Effects of microRNA-122 on proliferation and invasion of osteosarcoma cells and mechanisms

Objective To investigate the effects of microRNA (miRNA, miR)-122 on the proliferation and invasion of osteosarcoma MG-63 cells and the related mechanisms. Methods The expression of miR-122 in osteosarcoma MG-63 cells was detected by real-time quantitative polymerase chain reaction (Real-time PCR) after miR-122 mimic transfection. After the validation of miR-122 overexpression, cell count kit-8 (CCK-8) assay was used to examine the proliferation after miR-122 mimic transfection; Would scratch assay was performed to evaluate the migration activity of MG-63 cells, and the Transwell assay to determine the invasion activity. Then the expression levels of sex determining region Y-box 2 (SOX2) and matrix metalloproteinase (MMP)-9 were detected by Western blotting. Results After transfection of miR-122 mimic into OS MG-63 cells, the relative expression of miR-122 in mimic group (3.83±0.45) was significantly increased as compared with the negative-control (NC, 1.05±0.09) group (P<0.01). The proliferation at 24 and 48 h after miR-122 mimic transfection was significantly suppressed as compared with the NC group (P<0.05). Would scratch assay showed the migration activity in mimic group (0.47±0.04) was inhibited significantly as compared with the NC group (0.93±0.07, P<0.01). Transwell assay showed the invasive cells were significantly reduced in mimic group (84.01±5.69) as compared with the NC group (122.30±8.11, P<0.05). After the transfection, Western blotting results revealed that the relative expression of SOX2 in mimic group (0.51±0.10) decreased remarkably as compared with NC group (1.10±0.04, P<0.01), and that of MMP-9 in mimic group (0.40±0.06) was significantly lower than NC group (0.99±0.11, P<0.01) as well. Conclusion MiR-122 inhibited the proliferation and invasion of osteosarcoma MG-63 cells, which was probably related with the down-expression of SOX2 and MMP-9. Key words: Osteosarcoma; MicroRNA-122; Proliferation; Invasion