Network pharmacology and experimental validation reveal the therapeutic effect and chemosensitization mechanism of brusatol against oral squamous cell carcinoma.

Brusatol (BR) is a quassinoid from the traditional Chinese herb Brucea javanica, widely used for its anti-inflammatory and anti-tumor properties. This study aimed to investigate the molecular mechanisms through which BR enhances cisplatin (CDDP) sensitivity in oral squamous cell carcinoma (OSCC). Network pharmacology and molecular docking were used to prioritize candidate targets and pathways. Cell viability, clonogenic growth, apoptosis, ROS accumulation, and NRF2/HO-1/NQO1 signaling were evaluated using CCK-8, colony formation, Annexin V/PI flow cytometry, AO/EB staining, MitoSOX Red staining, and Western blotting. The synergistic efficacy of BR with CDDP was analyzed using the Chou-Talalay method, while NAC and tBHQ were used to assess the functional roles of ROS and NRF2, respectively. Antitumor efficacy was further examined in a CAL27/CDDP xenograft model. Network pharmacology identified NFE2L2 (encoding NRF2) as a core hub target and highlighted ROS-related signaling pathways. BR inhibited OSCC cell viability and synergistically enhanced CDDP cytotoxicity. BR/CDDP cotreatment reduced NRF2 nuclear accumulation and HO-1/NQO1 expression while increasing mitochondrial ROS accumulation. In vivo, BR/CDDP cotreatment inhibited xenograft growth and decreased Ki-67, NRF2, HO-1, and NQO1 expression. These findings indicate that BR enhances CDDP sensitivity in OSCC by disrupting NRF2/HO-1/NQO1 antioxidant pathway and promoting ROS-associated apoptosis.