MicroRNA-124 suppresses tumor cell proliferation and invasion by targeting CD164 signaling pathway in non-small cell lung cancer.

MicroRNAs play critical roles in regulating gene expression and various cellular processes in human cancer malignant progression. Down-regulated expression of miR-124 gene has been shown to be significantly associated with a poor prognosis in patients with non-small cell lung cancer (NSCLC) but its biological function and regulatory roles in lung cancer tumorigenesis are largely unknown. In this study, we aimed to determine effects of ectopic expression of miR-124 on tumor cell proliferation, invasion, and induction of apoptosis by DOTAP:Cholesterol nanoparticle-mediated gene transfer and identify its endogenous targets under physiological conditions in NSCLC cells. Overexpression of miR-124 significantly suppresses tumor cell proliferation, colony formation, migration, and induction of apoptosis in H322 and A549 cells. Two endogenous miR-124 targeting sites in the 3'UTR of CD164 mRNA are identified by a stem-loop-array reverse transcription PCR (SLA-RT-PCR) assay in H1299 cells under physiological condition. Ectopic expression of miR-124 induces CD164 mRNA cleavage and down-regulated its gene and protein expression. Our results suggest that miR-124 function as a tumor suppressor miRNA and suppress tumor proliferation and aggression by directly targeting oncogenic CD164 signaling pathway in NSCLC.