Targeting UBE2T by β-elemene inhibits prostate cancer stem cells and bone metastasis by blocking the TRIM28/pGSK3β/β-catenin signaling

BACKGROUND: Bone metastasis remains a major clinical challenge in advanced prostate cancer (PCa). Although β-elemene has been shown to suppress cancer stem cells and tumor progression, its mechanism in PCa is not fully understood. PURPOSE: This study investigated the specific mechanism by which β-elemene impeded prostate cancer stem cells (PCSCs) and PCa metastasis. METHODS: First, we constructed a progression-free survival (PFS) prediction model and performed survival analysis to screen candidate genes through bioinformatic analysis. Second, the direct binding of β-elemene to UBE2T was validated by molecular docking, molecular dynamics simulation, cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR). And In vivo xenograft tumorigenicity assays were conducted to assess the activation of PCSCs by UBE2T. Mechanistically, co-immunoprecipitation (Co-IP), in vivo ubiquitination assays, and immunoprecipitation-mass spectrometry (IP-MS) were employed to investigate the role of UBE2T in cooperating with E3 ubiquitin ligases to promote the degradation of the substrate protein pGSK3β. RESULTS: Functionally, β-elemene inhibited PCa cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and the self-renewal of PCSCs. In vivo, UBE2T promoted the activation and tumorigenicity of PCSCs, while β-elemene attenuated UBE2T-driven stemness, tumor growth, and bone metastasis. Mechanistically, UBE2T cooperated with TRIM28 to facilitate K48-linked ubiquitination and degradation of pGSK3β, thereby disrupting the β-catenin degradation complex, and promoting its nuclear translocation. These effects were partially reversed by β-elemene. Clinical tissue microarray analysis further confirmed UBE2T as an oncogene associated with poor prognosis in advanced PCa. CONCLUSION: Collectively, our findings demonstrate that β-elemene suppresses the self-renewal of PCSCs and bone metastasis by targeting the UBE2T/TRIM28/pGSK3β/β-catenin signaling axis.