Highlights d Activation of the mitochondrial ClpP induces p53independent cancer cell lethality d Imipridones are allosteric agonists of ClpP, being tested in human clinical trials d ClpP activation increases proteolysis of mitochondrial proteins d ClpP-mediated mitochondrial proteolysis impairs mitochondrial respiratory function
Acute myeloid leukemia (AML) is an aggressive hematologic malignancy for which new therapeutic approaches are required. One such potential therapeutic strategy is to target the ubiquitin-like modifier-activating enzyme 1 (UBA1), the initiating enzyme in the ubiquitylation cascade in which proteins are tagged with ubiquitin moieties to regulate their degradation or function. Here, we evaluated TAK-243, a first-in-class UBA1 inhibitor, in preclinical models of AML. In AML cell lines and primary AML samples, TAK-243 induced cell death and inhibited clonogenic growth. In contrast, normal hematopoietic progenitor cells were more resistant. TAK-243 preferentially bound to UBA1 over the related E1 enzymes UBA2, UBA3, and UBA6 in intact AML cells. Inhibition of UBA1 with TAK-243 decreased levels of ubiquitylated proteins, increased markers of proteotoxic stress and DNA damage stress. In vivo, TAK-243 reduced leukemic burden and targeted leukemic stem cells without evidence of toxicity. Finally, we selected populations of AML cells resistant to TAK-243 and identified missense mutations in the adenylation domain of UBA1. Thus, our data demonstrate that TAK-243 targets AML cells and stem cells and support a clinical trial of TAK-243 in this patient population. Moreover, we provide insight into potential mechanisms of acquired resistance to UBA1 inhibitors.
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