MiR-200a Regulates Epithelial-Mesenchymal to Stem-like Transition via ZEB2 and β-Catenin Signaling

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The emerging concept of generating cancer stem cells from epithelial-mesenchymal transition has attracted great interest; however, the factors and molecular mechanisms that govern this putative tumor-initiating process remain largely elusive. We report here that miR-200a not only regulates epithelial-mesenchymal transition but also stem-like transition in nasopharyngeal carcinoma cells. We first showed that stable knockdown of miR-200a promotes the transition of epithelium-like CNE-1 cells to the mesenchymal phenotype. More importantly, it also induced several stem cell-like traits, including CD133(+) side population, sphere formation capacity, in vivo tumorigenicity in nude mice, and stem cell marker expression. Consistently, stable overexpression of miR-200a switched mesenchyme-like C666-1 cells to the epithelial state, accompanied by a significant reduction of stem-like cell features. Furthermore, in vitro differentiation of the C666-1 tumor sphere resulted in diminished stem-like cell population and miR-200a induction. To investigate the molecular mechanism, we demonstrated that miR-200a controls epithelial-mesenchymal transition by targeting ZEB2, although it regulates the stem-like transition differentially and specifically by β-catenin signaling. Our findings reveal for the first time the function of miR-200a in shifting nasopharyngeal carcinoma cell states via a reversible process coined as epithelial-mesenchymal to stem-like transition through differential and specific mechanisms.