Lactylation of HIF-1α at K172 drives HIF1 complex assemble to promote hypoxia-induced immune evasion in esophageal squamous cell carcinoma [RNA-Seq]

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 HIF1 transcription complex. Specifically, mass spectrometry identified lactylation at the K172 site of HIF1α, which was crucial for its binding to HIF1β and subsequent target gene activation. Furthermore, in a preclinical ESCC model, pharmacological inhibition of HIF1α with PX-478 synergized with anti-PD-1 therapy, leading to superior tumor control and enhanced CD8+ T cell cytotoxicity. Our study identifies HIF1α K172 lactylation as a pivotal mechanism of hypoxia-mediated immune escape in ESCC, suggesting a therapeutic strategy to improve immunotherapy.