Endogenous IL-17 contributes to reduced tumor growth and metastasis

Abstract

It has been reported that ectopically expressed interleukin-17 (IL-17) in tumor cells suppresses tumor progression through enhanced antitumor immunity in immune competent mice or promote tumor progression through an increase in inflammatory angiogenesis in immunedeficient mice. The role of endogenous IL-17 in tumor immunity remains undefined. Here we showed that tumor growth and lung metastasis were enhanced in IL-17-deficient mice, associated with decreased interferon-γ+ natural killer cells and tumor specific interferon-γ+ T cells in the tumor draining lymph nodes and tumors. Together with the published data showing that in vitro transforming growth factor-β and IL-6-polarized Th17 cells induce tumor regression, our work supports the notion that endogenous IL-17 or/and Th17 cells may play a protective role in tumor immunity. © 2009 by The American Society of Hematology.