BI8622 is a selective HUWE1 (HECTH9; MULE; ARF-BP1) inhibitor (IC50 = 3.2 μM by HUWE1 HECT-domain auto-ubiquitination assay; IC50 >50 μM against other HECT-domain Ub ligases tested). BI8622 inhibits the degradation of HUWE1 target proteiins, including MCL1 (IC50 = 6.8 μM; UV irradiated HeLa MCL1 transfectants), MIZ1 (10 μM; Ls174T), and TopBP1. BI8622 suppresses Ls174T colony formation (IC50 = 8.4 μM in 5 days) and the growth of three colon carcinoma cell lines (20 μM for 5 days; HCT116, HT29, SW480).
