ATO alleviates T-cell immunosuppression by inducing apoptosis-associated secretion of IL-2 in FLT3-ITD-mutated acute myeloid leukemia

Background Arsenic trioxide (ATO) is effective against FLT3-mutant acute promyelocytic leukemia (APL), but its role in non-APL FLT3-ITD-mutant acute myeloid leukemia (AML) remains unclear. This study aims to investigate the mechanistic impact of ATO on FLT3-ITD-mutated AML cells. Methods This study utilized the CCK-8 assay, Wright–Giemsa staining, flow cytometry, Western blotting, and colorimetric assays to assess the effects of ATO on cell viability, cell morphology, apoptosis, Ki67 expression, reactive oxygen species (ROS), IL-2 levels, expression of apoptosis-related proteins, and LDH release in MV4–11 and HL-60 cells. Further validation was performed using NAC, PD98059 and LM22B-10. Following T-cell co-culture experiments, interferon-γ (IFN-γ) and granzyme B (GZMB) levels were measured. Differences in IL-2 expression were validated in primary cells from patients with AML. Results Compared to HL-60 cells, ATO-treated FLT3-ITD-mutated MV4–11 cells exhibited lower IC50, reduced Ki67 expression, and elevated LDH levels. ATO induced dose- and time-dependent apoptosis in MV4–11 cells, accompanied by increased Cleaved Caspase-3 expression and Bax/Bcl-2 ratio. NAC attenuated ATO-induced ROS accumulation and apoptosis. ATO suppressed extracellular signal-regulated kinase (ERK) phosphorylation in a concentration-dependent manner, which was reversed by LM22B-10 but exacerbated by PD98059. Additionally, ATO enhanced IL-2 secretion in MV4–11 cells, and their conditioned medium elevated IFN-γ and GZMB levels in CD4 + and CD8 + T cells. Similar IL-2 upregulation was observed in primary cells from FLT3-ITD+ AML patients. Conclusions ATO triggers apoptosis in FLT3-ITD-mutated AML cells via ROS/ERK signaling and modulates T-cell activity through IL-2 secretion, suggesting a dual role in tumor suppression and immune regulation. Significance This study confirms that ATO is a potential candidate drug for the treatment of FLT3-ITD-mutant AML and provides mechanistic insights into its cytotoxic and immunomodulatory functions.