N6-methyladenosine demethylase ALKBH5 suppresses malignancy of esophageal cancer by regulating microRNA biogenesis and RAI1 expression

Abstract

N⁶-Methyladenosine (m⁶A) is the most prevalent epigenetic RNA modification and is vital in regulating malignancies. The roles of m⁶A modifiers on noncoding RNAs have not been fully investigated in esophageal cancer. By screening all m⁶A modifiers, ALKBH5 was the most potent member related to patient outcomes and suppressing esophageal cancer malignancy in cell and animal models. It demethylated pri-miR-194-2 and inhibited miR-194-2 biogenesis through an m⁶A/DGCR8-dependent manner. RAI1, previously considered as a circadian clock transcriptional regulator, was the main target of miR-194-2. It enhanced transcription of Hippo pathway upstream genes by binding to their 3'UTR and suppressed YAP/TAZ nuclear translocation. The ALKBH5/miR-194-2/RAI1 axis was also validated in clinical samples. In addition, the increased malignancy by low ALKBH5 was abolished by the YAP inhibitor verteporfin. Our findings uncover a critical role of ALKBH5 in miRNAs biogenesis and provide novel insight for developing treatment strategies in esophageal cancer.