Graphical AbstractHighlights d Structure-guided design and optimization yield potent FTO inhibitors d mRNA m 6 A acts as the major effector of the inhibitor/FTO axis in AML cells d FTO inhibitor FB23-2 displays therapeutic effects in PDX AML models d Targeting epitranscriptomic RNA methylation holds potential to treat AML SUMMARY FTO, an mRNA N 6 -methyladenosine (m 6 A) demethylase, was reported to promote leukemogenesis. Using structure-based rational design, we have developed two promising FTO inhibitors, namely FB23 and FB23-2, which directly bind to FTO and selectively inhibit FTO's m 6 A demethylase activity. Mimicking FTO depletion, FB23-2 dramatically suppresses proliferation and promotes the differentiation/apoptosis of human acute myeloid leukemia (AML) cell line cells and primary blast AML cells in vitro. Moreover, FB23-2 significantly inhibits the progression of human AML cell lines and primary cells in xeno-transplanted mice. Collectively, our data suggest that FTO is a druggable target and that targeting FTO by small-molecule inhibitors holds potential to treat AML. SignificanceAs the most abundant internal mRNA modification, m 6 A impacts various biological processes. As a major m 6 A demethylase, FTO is overexpressed in certain subtypes of AMLs and promotes leukemogenesis. Thus, the development of effective inhibitors to target FTO's aberrant m 6 A demethylase activity is urgently needed for leukemia therapy. Here we report two selective FTO inhibitors that efficiently reverse/suppress FTO-mediated aberrant epitranscriptome in AML cells and significantly inhibit AML progression in vivo. Our studies provide the proof-of-concept evidence demonstrating that small-molecule inhibitors targeting oncogenic FTO represent a promising targeted therapeutic strategy for the effective treatment of AML. Moreover, given the overexpression of FTO in various cancers, our work may have a broad impact on cancer therapy by targeting the FTO-mediated epitranscriptome.

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Arachidonic acid (AA) signaling pathway is an important constituent of inflammatory processes. In our previous study, it was found that dihydro-stilbene gigantol relieved hepatic inflammation in mice with CCl4-induced acute liver injury. This study aimed to investigate the involvement of arachidonate metabolic cascade in this process. Our results showed CCl4 activated AA metabolism with the evidence of cPLA2 phosphorylation, which was dependent on the MAPK/JNK activation. Pretreatment with JNK inhibitor SU3327 or gigantol abolished the cPLA2 activation, along with the attenuation of liver damage. Besides, gigantol markedly decreased immune cells activation. Metabolomic analysis revealed that gigantol universally reversed the upregulation of major AA metabolites in injured mouse livers induced by CCl4, especially 12-hydroxyeicosatetraenoic acid (12-HETE). Gigantol also decreased the mRNA and protein expression of platelet-, and leukocyte-type 12-lipoxxygenase (LOX) in the liver. Furthermore, pan-LOX inhibitor nordihydroguaiaretic acid (NDGA) and specific 12-LOX inhibitors baicalein and ML351 attenuated the liver injury to the same extent as gigantol. Overall, our study elucidated a comprehensive profile of AA metabolites during hepatic inflammation caused by CCl4, highlighting the role of 12-LOX-12-HETE pathway in this process. And gigantol alleviated liver inflammation partly through inhibiting the JNK/cPLA2/12-LOX pathway.