Background: The poor prognosis of acute myeloid leukemia (AML) is partly due to the immunosuppressive leukemia environment. A therapeutic approach to induce pyroptosis is promising to work on this issue. Pyroptosis, a form of inflammatory cell death, is capable to release pro-immune factors and enhance the infiltration and cytotoxicity of natural killer (NK) cells. Chemical drugs have been verified to enhance anti-tumor immunity by inducing pyroptosis. Arsenic trioxide (ATO), a clinical drug in

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... leukemia, is reported to be effective to kill AML cells, but it's still unclear about its mechanism in AML. Our research is aimed at exploring the ATO effect on pyroptosis induction and the anti-tumor immunity of NK cells in AML.Methods: Pyroptotic phenomenon was detected by confocal microscopy, Annexin-V / propidium iodide staining, LDH release assay, and western blotting; The release of cytokines was detected by SDS-PAGE, proteomic analysis, ELISA, etc.; AML xenograft models were established to explore the ATO effect in vivo and the anti-tumor effect of ATO treatment was identified by tumor-volume measurement, HE staining and KI67 staining; The activity of NK cells was evaluated by immunofluorescence, flow cytometric analysis, etc.; The differential expressed proteins were identified by quantitative proteomic analysis and western blotting.Results: We first discovered that ATO induced pyroptosis in AML cells and activated caspase-3/gasdermin E (GSDME) pathway to induce pyroptosis, and enhances the release of LDH, HMGB1, and IL-1β. Moreover, we revealed that ATO treatment promoted the proliferation, tumor-infiltration, and degranulation of NK cells in AML and its leukemia microenvironment. The further proteomic clues indicate the potential mechanisms of the ATO anti-leukemia effect in vivo.Conclusions: These findings indicate that ATO treatment induces pyroptosis via caspase-3/GSDME pathway, enhances the release of pro-inflammatory cytokines, and activates NK cells in AML. Our data identify what is to our knowledge the first clinical drug that induces pyroptosis in AML, revealing the potential anti-leukemic and pro-immune properties of ATO treatment in the leukemia microenvironment of AML, which may be beneficial in reducing the recurrence problems associated with the leukemia microenvironment.