New evidence explains why fish oil fights breast cancer

Cancer cells can be killed in many ways.  Fish oil proves to be one of them.

U.S. researchers have discovered evidence that explains why taking fish oil helps prevent breast cancer, which has been observed in epidemiological studies.

One previous study reported in Cancer Epidemiology, Biomarkers & Prevention suggests that taking fish oil supplements may help prevent breast cancer.

The study led by Emily White at the Fred Hutchinson Cancer Research Center in Seattle, Washington showed that women who regularly used fish oil supplements were 32 percent less likely to develop breast cancer.

A similar case-control study led by Kim J. and colleagues from the National Cancer Center in South Korea also showed that women who ate fatty fish which is high in fish oil appeared to cut their breast cancer risk by at least 50 percent, compared with those who did not.

Kim's study was published in  the June 2009 issue of BMC Cancer.

These studies are not trials and they alone can't prove that taking fish oil supplements or eating fatty fish, which are high in docosahexaenoic acid (DHA) plus eicosapentaenoic acid (EPA), indeed prevents breast cancer.

Ghosh-Choudhury T and colleagues at the University of Texas Health Science Center at San Antonio in Texas conducted some lab studies and found evidence to support the observation that fish oil indeed protects against breast cancer.

The study considered the first of its kind demonstrated using the xenograft model in nude mice that the fish oil diet significantly increased the level of PTEN protein in the breast cancer.

PTEN or phosphate and tensin homolog is a protein that in humans serves as a tumor suppressor.  An increase in PTEN protein helps suppress the tumor growth.

"Fish oil diet also prevented the expression of anti-apoptotic proteins Bcl-2 and Bcl-XL in the breast tumors with concomitant increase in caspase 3 activity,"  Ghosh-Choudhury et al. wrote in their report.

This indicates that fish oil boosts apoptosis - the programmed cell deaths.  Cancer cells won't die naturally so promoting cell deaths is one way to fight cancer.

The researchers also found fish oil attenuated the PI 3 kinase and Akt kinase activity in the cells, significantly inhibiting NFkappaB activation.

Biswas D.K. and colleagues at Dana-Farber Cancer Institute, Boston reported in the July 6 2004 issue of Proc Natl Acad Sci. that activated NF-kappa B found in 86 percent of ER-negative and ErbB2-positive tumors (86%) is a new target of anti cancer drugs.

Ghosh-Choudhury et al. also demonstrated on cultured MDA MB-231 cells that DHA and EPA are the active ingredients  in fish oil responsible for these effects.

The findings suggest that fish oil may be used not only to prevent but to cure breast cancer.

In the United States, one in eight women will sooner or later be diagnosed with breast cancer.  The disease strikes 175,000 women each year and kills about 45,000 annually in the country, according to the National Cancer Institute.

Source:

Breast Cancer Res Treat. 2009 Nov;118(1):213-28. Epub 2008 Oct 26.

Fish oil targets PTEN to regulate NFkappaB for downregulation of anti-apoptotic genes in breast tumor growth.

By David Liu