homologous recombination (HR) repair through its interaction with MRE11. ZBP1 interacts with MRE11 through RHIM A and B domains and inhibits the enzymatic activity of MRE11, ultimately leading to the suppression of HR and DNA damage repair (DDR). These processes are initiated via ATM-mediated ZBP1 phosphorylation at S106. Consistent with these findings, in vitro and in vivo models both exhibit increased sensitivity to PARP inhibitor treatment following ZBP1 overexpression. Furthermore, in our neoadjuvant niraparib monotherapy study (NCT05407841) higher ZBP1 expression correlates with better response to PARP inhibition and prolonged PFS in high-grade serous ovarian cancer (HGSOC). This study describes a novel function of ZBP1 for regulating HR, which confers synthetic lethality to PARP inhibition in ovarian cancer. ZBP1 thus serves as a potential therapy target and biomarker of response to PARP inhibitors and potentially other therapeutic agents such as platin analogs that are synthetically lethal with defective HR.