USP14-mediated deubiquitination stabilizes integrin β1 to sustain malignant progression and chemotherapy resistance in osteosarcoma

Osteosarcoma patients with metastasis or chemotherapy resistance typically have a poor prognosis, yet the precise mechanisms underlying these adverse clinical outcomes remain elusive. In this study, we analyzed tissue proteomic data from our osteosarcoma cohort to compare protein expression profiles between metastatic and non-metastatic cases, as well as subgroups with low versus high chemotherapy-induced tumor necrosis rates. Our clinical analyses revealed that elevated ubiquitin-specific protease 14 (USP14) expression was associated with lung metastasis, a lower tumor necrosis rate, and shorter overall survival. Functional experiments in vitro and in vivo demonstrated that USP14 knockdown robustly suppressed the proliferation and metastatic potential of osteosarcoma cells. Mechanistically, USP14 interacted with and stabilized integrin β1 via deubiquitination, thereby activating the FAK/SRC axis and inducing inhibitory phosphorylation of GSK3β. This signaling cascade blocked β-catenin ubiquitin-dependent degradation to promote β-catenin accumulation, nuclear translocation, and subsequent activation of TCF/LEF-mediated transcription of downstream oncogenes, ultimately driving osteosarcoma progression. Moreover, chemotherapy upregulated USP14 expression, thereby promoting chemoresistance. Pharmacological inhibition of USP14 with IU1 synergistically enhanced the chemosensitivity of osteosarcoma cells to doxorubicin, effectively restraining tumor growth and metastasis. Collectively, our findings delineate a core USP14-driven oncogenic cascade governing osteosarcoma progression, highlighting USP14 as a promising therapeutic target to improve chemotherapy efficacy and clinical outcomes for osteosarcoma patients.