Berbamine exerts anti-breast-cancer effects in association with autophagy-related responses and PI3K/Akt1/mTOR signaling

Introduction Breast cancer remains a leading cause of cancer-related morbidity and mortality worldwide, and effective, well-tolerated therapeutic strategies are needed. Berbamine (BBM), a natural bisbenzylisoquinoline alkaloid, has anticancer activity, but its effects on autophagy- and lysosome-related processes in breast cancer remain incompletely understood. Methods We evaluated the effects of BBM on MDA-MB-231, MDA-MB-468, MCF-7, and 4T1 breast cancer cells and normal mammary epithelial cells using assays of cell viability, migration, invasion, autophagy-related responses, lysosome-associated changes, immunofluorescence, transmission electron microscopy, and Western blotting. Exploratory network analysis was used to prioritize candidate BBM-associated pathways, and molecular docking was used to predict interactions between BBM and selected pathway proteins. Antitumor activity was further assessed in an MCF-7 xenograft model. Results BBM inhibited the proliferation, migration, and invasion of breast cancer cells while showing relatively low cytotoxicity toward normal mammary epithelial cells. BBM treatment was associated with increased levels of p-ULK1, ATG5, ATG7, and Beclin1, increased LC3 puncta, and accumulation of double-membraned autophagosomes. BBM was also associated with TFEB nuclear translocation, increased LAMP2 expression, and enhanced LysoTracker staining. Network analysis prioritized the PI3K/Akt signaling pathway, and molecular docking predicted potential interactions between BBM and PI3K, Akt1, and mTOR. Western blot analysis showed reduced phosphorylation of these proteins in cultured breast cancer cells. In the MCF-7 xenograft model, BBM inhibited tumor growth and was associated with changes in autophagy-related markers. Discussion These findings support the involvement of autophagy-related responses, lysosome-associated changes, and PI3K/Akt1/mTOR pathway modulation in the anti-breast-cancer effects of BBM, while further studies are needed to establish direct target engagement and causal relationships.