Epithelial-to-mesenchymal transition (EMT) is central to embryonic development and carcinoma progression. The cell adhesion molecule E-cadherin critically maintains epithelial property and restricts epithelial cell proliferation and motility. The Snail family of transcription factors are core inducers of EMT in part through direct repression of E-cadherin transcription. The Snail factors are normally under tight control to safeguard epithelial identity and homeostasis. However, their physiological regulation remains largely elusive. In the present study, we show that the F-box protein FBXO11 binds to Snail in a phosphorylation-independent manner and targets it for ubiquitin-mediated proteasomal degradation. FBXO11 promotes the degradation of other Snail family members Slug and SCRT1 as well. Overexpression of FBXO11 in mesenchymal cells reduces Snail protein abundance and activates E-cadherin transcription. Conversely, depletion of endogenous FBXO11 in epithelial cancer cells causes Snail protein accumulation, EMT, and tumor invasion. Human cancer-derived FBXO11 missense mutants are impaired to degrade Snail. In human cancer, FBXO11 expression correlates with E-cadherin, and decreased expression of FBXO11 is robustly associated with adverse clinical outcomes. Inactivation of FBXO11 in mice results in neonatal lethality, increased Snail and Slug protein levels, decreased E-cadherin expression, and epidermal hyperplasia, which phenotypically resemble epidermis-specific transgenic overexpression of Snail or deletion of E-cadherin. These findings establish FBXO11 as a physiological ubiquitin ligase of Snails that is indispensable for suppressing epithelial hyperproliferation and plasticity during embryonic development and carcinoma progression.
Note: This abstract was not presented at the meeting.
Citation Format: Jianrong Lu, Yue Jin, Anitha K. Shenoy, Hao Chen, Huacheng Luo,Lizi Wu, Kamal A. Mohammed. FBXO11 suppresses epithelial plasticity and proliferation by ubiquitinating the Snail family of transcription factors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1425. doi:10.1158/1538-7445.AM2015-1425