SREBP2-activated CNPY3 Phase Separation Promotes Colorectal Cancer by Enhancing MDM2-mediated p53 Degradation.

Dysregulated cholesterol metabolism is a recognized metabolic hallmark of cancer. While the transcription factor SREBP2 is a master regulator of this pathway, how its activation converts metabolic stress into the development of carcinogenic signals in colorectal cancer (CRC) remains unclear. Through clinical and preclinical analyses, we first confirmed that hypercholesterolemia and elevated tumoral SREBP2 are hallmarks of CRC. Using multi-omics integration, we identified CNPY3 as a direct transcriptional target of SREBP2. Functionally, CNPY3 drives CRC cell proliferation, invasion, and tumor growth via a cholesterol synthesis-independent oncogenic program. Clinically, high CNPY3 expression robustly correlated with advanced disease and poor patient survival. Mechanistically, we discovered that CNPY3 undergoes liquid-liquid phase separation (LLPS), a property dependent on its intrinsically disordered C-terminal region. This LLPS capacity is essential for its oncogenic function, as it enables CNPY3 to enhance MDM2 phosphorylation at the activating Ser166 site and promote its nuclear translocation. Consequently, CNPY3 potentiates MDM2-mediated ubiquitination and degradation of the tumor suppressor p53. Genetic ablation of p53 completely abolished the pro-tumorigenic effects of CNPY3, confirming p53 as the critical downstream effector. Crucially, this axis specifically targets wild-type p53, having no effect on common p53 mutants. Pharmacological disruption of the MDM2-p53 interaction with Nutlin-3 effectively reversed CNPY3-driven malignancy both in vitro and in vivo. Our work unveils a SREBP2-CNPY3-MDM2-p53 signaling axis that links cholesterol metabolic dysregulation to p53 pathway inactivation in CRC. We further established that the oncogenic activity of CNPY3 is mediated through its biophysical property of LLPS. These findings nominate CNPY3 as a novel prognostic biomarker and a compelling therapeutic target for p53-wild-type CRC.