Study of the effects of IL-17/IL17R signaling on different murine tumors and their impact on tumor progression

C ARAUJO FURLAN; S BOSSIO; C MONTES; J TOSELLO BOARI; S BOCCARDO; A GRUPPI; C RODRIGUEZ; F CANALE; C BECCARIA; E ACOSTA RODRIGUEZ

Viena

Congreso; Cytokines 2019 - International Cytokine & Interferon Society Meeting; 2019

Introduction: The roles of IL-17 cytokines in cancer remain controversial. Previously, others and we showed that IL-17 signaling iscritical for sustaining functional CD8+ T cell(CTL) and NK cell responses during different infections. As these cytotoxic subsets arecritical for immunity against tumors, IL-17 may be critical to control tumor progression. Yet, there are evidences that IL-17 maydirectly promote tumor cell growth. Therefore, our aim is to determine the role of IL-17 signaling in the overall progression ofdifferent cancer types, dissecting the possible pro- and anti-tumoral effects.Results: We assessed tumor progression in WT(B6), IL-17RA deficient(RKO) and IL-17A and IL-17F deficient(DKO) miceinjected subcutaneously with different syngeneic models:melanoma (B16-SIY), fibrosarcoma (MC57-SIY and MCA-OVA),lymphoma (EL4-SIY) and acute myeloid leukemia (C1498-SIY). Upon injection of B16-SIY or MC57-SIY, RKO and DKO miceexhibited increased tumor volume compared to WT. In contrast, both KO strains showed reduced tumor volume when injected withEL4-SIY or C1498-SIY compared to WT and all mice strains presented similar tumor volume after injection of MCA-OVA. Todetermine if these differences may be explained by the effect of IL-17 signaling on tumor cells or on antitumoral CTLs development,we first quantified the amounts of transcripts encoding IL-17A, IL-17F, IL-17RA, IL-17RC and IL-17RD in cell lines.IL-17F, IL-17RA and IL-17RD transcripts were detected in all cell lines, while IL-17A transcript was quantified only in EL4-SIY and IL-17RCtranscript was restricted to B16-SIY, MC57-SIY and MCA-OVA. Given that cells showed expression of two or three IL-17Rsubunits, we next evaluated the effect of tumor cells exposure to IL-17A and IL-17F.By MTT and EdU proliferation as well as woundhealing assays we determined that IL-17A and IL-17F showed no or very marginal effect on proliferation and migration of tumor celllines. Furthermore, although cell lines produced cytokines such as IL-1b, TNF and IL-6, secretion of these proinflammatorymediators was not enhanced by IL-17A or IL-17F. In contrast, we determined that IL-17A and IL-17F modulated the amounts oftranscripts encoding genes associated to tumor progression such as VEGF, HIF1a, MMP9, MMP2 and CDH2. A 24h treatment withIL-17A up-regulated the expression of VEGF, HIF1a and CDH2 in B16-SIY and MC57-SIY. MC57-SIY cells also up-regulatedMMP2, MMP9 in response to IL-17A. On the contrary, MCA-OVA showed downregulation of all mediators evaluated and EL4-SIYand C1498-SIY cells showed no response to IL-17 cytokines. Finally, we evaluated the CTLs antitumoral immune response in RKOand DKO mice. Interestingly, both strains showed reduced tumor-specific CTL numbers in tumor and draining lymph nodescompared to WT mice when injected with B16-SIY or MC57-SIY.Conclusion: Our results highlight that while the effect of IL-17 on antitumor immunity may be general, the overall impact of IL-17/IL-17R signaling in tumor progression is particular to each tumor type. Indeed, a direct role of IL-17 cytokines on tumor cell linesmay depend on the expression of IL17RC. Further research will establish the relative influence of pro- and anti-tumoral effectsaccording to the cancer phenotype.