The USP8/CEP55/CHMP6 Axis Orchestrates Triple-Negative Breast Cancer Progression by Regulating Ferroptosis and Macrophage M2 Polarization.

Background: Triple-negative breast cancer (TNBC) carries a substantial risk of recurrence and metastasis, posing significant threats to patients' health and quality of life. Centrosomal protein 55 (CEP55) has been demonstrated to exhibit elevated expression levels in TNBC. However, its molecular regulatory mechanism in TNBC remains unclear.

Methods: Bioinformatics databases, qRT-PCR, and Western blot were employed to analyze CEP55 expression in TNBC tissues and cells. EdU assays, flow cytometry, and Transwell assays were utilized to monitor cell proliferation, apoptosis, and invasion. Subsequently, macrophage polarization was detected by flow cytometry. Fe²⁺, malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) levels were determined using corresponding kits. Immunoprecipitation (IP) was used to detect the ubiquitination level of CEP55, and co-IP was applied to confirm the interaction between CEP55 and Charged Multivesicular Body Protein 6 (CHMP6). Finally, a xenograft tumor model was established, and immunohistochemistry (IHC) was conducted to evaluate the expression of specific proteins.

Results: CEP55 levels were increased in TNBC tissues and cells. Silencing CEP55 repressed TNBC cell proliferation, invasion, and macrophage M2 polarization, and facilitated cell apoptosis and ferroptosis. Additionally, ubiquitin-specific protease 8 (USP8) maintained CEP55 stability through deubiquitination, and CEP55 overexpression reversed the cellular effects caused by USP8 knockdown. Moreover, CEP55 bound to CHMP6 to promote its expression, thereby facilitating the malignant progression of TNBC cells. CEP55 overexpression abolished the inhibitory influence of USP8 silencing on tumor growth in vivo.

Conclusion: USP8 stabilized CEP55 expression through deubiquitination, and CEP55 further promoted CHMP6 expression to inhibit ferroptosis progression, thereby facilitating macrophage M2 polarization and malignant biological behaviors of TNBC cells.