The Role of the Hexosamine-Sialic Acid Metabolic Pathway Mediated by GFPT1/NANS in c-Myc-Driven Hepatocellular Carcinoma.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) frequently involves metabolic reprogramming, which promotes oncogenesis and metastasis. However, the underlying molecular mechanisms remain insufficiently explored. In this study, we aim to investigate the metabolic abnormalities in c-Myc-driven HCC development and their potential therapeutic implications. METHODS: RNA sequencing and metabolomics were performed on HCC and adjacent tissues in a murine HCC model established by hydrodynamic tail-vein injection of c-Myc and sgTrp53/Cas9 plasmids. Key catalytic enzyme gene knockout was used to assess tumor formation and murine survival. Gene expression was analyzed using quantitative polymerase chain reaction, immunohistochemistry, and Western blot. Chromatin immunoprecipitation followed by quantitative polymerase chain reaction and luciferase assays verified c-Myc regulation. RESULTS: RNA sequencing data revealed that the hexosamine biosynthetic pathway was significantly activated in c-Myc-driven HCC. The rate-limiting enzyme GFPT1 (rather than GFPT2) was up-regulated in the first step of this pathway. Knocking out GFPT1 reduces tumor growth and prolongs murine survival. Human specimens showed that GFPT1 was overexpressed in HCC tissues and was associated with advanced Edmondson-Steiner grades and short patient survival. Further luciferase reporter assays confirmed that c-Myc binds directly to the promoter region of GFPT1 and activates its transcription. Subsequent examination of the downstream pathways of the hexosamine biosynthetic pathway showed that the sialic acid synthesis (but not O-GlcNac glycosylation) pathway was enhanced, which was mediated by a key enzyme, N-acetylneuraminic acid synthase. Knockout of N-acetylneuraminic acid synthase also inhibits tumor growth and extends murine survival in c-Myc-driven HCC models. CONCLUSIONS: These findings indicate that the activation of the hexosamine biosynthetic pathway/sialic acid pathway is an important mechanism underlying the development of c-Myc-driven HCC. Inhibitors of GFPT1, along with anti- N-acetylneuraminic acid synthase may offer a promising therapeutic strategy.