Lactylation of HIF-1α at K172 drives HIF-1 complex assembly to promote hypoxia-induced immune evasion in esophageal squamous cell carcinoma

Hypoxia is a hallmark of the tumor microenvironment, but its role in immune evasion in esophageal squamous cell carcinoma (ESCC) remains to be fully elucidated. Here, we demonstrate hypoxia inversely correlated with anti-tumor immune signatures and CD8⁺ T cell infiltration in clinical samples and murine models. Functionally, reducing hypoxia with the agents TH-302 or PX-478 in the AKR model enhanced intratumoral CD8⁺ T cell infiltration and increased their expression of Granzyme B, IFNγ, and TNFα. Mechanistically, hypoxia-induced immune suppression was dependent on protein lactylation. Inhibiting lactylation reversed the hypoxic suppression of CD8⁺ T cell function and abrogated the hypoxia-driven transcriptional program, which involved pathways like glycolysis, TGFβ, and Notch signaling. This lactylation-dependent regulation operated by facilitating the formation of the HIF-1 transcription complex. Specifically, mass spectrometry identified lactylation at the K172 site of HIF-1α, which was crucial for its binding to HIF-1β and subsequent target gene activation. Furthermore, in a preclinical ESCC model, pharmacological inhibition of HIF-1α with PX-478 synergized with anti-PD-1 therapy, leading to superior tumor control and enhanced CD8⁺ T cell cytotoxicity. Our study identifies HIF-1α K172 lactylation as a pivotal mechanism of hypoxia-mediated immune escape in ESCC, suggesting a therapeutic strategy to improve immunotherapy.