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 <i>Solaster pacificus</i>. 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.