Abstract

The role of IL-17 mediated immune responses in cancer is conflicting as pre-clinical and clinical results show tumor-promoting as wel as tumor-repressing functions. Herein, we used syngeneic tumor models from different tissue origins as a tool to evaluate the role of IL-17 signaling in cancer progression, dissecting the effects in cancer cell growth and tumor immunity. We show that absence of IL-17RA or IL-17A/F expression in the host has contrasting effects in the in vivo growth of different tumor types. We observed that lack of IL-17A/F-IL-17RA signaling in host cells changed the expression pattern of several mediators within the tumor microenvironment in a cancer-type specific manner. Deficiencies in host IL-17RA or IL-17A/F expression resulted in reduced antitumor CD8+ T cell immunity in all cancer models and in tumor-specific changes in several lymphoid cell populations. These findings were associated to particular patterns of expression of cytokines (IL-17A and IL-17F) and receptor subunits (IL-17RA, IL-17RC and IL-17RD) of the IL-17 family in the injected tumor cell lines that, in turn, dictated tumor cell responsiveness to IL-17. We identified IL-17RC as an important determinant of the IL-17-mediated transcriptional response in tumor cells and; consequently, as a predictive biomarker of the overall effect of IL-17 signaling in tumor progression. Our findings contribute to unraveling the molecular mechanisms underlying the divergent activities of IL-17 in cancer and provide rational targets for immunotherapies based on personalized approaches.