MicroRNA-136 functions as a tumor suppressor in osteosarcoma via regulating metadherin.

BACKGROUND: Accumulating studies have reported the abnormal expression of microRNA-136 (miR-136) in numerous types of human cancer, and its involvement in cancer initiation and progression. However, there are no investigations of miR-136 in osteosarcoma (OS).

OBJECTIVE: To explore the expression pattern, clinical significance and potential roles of miR-136 in OS.

METHODS: miR-136 expression in clinical OS tissues and human OS cell lines were detected by qPCR, and its associations with clinicopathological characteristics of OS patients were statistically analyzed. Then, the effects of miR-136 on OS cell proliferation, migration and invasion were assessed in vitro. Its underling mechanisms were also investigated.

RESULTS: miR-136 expression in OS tissues and cells were dramatically decreased compared with corresponding non-cancerous tissues and cells, respectively. Low miR-136 expression was significantly associated with aggressive clinical features, including the advanced clinical stage, the presence of lung and distant metastasis (all P< 0.05). Additionally, enforced expression of miR-136 obviously inhibited the proliferation, migration and invasion of OS cells in vitro. Mechanistically, metadherin (MTDH) was predicted and verified as a target gene of miR-136. Further functional experiments indicated that the loss of MTDH abrogated the tumor suppressive roles of miR-136 in OS cells.

CONCLUSION: Our findings provide the first evidence that the aberrant expression of miR-136 may be implicated into carcinogenesis and cancer progression of OS. Functionally, miR-136 may inhibit the proliferation, migration and invasion of OS cells via negatively regulating its target gene MTDH. Thus, miR-136-MTDH axis may be a potential therapeutic targets for the treatment of OS.