The biphenyl dimeric compound 3,3’,5,5’-tetramethoxybiphenyl-4,4’-diol disrupts redox homeostasis and mitochondrial function to inhibit growth and induce apoptosis in breast cancer monolayers and 3D tumor spheroids

Breast cancer remains a significant health concern for women worldwide. Here, we investigate the potential therapeutic role of the biphenyl dimeric compound 3,3’,5,5’-tetramethoxybiphenyl-4,4’-diol (TMBP), enzymatically synthesized from 2,6-dimethoxyphenol through an enzyme-catalyzed oxidation reaction. TMBP has shown the ability to diminish viability across various cancer cell lines by modulating oxidative and metabolic pathways, ultimately inducing cell death. We investigated the antiproliferative effects of TMBP in the MCF-7 breast cancer cell line and in 3D tumor spheroids. Cells were exposed to TMBP treatment, followed by comprehensive assessments of viability, migration, morphology, oxidative and metabolic stress markers, and cell death. Our findings reveal that TMBP treatment results in reduced viability, accompanied by morphological alterations including structural disruptions pertinent to cell migration, as well as the induction of autophagy-related morphological changes, lipid droplets, and disruption of mitochondrial membrane potential. TMBP triggered a pronounced oxidative imbalance, evidenced by increased ROS and NO production, elevated malondialdehyde (MDA) indicating lipid peroxidation, heightened catalase and superoxide dismutase activities, and a concomitant decrease in total glutathione. TMBP disrupted redox-mitochondrial homeostasis and compromised detoxification capacity. In the 3D tumor spheroids model, TMBP markedly decreased volume and viability, disrupted mitochondrial potential, and expanded the necrotic core relative to untreated controls. Altogether, these findings indicate that TMBP as a promising therapeutic agent capable of inhibiting tumor growth and inducing cell death in breast cancer models, supporting its potential development as a future treatment strategy. TMBP reduces cancer cells viability, clonogenic survival and triggers G2/M arrest. Marked morphological disruptions are observed following TMBP exposure. TMBP-treatment provokes strong oxidative and metabolic stress responses. 2D and 3D tumor spheroids exhibit clear signs of TMBP-induced cell death. In 3D tumor spheroids, TMBP attenuates growth and expands the necrotic core.