miR-19 targeting of GSK3β mediates sulforaphane suppression of lung cancer stem cells

Cancer stem cells (CSCs) play a central role in the development of cancer. The canonical Wnt/β-catenin pathway is critical for maintaining stemness of CSCs. Phytochemicals from dietary compounds possess anti-CSCs properties and have been characterized as promising therapeutic agents for the prevention and treatment of many cancers. To date, the involvement and function of miR-19, a key oncogenic miRNA, in regulating Wnt/β-catenin pathway and lung CSCs has not been defined. Meanwhile, the effect of sulforaphane (SFN) on lung CSCs also remains to be elucidated. Here, we reported that lung CSCs up-regulated miR-19a and miR-19b expression. Overexpression of miR-19a/19b enhanced the ability of tumorsphere formation, up-regulated the expression of lung CSCs markers, increased Wnt/β-catenin pathway activation and β-catenin/TCF transcriptional activity in lung CSCs. In contrary, down-regulation of miR-19 suppressed lung CSCs activity and Wnt/β-catenin activation. We further revealed that miR-19 activated Wnt/β-catenin pathway by directly targeting GSK3β, the key negative modulator of this pathway. Moreover, we showed that SFN exhibited inhibitory effect on lung CSCs through suppressing miR-19 and Wnt/β-catenin pathway. Taken together, these data illustrate the role of miR-19 in regulating lung CSCs traits and miR-19/GSK3β/β-catenin axis in SFN intervention of lung CSCs. Findings from this study could provide important new insights into the molecular mechanisms of lung CSCs regulation as well as its target intervention.