MiR-145 Inhibits Lung Adenocarcinoma Stem Cells Proliferation By Targeting OCT4 Gene

Background and Objective MiR-145 is a protective miRNA identified in tumor tissues of lung adenocarcinoma patients via miRNA microarray chips screening and real-time PCR validation. The present study is aim to investigate the relationship between miR-145 and lung cancer stem cells proliferation and involved molecular mechanisms in human lung adenocarcinaoma A549 cell line.Methods MicroRNA microarray technology was conducted to compare miRNA signature between tumor and adjacent normal tissue of lung adenocarcinaoma patients. The potential target gene of miR-145 was predicted by online bioinformatic softwares. Pre-miR-145 mimics and anti-miR-145 inhibitor were transfected into A549 cell line by lipofectamine 2000. miR-145 expression in each group was detected by real-time PCR. The OCT4 protein level was analyzed by western blot. The predicted miR-145 binding site in OCT4 3'untranslated region (UTR) was validated by dual-luciferase reporter gene assay. CCK-8 assay was employed to test the proliferation activity in each group. Cell invasion ability was examined by transwell assay. The ratio of CD133 positive cells in each group and cell cycle were analyzed by flow cytometry. The tumorsphere was cultured and calculated by density.Results miR-145 expression was significantly down-regulated in lung adenocarcinoma compaered to djacent normal tissue. OCT4 is a potential target gene of miR-145 predicted by miRbase. As compared with control group, miR-145 was significantly up-regulated and down-regulated in the pre-miR-145 mimics and anti-miR-145 inhibitor groups respectively. Both the OCT4 protein level and CD133 positive ratio were remarkably decreased in the pre-miR-145 mimics group, whereas significantly rose in the anti-miR-145 inhibitor group. Dual-luciferase reporter gene assay validated the predicted miR-145 binding site of OCT4 3'UTR. Both proliferation activity and invasion ability of A549 cells were inhibited by miR-145. S phase ratio of A549 cells was decreased by miR-145. miR-145 inhibits the colony ability of tumorsphere.Conclusion MiR-145 is capable to inhibit the proliferation of lung cancer stem cells via down-regulating OCT4 expression and therefore restrain the progression of lung adenocacinoma. MiR-145 is a potential protective miRNA of lung cancer.