Background: Metabolic dysfunction-associated steatohepatitis-related hepatocellular carcinoma (MASH-HCC) has been reported to be less responsive to immune checkpoint inhibitors, which may be associated with metabolic reprogramming of tumour cells and abnormal tumour microenvironment.
Objective: Here, we aim to investigate the role of gluconeogenic enzyme phosphoenolpyruvate carboxykinase 1 (PCK1) in MASH-HCC and its interplay with the tumour microenvironment.
Design: Hepatocyte-specific phosphatase and tensin homologue (Pten) and Pck1 biallelic knockout mice were established to induce MASH-HCC. Single-cell RNA sequencing and multiparametrical flow cytometry were performed to analyse the immune landscape alterations. Untargeted metabolomics was conducted to elucidate the hepatic metabolism dysregulation.
Results: PCK1 is downregulated in tumour tissues compared with adjacent non-cancerous tissues from patients with MASH-HCC. Hepatocyte-specific Pck1 knockout mice exhibited markedly increased tumorigenesis in dietary models and genetic models of spontaneous MASH-HCC, together with inhibited effector function of tumour-infiltrating CD8+ T cells. Mechanistically, PCK1 deficiency induces the accumulation of endogenous metabolite 12-hydroxyeicosatetraenoic acid (12-HETE), which can be taken up by CD8+ T cells and activate the p38 mitogen-activated protein kinase pathway by directly interacting with the BTB and CNC homology 1 transcription factor, ultimately leading to CD8+ T cells dysfunction. Notably, PCK1 restoration or 12-HETE inhibition combined with anti-PD-1 treatment increases the antitumour capability of CD8+ T cells and suppresses MASH-HCC development.
Conclusion: This study reveals the pivotal role of the hepatic cell-intrinsic enzyme PCK1 in mediating CD8+ T cell dysfunction via 12-HETE-p38 signalling in MASH-HCC. PCK1 could be a metabolic checkpoint to enhance the efficacy of anti-PD-1 immunotherapy in MASH-HCC.
Keywords: CARCINOGEN METABOLISM; FATTY LIVER; HEPATOCELLULAR CARCINOMA.
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