Quantitative Proteomics Reveals Down-Regulated Glycolysis/ Gluconeogenesis in the Large-Duct Type Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is a lethal hepatobiliary malignancy that arises from the epithelial cells of the intrahepatic bile ducts, accounting for approximately 10% of cholangiocarcinoma (CCA). According to the 2019 World Health Organization (WHO) classification of tumors of the digestive system, iCCA is divided into small-duct type (SD-type) and large-duct type (LD-type). However, it remains unknown which molecular events contribute to the disparity. To explore the proteomic characteristics of iCCA, we used an isobaric tag for relative and absolute quantitation (iTRAQ) based quantitative proteomics strategy to investigate stably dysregulated proteins in the SD-type and LD-type of iCCA tissues. Importantly, we found three glycolysis/gluconeogenesis-related enzymes, triosephos-phate isomerize 1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and phosphoglycerate kinase 1 (PGK1), were significantly down-regulated in the LD-type iCCA, which were further confirmed by immunohistochemistry using tissue microarray. Moreover, we demonstrated that the knockdown of these three candidate proteins by siRNAs notably increased the ability of proliferation in two CCA cell lines (HuH28 and RBE), suggesting that effective down-regulation of the glycolysis/gluconeogenesis pathway might be an underlying novel mechanism contributing to the LD-type iCCA.