Inflammation appears to act together with estrogen to fuel breast cancer growth by altering gene expression, according to a new study being presented Tuesday, June 5, at The Endocrine Society’s 89th Annual Meeting in Toronto.

Most breast cancers depend on the female hormone estrogen for their development, said study author Jonna Frasor, PhD, assistant professor of physiology and biophysics at the University of Illinois at Chicago College of Medicine. Recent studies have shown that inflammation also may play an important part in the growth of breast cancer. Researchers are studying the effect of mediators of inflammation, called proinflammatory cytokines.

In this laboratory study, Frasor’s group treated human breast cancer cells with proinflammatory cytokines and estrogen, and then measured the levels of expression of a gene called prostaglandin E synthase. This gene is an enzyme that is responsible for producing prostaglandins, which regulate inflammation and increase estrogen production in breast cells. The researchers found that the levels of this enzyme were enhanced by the combination of estrogen and cytokines to a greater extent than with either alone.

“We found a new mechanism where inflammation could influence progression of hormone-dependent breast cancer,” Frasor said. “Estrogen and cytokines in combination increase each other’s production, which can cause more aggressive tumors or faster tumor growth than estrogen alone.”

The next step, she said, is to find out if the prostaglandin E synthase gene contributes to growth of estrogen-dependent breast cancer in a mouse model. According to Frasor, no medications are available yet that specifically target the prostaglandin E synthase gene. Currently hormone therapy is used to treat estrogen-dependent breast cancer, to block the effect of the female hormones.

“Our findings could potentially have an impact on how women with breast cancer are treated,” Frasor said. “Treatment with anti-inflammatory agents in combination with hormonal therapy warrants investigation.”

The Illinois Division of the American Cancer Society helped fund this study.

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