Olive Oil Polyphenol Oleuropein Inhibits Smooth Muscle Cell Proliferation

ObjectivesThe Mediterranean diet, with a high content of olive oil, is associated with a reduced risk of coronary artery disease. The aim of this study was to determine the effect of oleuropein, one of the polyphenols in olive oil, on vascular smooth muscle cell (SMC) proliferation in vitro.DesignThis was an experimental study.Materials and methodsBovine vascular SMCs were cultured in the presence of 100 μM of oleuropein. On days 1, 3 and 5, cell number was counted. Cell cycle analysis was performed by flow cytometry. Cell cycle regulators were assessed by immunoblotting.ResultsCell proliferation in the presence of oleuropein was significantly inhibited by 92%. Cell cycle analysis revealed that oleuropein treatment blocked cells in the G1–S phase compared with the non-treated group. Among G1 phase regulators, retinoblastoma protein, cyclinD, p21 and p27 were not affected by oleuropein, but extracellular signal-regulated kinase 1/2 (ERK1/2) activation was inhibited. Growth of SMC treated with 100 μM of the mitogen-activated protein (MAP) kinase/ERK kinase 1 (MEK1) inhibitor PD98059 was also significantly inhibited by 70%.ConclusionsOleuropein inhibited SMC proliferation through a cell cycle block between the G1 and the S phases, which may be regulated by ERK1/2. These results suggest a mechanism by which olive oil consumption may have beneficial effects on cardiovascular mortality by inhibiting SMC proliferation.