miR-187 inhibits tumor growth and invasion by directly targeting MAPK12 in osteosarcoma

MicroRNAs (miRNAs/miRs) play crucial roles in cancer development and progression. The purposes of this study were to investigate the role of miR-187 in osteosarcoma and clarify the regulation of MAPK12 by miR-187. Quantitative polymerase chain reaction was used to examine miR-187 expression in osteosarcoma tissues and cell lines. The clinicopathological significance of miR-187 downregulation was further analyzed. Transwell migration and invasion assays were performed. A luciferase reporter assay was conducted to confirm the target gene of miR-187, and the results were validated in cervical cancer tissues and cell lines. MiR-187 was significantly decreased in clinical tissues and osteosarcoma cell lines. The low miR-187 level was significantly correlated with stage, node metastasis, and deep stromal invasion. Upregulation of miR-187 suppressed cell migration and invasion in vitro. MAPK12 was verified as a direct target of miR-187, which was further confirmed by the inverse expression of miR-187 and MAPK12 in patients' specimens. The newly identified miR-187/MAPK12 pathway provides an insight into osteosarcoma metastasis and may represent a novel therapeutic target.