Metabolic Signaling Meets Epigenetic Regulation: How Protein Lactylation Remodels the Tumor Immune Microenvironment in Gastric Cancer

This review argues that protein lactylation—a lactate-driven posttranslational modification—serves as the long-sought molecular bridge that coordinates these two hallmarks in gastric cancer (GC). Far from being a passive metabolic byproduct, lactylation operates as a central molecular hub with a dual function: intracellularly, it directly drives malignant phenotypes by modifying key oncoproteins such as YAP and metabolic enzymes; extracellularly, it remodels the tumor immune microenvironment by polarizing tumor-associated macrophages toward an immunosuppressive M2 phenotype, upregulating PD-L1 expression, and impairing CD8+ T-cell function. We propose that these two arms constitute a self-reinforcing metabolic–epigenetic–immunological circuit, wherein lactylation both originates from and perpetuates the Warburg effect, creating a vicious cycle that sustains malignancy and immune evasion. This framework positions lactylation not merely as a mechanistic detail, but as a unifying principle that integrates metabolic reprogramming, epigenetic regulation, and immune suppression in GC. We critically evaluate the current landscape of lactylation “writers,” “erasers,” and “readers”; highlight the translational potential of targeting this pathway; and identify the conceptual and technical bottlenecks that must be overcome—including the lack of causality in current studies, the absence of specific research tools, and the unresolved heterogeneity of lactylation across cell types and disease stages. By reframing lactylation as an actionable hub rather than a downstream consequence, this review provides a roadmap for advancing lactylation-based precision medicine in GC.