Calycosin triggers ferroptosis through modulation of the OTUD6B/GPX4 axis to suppress triple-negative breast cancer.
BACKGROUND Triple-negative breast cancer (TNBC) is a clinically challenging disease subtype of breast cancer, with therapeutic outcomes remaining unsatisfactory due to its highly invasive potential. Ferroptosis, a newly identified type of programmed cell death, is mediated by the iron-dependent accumulation of lipid peroxides, presenting a potential therapeutic avenue for the treatment of TNBC. Calycosin (Cal) has demonstrated antitumor effects across various tumors; however, its therapeutic potential based on the ferroptosis pathway for TNBC treatment and the associated mechanisms remains unclear. METHODS To achieve this, the cell counting kit-8 assay, flow cytometry assay, wound healing assay, colony formation assay, EdU assay, and xenograft mouse models were performed. Mechanisms were investigated using transcriptomic sequencing, quantitative reverse transcription polymerase chain reaction, and Western blot in vitro and in vivo. RESULTS Our findings indicated that Cal significantly reduces the viability of TNBC cells, primarily manifested as suppression of growth, migration, and colony formation through the induction of ferroptosis. Additionally, Cal impairs mitochondrial function in TNBC cells by reducing mitochondrial membrane potential and elevating ferroptosis-related markers, including MDA and 4-HNE accumulation, reactive oxygen species formation, and GSH depletion. Mechanistically, Cal administration may reduce GPX4 levels through the OTUD6B-mediated ubiquitination pathway, thereby enhancing the ubiquitination and degradation of the GPX4 protein. The decreased OTUD6B and GPX4 expression significantly inhibited TNBC growth both in vivo and in vitro, resulting in ferroptosis induction in TNBC cells. CONCLUSION This is the first study to demonstrate that Cal exerts anti-TNBC activity through a novel OTUD6B/GPX4-dependent ferroptosis regulatory axis. These findings highlight that Cal warrants further investigation as a potential candidate, and the OTUD6B/GPX4 signaling pathway may represent a significant target for TNBC treatment.