Extra virgin olive oil potentiates the effects of aromatase inhibitors via glutathione depletion in estrogen receptor-positive human breast cancer (MCF-7) cells

There have been numerous evidences supporting the relationship between olive oil and cancer, with most of the attention being directed toward its fat and phenolic content. The aims of this study were to investigate whether EVOO and OA could enhance the effects of aromatase inhibitors (letrozole and anastrozole) in ER-positive MCF-7 cells, as well as to investigate its influence on cytochrome c release and GSH levels. It was observed that upon combination treatment, anti-proliferation effects and apoptosis induction were augmented. Apoptosis was triggered via the intrinsic pathway in accordance with cytochrome c release into the cytosol based on IF–IC and ELISA observations. Intracellular GSH levels were also reduced upon EVOO/OA treatment in combination with aromatase inhibitors, and were found to be inversely correlated to cytosolic cytochrome c levels. Additionally, the estrogenic suppressive effects of letrozole and anastrozole were amplified when used in combination with EVOO/OA. Therefore, the employment of aromatase inhibitors in combination with EVOO/OA could orchestrate a reduction in intracellular estrone biosynthesis which feeds ER-positive cells, while simultaneously depleting GSH levels and increasing ROS generation, thus releasing cytochrome c and subsequent induction of apoptosis in MCF-7 cells.