Biological roles of microRNA-140 in tumor growth, migration, and metastasis of osteosarcoma in vivo and in vitro.

The objective of this study was to explore the biological roles of microRNA-140 (miR-140) in tumor growth, migration, and metastasis of osteosarcoma (OS) in vivo and in vitro. Between 2007 and 2014, 47 cases of OS samples and normal bone tissue samples adjacent to OS were selected from our hospital. Tissue biopsies from OS patients were used to measure miR-140 levels to obtain a correlation between clinicopathological features and miR-140 expression. In vitro, MG63 human osteosarcoma cells were divided into four groups: blank group, miR-140 mimic group, miR-140 inhibitor group, and negative control (NC; empty plasmid) group. qRT-PCR was used to detect miR-140 expression, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect cell proliferation, flow cytometry was used to detect cell cycle distribution, and scratch migration assay was used to detect cell migration. In vivo, the relative expression of miR-140 level in OS tissue was lower than that in the adjacent normal bone tissue. miR-140 expression is inversely correlated with tumor size, Enneking stage, and tumor metastasis. In vitro, compared with blank group and NC group, relative miR-140 expression was increased, cell proliferation was inhibited, cell population in G0/G1 phase was increased, cell population in G2/M phase and S phases and proliferation index (PI), and cell migration distance were decreased in the miR-140 mimic group, but the relative expression and all the cell indexes were found opposite trend in the miR-140 inhibitor group. In conclusion, in vivo and vitro findings provided evidence that miR-140 could inhibit the growth, migration, and metastasis of OS cells.