Activation of CASP1 induces AML cell pyroptosis and sensitizes to ATRA treatment

Acute myeloid leukemia (AML) is characterized by the accumulation of immature leukemic blasts. The application of all-trans retinoic acid (ATRA) treatments have markedly transformed acute promyelocytic leukemia (APL, the M3 subtype of AML) to a highly manageable disease, and research strategies that seek to extend the application of ATRA-based treatment to other AML subtypes are an important area of investigation. Here, we found CASP1/GSDMD was lower expressed in APL and most other subtypes of primary de novo AML patients and increased in ATRA-treated APL cells. We showed that ATRA increased and activated CASP1 to trigger pyroptosis and differentiation of APL cells. Mechanistically, ATRA could induce CASP1 expression via IFNγ/STAT1 in APL and non-APL AML cells, while do not activate CASP1 in non-APL AML cells. Accordingly, pharmacological activation of CASP1 by Val-boroPro (DPP8/9 inhibitor) enhanced pyroptosis and differentiation induced by ATRA in AML cells. Moreover, the combination of ATRA and Val-boroPro enhanced anti-leukemia activity in primary AML cells. Our study demonstrates that the ATRA-mediated anti-leukemia effect requires a functional activated CASP1 and provides a highly attractive therapeutic strategy for the treatment of AML.