Exosomal miR-660-5p promotes tumor growth and metastasis in non-small cell lung cancer.

PURPOSE: Non-small cell lung cancer (NSCLC) is still the commonest fatal malignancy worldwide. The relationship between miR-660-5p and progress of NSCLC has not been well confirmed in recent studies. This manuscript focused to the function of miR-660-5p during the appearance and progression of NSCLC. METHODS: To identify the expression level of miR-660-5p in NSCLC, patient plasma and exosomes, quantitative real-time polymerase chain reaction (qRT-PCR) assay was performed. Cell proliferation and colony formation abilities were examined by Cell Counting Kit-8 (CCK-8) assay and colony formation assay. Then, the influence of miR-660-5p on migration and invasion was analyzed by transwell assay. Bioinformatics and Luciferase report assay were used to find potential target genes. Western blot was chosen to assess the expression level of KLF9. Stably transfected NSCLC cells (A549 and H1299) were injected into nude mice to identify the function of miR-660-5p in tumorigenesis in vivo. RESULTS: Compared with healthy controls, the release of miR-660-5p in plasma and exosomes was increased in patients with NSCLC (n=80). Knockdown of miR-660-5p significantly suppressed proliferation, migration, and invasion, whereas overexpression of miR-660-5p had the opposite effect. KLF9 might be a potential target of miR-660-5p. In addition, up-regulation of miR-660-5p promoted tumorigenesis in vivo, and the protein level of KLF9 also decreased in xenografts. CONCLUSIONS: Our current study suggests that miR-660-5p may control NSCLC proliferation, viability, and metastasis by targeting KLF9, which provides a potential therapeutic target for NSCLC.