Aim: This study aimed to investigate the effects of glucosamine, a glucose analogue mainly transported via glucose transporter (GLUT) 2, on the progression of cholangiocarcinoma (CCA) cells.
Methods: Differential expressions of GLUTs in CCA and normal bile ducts were analyzed using a public transcriptomic dataset. The effects of glucosamine on CCA cell viability and proliferation were examined using an MTT assay and flow cytometry. Molecular mechanisms were investigated using Western blots and lectin blots.
Results: GLUT2 expression was significantly decreased in CCA compared with the normal bile duct tissues. Glucosamine significantly reduced CCA cell viability in a dose-dependent manner (p < .05), while flow cytometry showed increased G1 cell cycle arrest and apoptosis in glucosamine-treated cells (p < .05). Glucosamine significantly suppressed high-mannose type N-glycosylation in CCA cells, as shown in concanavalin A lectin blots and the Western blots of glycoprotein 130 (p < .05), leading to a reduced epidermal growth factor receptor (EGFR) expression and STAT3 phosphorylation. Cell viability and high-mannose type N-glycosylation could be partially rescued by high-glucose supplementation, confirming that disrupting high-mannose type N-glycosylation and EGFR/STAT3 signaling are part of the underlying mechanisms.
Conclusion: Glucosamine exerted anti-cancer effects on CCA cells, suggesting its potential for further study as a repurposing drug for CCA.
Keywords: Cholangiocarcinoma; N-glycosylation; food supplement; glucosamine; intracellular signaling.
This study explored whether glucosamine can slow the growth of bile duct cancer cells and how it works by using laboratory experiments. We first examined public gene expression data and found that glucose transporter 2, a transporter bringing glucosamine into the cells, is expressed at lower levels in bile duct cancer tissue than in the normal counterparts. The treated bile duct cancer cells showed a dose-dependent reduction in cell number with increasing glucosamine dose. Further analyses showed that glucosamine arrests cancer cell division and induces cancer cell death. To understand the mechanism, the effects of glucosamine on the inhibition of a sugar modification of protein called N-glycosylation were also studied. Glucosamine markedly reduced a sugar modification (N-glycosylation) of proteins within the cells, including those involved in signaling, thereby disrupting their signaling functions. However, when high glucose was added to the cells, some of the damaging effects of glucosamine on the cells and their sugar modification were partially reversed. This supports the idea that glucosamine works by disturbing these sugar modifications and the growth signals they control. In summary, our experiments showed that glucosamine slowed growth and increased cell death in bile duct cancer cells. This suggests that glucosamine might be worth further study as a possible treatment.