Isoalantolactone induces AML pyroptosis and potentiates α-PD-1 efficacy by targeting selenoprotein TXNRD1

The suppressive microenvironment of AML limits anti-PD-1 efficacy, making pyroptosis induction a key strategy for its remodeling. Isoalantolactone (IAL), a naturally occurring small molecule, has been identified herein to inhibit cytosolic thioredoxin reductase1 (TXNRD1) and trigger pyroptosis in AML cells, thereby enhancing the efficacy of anti-PD-1 antibody therapy. Mechanistically, the α,β-unsaturated carbonyl group of IAL covalently bound to the selenocysteine residue at the position 498 (Sec498) of TXNRD1 through a Michael addition reaction. Clinical sample analysis revealed that TXNRD1 is overexpressed in AML, which correlates with poor prognosis. Additionally, we found that the TXNRD inhibitor auranofin has demonstrated good efficacy against AML. The inhibition of TXNRD1 activates the transcription factor peroxisome proliferator-activated receptor gamma (PPARγ), which, in turn, upregulates the transcription of caspase-3, subsequently increasing the cleavage of gasdermin E to induce pyroptosis via the non-classical pathway in AML cells. Additionally, enhanced caspase-3 activity promotes poly ADP-ribose polymerase 1 (PARP-1) cleavage and upregulates PD-L1 expression, thereby increasing sensitivity to anti-PD-1 monoclonal antibodies. Overall, the current study highlights a promising approach for augmenting therapy using anti-PD-1 monoclonal antibodies in AML by targeting TXNRD1 to induce pyroptosis and ameliorate the immunosuppressive microenvironment.