Researchers attempting to define role of cytokines in cancer risk.

Earlier this year, a team of researchers from Austria found in a case – control study that women who produced more of the cytokine interleukin 10 (IL-10) due to a genetic variation or polymor-phism had a lower incidence of breast cancer. " The mechanism remains to be determined but may include antiangiogenic functions of IL-10, " said study leader Uwe Langsenlehner, M. Austria. " If this result can be confi rmed in additional studies, determination of IL-10 genotypes may help give a more precise individual breast cancer risk profi le. " This research, published in March in Breast Cancer Research and Treatment, is one of a growing number of studies that are helping to defi ne how cytokine polymorphisms affect cancer risk, initiation, and progression. IL-10 is one of more than 300 – 400 known cytokines produced by the immune system that are mediators of immunity, infection, and infl amma-tion, said Joost Oppenheim, M.D., chief of molecular immunology in the Division of Basic Sciences at the National Cancer Institute. " Certain cytokines [such as tumor necrosis factor α (TNF-α) and IL-6] may promote cancer growth and spreading, stimulate cells to survive longer, are proangiogenic, encourage infl ammation, and cause free radical damage of DNA and instability , " he said. Others, such as IL-2, granulocyte – macrophage colony-stimulating factor (GM-CSF), and interferons, inhibit cancer growth and spreading by stimulating other immune cells, such as T cells and natural killer cells. Animal models show that IL-10 can have immunosuppressive activity, Oppen-heim said. " Many of the cytokines such as TNF α , IL-10, IL-1, and IL-6 have multiple biological roles, based on the fact that their receptors are expressed by diverse cell populations, which may result in apparently opposing effects, " Oppenheim added. Since the early 1990s, researchers have tested recombinant cytokines, including IL-2, GM-CSF, and interferon, as local and systemic immunotherapies for cancer, in combination with chemo-therapy in gene transfer experiments, and in vaccines — with limited success. These cytokines have also been studied for their potential antitumor properties since recombinant cytokines became available in suffi cient quantities more than 20 years ago, starting with interferons and IL-2, said Oppenheim. Only in the past few years have researchers begun focusing on the role that endogenous cytokines may play in increasing cancer risk. Langsenlehner's study adds to other research that suggests that low IL-10 levels are associated with risk for pros-tate, …