Dddt_a_338881 129..141

1Department of Cadre Health, Tongde Hospital of Zhejiang Province, Hangzhou, 310012, Zhejiang, People’s Republic of China; 2Department of Gastroenterology, Tongde Hospital of Zhejiang Province, Hangzhou, 310012, Zhejiang, People’s Republic of China; 3Department of Oncology, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, 310012, People’s Republic of China; 4Department of Pharmacy, Tongde Hospital of Zhejiang Province, Hangzhou, Zhejiang, 310012, People's Republic of China; 5Department of Rehabilitation Medicine, Tongde Hospital of Zhejiang Province, Hangzhou, 310012, Zhejiang, People’s Republic of China Purpose: Berbamine (Ber), a bioactive constituent extracted from a traditional Chinese medicinal herb, has been shown to exhibit broad inhibitory activity on a panel of cancer cell types. However, its effects and the underlying molecular mechanisms on gastric cancer (GC) remain poorly understood. Methods: The anti-growth activity of Ber on two GC cell lines and normal gastric epithelial cell line were evaluated using MTS and clone formation assay. Flow cytometry analysis was employed to evaluate the cell cycle distribution and apoptosis of GC cells. Western blot and quantitative PCR (qPCR) analysis were employed to investigate the anti-GC mechanism of Ber. The inhibitory activity and binding affinity of Ber against BRD4 were evaluated by homogeneous time-resolved fluorescence (HTRF) and surface plasmon resonance (SPR) assay, respectively. Molecular docking and molecular simulations were conducted to predict the interaction mode between BRD4 and Ber. Results: The results demonstrated that Ber reduced the proliferation of GC cell lines SGC7901 and BGC-823 and induced cell cycle arrest and apoptosis. Mechanistically, Ber was identified as a novel natural-derived BRD4 inhibitor through multiple experimental assay, and its anti-GC activity was probably mediated by BRD4 inhibition. Molecular modeling studies suggested that Ber might bind to BRD4 primarily through hydrophobic interactions. Conclusion: Our study uncovered the underlying anti-GC activity of Ber in vitro and suggested that Ber holds promise as a potential lead compound in the discovery of novel BRD4 inhibitors.