Until now, very little has been known about the
antioxidant capacity of
squalene and its effect on human breast tumourigenesis. In the present work, we investigated
squalene's scavenging properties and its effect on cell proliferation, cell cycle profile, apoptosis,
reactive oxygen species (ROS) level and oxidative DNA damage, using human breast cell lines. Our results showed that
squalene neither possesses scavenging activity nor significantly alters cell proliferation rates, the cell cycle profile or cell apoptosis in human mammary epithelial cells (MCF10A), minimally invasive (MDA-MB-231)
breast cancer cells, and highly invasive (MCF7)
breast cancer cells. However, we found that
squalene did exert the following effects on MCF10A epithelial cells in a dose-dependent manner: (a) it decreased intracellular ROS level, (b) it prevented H(2)O(2)-induced oxidative injury, and (c) it protected against oxidative DNA damage. Interestingly,
squalene did not exert these effects on MCF7 and MDA-MB-231
cancer cells. Therefore, our data suggest that
squalene, found in high amounts in virgin
olive oils, could be partially responsible for the lower incidence of
breast cancer in populations that consume the
Mediterranean diet due to its protective activity against oxidative DNA damage in normal mammary cells.