miR ‐138 inhibits proliferation by targeting 3‐phosphoinositide‐dependent protein kinase‐1 in non‐small cell lung cancer cells

OBJECTIVE: Underlying mechanisms of non-small cell lung cancer (NSCLC) development remain poorly understood. miR-138 and 3-phosphoinositide-dependent protein kinase-1 (PDK1) have been reported to be involved in the genesis of NSCLC. The aim of this study was to investigate the role and mechanisms of miR-138 and PDK1 in human NSCLC cells. METHODS: The effect of miR-138 on proliferation of A549 lung cancer cells was first examined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. The expression of PDK1 in A549 lung cancer cells was assessed by real-time polymerase chain reaction further. A luciferase reporter activity assay was conducted to confirm target association between miR-138 and 3' untranslated region (3'-UTR) of PDK1. Finally, the role of PDK1 on proliferation of A549 cells was evaluated by transefection of PDK1 small interfering RNA (siRNA). RESULTS: Proliferation of A549 lung cancer cells was suppressed by miR-138 in a concentration-dependent manner. Furthermore, miR-138 can bind to the 3'-UTR of PDK1 and downregulate expression of PDK1 at both mRNA and protein levels. Knockdown of PDK1 by siRNA significantly inhibits the proliferation of A549 lung cancer cells. CONCLUSIONS: These findings suggest that miR-138 as a potential tumor suppressor could inhibit cell proliferation by targeting PDK1 in NSCLC cells, which could be employed as a potential therapeutic target for miRNA-based NSCLC therapy.