Investigating the Role of Peroxisomes in Regulating Breast Cancer Stem Cell Mechanisms

Cancer and ageing remain major challenges for humanity, requiring innovative solutions. While the role of mitochondria in cancer and ageing has been extensively studied, peroxisomes have received comparatively little attention in this context. In our study, we investigated the impact of peroxisomes on cancer stemness. We systematically analysed the metabolic differences between MCF-7 cells with low- and high-peroxisome levels. Briefly, MCF-7 cells were stably transduced with GFP- and RFP-fluorescent reporters that were targeted to peroxisomes, by addition of a C-terminal SKL (Serine-Lysine-Leucine) peroxisomal targeting signal. To independently validate our observations, MCF-7 cells were also treated with Rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist that enhances peroxisome levels. Key parameters examined included cancer stemness, levels of reactive oxygen species (ROS), cell division dynamics, autophagy activity, the DNA damage response, susceptibility to ferroptosis, mitochondrial respiration, and aerobic glycolysis in cells with low- and high-peroxisome profiles. Our results demonstrated that elevated peroxisome levels significantly decrease the capacity of breast cancer stem cells (BCSCs) to form mammospheres or colonies, thus reducing their stemness potential. In high-peroxisome cells, Mammosphere formation was reduced by approximately 50%, and colony formation by 80% compared to low-peroxisome cells. This decline in stemness was accompanied by an approximately one-and-a-half-fold increase in ROS levels and a five-fold increase in lipid peroxidation, reflecting increased mitochondrial lipid peroxidation and ferroptosis. Continued research is, however, essential to further validate these findings and to elucidate the underlying mechanisms.