Beauvericin Exerts Antitumor Effects on Multiple Myeloma by Disrupting the USP9X-Bcl-2 Interaction to Promote Bcl-2 Degradation.

BACKGROUND: Beauvericin is a cyclic hexadepsipeptide derived from Bombyx batryticatus. It is known as Jiangcan in traditional Chinese medicine and has diverse pharmacological properties, including antitumor, antiviral, insecticidal, and antibacterial effects. However, its specific mechanisms against multiple myeloma (MM) are not fully understood. The aim of this study was to elucidate the mechanism of beauvericin in MM. METHODS: This study utilized the mouse Sp2/0 cell line, the human U266 cell line, and a subcutaneous tumor allograft model in C57BL/6J mice. Flow cytometry was employed to evaluate apoptosis, and the Cell Counting Kit-8 (CCK-8) assay was used to measure cellular viability. Network pharmacology was employed for target prediction, followed by molecular docking analyses to confirm drug-target interactions. The protein expression levels of Ubiquitin-Specific Protease 9X (USP9X) and Bcl-2 were assessed by Western blotting following USP9X knockdown. Additionally, co-immunoprecipitation assays were performed to evaluate whether beauvericin modulates the Bcl-2/USP9X interaction and affects Bcl-2 ubiquitination. The antitumor effects of beauvericin were further evaluated through in vivo experiments. RESULTS: Network pharmacology analysis identified 82 MM-related target genes for beauvericin. These included key targets such as Caspase-3, Bcl-2, Matrix metallopeptidase 9 (MMP9), and Caspase-8, which may contribute to the anti-MM effects of beauvericin. Molecular docking revealed strong affinity and stability between beauvericin and Bcl-2. In vitro experiments confirmed that beauvericin inhibits MM cell proliferation, promotes apoptosis, and enhances Bcl-2 ubiquitination and degradation by disrupting the interaction between the deubiquitinating enzyme USP9X and Bcl-2. In vivo studies demonstrated that beauvericin treatment suppressed the growth of subcutaneous MM tumors C57BL/6J mice. CONCLUSION: Beauvericin may exert its anti-MM effects by disrupting the USP9X-Bcl-2 interaction, thereby promoting Bcl-2 ubiquitination and degradation, and inducing cell apoptosis in MM cells.