Gene may fend off breast cancer

Research recently completed by the University's Medical School has uncovered a gene that may offer protection against breast cancer. Because the gene itself was only identified a year ago, researchers are not yet sure when and where it may be activated, according to Lewis Chodosh, assistant professor of Molecular and Cellular Engineering, who is one of the authors of the new study. "This gene plays a fundamental role in a number of tissues," he explained. Chodosh added that there is evidence showing that women with a defective copy of the gene -- known as BRCA1 -- have an 85 percent chance of getting breast cancer and an increased risk of ovarian cancer. "If you are born with a defective gene, you are missing the protein encoded by this gene," he said. "There is a loss of protection when the breast is susceptible to early events in cancer." Researchers studied the gene's performance in mice in utero, during puberty and in adulthood. They also examined the gene's role in breast development, Chodosh said. Findings show that BRCA1 is most active when cells are growing rapidly and qualitatively changing cell type. And in the breast, cells are changing and dividing most during puberty and early pregnancy. Chodosh added that it is during these periods that the breast is most susceptible to cancer, and in response, the gene acts as a protective mechanism. Testing mice also showed that the hormones progesterone and estrogen stimulated expression of the gene, Chodosh explained. Therefore, an increase of BRCA1 expression can be mimicked simply by giving mice doses of the hormones typical during puberty and pregnancy. "We could potentially use currently available [hormone-mimicking] drugs to protect against breast cancer," Chodosh told Science News earlier this month. Since the gene remains overactive after pregnancy, it may play a role in the long-term anti-cancer benefit of having a child, Chodosh said. He also stressed the tentativeness of the study's findings, saying it will be years before researchers determine how to reduce breast cancer risk. "What we are doing is at a very basic level," Chodosh said. "We are trying to understand more how things work so we can know how things go wrong. "Our goal is to figure out which parts are relevant and irrelevant," he added. Myles Brown of the Dana Farber Cancer Institute in Boston agreed that current research for a lasting cure for breast cancer is still in its infancy stages. "The work is an important first step, but only a first step, in understanding BRCA1," he explained in Science News.

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