miR-214-3p promotes the proliferation, migration and invasion of osteosarcoma cells by targeting CADM1

Although osteosarcoma (OS) is the most common type of primary bone tumor in adolescents and young adults, its mechanism remains unclear. A previous study by the authors demonstrated that miR-214-3p was upregulated in OS patients. Therefore, the present study aimed to investigate the effect and molecular mechanism of miR-214-3p in OS cells. OS cell lines, U2OS and MNNG/HOS Cl#5, were transiently transfected with miR-214-3p mimics, a control mimic, miR-214-3p inhibitors and a control inhibitor. Subsequent assays revealed that elevated miR-214-3p promoted the proliferative, migratory and invasive abilities of OS cells, while the opposite effects were observed in cells that were transfected with miR-214-3p inhibitors. The interaction between miR-214-3p and cell adhesion molecule 1 (CADM1) 3'untranslated region (UTR) was verified by a dual luciferase assay, which indicated that the relative luciferase activity was decreased in 293T cells that were co-transfected with miR-214-3p mimic and psiCHECK2-CADM1-3'UTR compared with cells that were co-transfected with psiCHECK2-CADM1-3'UTR and control mimic. The knockdown of CADM1 using small-interfering RNA enhanced the proliferative, migratory and invasive abilities of OS cells. Furthermore, downregulated CADM1 expression increased the expression of phosphorylated P44/42 mitogen activated kinase (MAPK). In conclusion, miR-214-3p was able to directly target CADM1 and decrease its expression. This resulted in the activation of the P44/42 MAPK signaling pathway, and thereby promoted the proliferation, migration and invasion of OS cells.