Abstract 326: Baseline IL-17 receptor signaling is essential for controlling aberrant JNK-dependent cellular proliferation via maintenance of endogenous level of ubiquitin-editing enzyme A20

Abstract

Abstract The molecular mechanisms underlying aberrant activation of NF-κB and JNK in cancer remain incompletely understood. Here, we demonstrate that baseline IL-17 receptor (IL-17R) signaling is essential for controlling aberrant NF-κB and JNK activation, and restraining JNK-dependent homeostatic cellular proliferation. Using a shRNA knockdown approach, we demonstrated in B16 melanoma and 4T1 breast carcinoma murine cell lines that IL-17RA silencing markedly enhanced tumor cell growth in vitro and in vivo. Through mapping IL-17R signaling pathways, we further demonstrated that baseline IL-17A/IL-17R signaling actively restrained JNK phosphorylation in vitro and in vivo via the maintenance of basal expression of the ubiquitin-editing enzyme A20, a negative regulator of NF-κB and JNK. Remarkably, IL-17RA reconstitution evidently restored the A20 level, and suppressed cell proliferation and JNK activity in tumor cells. The reconstitution of A20 in IL-17RA knockdown subclones was able to restore the normal rate of cellular proliferation and associated JNK/c-Jun activity. Finally, meta-analysis of human cancer microarray and RNA-Seq datasets confirmed significant co-expression of IL-17RA and A20. Furthermore, alterations (mutation, upregulation or downregulation) of IL-17RA level in melanoma, ER+ breast cancer and colorectal cancer patients were associated with poorer overall survival compared to the respective patients with normal baseline IL-17RA expression. Together, our data demonstrates a previously unrecognized molecular mechanism underlying aberrant activation of NF-κB and JNK in cancer cells. This work highlights the unique biological role of proinflammatory IL-17R signaling in the maintenance of A20 to regulate the pathogenesis of human cancer, which draws caution on the utility of IL-17A neutralizing antibody in cancer therapy. CY is a PhD student supported by the graduate student scholarship from the IWK Health Centre and received a trainee award from the Beatrice Hunter Cancer Research Institute with funds provided by the Cancer Research Training Program as part of The Terry Fox Foundation Strategic Health Research Training Program in Cancer Research in CIHR. Citation Format: Chi Yan, Yang Lei, Anna L. Greenshields, David W. Hoskin, Tong-Jun Lin, Jun Wang. Baseline IL-17 receptor signaling is essential for controlling aberrant JNK-dependent cellular proliferation via maintenance of endogenous level of ubiquitin-editing enzyme A20 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 326. doi:10.1158/1538-7445.AM2017-326