MiR-136 targets E2F1 to reverse cisplatin chemosensitivity in glioma cells.

MicroRNAs (miRNAs) have gained much attention due to their critical roles in diverse biological events, including tumorigenesis. In this study, we demonstrate that miR-136 is down-regulated in two cohorts of patients with glioma. Furthermore, the low-level expression of miR-136 is significantly associated with a more aggressive and/or poor prognostic phenotype of patients with gliomas. Both gain- and loss-of-function experiments showed that miR-136 expression can reverse cisplatin resistance and enhance the response to cisplatin treatment. Furthermore, we identified a novel direct target of miR-136, the E2F transcription factor 1 (E2F1) oncogene. Depletion of E2F1 recapitulated the tumor-suppressive functions of miR-136, whereas re-expression of E2F1 attenuated the function of miR-136 in glioma cells. Finally, we revealed that miR-136 is inversely correlated with E2F1 expression in human glioma samples. The present study provides functional and mechanistic links between the tumor suppressor miR-136 and the oncogene E2F1 for the development of chemoresistance in human glioma. Our results indicate that targeting of the miR-136/E2F1 axis may provide a promising therapeutic approach to treat glioma.