CHICAGO, IL (April 3, 2012)––The hormone estrogen may help promote lung cancer— including compounding the effects of tobacco smoke on the disease—pointing towards potential new therapies that target the hormone metabolism, according to new research presented at the AACR Annual Meeting 2012 on Tuesday, April 3 by scientists at Fox Chase Cancer Center in Philadelphia.
"This research provides the link between estrogen and tobacco smoke," says study author Jing Peng, Ph.D., postdoctoral associate in the lab of Margie L. Clapper, Ph.D., also a co-author on the paper.
The researchers found that estrogen is metabolized into toxic derivatives in the mouse lung. The level of these toxic metabolites increased when mice were exposed to tobacco smoke. The results suggest that new therapies which prevent estrogen from being converted into toxins could one day help treat—or even prevent—lung cancer, says Peng. "In the future, we would like to target estrogen-metabolizing pathways as a form of treatment or prevention of lung cancer."
Researchers have long known that tobacco smoke is the number one cause of lung cancer. But recent findings suggest that estrogen may also play a role in the disease. If so, it wouldn't be the first form of cancer linked to estrogen—this hormone is known to promote breast cancer as well as other gynecologic cancers.
To investigate, Peng, Clapper and their colleagues examined the lungs of healthy mice and found that they contained high levels of estrogen metabolites, known as 4 hydroxy- estrogens (4-OHEs), which are carcinogenic. Specifically, these 4-OHEs help activate processes that promote cell growth, and generate free radicals that damage cells.
When the researchers exposed the mice to tobacco smoke for 8 weeks, they found that the levels of 4-OHEs increased. "We believe that these metabolites of estrogen can damage cells and contribute to lung cancer," says Clapper.
Female mice had twice as much 4-OHE in their lungs compared to male mice after controlling for the level of total estrogen present. Whether this is the same in humans remains to be determined. "While lung cancer is not more common in women, the number of nonsmokers who develop lung cancer is greater for men than for women," explains Clapper.
In the future, Peng and Clapper hope these results will help researchers develop new therapies that target estrogen metabolism as a way to treat or prevent lung cancer. Already, patients are enrolling in clinical trials that are using anti-estrogen drugs to treat lung cancer.
"We believe that levels of these toxic estrogen metabolites may one day be useful in predicting a person's lung cancer risk or prognosis", adds Peng. "If levels are particularly high, for instance, that may suggest the person is more prone to developing the disease, or has a worse prognosis. We'd definitely like to be able to use this information to develop a more personalized treatment approach," she says.
Other co-authors include Lisa Vanderveer, from Fox Chase, as well as researchers from SAIC-Frederick, Inc. and Duke University. The work was supported by funds from the Estate of Jane Villon and the Kitty Jackson Fund.
Fox Chase Cancer Center is one of the leading cancer research and treatment centers in the United States. Founded in 1904 in Philadelphia as one of the nation's first cancer hospitals, Fox Chase was also among the first institutions to be designated a National Cancer Institute Comprehensive Cancer Center in 1974. Fox Chase researchers have won the highest awards in their fields, including two Nobel Prizes. Fox Chase physicians are also routinely recognized in national rankings, and the Center's nursing program has received the Magnet status for excellence three consecutive times. Today, Fox Chase conducts a broad array of nationally competitive basic, translational, and clinical research, with special programs in cancer prevention, detection, survivorship, and community outreach. For more information, visit Fox Chase's Web site at www.foxchase.org or call 1-888-FOX CHASE or (1-888-369-2427).