Histone demethylase KDM6A coordinating with KMT2B regulates self-renewal and chemoresistance of non-small cell lung cancer stem cells

BACKGROUND AND AIMS: Wnt signaling is essential for the maintenance of cancer stem cells (CSCs), but mutations in the β-catenin and APC genes are less common in non-small cell lung carcinoma (NSCLC). Thus, the mechanism underlying the constitutive activation of Wnt signaling in lung CSCs is still unknown. MATERIALS AND METHODS: Gene set enrichment analysis and immunohistochemistry were performed to establish the correlation between KDM6A/KM2B and CSC stemness. Human NSCLC cell lines were genetically manipulated for functional studies. Sphere formation assay and stemness gene expression profiling were examined to investigate the role of KDM6A/KMT2B in lung CSCs. Tumor xenograft assay were used to identify the function of KDM6A/KMT2B on tumorigenicity and tumor recurrence in vivo. Western blot analysis, coimmunoprecipitation and chromatin immunoprecipitation were performed to understand KDM6A/KMT2B mediated epigenetic regulation of Histone 3 lysine 4 methylation (H3K4me) on Wnt signaling pathway. RESULTS: We discovered that the expression of Histone demethylase KDM6A and methyltransferase KMT2B correlate with the stemness of CSCs in NSCLC. KDM6A coordinates with KMT2B to activate the Wnt/β-catenin signaling pathway by regulating the H3K4me3 level and promotes the tumorigenicity and maintenance of CSC stemness. Furthermore, KDM6A/ KMT2B overexpression promotes the CSC chemoresistance and tumor recurrence both in vitro and in vivo. Inhibition of KDM6A and KMT2B potently suppress tumor initiation and recurrence in xenografted animal models. CONCLUSION: Our findings suggest that KDM6A and KMT2B mediate the constitutive activation of Wnt/β-catenin signaling in lung CSCs, potentially providing a therapeutic target for NSCLC.