NUDT16 enhances the resistance of cancer cells to DNA-damaging agents by regulating replication fork stability via reversing HMGA1 ADP-ribosylation.

Precise DNA replication is the basis for maintaining cell proliferation and genome stability. Current chemotherapy drugs and radiotherapy induce cell death by aggravating replication stress, albeit with poor efficacy. The replication stress response has been shown to play fundamental roles in resistance to radiotherapy and chemotherapy. High mobility group A1 (HMGA1) promotes tumor progression by regulating autophagy, angiogenesis, and chemoresistance; however, its role in coordinating replication stress and cell cycle progression remains elusive. Our results indicated that HMGA1 recruited FANCD2 to promote DNA replication and cell cycle progression both by attenuating R-loop-induced replication stress and by protecting stalled replication forks from degradation, ultimately enhancing tumor resistance to chemotherapy and irradiation treatment. We also identified HMGA1 as a novel substrate for the dePARylase NUDT16. NUDT16 was found to suppress the binding of HMGA1 to the E3 ubiquitin ligase CHFR by removing its PARylation at Glu 50, thereby reducing its ubiquitin-proteasome pathway-mediated degradation and enhancing HMGA1 protein stability. NUDT16-HMGA1 inhibition can significantly improve the sensitivity of tumor cells to chemotherapy and irradiation treatment. Collectively, these data suggest that NUDT16 enhances the ability of tumor cells to cope with replication stress by reversing the PARylation and positively regulating the protein expression of HMGA1. Therefore, targeting the NUDT16-HMGA1 pathway may be a novel strategy to enhance the sensitivity of radiotherapy and chemotherapy.