Radiation-induced nuclear translocation of NPRL2 hijacks E3 ubiquitin ligases to enhance DNA repair via the AMPK/WDR24 axis, contributing to CRC radioresistance

Radiotherapy resistance remains a major clinical challenge in colorectal cancer (CRC) treatment. Our study reveals that the regulation of nuclear E3 ubiquitin ligase maintains K48-ubiquitin levels that correlate with CRC radiotherapy sensitivity. We identify NPRL2 as the central mediator of this process. Following radiation, NPRL2 rapidly translocates to the nucleus, where it directly binds to the catalytic domains of key E3 ubiquitin ligases, including HERC2 and RNF8, and functionally inactivates them. This NPRL2-mediated inhibition of E3 ligase activity prevents the degradation of critical DNA repair proteins. Importantly, clinical analyses demonstrate that nuclear NPRL2 plays a role in sustaining radioresistance. Mechanistic investigations reveal that radiation-induced AMPK activation initiates this process by phosphorylating WDR24, which promotes NPRL2 dissociation from the GATOR1 complex and facilitates its nuclear translocation. Therapeutic targeting through AMPK inhibition effectively blocks NPRL2 nuclear accumulation, leading to impaired DNA damage repair and significant radiosensitization of CRC cells in both <i>in vitro</i> and <i>in vivo</i> models. These findings not only elucidate the AMPK/WDR24/NPRL2 signaling axis as a fundamental regulator of DNA repair machinery in CRC, but also provide compelling evidence for its potential as a novel therapeutic target to overcome radioresistance and improve radiotherapy efficacy in CRC patients.