MicroRNA-181c Suppresses the Biological Progression of Osteosarcoma via Targeting SMAD7 and Regulating Transforming Growth Factor-β (TGF-β) Signaling Pathway

BACKGROUND Osteosarcoma is a primary bone aggressive cancer, affecting adolescents worldwide. Increasing evidence suggests that dysfunction of microRNAs (miRNAs) plays a pivotal role in malignancies. The aim of this study was to evaluate the potential functions of miR-181c and verifying its regulatory effects on SMAD7 in osteosarcoma. MATERIAL AND METHODS The expressions of miR-181c and SMAD7 in osteosarcoma were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, invasion and migration abilities were assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and Transwell assay. Bioinformatics analysis and luciferase reporter assay were used to explore the interaction between miR-181c and SMAD7. Western blot was performed to determine the functions of miR-181c on osteosarcoma cell epithelial-to-mesenchymal transition (EMT) and transforming growth factor-ß (TGF-ß) signaling pathway. RESULTS Decreased expression levels of miR-181c and SMAD7 were identified in osteosarcoma using qRT-PCR. The downregulated miR-181c and SMAD7 expressions indicated poor prognosis of osteosarcoma patients. Moreover, miR-181c overexpression prominently repressed osteosarcoma cell proliferation, invasion, and migration abilities via modulating EMT and TGF-ß signaling pathway. SMAD7 functioned as an important target for miR-181c in osteosarcoma cells. Furthermore, upregulation of miR-181c dramatically suppressed osteosarcoma tumorigenesis in vivo. CONCLUSIONS These findings indicated that miR-181c suppressed osteosarcoma progression, providing new insight into the pathogenesis and representing a potential therapeutic target for osteosarcoma.