miR-550-1 functions as a tumor suppressor in acute myeloid leukemia via the hippo signaling pathway.

MicroRNAs (miRNAs) and N6 -methyladenosine (m6 A) are known to serve as key regulators of acute myeloid leukemia (AML). Our previous microarray analysis indicated miR-550-1 was significantly downregulated in AML. The specific biological roles of miR-550-1 and its indirect interactions and regulation of m6 A in AML, however, remain poorly understood. At the present study, we found that miR-550-1 was significantly down-regulated in primary AML samples from human patients, likely owing to hypermethylation of the associated CpG islands. When miR-550-1 expression was induced, it impaired AML cell proliferation both in vitro and in vivo , thus suppressing tumor development. When ectopically expressed, miR-550-1 drove the G0/1 cell cycle phase arrest, differentiation, and apoptotic death of affected cells. We confirmed mechanistically that WW-domain containing transcription regulator-1 ( WWTR1 ) gene was a downstream target of miR-550-1. Moreover, we also identified Wilms tumor 1-associated protein ( WTAP ), a vital component of the m6 A methyltransferase complex, as a target of miR-550-1. These data indicated that miR-550-1 might mediate a decrease in m6 A levels via targeting WTAP , which led to a further reduction in WWTR1 stability. Using gain- and loss-of-function approaches, we were able to determine that miR-550-1 disrupted the proliferation and tumorigenesis of AML cells at least in part via the direct targeting of WWTR1 . Taken together, our results provide direct evidence that miR-550-1 acts as a tumor suppressor in the context of AML pathogenesis, suggesting that efforts to bolster miR-550-1 expression in AML patients may thus be a viable clinical strategy to improve patient outcomes.