Synergistic effects of BET inhibitors and ferroptosis inducers via targeted inhibition of the BRD4/c-Myc/NRF2 pathway in AML

Abstract

In acute myeloid leukemia (AML), high expression of BRD4 is associated with poor prognosis. BET inhibitors that mainly inhibit BRD4 can induce AML cell death, but some AML cells are insensitive to BET inhibitors. We found that BET inhibitors could promote the up-regulation of the ferroptosis signaling pathway in AML. In this study, we intend to investigate the synergistic effects of BET inhibitors with ferroptosis inducers in AML cells. The combination of BET inhibitors with ferroptosis inducers (RSL3, FIN56, and Erastin) markedly reduced AML cell viability and increased cell death, as demonstrated by CCK-8 assays and flow cytometry analysis across multiple AML cell lines and primary AML patient samples. Moreover, BET inhibitors combined with ferroptosis inducers elevated the lipid reactive oxygen species (ROS) levels, indicating heightened lipid peroxidation, a hallmark of ferroptosis. Mechanistically, BET inhibitor and ferroptosis inducer co-targeted the BRD4/c-Myc/NRF2 axis, leading to downregulation of NRF2, key regulators of AML cell survival and oxidative stress resistance. NRF2 knockdown amplified the anti-AML effect of this combined treatment, whereas NRF2 overexpression negated this synergy, highlighting its critical role in mediating ferroptosis resistance. Finally, survival analyses of AML patients from the TCGA and GSE71014 datasets revealed that elevated expression of BRD4, NRF2, and its downstream target GPX4, an essential ferroptosis regulator, correlated with poor overall survival, highlighting the clinical relevance of our findings. In all, combining BET inhibition with ferroptosis induction could enhance anti-leukemia effect and represent a novel therapeutic strategy for targeting AML cells.