Brucein D suppresses breast cancer proliferation and migration via targeting the FAK/LRG1 signaling pathway.

Breast cancer (BC) is a leading cause of cancer-related mortality in women worldwide, underscoring the need for novel therapeutic strategies. Focal adhesion kinase (FAK) has emerged as a promising oncological target due to its central role in tumor progression. Bruceine D (BD), a natural compound from Brucea javanica, exhibits anti-cancer properties, but its mechanism in BC via FAK inhibition remains unclear. We conducted a comprehensive investigation using BC cell lines. Cell viability and migration were assessed by MTT and transwell assays, respectively. The tube formation assay examines the effect of BD on angiogenesis. Mitochondrial function was evaluated by measuring reactive oxygen species (ROS), ATP production, and mitochondrial membrane potential (ΔΨm). Apoptosis was quantified via flow cytometry. RNA sequencing (RNA-seq) with pathway enrichment analysis was employed to identify FAK-associated signaling pathways, and key protein expression changes, including FAK and downstream factors, were validated by western blotting. BD significantly suppressed BC cell proliferation, migration, and angiogenesis by inducing mitochondrial dysfunction, characterized by elevated ROS levels, depleted ATP, and loss of ΔΨm. Clinical analysis confirmed FAK overexpression in BC tissues. Mechanistically, BD inhibited FAK signaling. RNA-seq further revealed that FAK inhibition modulated several downstream pathways, including the expression of LRG1, collectively leading to the induction of apoptosis. This study identifies BD as a potent small-molecule FAK inhibitor. Our findings delineate a FAK-centered mechanism of action for BD, supporting its further development as a promising therapeutic agent for BC.