Identification of a small molecule splicing inhibitor targeting UHM domains

Splicing factor mutations are frequent in myeloid neoplasms, blood cancers, and solid tumors. Cancer cells harboring these mutations present a particular vulnerability to drugs that target splicing factors such as SF3b155 or CAPER alpha. Still, the arsenal of chemical probes that target the spliceosome is very limited. U2AF homology motifs (UHMs) are common protein interaction domains among splicing factors. They present a hydrophobic pocket ideally suited to anchor small molecules with the aim to inhibit protein-protein interaction. Here, we combined a virtual screening of a small molecules database and an in vitro competition assay and identified a small molecule, we named UHMCP1 that prevents the SF3b155/U2AF(65) interaction. NMR analyses and molecular dynamics simulations confirmed the binding of this molecule in the hydrophobic pocket of the U2AF(65) UHM domain. We further provide evidence that UHMCP1 impacts RNA splicing and cell viability and is therefore an interesting novel compound targeting an UHM domain with potential anticancer properties.