Abstract
Protein glycosylation is the most common posttranslational modification in mammalian cells. Aberrant protein glycosylation has been reported in various diseases, including cancer. We identified and quantified the glycan structures of O-linked glycoprotein from cholangiocarcinoma (CCA) cell lines from different histological types and compared their profiles by nanospray ionization-linear ion trap mass spectrometry (NSI-MSn). Five human CCA cell lines, K100, M055, M139, M213 and M214 were characterized. The results showed that the O-linked glycans of the CCA cell lines comprised tri- to hexa-saccharides with terminal galactose and sialic acids: NeuAc1Gal1GalNAc1, Gal2GlcNAc1GalNAc1, NeuAc2Gal1GalNAc1 NeuAc1Gal2GlcNAc1GalNAc1 and NeuAc2Gal2GlcNAc1GalNAc1 All five CCA cell lines showed a similar glycan pattern, but with differences in their quantities. NeuAc1Gal1GalNAc1 proved to be the most abundant structure in poorly differentiated adenocarcinoma (K100; 57.1%), moderately differentiated adenocarcinoma (M055; 42.6%) and squamous cell carcinoma (M139; 43.0%), while moderately to poorly differentiated adenocarcinoma (M214; 40.1%) and adenosquamous cell carcinoma (M213; 34.7%) appeared dominated by NeuAc2Gal1GalNAc1. These results demonstrate differential expression of the O-linked glycans in the different histological types of CCA. All five CCA cell lines have abundant terminal sialic acid (NeuAc) O-linked glycans, suggesting an important role for sialic acid in cancer cells. Our structural analyses of glycans may provide important information regarding physiology of disease-related glycoproteins in CCA.
Highlights
Cholangiocarcinoma (CCA) is a malignancy of the bile duct epithelium
We identified and quantified the glycan structures of O-linked glycoprotein from cholangiocarcinoma (CCA) cell lines from different histological types and compared their profiles by nanospray ionization-linear ion trap mass spectrometry (NSI-MSn)
Many reports suggests that changes in protein glycosylation may play an important role in promoting tumors and may, provide biomarkers for tumor progression
Summary
Cholangiocarcinoma (CCA) is a malignancy of the bile duct epithelium. The incidence of CCA is rare worldwide, but it is high in East and Southeast Asia. Recent studies in serum of CCA patients by sandwich ELISA showed the glycan epitope CA-S27 was related to prognosis and specific to CCA and may have immunodiagnostic value (Silsirivanit et al, 2013). The structural detail and the quantities of O-linked glycans from the 5 different histological types of CCA cell lines were demonstrated. Knowledge of these specific O-glycans may help in understanding the mechanisms of tumorigenesis, progression and metastasis of CCA, and may be applied for clinical diagnosis or effective treatment. The nomenclature used by Domon and Costello (Domon and Costello, 1988) was used to describe the fragmentation derived from the MS/MS spectra
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