In a new study in Cancer Discovery, researchers at the Lankenau Institute for Medical Research in Pennsylvania and their colleagues describe how an enzyme called indoleamine 2,3-dioxygenase, or IDO, helps cancer cells grow, reports The Augusta Chronicle's Tom Corwin. In 1998, researchers at the Georgia Health Sciences University discovered that IDO is part of the mechanism that protects a fetus from attacks by the mother's immune system, and it has also been implicated in the mechanisms cancer cells use to get around the immune system. In the new study, researchers show that IDO is more than just an unwitting accomplice in the spread of cancer — it is a fully involved co-conspirator. In working with mice bred to develop lung cancer, the researchers found that mice with low levels of IDO survived longer than mice with high levels of the enzyme, Corwin says. They later found that mice without IDO lacked the vasculature in the lungs that the tumors needed to grow, a finding which surprised the researchers. The IDO-less mice also had fewer metastases. "IDO appeared to increase an important inflammatory protein called interleukin-6 that has been shown to help feed the growth of cancer and to recruit cells called myeloid-derived suppressor cells that suppress the immune response to the tumors, another unexpected role for IDO," Corwin adds. "Inhibitors of IDO are already being tested in some early clinical trials in cancer, often in conjunction with other therapies."
Jul 19, 2012