Liquid-liquid phase separation of CBX2 regulates lipid raft-mediated extracellular vesicle biogenesis to facilitate ovarian carcinoma metastasis

Extracellular vesicle (EV)-mediated intercellular communication plays a vital role in ovarian carcinoma (OvCa) metastasis. However, the mechanisms underlying EV biogenesis in metastatic OvCa remain largely unclear. In this study, CBX2 was identified as the most significant molecule, with elevated expression in omental metastases and association with poor prognosis. Functionally, CBX2 promotes tumor cell migration, invasion, and omental metastasis both in vitro and in vivo. Mechanistically, CBX2 enhances EV secretion and pro-metastatic cargoes loading by remodeling lipid rafts, cholesterol-rich membrane microdomains, which are essential for EV formation. Mutation of the intrinsically disordered region (IDR) of CBX2 abrogated its ability to remodel lipid rafts and alter multivesicular body distribution, indicating that this process largely depends on liquid-liquid phase separation (LLPS). Furthermore, CBX2 upregulates FLOT1 expression, a lipid raft-associated scaffolding protein highly expressed in metastatic lesions. Notably, this upregulation is attenuated in cells after upregulation of the LLPS-deficient CBX2, suggesting FLOT1 induction is at least partially dependent on LLPS of CBX2. Disruption of lipid rafts or inhibition of CBX2 phase separation significantly impairs EV production and metastatic potential. In summary, these findings reveal an LLPS-dependent mechanism by which CBX2 regulates lipid raft-mediated EV biogenesis and identify CBX2 as a potential therapeutic target to restrict omental metastasis in OvCa.