Epigenetic Regulation of G6PD Drives Metabolic Reprogramming in Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive malignancy with poor prognosis and significant molecular heterogeneity. This study investigates the role of tumor-specific enhancers in metabolic reprogramming, focusing on glucose-6-phosphate dehydrogenase (G6PD) and the pentose phosphate pathway (PPP). Using native elongating transcript-cap analysis of gene expression and single-cell RNA sequencing, tumor-specific enhancers driving G6PD overexpression were identified in ICC tumor epithelial cells. Functional assays demonstrated that G6PD promotes tumor proliferation by enhancing PPP activity and maintaining redox homeostasis, which provides NADPH to counter oxidative stress. Enhancer knockdown disrupted G6PD expression and PPP activity, increasing reactive oxygen species levels and reducing the NADPH/NADP⁺ ratio. These metabolic changes impaired tumor cell proliferation and sensitized ICC cells to cisplatin, emphasizing the dual therapeutic potential of targeting G6PD to inhibit tumor growth and overcome chemoresistance. Survival analyses showed that high G6PD expression correlates strongly with poor overall survival in ICC patients. While previous studies have recognized the roles of G6PD and PPP in cancer metabolism, this study uniquely links enhancer-mediated regulation to these processes in ICC, offering novel insights into epigenetic mechanisms driving metabolic reprogramming. Moreover, the findings highlight tumor-specific enhancers as critical epigenetic drivers of ICC progression, with potential as therapeutic targets. Future research should explore the integration of enhancer profiling into precision medicine frameworks and the development of novel enhancer-targeting strategies. These efforts could uncover additional metabolic vulnerabilities and provide effective treatments for this highly aggressive cancer.