Abstract A38: A critical role of Wnt5a-Axin2 axis in small-cell lung cancer development

Abstract

Abstract The paucity of readily actionable alterations in the small-cell lung cancer (SCLC) genome necessitates exploration of alternative targets for clinical intervention, including reactivated developmental signaling pathways. Despite the widespread implication of deregulated WNT signaling in cancer, its role in the pathogenesis of SCLC remains unknown. In this study, we observe selective induction of Axin2, a target of WNT pathway, and its genetic reporter in the lung tumors developed in genetically engineered mouse models (GEMM) of SCLC. Intriguingly, however, other transcription targets of b-catenin-dependent “canonical” pathway are downregulated in tumors relative to normal lung, and knockout of Ctnnb1 encoding b-catenin does not affect tumor development in the GEMM. On the other hand, Axin2 knockout, which enhances b-catenin level, suppresses the tumor development. These findings suggest not only the dispensability of b-catenin-dependent pathway but also the significant role of Axin2 in SCLC. Meanwhile, we observe that tumors and cell lines express significantly higher levels of ligands for b-catenin-independent “noncanonical” pathway, including Wnt5a, than precancerous cells (preSC) as well as whole lung. Ectopic Wnt5a in preSC enhances cell proliferation in culture and tumorigenic capacity in athymic nude mice while increasing Axin2 expression. Depletion of Wnt5a suppresses cell proliferation and tumor development. Taken together, these results suggest a critical role of the Wnt5a-Axin2 axis in SCLC development. Citation Format: Kee-Beom Kim, Dong-Wook Kim, Youngchul Kim, Jae-Il Park, Kwon-Sik Park. A critical role of Wnt5a-Axin2 axis in small-cell lung cancer development [abstract]. In: Proceedings of the AACR Special Conference on the Evolving Landscape of Cancer Modeling; 2020 Mar 2-5; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2020;80(11 Suppl):Abstract nr A38.