ABSTRACT
SUMOylation is a reversible post-translational modification that regulates protein function through covalent attachment of small ubiquitin-like modifier (SUMO) proteins. The process of SUMOylating proteins involves an enzymatic cascade, the first step of which entails the activation of a SUMO protein through an ATP-dependent process catalyzed by SUMO-activating enzyme (SAE). Here, we describe the identification of TAK-981, a mechanism-based inhibitor of SAE which forms a SUMO-TAK-981 adduct as the inhibitory species within the enzyme catalytic site. Optimization of selectivity against related enzymes as well as enhancement of mean residence time of the adduct were critical to the identification of compounds with potent cellular pathway inhibition and ultimately a prolonged pharmacodynamic effect and efficacy in preclinical tumor models, culminating in the identification of the clinical molecule TAK-981.
Subject(s)
Antineoplastic Agents/therapeutic use , Enzyme Inhibitors/therapeutic use , Neoplasms/drug therapy , Sulfonic Acids/therapeutic use , Sumoylation/drug effects , Ubiquitin-Activating Enzymes/antagonists & inhibitors , Adenosine/analogs & derivatives , Adenosine/metabolism , Adenosine/therapeutic use , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/metabolism , Cell Line, Tumor , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/metabolism , Humans , Mice , Molecular Structure , Protein Binding , Protein Processing, Post-Translational/drug effects , Structure-Activity Relationship , Sulfonic Acids/chemical synthesis , Sulfonic Acids/metabolism , Ubiquitin-Activating Enzymes/metabolism , Xenograft Model Antitumor AssaysABSTRACT
The ubiquitin-proteasome system (UPS) comprises a network of enzymes that is responsible for maintaining cellular protein homeostasis. The therapeutic potential of this pathway has been validated by the clinical successes of a number of UPS modulators, including proteasome inhibitors and immunomodulatory imide drugs (IMiDs). Here we identified TAK-243 (formerly known as MLN7243) as a potent, mechanism-based small-molecule inhibitor of the ubiquitin activating enzyme (UAE), the primary mammalian E1 enzyme that regulates the ubiquitin conjugation cascade. TAK-243 treatment caused depletion of cellular ubiquitin conjugates, resulting in disruption of signaling events, induction of proteotoxic stress, and impairment of cell cycle progression and DNA damage repair pathways. TAK-243 treatment caused death of cancer cells and, in primary human xenograft studies, demonstrated antitumor activity at tolerated doses. Due to its specificity and potency, TAK-243 allows for interrogation of ubiquitin biology and for assessment of UAE inhibition as a new approach for cancer treatment.
