Structure-Activity Relationships of 2-(Arylthio)benzoic Acid FTO Inhibitors

The biological role of the fat mass and obesity-associated protein (FTO) in the initiation and progress of acute myeloid leukemia (AML) has been elucidated, and several representative FTO inhibitors can markedly suppress the proliferation of AML cells. We previously developed FTO inhibitors including FB23. In this study, we adopted bioisosteric replacement of the intramolecular hydrogen bond in FB23 with a sulfur-oxygen interaction to generate a series of 2-(arylthio)benzoic acid FTO inhibitors and established their structure-activity relationships. Compound 8c was the most potent 2-(arylthio)benzoic acid FTO inhibitor with an IC₅₀ value of 0.3±0.1 μM, which was comparable with that of FB23 in vitro. To enhance the antiproliferative effects in AML cell lines, we applied a prodrug strategy and prepared some esters. 7l, the methyl ester of 8l, exerted a superior inhibitory effect on a panel of AML cancer cell lines. Additionally, 7l treatment notably increased global m⁶A abundance in AML cells. Collectively, our data suggest that 2-(arylthio)benzoic acid may be a new lead compound for inhibition of FTO, and the prodrug analog exhibit potential in the treatment of AML.