MiR-100 up-regulation enhanced cell autophagy and apoptosis induced by cisplatin in osteosarcoma by targeting mTOR.

OBJECTIVE

Mammalian target of rapamycin (mTOR) can negatively regulate cell autophagy, while its expression and activity are associated with the pathogenesis of osteosarcoma. MicroRNA 100 (MiR-100) down-regulation is associated with the pathogenesis and chemo-sensitivity of osteosarcoma. Bioinformatics analysis revealed the targeted relationship between miR-100 and the 3'-UTR of mTOR. We investigate the role of miR-100 in affecting mTOR expression, osteosarcoma cell autophagy, and sensitivity to cisplatin.

PATIENTS AND METHODS

MiR-100, mTOR, and Beclin-1 expressions in osteosarcoma tissue and normal control were compared. The relationship between miR-100 and mTOR was verified by dual luciferase assay. MiR-100, mTOR, and Beclin-1 levels in MG-63 cells and MG-63/DDP cells were tested. Cell apoptosis was determined by using flow cytometry. Cell malignancy was evaluated by colony formation assay.

RESULTS

MiR-100 and Beclin-1 significantly declined, while mTOR significantly increased in osteosarcoma tissue compared with that of normal tissue (p<0.05). MiR-100 targeting significantly inhibited mTOR expression compared to that of untreated (p<0.05). MiR-100 expression was down-regulated and mTOR level was elevated in MG-63/DDP cells compared with MG-63 cells (p<0.05). MG-63/DDP cells exhibited reduced cell autophagy and apoptosis, and enhanced colony formation induced by DDP. MiR-100 mimic and/or small interfere mTOR (si-mTOR) significantly promoted Beclin-1 expression, cell autophagy, and cell apoptosis, while attenuated colony formation.

CONCLUSIONS

MiR-100 declined, while mTOR up-regulated in osteosarcoma tissue. MiR-100 up-regulation enhanced cell autophagy and apoptosis induced by cisplatin via targeted inhibiting of mTOR.