MiR-125b Functions as a Tumor Suppressor and Enhances Chemosensitivity to Cisplatin in Osteosarcoma

MicroRNAs are highly conserved noncoding RNA that negatively modulate protein expression at a posttranscriptional and/or translational level and are deeply involved in the pathogenesis of several types of cancers. To date, the potential microRNAs regulating the growth and progression of osteosarcoma are not fully identified yet. Previous reports have shown differentially expressed miR-125b in osteosarcoma. However, the role of miR-125b in human osteosarcoma has not been totally illuminated. In this study, we have shown that miR-125b was downregulated in human osteosarcoma tissues compared to the adjacent tissues and effects as a tumor suppressor in vitro. We found that stable overexpression of miR-125b in osteosarcoma cell lines U2OS and MG-63 inhibited cell proliferation, migration, and invasion. Our data also verified that Bcl-2 is the target of miR-125b. Meanwhile, we showed that Bcl-2 was inversely correlated with miR-125b in osteosarcoma tissues. More importantly, we proved that miR-125b increased the chemosensitivity of osteosarcoma cell lines to cisplatin by targeting Bcl-2. In conclusion, our data demonstrate that miR-125b is a tumor suppressor and support its potential application for the treatment of osteosarcoma in the future.