The USP1 deubiquitinating enzyme, which regulates the DNA translesion synthesis (TLS) and Fanconi anemia (FA) DNA damage response pathways by deubiquitinating the central players of these pathways, is activated by the WD40-repeat containing UAF1 protein through formation of a stable USP1-UAF1 protein complex. ML-323 is an inhibitor of the USP1-UAF1 deubiquitinase complex with an IC50 value of 76 nM. It demonstrates excellent selectivity against other human deubiquitinases, deSUMOylase, deneddylase, and unrelated proteases. ML-323 has been shown to inhibit the deubiquitination of proliferating cell nuclear antigen and FA complementation group D2 by inhibiting USP1-UAF1 activity in H596 cells. ML-323 potentiates cisplatin cytotoxicity in NSCLC H596 cells and U2OS osteosarcoma cells by targeting the TLS and FA DNA damage response pathways.
