Cell-Membrane Permeable Redox Phospholipid Polymers Induce Apoptosis in MDA-MB-231 Human Breast Cancer Cells

Induction of oxidative stress is an effective approach to causing apoptotic death of cancer cells. Since oxidative stress is generally caused by an intracellular redox imbalance, altering the intracellular redox is a promising strategy toward the growth suppression of cancer cells. Here, we attempted to induce apoptosis in MDA-MB-231 human breast cancer cells by adding a cell-membrane permeable redox phospholipid polymer that can alter the intracellular redox. We found that apoptosis and the deactivation of oxidative phosphorylation were induced in the MDA-MB-231 cells in the presence of the oxidized form of the redox polymer. Remarkably, such phenomena were not observed in the presence of the reduced form of the redox polymer that cannot intercept metabolic electrons. These results indicate that the redox polymer that mediates extracellular electron transfer (EET) generates oxidative stress, leading to the apoptosis of the cancer cells.