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THURSDAY, Feb. 11 (HealthDay News) -- A hormone responsible for milk production blocks a gene that makes breast cancer more aggressive, according to new research by U.S. scientists.
The discovery, they say, could lead to better diagnostic tests for breast cancer and new treatments for the disease.
The researchers found that the hormone prolactin, which normally stimulates breast development and milk production, reduces levels of an oncogene called BCL6. Previous studies had shown that BCL6 plays a role in poorly differentiated breast cancer. Women with this type of breast cancer have a poor prognosis.
To a large extent, prolactin's role in breast cancer is carried out by a protein pathway called Stat5, the researchers explained, and inactivation of Stat5 is related to poorly differentiated breast cancer.
"We found that prolactin will block expression of the BCL6 protein and showed that Stat5a, but not the very similar Stat5b variant, is involved in this process as a mediator of prolactin," Dr. Hallgeir Rui, a professor of cancer biology and medical oncology at Jefferson Medical College at Thomas Jefferson University, said in a university news release.
"We think that prolactin plays an important role in preventing aggressive breast cancers and that there is a connection between the loss of Stat5 and the increase of BCL6 in making breast cancer more aggressive," Rui said.
His research team found that the connection was consistent in several different breast cancer cell lines grown in the laboratory as well as those in mice and in human breast cancer samples.
The study was published online Feb. 2 in Cancer Research.
The American Cancer Society has more about breast cancer.