Mir-505-5p Inhibits Proliferation And Promotes Apoptosis Of Osteosarcoma Cells Via Regulating Rassf8 Expression

Purpose: The purpose of this study was to observe the effects of micro ribonucleic acid (miR)-505-5p on the proliferation and apoptosis of osteosarcoma cells, and to further investigate its potential mechanism.Methods: Human osteosarcoma U2-OS cell lines were divided into Control group, miR-505-5p nonsense sequence (NS) group and miR-505-5p inhibitor group. Subsequently, cell proliferation and apoptosis in each group were observed. Finally, the effect of miR-505-5p on the in vivo growth of osteosarcoma was explored by means of subcutaneous tumor formation assay.Results: The expression of miR-505-5p in the cancer tissues was remarkably higher than in normal paracancer tissues of osteosarcoma patients. U2-OS cell lines cultured in vitro in miR-505-5p inhibitor group manifested notably weakened proliferative ability after transfection with miR-505-5p inhibitor. Colony formation assay showed that the number of colonies formed in miR-505-5p inhibitor group was obviously smaller than that in Control group. The results of Western blotting assay indicated that the inhibition of miR-505-5p markedly increased the expression of Bax and decreased Bcl-2 in cancer cells (p<0.05). Furthermore, it was revealed that the inhibited miR-505-5p could distinctly up-regulate the protein expression level of RASSF8 in cancer cells. Furthermore, the miR-505-5p inhibition was able to prominently repress the subcutaneous tumor formation ability of osteosarcoma cells.Conclusions: The expression level of miR-505-5p is raised significantly in the cancer tissues of osteosarcoma patients, and the inhibition of miR-505-5p can up-regulate RASSF8 to suppress the proliferation and promote the apoptosis of osteosarcoma cells.