They might lurk in the garden, in a plastic bottle or in a tub of laundry. Swirling in the air around us and in the water we drink, environmental chemicals could pose a significant threat to women’s health.

Shiuan Chen is identifying cancer-promoting chemicals in the environment thanks to a California Breast Cancer Research Program grant. (Photo by Walter Urie)

Fortunately, Shiuan Chen, Ph.D., is working to bring these potentially cancer-boosting agents to light.

Chen, director of City of Hope’s Division of Tumor Cell Biology, is combing the environment for chemicals that may increase women’s risk of breast cancer or spur on existing disease.

Supported by a new, $1.5 million grant from the California Breast Cancer Research Program, Chen will lead a team to identify chemicals in the environment that can mimic hormones and stimulate breast cancer cells.

Scientists have known for decades that some chemicals, including certain industrial pollutants, pesticides and detergents, can act like hormones and disrupt normal bodily processes. These “endocrine disruptors” may have significant health effects. The U.S. Environmental Protection Agency has been studying them since the mid-1990s through its Endocrine Disruptor Screening Program.

Still, many questions remain, including which environmental chemicals, if any, affect breast cancer risk — and to what degree.

“Although extensive efforts have been made by many outstanding researchers worldwide, a definitive conclusion regarding the impact of such chemicals in breast cancer has not been established,” Chen said. “Our goal is to develop screening assays to identify and test chemicals we suspect may cause hormone-dependent breast cancer.”

Most breast cancers need hormones to grow. These breast cancers feature certain proteins that respond to hormones like estrogen. Chen and his colleagues will focus on three proteins:

• the estrogen receptor, which couples with estrogen and stimulates growth
• the estrogen-related receptor alpha, which acts like the estrogen receptor but doesn’t need estrogen
• aromatase, an enzyme that helps turn other hormones into estrogen

Chen’s team aims to create an automated way to quickly test chemicals to see if they stimulate cancer cells that feature these proteins. If they turn up any suspicious chemicals, they’ll run more tests to see if the chemicals affect any genes related to breast cancer.

They’ll also look for completely new clues that show how environmental chemicals affect breast cancer.

Chen hopes the work will help patients understand the role of environmental chemicals in breast cancer.

“Information about the risk of these chemicals on breast cancer is uncertain and can be very confusing to patients and advocates,” Chen said. “The tools we develop could help alleviate the confusion and empower patients and their supporters to make good decisions about disease management.”