Olive oil compounds may counter HER-2-driven breast cancer

MedWire News: Naturally occurring phenolic compounds found in extra-virgin olive oil appear to counter the oncogenic effects of human epidermal growth factor receptor (HER)-2 in breast cancer cells grown in vitro, study results show.

The findings may partly explain why previous studies have shown that women who eat a Mediterranean diet have a reduced risk for breast cancer compared with other women, say Javier Menendez (Catalan Institute of Oncology, Barcelona, Spain) and colleagues.

Studies of olive oil have generally focused on the potential anti-cancer effects of the main omega-9 fatty acid triacylglycerols such as oleic acid.

However, the main non-glyceridic constituents – which consist of at least 30 phenolic compounds – remained to be evaluated.

Menendez and colleagues explain that these phenolic compounds can only be found in extra-virgin olive oil, which results from pressing olives without the use of damaging heat or chemical treatments.

The researchers separated the oil into fractions and tested these against breast cancer cells in lab experiments. All the fractions containing the major extra-virgin phytochemical polyphenols (lignans and secoiridoids) were found to effectively inhibit HER-2 expression and activity.

Although the findings provide insights on the mechanisms by which polyphenol-rich extra-virgin olive oil might contribute to a lowering of breast cancer risk in a HER2-dependent manner, Menendez et al say that extreme caution must be applied when applying the lab results to the clinic.

"The active phytochemicals (ie, 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,” they comment in the journal BMC Cancer.

Nevertheless, the researchers add that polyphenols such as those found in extra-virgin olive oil “might provide an excellent and safe platform for the design of new anti-breast cancer drugs.”