Overexpression of miR-214 promotes the progression of human osteosarcoma by regulating the Wnt/β-catenin signaling pathway

The aberrant expression of microRNA (miR)-214 contributes to the regulation of normal and cancer cell biology, and is associated with human malignancies, however, it can operate in a contradictory manner. The role of miR-214 in osteosarcoma remains to be fully elucidated. The aim of the present study was to investigate the effects of miR-214 on osteosarcoma progression and tumor cell proliferation, and examine the molecular mechanism underlying osteosarcoma. The level of miR-214 was determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis in osteosarcoma and matched paracancerous tissues, and in human osteosarcoma cancer cell lines. The roles of miR-214 in cell proliferation, survival and cell cycle were analyzed using miR-214 lentivirus (LV-miR-214)-infected osteosarcoma cells. In addition, the downstream target proteins in the Wnt/ beta-catenin signaling pathway were evaluated using western blot analysis in the LV-miR-214-infected cells. The LV-miR-214-infected MG63 cells were also treated with exogenous beta-catenin for 24, 48 and 72 h, respectively, following which the expression of beta-catenin was measured using western blot analysis and survival was determined using a 3-(4,5-cimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide (MTT) assay. The results of the RT-qPCR analysis showed that the expression level of miR-214 was significantly higher in the osteosarcoma tissues, compared with that in the matched paracancerous tissues, and the same was observed in the osteosarcoma cell lines. The MG63, Saos-2 and U2OS cells were infected with the hsa-mir-214 lentivirus for 48 h, and the levels of miR-214 were significantly upregulated in the human osteosarcoma cancer cells. The overexpression of miR-214 in the MG-63 and Saos-2 cells promoted cell growth, and treatment of the cells with specific antisense-microRNA oligonucleotides (AMOs) for miR-214 for indicated durations reversed the effects of miR-214. Additionally, the AMO-treated MG63 cells showed G0/G1 phase arrest, suggesting that miR-214 contributed to regulation of the cell cycle. In addition, the results of western blot analysis showed that, in the miR-214 lentivirus-infected cells, the levels of cyclin-D1, c-myc and lymphoid enhancer-binding factor-1 were significantly increased, compared with those in the control lentivirus-infected cancer cells. Of note, infection with the miR-214 lentivirus did not affect the levels of Wnt1, Wnt2, Wnt4, Axin or glycogen synthase kinase beta in the U2OS cells, whereas the expression levels of beta-catenin in the MG63 cells and Saos-2 cells were significantly increased. The addition of exogenous beta-catenin effectively reversed the efficiency of miR-214-specific AMOs, which was detected using an MTT assay. These data suggested the critical role of miR-214 in human osteosarcoma via regulation of the Wnt/beta-catenin signaling pathway and demonstrated that miR-214 is as an oncogene for human osteosarcoma.