ACOD1 enhances the ferroptosis resistance of tumor-associated macrophages through the KEAP1/NRF2 axis and promotes triple-negative breast cancer progression.
BACKGROUND Tumor-associated macrophages (TAMs), as core components of the triple-negative breast cancer (TNBC) tumor microenvironment (TME), can promote tumor progression. Ferroptosis has been shown to be involved in TNBC progression, but its regulatory mechanisms in TNBC TAMs remain incompletely understood. METHODS Clinical samples of TNBC were collected, and in vitro co-culture systems and BC xenograft models were established. By combining the results of the TCGA-BRCA and METABRIC transcriptomic cohort analyses, the expression characteristics and immune associations of ACOD1 were examined. Functional exploration was conducted through CCK-8, EdU, and colony formation assays and the detection of ferroptosis-related indicators. Molecular mechanisms were investigated using co-immunoprecipitation (Co-IP), CETSA, DARTS, SPR, and molecular docking. RESULTS ACOD1 expression was upregulated in immune-infiltrated subtypes, such as Basal-like/TNBC and HER2-enriched subtypes and significantly positively correlated with the infiltration of myeloid immune cells, including macrophages. Further results revealed that ACOD1 is highly expressed in TNBC TAMs and is driven by TME signals, independent of the classical M2 polarization pathway. The knockdown of ACOD1 in TAMs inhibited MDA-MB-231 cell proliferation and in vivo tumor growth and reduced ferroptosis resistance in TAMs. Mechanistically, ACOD1 knockdown did not affect KEAP1 expression but did reduce the expression of NRF2 and its downstream target genes HO-1 and NQO1, decreased NRF2 nuclear translocation, and increased KEAP1-NRF2 binding. Knockdown of KEAP1 or overexpression of NRF2 enhanced ferroptosis resistance. Additionally, ACOD1 knockdown decreased itaconate (ITA) levels in TAMs. The ITA derivative 4-OI was directly bound to KEAP1, weakened the KEAP1-NRF2 interaction, inhibited NRF2 ubiquitination, and stabilized NRF2 expression. CONCLUSION ACOD1, through its enzymatic product ITA, promotes ITA binding to KEAP1, which inhibits the KEAP1-NRF2 interaction and thus activates NRF2-mediated antioxidant and ferroptosis resistance responses in TAMs, promoting TNBC progression.