Abstract

Circadian disruption is linked to colorectal cancer (CRC) progression. We investigated the role of the tumor suppressor N-myc downstream-regulated gene 2 (NDRG2) in this context. Intestinal-specific Ndrg2 knockout exacerbated colorectal tumorigenesis in mice under circadian disruption. We identified NDRG2 as a novel stabilizer of the core clock protein Circadian Locomotor Output Cycles Kaput (CLOCK). Mechanistically, NDRG2 bidirectionally regulates CLOCK ubiquitination, inhibiting its degradation by the E3 ligase STIP1 Homology and U-Box Containing Protein 1 (STUB1) while promoting stabilization by the deubiquitinase Ubiquitin Specific Peptidase 8 (USP8). This NDRG2-CLOCK axis was crucial for oxaliplatin sensitivity. Integrated RNA sequencing and functional studies revealed that CLOCK transcriptionally represses Fibroblast Growth Factor 2 ( FGF2 ), a chemoresistance driver. Thus, NDRG2 enhances CLOCK activity to suppress FGF2 and promote oxaliplatin efficacy. Clinically, oxaliplatin-sensitive CRC tissues showed higher NDRG2/CLOCK co-expression and lower FGF2 levels. Our work defines a pathway wherein NDRG2 inhibits tumorigenesis and chemoresistance by stabilizing CLOCK to transcriptionally represses FGF2 , linking circadian regulation to therapy response, and nominating the NDRG2-STUB1/USP8-CLOCK-FGF2 axis as a therapeutic target. The alternative text for this image may have been generated using AI.