miR-145通过下调OCT4基因抑制肺腺癌干细胞增殖

BACKGROUND AND OBJECTIVE: MiR-145 functions as a protective miRNA identifed in tumor tissues of lung adenocarcinoma patients. The aim of this study is to investigate the relationship between miR-145 and proliferation of lung cancer stem cells 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. The potential target gene of miR-145 was predicted by online bioinformatic sofwares. 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 observe the proliferation activity of A549 cells. The ratio of CD133 positive cells in each group was analyzed by flow cytometry. RESULTS: miR-145 expression was signifcantly down-regulated in lung adenocarcinoma compared with ajacent normal tissue. OCT4 is a potential target gene of miR-145 predicted by miRanda. Compared with control group, miR-145 was signifcantly up-regulated and down-regulated in the pre-miR-145 mimics and anti-miR-145 inhibitor groups respectively. Overexpression of miR-145 inhibited the proliferation of A549 cells. Both the OCT4 protein level and CD133 positive ratio were remarkably decreased in the pre-miR-145 mimics group, whereas signifcantly increased in the anti-miR-145 inhibitor group. Dual-luciferase reporter gene assay validated the predicted miR-145 binding site of OCT4 3'UTR. CONCLUSION: MiR-145 can inhibit the proliferation of lung cancer stem cells in A549 cell line via down-regulating OCT4 expression. MiR-145 is a potential protec-ive miRNA of lung cancer.