MiR-509-5p Suppresses The Proliferation,Migration,and Invasion Of Non-small Cell Lung Cancer By Targeting YWHAG

Objective:Among the causes of cancer-associated mortality worldwide,particularly in China,non-small lung cancer(NSCLC)is the leading one.Therefore,constantly exploring of novel and effective molecular biomarkers that can suppress the progression of lung cancer is urgently needed.MicroRNAs(miRNAs),a family of endogenous,small non-coding single stranded RNAs,can regulate gene expression at the transcriptional or translational level via binding to the mRNA 3'-UTR of the target gene.Particularly,the function of miR-509-5p has been reported in multiple human cancers as a key regulator of oncogenic processes.However,the function of miR-509-5p in NSCLC remains unknown.Therefore,it is of great significance to make a better understanding of the function and regulatory mechanism of miR-509-5p in NSCLC,for the purpose to identifying miR-509-5p as a potential diagnostic and therapeutic target for NSCLC.Methods and Results:In the present study,we demonstrated that the average level of miR-509-5p was significantly lower in tumor tissues as compared with normal tissues(p= 0.0085).Compared with human bronchial epithelial cell BEAS-2B,we found the expression of miR-509-5p was down-regulated in NSCLC cell lines(A549,SPC-A-1,PC9 and H1793).Up-regulation of miR-509-5p observably inhibits cell proliferation,migration,invasion and and phosphorylation of Akt in A549 and SPC-A-1,and vice versa.Dual luciferase reporter assay revealed tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein gamma(YWHAG)is the direct target gene of miR-509-5p.Experimental validation demonstrated that expression of YWHAG was suppressed by miR-509-5p on protein and mRNA levels.Furthermore,we found a negative correlation between the expression of miR-509-5p and YWHAG in 20 pairs NSCLC specimens(r=-0.425,P= 0.031).Knockdown of YWHAG by siRNA imitates the effect of miR-509-5p on NSCLC cells,which markedly inhibited cell proliferation,migration and invasion of A549 and SPC-A-1.Conclusion : Taken together,our study demonstrated that miR-509-5p was significantly decreased in NSCLC tissues and cells,and simultaneously revealed the tumor suppressive role of miR-509-5p in observably inhibiting proliferation,migration,invasion and Akt's phosphorylation of NSCLC cells.Furthermore,we also identified YWHAG as a direct and functional target of miR-509-5p at experimental and clinical levels.In summary,our finds provide powerful evidence that restoration of miR-509-5p or silence of YWHAG might be potential novel and specific targets for the diagnosis,prognosis and therapy of NSCLC.