WEDNESDAY, May 6 (HealthDay News) -- Three genes linked to the spread of breast cancer to the brain have been identified by U.S. researchers, who say the finding could help lead to new treatments.

The spread, or metastasis, of breast cancer to the brain typically occurs years after a breast tumor has been removed. Experts say this suggests that the cancer cells initially lack the ability to penetrate the blood-brain barrier, which prevents the entry of circulating cells and regulates the transport of molecules into the brain tissue.

The new study found that two genes, COX2 and HB-EGF, are prime breast cancer cells for entrance into the brain. Another gene, ST6GALNAC5 -- which is normally active only in brain tissue -- causes a chemical reaction that creates a coating on the surface of breast cancer cells that enhances their ability to breach the blood-brain barrier.

"Our results draw attention to the role of the cell surface coating as a previously unrecognized participant in brain metastasis, and to the possibility of using drugs to disrupt its interactions," Joan Massague, chair of the Cancer Biology and Genetics Program at Memorial Sloan-Kettering Cancer Center in New York City and a Howard Hughes Medical Institute investigator, said in a news release from the cancer center.

The study appears online in the journal Nature.

Previous research found that COX2 and HB-EGF are involved in the spread of breast cancer to the lungs. The new finding, that the genes also play a role in its spread to the brain, might explain the association of brain and lung relapse in breast cancer patients, the researchers said.

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