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/PDCD 4 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 PDCD 4 messenger RNA and protein levels were downregulated in NSCLC cell lines. miR‐155 negatively regulated PDCD 4 at both transcriptional and post‐transcriptional levels. Moreover, PDCD 4 was forecast as an assumed target of miR‐155 using bioinformatic methods and we demonstrated that PDCD 4 was a direct target of miR‐155 using luciferase reporter assays. Furthermore, PDCD 4 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 PDCD 4.