MiR‐155 inhibits proliferation and invasion by directly targeting PDCD4 in non‐small cell lung cancer

BACKGROUND MicroRNAs are often abnormally expressed in human non-small cell lung cancer (NSCLC) and are thought to play a critical role in the emergence or maintenance of NSCLC by binding to its target messenger RNA. We assessed the effects of miR-155 on cell proliferation and invasion to elucidate the role played by miR-155/PDCD4 in NSCLC. METHODS Quantitative reverse transcription-PCR, Western blotting, and cell counting kit-8, luciferase, and transwell invasion assays were conducted on a normal human bronchial epithelial cell line (BEAS-2B) and three NSCLC cell lines (SPC-A-1, A549, and H2170). RESULTS We confirmed that miR-155 was upregulated, while PDCD4 messenger RNA and protein levels were downregulated in NSCLC cell lines. miR-155 negatively regulated PDCD4 at both transcriptional and post-transcriptional levels. Moreover, PDCD4 was forecast as an assumed target of miR-155 using bioinformatic methods and we demonstrated that PDCD4 was a direct target of miR-155 using luciferase reporter assays. Furthermore, PDCD4 overexpression could restrain NSCLC proliferation and invasion induced by miR-155. CONCLUSION Our results collectively demonstrate that miR-155 exerts an oncogenic role in NSCLC by directly targeting PDCD4.