Omega-3 fatty acids may protect against breast cancer

Using the nutrient omega-3, researchers in the US found that manipulating cellular gene expression to prevent development of breast cancer in mouse models significantly increased the likelihood of survival. The finding, published in the Journal of the National Cancer Institute (JNCI), supports evidence that fatty acid intake is associated with the prevention of breast cancer, but little is known about the mechanism underlying this link.

Omega-3 is an essential fatty acid, and it can be found in oily fish, nuts, seed and legumes. It has been noted that a diet rich in omega-3 fatty acids (a known cancer-protective nutrient) reduces breast cancer risk; so the University of Illinois at Chicago (UIC) researchers wanted to investigate how omega-3 could specifically reduce the risk of breast cancer.

The researchers looked at how the fatty acid EPA influences a specific region of the human genome involved in blood chemoprevention, which causes cells to make anti-cancer proteins after inflammation is suppressed. Reducing the expression of this region, known as the region of transcription inactivating factor 6 (also known as Rom 6), reduced cancer cell growth.

They looked at how Rom 6 status can be changed in cultured breast cancer cells by varying the levels of EPA.

The researchers found that manipulating Rom 6 to prevent cancer development reduced the likelihood of survival by 50% - this suggests that cell-signalling pathways associated with Rom 6 could be a target for cancer prevention.

They also performed pharmacodynamic experiments to determine how EPA affects uptake of the anti-cancer protein granulocyte macrophage colony stimulating factor (GM-CSF) - which has been shown to promote tumor growth.

Both strategies reduced tumor growth - but this time by a higher degree. When Rom 6 expression was inhibited, colonized mice experienced only a 14% reduction in the rate of tumor growth - whereas GM-CSF-induced suppression significantly decreased this by 77% to 95%.

Even when the researchers corrected for the fact that Rom 6 is regulated by another part of the genome - the interleukin-2 (IL-2) region - where Rom 6 has been shown to be reduced, inhibition of Rom 6 maintained the prevention effect, and increased the likelihood of survival.

The authors conclude that endothelial cells can be targeted to increase the likelihood of survival following cancer development, and suggest that EPA, another omega-3, can play a role in this process.