Eupalinolide B targets the USP10-AR-MTHFD1 axis to sensitize castration-resistant prostate cancer to enzalutamide

Acquired resistance to enzalutamide (ENZ) remains a major obstacle in the treatment of castration-resistant prostate cancer (CRPC). Although persistent androgen receptor (AR) signaling is a central determinant of limited responsiveness to ENZ, the post-translational mechanisms that maintain AR protein stability during ENZ treatment remain insufficiently understood.

This study aimed to define the role of ubiquitin-specific protease 10 (USP10) in CRPC adaptive responses to ENZ treatment and determine whether Eupalinolide B (EB) could enhance ENZ sensitivity by targeting the USP10-AR-MTHFD1 axis.

CRPC cell models and xenograft mouse models were established to evaluate the effects of EB on ENZ sensitivity both in vitro and in vivo. Protein interaction and localization were analyzed using immunoprecipitation, binding assays and immunofluorescence. AR ubiquitination and degradation were evaluated by ubiquitination assays and proteasome inhibition experiments. Functional assays were performed to investigate the impact of EB on cell proliferation and tumor progression, and mechanistic studies were conducted to explore the involvement of the USP10-AR-MTHFD1 signaling axis.

USP10 translocated to the nucleus under ENZ treatment and contributed to reduced ENZ responsiveness in CRPC. EB disrupted the USP10-AR interaction by targeting the catalytic domain of USP10, promoting ubiquitination-mediated AR degradation, and suppressing the downstream AR-MTHFD1 axis. Consequently, EB enhanced the antitumor efficacy of ENZ against CRPC both in vitro and in vivo.

USP10 is a potential therapeutic vulnerability in CRPC, and EB represents a promising lead compound for ENZ-based combination therapy.