Discovery of a Novel Target Inhibitor Theaflavin against UDP-Glucose Pyrophosphorylase 2 and Its Role in Attenuating the Malignant Phenotype of Liver Cancer Cells via Perturbation of Glucose Metabolism

UDP-glucose pyrophosphorylase 2 (UGP2), the unique mammalian enzyme converting glucose-1-phosphate to UDP-glucose, is upregulated in hepatocellular carcinoma (HCC) and other malignancies. It promotes tumor progression through glycogen metabolism and glycosylation, thereby emerging as a promising yet undrugged therapeutic target. Utilizing high-throughput screening coupled with AI-based modeling, we identified Theaflavin, a food-derived natural product, as a targeted inhibitor of UGP2, exhibiting an IC₅₀ of 27.24 μM. The results showed that Theaflavin, as a competitive inhibitor, mainly binds to the region of UGP2 centered around the key residues Lys396 and Asp253, and has minimal inhibitory effect on its homologous enzyme galactose-1-phosphate uridylyltransferase (GALT). Theaflavin inhibits UGP2-mediated UDPG synthesis and intracellular glycogen accumulation, attenuating malignant phenotypes (proliferation, migration, invasion) in HCC cells. Our findings identify Theaflavin as a selective UGP2 inhibitor, providing a novel dietary-derived candidate for HCC therapy targeting glucose metabolism and establishing UGP2 as its direct cellular target.