A novel strategy for stabilizing the β-catenin destruction complex: Phillygenin targets AXIN1–Dvl interaction to inhibit triple-negative breast cancer

Triple-negative breast cancer (TNBC) has a dismal prognosis and few available treatments, posing it a formidable clinical challenge. Here, we identify axis inhibition protein 1 (AXIN1), a key scaffold protein in the Wingless/Int-1 (Wnt) signaling destruction complex, as the direct molecular target of phillygenin. Using integrated approaches including proteomics, bio-layer interferometry, Cellular Thermal Shift Assay (CETSA), and Drug Affinity Responsive Target Stability (DARTS) assays, we demonstrate that phillygenin specifically binds to AXIN1 at Glycine 766 within its Dishevelled (Dvl)-interacting domain (residues 732–862). This binding stabilizes AXIN1 and potently blocks its interaction with Dvl, preventing Dvl-mediated recruitment of AXIN1 to the cell membrane. Consequently, phillygenin maintains the integrity of the β -catenin destruction complex, promotes β -catenin degradation, and suppresses aberrant Wnt/ β -catenin pathway activation in TNBC cells. In vitro , phillygenin dose-dependently inhibits TNBC cell proliferation, migration, and induces apoptosis, effects dependent on AXIN1 expression. In vivo , phillygenin administration significantly suppresses tumor growth and metastasis in both orthotopic 4T1 and patient-derived xenograft (PDX) TNBC models, with efficacy abolished upon AXIN1 knockout. Importantly, phillygenin exhibits minimal cytotoxicity in normal cells. Our findings unveil phillygenin as a first-in-class inhibitor specifically targeting the AXIN1–Dvl interaction, providing a novel and potent therapeutic strategy for TNBC by selectively inhibiting oncogenic Wnt signaling.