Gamma-linolenic acid (GLA), a substance in evening primrose oil and several other plant oils used in herbal medicine, inhibits action of Her-2/neu, a cancer gene that is responsible for almost 30 percent of all breast cancers, Northwestern University researchers report.
"Breast cancer patients with Her-2/neu-positive tumors have an aggressive form of the disease and a poor prognosis," said Ruth Lupu, director of Evanston Northwestern Healthcare Breast Cancer Translational Research Program, who led the study, published in the Nov. 2 issue of the Journal of the National Cancer Institute.
Lupu is professor of medicine at Northwestern University Feinberg School of Medicine and a researcher at The Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
Lupu and co-investigator Javier Menendez showed that treating cancer cells that overexpressed Her-2/neu with GLA not only suppressed protein levels of the oncogene, but also caused a 30- to 40-fold increased response in breast cancer cells to the drug Herpetin (trastuzumab), a monoclonal antibody that is used for the treatment of many women with breast cancer.
Menendez is research assistant professor of medicine at Feinberg and a scientist at Evanston Northwestern Healthcare Research Institute.
"In our tests, treating the cancer cell lines with both GLA and Herceptin led to a synergistic increase in apoptosis [cell death] and reduced cancer growth. Therefore, although further studies are necessary before GLA can enter clinical trials, these findings may reveal a previously unrecognized way of influencing the poor outcome of Her-2/neu-positive cancer patients," Lupu said. "GLA's inhibition of Her-2/neu works in a different manner from that of Herceptin," Menendez said.