MicroRNA-100 Resensitizes Resistant Chondrosarcoma Cells to Cisplatin through Direct Targeting of mTOR

Chondrosarcomas are malignant cartilage-forming tumors of bone which exhibit resistance to bothchemotherapy and radiation treatment. miRNAs have been well demonstrated to regulate gene expression andplay essential roles in a variety of biological processes, including proliferation, differentiation, migration, cellcycling and apoptosis. In this study, we obtained evidence that miR-100 acts as a tumor suppressor in humanchondrosarcomas. Interestingly, cisplatin resistant chondrosarcoma cells exhibit decreased expression of miR-100compared with parental cells. In addition, we identified mTOR as a direct target of miR-100. Overexpression ofmiR-100 complementary pairs to the 3’ untranslated region (UTR) of mTOR, resulted in sensitization of cisplatinresistant cells to cisplatin. Moreover, recovery of the mTOR pathway by overexpression of S6K desensitizedthe chondrosarcoma cells to cisplatin, suggesting the miR-100-mediated sensitization to cisplatin dependent oninhibition of mTOR. In summary, the present studies highlight miR-100 as a tumor suppressor in chondrosarcomacontributing to anti-chemoresistance. Overexpression of miR-100 might be exploited as a therapeutic strategyalong with cisplatin-based combined chemotherapy for the treatment of clinical chondrosarcoma patients.