Anticancer Effect of Pacificusoside D from the Starfish Solaster pacificus in Combination with 2-Deoxy-D-glucose on Oxidative Phosphorylation in Triple-Negative Breast Cancer Cells MDA-MB-231

Triple-negative breast cancer (TNBC) represents significant therapeutic challenges due to its aggressive behavior, metabolic plasticity, and lack of targeted treatments, prompting investigation of biologically active triterpene glycosides from the starfish Solaster pacificus. This study evaluated the ability of pacificusoside D (SpD) to synergistically enhance the anticancer efficacy of the glycolytic inhibitor 2-deoxy-D-glucose (2-DG) in TNBC MDA-MB-231 cells by targeting mitochondrial oxidative phosphorylation (OXPHOS). Methods included metabolic profiling via glucose uptake, lactate, and glutamate Glo assays; IC50 determination by MTS and trypan blue assays; colony formation evaluation using a soft agar assay; and molecular mechanism elucidation by Western blot, fluorescence microscopy and spectrometry, and flow cytometry analyses. Results demonstrated that MDA-MB-231 cells predominantly utilized glycolysis under basal conditions, shifting to OXPHOS with 2-DG (0.5 mM). IC50 values were 8.0/8.4 mM for 2-DG and 0.3/0.25 μM for SpD after 24 h of cell treatment. SpD exhibited a significant decrease in the number of colonies in MDA-MB-231 cells and possessed synergistic anticancer effects with 2-DG. Mechanistically, SpD increased tumor suppressor VHL expression level, down-regulated expression level of electron transport chain enzymes, generated reactive oxygen species, induced mitochondrial dysfunction, and triggered Bax/Bak-mediated apoptosis. These findings highlighted the synergistic anticancer potential of SpD in combination with 2-DG in aggressive breast cancer, offering insights into improved clinical outcomes in the future.