Discovery helps show how breast cancer spreads
ST. LOUIS. – Researchers at Washington University School of Medicine in St. Louis have discovered why breast cancer patients with dense breasts are more likely than others to develop aggressive tumors that spread. The finding opens the door to drug treatments that prevent metastasis. It has long been known that women with denser breasts are at higher risk for breast cancer. This greater density is caused by an excess of a structural protein called collagen. “We have shown how increased collagen in the breasts could increase the chances of breast tumors spreading and becoming more invasive,” says Gregory D. Longmore, MD, professor of medicine. “It doesn’t explain why women with dense breasts get cancer in the first place. But once they do, the pathway that we describe is relevant in causing their cancers to be more aggressive and more likely to spread.” The results appear online May 5 in Nature Cell Biology. Working in mouse models of breast cancer and breast tumor samples from patients, Longmore and his colleagues showed that a protein that sits on the surface of tumor cells, called DDR2, binds to collagen and activates a multistep pathway that encourages tumor cells to spread. “We had no idea DDR2 would do this,” says Longmore, also professor of cell biology and physiology. “The functions of DDR2 are not well understood, and it has not been implicated in cancer – and certainly not in breast cancer – until now.