Discovery of the U2AF1-UHM Inhibitor That Possesses Anti-Leukemia Activity In Vitro

In the early step of RNA splicing, U2AF1 and U2AF2 form a heterodimer that binds to the 3' exon-intron junction to define the 3' splice site. Mutations of U2AF1 dysregulate the splicing process and are frequently observed in subtypes of hematological neoplasms. No potent inhibitor of U2AF1 has been reported. Here, we report on the development of AP232 that targets the U2 auxiliary homology motif (UHM) of U2AF1, based on our previously reported SF153. We showed that AP232 had a 31-fold improvement in IC₅₀ over SF153 against U2AF1 and demonstrated a 3-24-fold selectivity against Other UHM proteins. AP232 exerted anti-leukemia activity, with higher activities observed in cell lines carrying splicing factor mutations. Further, AP232 induced G2/M and G1 arrest, impaired lysosome acidification, and inhibited Autophagy in leukemia cells. AP232 can serve as a useful tool for interrogating U2AF1 function in cells and as a lead for future optimization.

Autophagy; Cell cycle; Homogenous time resolved fluorescence assay; Lysosome; RNA binding protein; Small-molecule inhibitors; Splicing factor; U2AF homology motif; U2AF1.