HIF-1α enhances ferroptosis resistance in anaplastic thyroid carcinoma by suppressing ACSL4-mediated lipid metabolic homeostasis

Abstract Background Anaplastic thyroid carcinoma (ATC) exhibits extreme malignancy with a median survival of less than 6 months. Traditional therapeutic approaches yield limited efficacy, necessitating the urgent identification of novel treatment strategies. The tumor hypoxic microenvironment serves as a key driver of ATC progression and drug resistance, in which the transcription factor hypoxia-inducible factor 1α (HIF-1α) orchestrates key processes in regulating tumor metabolism, immune evasion, and resistance to cell death. Ferroptosis is a novel iron-dependent form of programmed death, defined by excessive peroxidation of polyunsaturated fatty acid phospholipids (PUFA-PL) within cellular membranes. Methods In this study, cellular and xenograft models were employed to demonstrate that hypoxia confers ferroptosis resistance to ATC cells. Lipid metabolomics analysis revealed HIF-1α regulates lipid metabolism, and acyl-CoA synthase 4 (ACSL4) was identified as key lipid metabolism-related candidate. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were used to assess the binding of HIF-1α to the hypoxia-response element (HRE) within the ACSL4 promoter region. Flow cytometric analysis was performed to investigate how HIF-1α inhibition augments the antitumor immunogenicity of PD-1 blockade, as evidenced by enhanced intratumoral CD8 + T-cell infiltration and cytokine secretion. Results This study identifies a key mechanism by which HIF-1α provides ferroptosis resistance in ATC under the intrinsically hypoxic tumor microenvironment. HIF-1α directly binds the HRE within the ACSL4 promoter, transcriptionally repressing ACSL4 and consequently curtailing PUFA-PL biosynthesis, thereby conferring ferroptosis resistance on ATC cells. In addition, combined treatment with HIF-1α inhibitor and PD-1 blockade effectively suppresses tumor progression and enhances intratumoral CD8 + T-cell infiltration. Conclusions This study elucidates the molecular mechanism by which HIF-1α mediates anti-ferroptosis in ATC through regulating lipid metabolism and proposes a promising therapeutic strategy in which HIF-1α inhibition acts synergistically with PD-1 blockade for the treatment of ATC.