Studies have proved that micro RNA-101(mi R-101) functions as a tumor suppressor and is associated with growth and apoptosis of various human cancers. However, the role of mi R-101 in osteosarcoma and the possible mechanism by which mi R-101 affects the tumor growth and apoptosis have not been fully elucidated. In this study, we found that the expression of mi R-101 was down-regulated in osteosarcoma tissues and Saos-2 cell line as compared with that in adjacent non-neoplastic bone tissues and the osteoblastic cell line. To better characterize the role of mi R-101 in osteosarcoma, we used a gain-of-function analysis by transfecting human osteosarcoma cell line Saos-2 with chemically synthesized mi R-101 mimics. The results showed that overexpression of mi R-101 inhibited the proliferation and promoted the apoptosis of Saos-2 cells. Meanwhile, bioinformatic analysis demonstrated that m TOR gene was a direct target of mi R-101. Overexpression of mi R-101 significantly decreased the expression of mT OR at both mR NA and protein levels in Saos-2 cells, consequently inhibiting Saos-2 cells proliferation and promoting cells apoptosis in an m TOR-dependent manner. Taken together, these data suggest that mi R-101 may act as a tumor suppressor, which is commonly downregulated in both osteosarcoma tissues and cells. mT OR plays an important role in mediating mi R-101 dependent biological functions in osteosarcoma. Reintroduction of mi R-101 may be a novel therapeutic strategy by down-regulating m TOR expression.
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