Down-Regulation of C1GALT1 Enhances the Progression of Cholangiocarcinoma through Activation of AKT/ERK Signaling Pathways

Abstract

Alteration of mucin-type O-glycosylation is implicated in tumor progression and metastasis of cholangiocarcinoma (CCA). Core 1 β1-3 Galactosyltransferase (C1GALT1) is a primary enzyme that regulates the elongation of core 1-derived mucin-type O-glycans. Dysregulation of C1GALT1 has been documented in multiple cancers and is associated with aberrant core 1 O-glycosylation and cancer aggressiveness; however, the expression of C1GALT1 and its role in CCA progression remains unknown. Our study demonstrated that C1GALT1 was downregulated in CCA tissues at both the mRNA and protein levels. The biological function of C1GALT1 using siRNA demonstrated that suppression of C1GALT1 in the CCA cell lines (KKU-055 and KKU-100) increased CCA progression, evidenced by: (i) Induction of CCA cell proliferation and 5-fluorouracil resistance in a dose-dependent manner; (ii) up-regulation of growth-related genes, ABC transporter genes, and anti-apoptotic proteins; and (iii) an increase in the activation/phosphorylation of AKT and ERK in silencing C1GALT1 cells. We demonstrated that silencing C1GALT1 in CCA cell lines was associated with immature core 1 O-glycosylation, demonstrated by high expression of VVL-binding glycans and down-regulation of other main O-linked glycosyltransferases β1,3-N-acetylglucosaminyltransferase 6 (B3GNT6) and ST6 N-Acetylgalactosaminide Alpha-2,6-Sialyltransferase 1 (ST6GALNAC1) in C1GALT1 knockdown. Our findings demonstrate that down-regulation of C1GALT1 in CCA increases the expression of immature core 1 O-glycan, enhancing CCA progression, including growth and 5-fluorouracil resistance via the activation of the AKT/ERK signaling pathway.

Bittersweet Sugars: How Unusual Glycan Structures May Connect Epithelial-to-Mesenchymal Transition and Multidrug Resistance in Cancer

“…In 2015, Hofmann and colleagues demonstrated that the knockdown of the COSMC chaperone, preventing O -glycan elongation beyond the initial GalNAc α 1- residue on O -linked glycoproteins [ 31 ], was associated with elevated migration and reduced apoptosis of pancreatic cancer cells, suggesting that such a simple O -linked glycan may modulate the survival of transformed cells [ 31 ]. Recently, it has been revealed that the down-regulation of C1GALT1 in cholangiocarcinoma (CCA) promoted the expression of immature core 1 O -glycan, enhancing CCA progression, which was associated with the up-regulation of ABC transporter genes and anti-apoptotic proteins [ 32 ], which are both effects associated with the emergence of MDR phenotypes. In addition, C1GALT1 knockdown cells showed resistance to 5-fluorouracil via the activation of the AKT/ERK signaling pathway [ 32 ].…”

“…Recently, it has been revealed that the down-regulation of C1GALT1 in cholangiocarcinoma (CCA) promoted the expression of immature core 1 O -glycan, enhancing CCA progression, which was associated with the up-regulation of ABC transporter genes and anti-apoptotic proteins [ 32 ], which are both effects associated with the emergence of MDR phenotypes. In addition, C1GALT1 knockdown cells showed resistance to 5-fluorouracil via the activation of the AKT/ERK signaling pathway [ 32 ]. One of the glycoconjugates that are directly affected by overexpression of the STn antigen is MUC1.…”

Unraveling the role of C1GALT1 in abnormal glycosylation and colorectal cancer progression

“…Through the regulation of protein stability, subcellular localization, activity, and interactions, glycosylation plays a wide-ranging role in key cellular processes, including gene transcription, cell cycle regulation, DNA repair, apoptosis, virus budding, receptor endocytosis, and various physiological and pathological processes ( 16 – 18 ). Tumor cells exhibit extensive glycosylation changes compared to untransformed cells, and glycosylation has been closely associated with various cancers, including hepatocellular cancer ( 19 – 21 ), pancreatic cancer ( 22 , 23 ), gastric cancer ( 24 ), bladder cancer ( 25 ), breast cancer ( 21 ), esophageal cancer ( 26 ), cholangiocarcinoma ( 27 ) etc. In colorectal cancer (CRC), glycosylation can impact cell migration, intercellular adhesion, actin polymerization, mitosis, cell membrane repair, apoptosis, cell differentiation, stem cell regulation, intestinal mucosal barrier integrity, immune system regulation, T cell polarization, and intestinal microbiota composition ( 28 , 29 ).…”

Altered O-linked glycosylation in benign and malignant meningiomas

“…Reports of tumor-associated O-linked glycosylation includes Core 1 β1-3 galactosyltransferase (C1GALT1), C1GALT1-specific chaperone (COSMC), Core 2 β1,6-N-acetylglucosaminyltransferase-1 (C2GNT1), Core 2 β1,6-N-acetylglucosaminyltransferase-2 (C2GNT2), and Core 3 β1,3-N-acetylglucosaminyltransferase 6 (B3GNT6) ( Curigliano et al, 2020 ; Martinez-Saez, Peregrina & Corzana, 2017 ; Miyamoto et al, 2013 ; Okamoto et al, 2013 ; Schachter & Brockhausen, 1989 ; Sindrewicz, Lian & Yu, 2016 ). Down-regulation of C1GALT1 and its chaperone, COSMC, contributed to increased truncation of O-glycans, Tn and sialyl-Tn (sTn) antigens, on mucin glycoproteins ( Chugh et al, 2018 ; Khiaowichit et al, 2022 ; Liu et al, 2020 ; Sagar et al, 2021 ). C2GNT1 competes with ST3 β-galactoside α-2,3-sialyltransferase 1 (ST3GAL1) and further truncated O-glycosylation by capping the T-antigen with sialic acid ( Chandrasekaran et al, 2006 ).…”