Olive Oil Fights Breast Cancer 

A compound in olive oil dramatically cuts the activity of a gene implicated in breast cancer, likely explaining the protective effect of the staple of the Mediterranean diet.

Tests on breast cancer cell lines by American researchers have shown that the compound, Oleic acid, cuts the activity of the Oncogene Her-2/neu (also known as erb B-2). Excess expression of this gene has been found in more than a fifth of breast cancer cases and been linked with highly aggressive tumors with a poor prognosis. 
Oleic acid was also found to boost treatment with trastuzumab (Herceptin), a monoclonal antibody treatment that targets the Her-2/neu gene and has proven to prolong the lives of people with breast cancer.
"Our findings underpin epidemiological studies that show that the Mediterranean diet has significant protective effects against cancer, heart disease and aging," says Javier Menendez of Northwestern University in Illinois.

Studies of southern European populations have shown that monounsaturated fatty acids such as oleic acid may reduce breast cancer risk. Animal studies, however, have had inconsistent resultspossibly because olive oil was administered in mixtures rather than on its own. 

In their research on cell lines, Menendez and colleagues found that oleic acid cut the expression of Her-2/neu by up to 46% and assisted with Herceptin treatment by promoting the death of breast cancer cells having high levels of the oncogene. They also found that it increased the expression of a tumor suppressor protein called p27Kip1. 
Menendez says that the findings not only help in explaining how dietary fatty acids regulate the malignant behavior of breast cancer cells, but also suggest that oleic acid-based dietary interventions could help delay or prevent Herceptin resistance. 
The next step is to determine the molecular mechanisms by which oleic acid inhibits Her-2/neu, because this action appears different from that of Herceptin. Another goal is to study whether a high virgin olive oil diet can decrease the aggressiveness of human breast tumors in animals. 

Source: The Annals of Oncology