Phytochemicals in Olive Oil Suppress Growth of Breast Cancer Cells

Spanish cancer researchers have found that the phytochemical components of extra-virgin olive oil repress the HER2/neu cancer oncogene and can effectively suppress growth of breast cancer cells overexpressing this gene.

Approximately 15-20% of breast cancers have an amplification of the HER2/neu gene or overexpression of its protein product. Overexpression of this receptor in breast cancer is associated with increased disease recurrence and worse prognosis. The acronym HER2/neu (also known as ErbB-2) stands for human epidermal growth factor receptor 2, which is a member of the ErbB protein family, more commonly known as the epidermal growth factor receptor family.

Researchers in biomedical fields as diverse as cardiovascular diseases, autoimmune diseases, and cancer are seeking the molecular basis for the health benefits imparted by the "Mediterranean diet,” which is highly enriched with olive oil. In the current study, investigators from the Catalan Institute of Oncology (Spain) and the University of Granada (Spain) studied the effect of various components of extra-virgin olive oil (EVOO) on breast cancer. Since extra-virgin olive oil is obtained by pressing olives without the use of heat or chemical treatments, it contains phytochemicals that are otherwise lost in the refining process.

The investigators used solid phase extraction followed by semi-preparative high-performance liquid chromatography (HPLC) to isolate phenolic fractions from commercial EVOO. Analytic capillary electrophoresis coupled to mass spectrometry was performed to confirm the identity of the isolated fractions.

EVOO polyphenolic fractions were tested for their tumoricidal ability against HER2-negative and HER2-positive breast cancer cells growing in tissue culture using various chemical and immunological methods. Results presented in the December 18, 2008, online edition of the journal BMC Cancer revealed that all the major complex phenols present in extra-virgin olive oil drastically suppressed overexpression of the cancer gene HER2 in human breast cancer cells.

While this finding is of considerable interest in its own right, the investigators did caution that, "The active phytochemicals [i.e., lignans and secoiridoids] exhibited tumoricidal effects against cultured breast cancer cells at concentrations that are unlikely to be achieved in real life by consuming olive oil.” This fact notwithstanding, they went on to report that, "These findings, together with the fact that that humans have safely been ingesting significant amounts of lignans and secoiridoids as long as they have been consuming olives and extra-virgin oil, strongly suggest that these polyphenols might provide an excellent and safe platform for the design of new anti breast-cancer drugs.”

Related Links:
Catalan Institute of Oncology
University of Granada