MicroRNA-335/ID4 dysregulation predicts clinical outcome and facilitates leukemogenesis by activating PI3K/Akt signaling pathway in acute myeloid leukemia

MircoRNA-335 (miR-335) has been reported as a significant cancer-associated microRNA, which was often epigenetically silenced and acted as a tumor suppressor gene in diverse human solid tumors. Conversely, recent studies show that miR-335 overexpression was identified in both adult and pediatric acute myeloid leukemia (AML), suggesting that it might play an oncogenic role of miR-335 in AML. However, the role of miR-335 during leukemogenesis remains to be elucidated. MiR-335/ID4 expression was detected by real-time quantitative PCR and/or western blot. Survival analysis was performed to explore the association between miR-335/ID4 expression and the prognosis, and further validated by public databases. Gain-of-function experiments determined by cell proliferation, apoptosis, and differentiation were conducted to investigate the biological functions of miR-335/ID4. Herein, we found that miR-335 expression, independent of its methylation, was significantly increased and negatively correlated with reduced ID4 expression in AML. Moreover, aberrant miR-335/ID4 expression independently affected chemotherapy response and leukemia-free/overall survival in patients with AML. Gain-of-function experiments in vitro showed the oncogenic role of miR-335 by affecting cell apoptosis and proliferation in AML, and could be rescued by ID4 restoration. Mechanistically, we identified and verified that miR-335/ID4 contributed to leukemogenesis through activating PI3K/Akt signaling pathway. Collectively, aberrant miR-335/ID4 expression was an independent prognostic biomarker in AML. MiR-335/ID4 dysregulation facilitated leukemogenesis through the activation of PI3K/Akt signaling pathway.