Downregulation of 15-PGDH enhances MASH-HCC development via fatty acid-induced T-cell exhaustion

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) mainly develops from chronic hepatitis. Metabolic dysfunction-associated steatohepatitis (MASH) has gradually become the main pathogenic factor for HCC given the rising incidence of obesity and metabolic diseases. 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) degrades prostaglandin 2 (PGE2), which is known to exacerbate inflammatory responses. However, the role of PGE2 accumulation caused by 15-PGDH downregulation in the development of MASH-HCC has not been determined. METHODS: We utilised the steric animal model to establish a MASH-HCC model using wild-type and 15-Pgdh(+/−) mice to assess the significance of PGE2 accumulation in the development of MASH-HCC. Additionally, we analysed clinical samples obtained from patients with MASH-HCC. RESULTS: PGE2 accumulation in the tumour microenvironment induced the production of reactive oxygen species in macrophages and the expression of cell growth-related genes and antiapoptotic genes. Conversely, the downregulation of fatty acid metabolism in the background liver promoted lipid accumulation in the tumour microenvironment, causing a decrease in mitochondrial membrane potential and CD8+ T-cell exhaustion, which led to enhanced development of MASH-HCC. CONCLUSIONS: 15-PGDH downregulation inactivates immune surveillance by promoting the proliferation of exhausted effector T cells, which enhances hepatocyte survival and proliferation and leads to the development of MASH-HCC. IMPACT AND IMPLICATIONS: The suppression of PGE2-related inflammation and subsequent lipid accumulation leads to a reduction in the severity of MASH and inhibition of subsequent progression toward MASH-HCC.