Downregulation of DNMT3A by miR-708-5p Inhibits Lung Cancer Stem Cell-like Phenotypes through Repressing Wnt/β-catenin Signaling.

Abstract

<b>Purpose:</b> Lung cancer is the leading cause of cancer-related death in the world, and emerging evidences suggest that lung cancer stem cells (CSC) are associated with its poor prognosis, tumor recurrence, and therapy resistance. Here we reveal a novel role for miR-708-5p in inhibiting lung CSC-like features.<b>Experimental Design:</b> Phenotypic effects of miR-708-5p on the lung CSC-like properties were examined by <i>in vitro</i> sphere formation assay and in xenografted animal models. Immunoblotting, dual luciferase reporter, and immunocytochemistry were performed to determine the target of miR-708-5p. DNA methylation of CDH1 promoter region was tested using bisulfate sequencing. Genome-wide miRNA sequencing data of 990 patients from The Cancer Genome Atlas (TCGA) dataset and 148 patients from China cohort were analyzed to excavate the pathogenic implications of miR-708-5p.<b>Results:</b> Expression of miR-708-5p inhibits the CSC traits of NSCLC cells <i>in vitro</i> while antagonizing miR-708-5p promotes tumorigenesis <i>in vivo</i> miR-708-5p directly suppresses the translation of DNMT3A, which results in a substantial reduction of global DNA methylation and the upregulated expression of tumor suppressor CDH1. The upregulation of CDH1 decreased the activity of Wnt/β-catenin signaling and then impaired the stemness characteristics of NSCLC cells. Clinically, patients with high miR-708-5p expression show significantly better survival and lower recurrence. Furthermore, miR-708-5p has a promising potential to apply to differentiating histologic subtypes in NSCLC.<b>Conclusions:</b> Our findings support that miR-708-5p suppresses NSCLC initiation, development, and stemness through interfering DNMT3A-dependent DNA methylation. miR-708-5p may function as a novel diagnostic and prognostic biomarker in NSCLC. <i>Clin Cancer Res; 24(7); 1748-60. ©2017 AACR</i>.