Oleuropein Induces Cytotoxicity and Peroxiredoxin Over-expression in MCF-7 Human Breast Cancer Cells

Background/Aim: As a fundamental staple of the Mediterranean diet, olive oil has long been recognized for its health benefits, including its ability to reduce cardiovascular and neurological disease. Oleuropein is the primary phenolic chemical found in all parts of the olive tree, especially in the leaves and fruit. Oleuropein exhibits anti-inflammatory and antioxidant properties, and has been associated with cancer inhibition in various animal and cell models. We investigated the effects of oleuropein on the MCF-7 human breast cancer cell line, and compared it to the non-cancerous MCF-10A breast epithelial line. Materials and Methods: Both cell lines were treated with two different concentrations of oleuropein for 48 and 72 hours. Cytotoxicity, apoptosis, and peroxiredoxin expression were measured. Results: Forty-eight hours of oleuropein treatment induced cytotoxicity in MCF-7 cells, whereas it had no effect on MCF-10A cells. Furthermore, oleuropein-induced cytotoxicity in MCF-7 cells involved a measurable increase in apoptosis. Oleuropein treatment of MCF-7 cells significantly and dramatically increased expression of all six peroxiredoxin mRNAs (Prdx1-Prdx6), whereas oleuropein treatment of MCF-10A cells resulted in only a small increase in Prdx1 and Prdx6 expression, with no change in the expression of the other peroxiredoxins. Together, these data demonstrate differential susceptibility to oleuropein-induced cell death between the two lines, and differential regulation of peroxiredoxins. Conclusion: Oleuropein-induced over -expression of peroxiredoxins in MCF-7 cells may either facilitate its cancer-specific cytotoxicity or, alternatively, is a consequence of an altered response of cancer cells.