Document resource
Background Lactate accumulation in hepatocellular carcinoma (HCC) contributes to immune evasion and metabolic adaptation. 1–4 However, the functional landscape and regulatory consequences of protein lactylation in HCC remain largely unexplored.Methods We performed a comprehensive lactylome analysis in human HCC tissues using affinity enrichment and mass spectrometry, 5 identifying differential lactylation sites. Functional assays, metabolomic profiling, and murine models were applied to characterize lactylation-regulated pathways and assess their impact on tumor progression and immune activity.Results We identified over 1,400 lactylation sites across 700+ proteins, with significant enrichment in metabolic enzymes and mitochondrial pathways. AK2 was found to be a key lactylated enzyme regulating oxidative phosphorylation and nucleotide synthesis. Loss of AK2 lactylation impaired mitochondrial function and promoted immune evasion. Lactylation of metabolic regulators also affected antigen presentation and T cell infiltration. Targeting lactate production or lactylation rewired tumor metabolism and sensitized tumors to immune checkpoint blockade in vivo.Conclusions Our findings reveal that protein lactylation is a critical epigenetic-metabolic mechanism driving HCC progression and immune escape. Targeting lactylation-dependent pathways may offer novel therapeutic strategies to enhance immunotherapy efficacy in liver cancer ( figure 1).References Zhang D, Tang Z, Huang H, et al. Metabolic regulation of gene expression by histone lactylation. Nature. 2019;574:575–580.Yang K, Fan M, Wang X, et al. Lactylation-dependent activation of metabolic reprogramming promotes tumor progression in hepatocellular carcinoma. Cell Metab. 2023;35:1183–1199.e6.Guo J, Liu Z, Zhang X, et al. Tumor cell-derived lactate induces T cell exhaustion in the tumor microenvironment. Nat Commun. 2021;12:4583.Choi J, Jung JH, Lee M, et al. Targeting lactate metabolism for cancer immunotherapy. Int J Mol Sci. 2023;24:13249.Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem. 1987;162:156–159.Ethics Approval Human tissue samples were collected with informed consent and approved by the Ethics Committee of Zhongshan Hospital, Fudan University (Approval No. B2022-198R). All animal experiments were conducted in accordance with institutional guidelines and approved by the Animal Care and Use Committee of Zhongshan Hospital, Fudan University (Approval No. 2022-041).Consent Written informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.Abstract 1218 Figure 1Kla regulation mechanisms