Comprehensive glycomics comparison between colon cancer cell cultures and tumours: implications for biomarker studies.
Altered glycosylation is commonly observed in colorectal cancer. In vitro models are frequently used to study this cancer but little is known about the differences that may exist between these model cell systems and tumour tissue. We have compared the membrane protein glycosylation of five colorectal cancer cell lines (SW1116, SW480, SW620, SW837, LS174T) with epithelial cells from colorectal tumours using liquid chromatography tandem mass spectrometry. Remarkably, there were five abundant O-glycans in the tumour cells that were undetected in the low-mucin producing cell lines, although two were found in the mucinous LS174T cells. The O-glycans included the well-known glycan cancer marker, sialyl-Tn, which has been associated with mucins. Using qRT-PCR, sialyl-Tn expression was found to be associated with an increase in α2,6-sialyltransferase gene (ST6GALNAC1) and a decrease in core 1 synthase gene (C1GALT1) in LS174T cells. The expression of a subset of mucins (MUC2, MUC6, MUC5B) was also correlated with sialyl-Tn expression in LS174T cells. Overall, the membrane protein glycosylation of the model cell lines was found to differ from each other and from the epithelial cells of tumour tissue. These findings should be noted in the design of biomarker discovery experiments particularly when cell surface targets are being investigated.


CONCLUSIONS
The extent of protein glycosylation differences between in vitro cell lines and ex vivo tumours in colorectal cancer research is unknown. Our study expands current knowledge by characterising the membrane protein glycosylation profiles of five different colorectal cancer cell lines and of epithelial cells derived from resected colorectal cancer tumour tissue, using liquid chromatography tandem mass spectrometry. The detailed structural differences found in both N- and O-linked glycan structures on the membrane glycoproteins were determined and correlated with the mRNA expression of the relevant proteins in the cell lines. The glycosylation differences found between cultured cancer cell lines and epithelial cells from tumour tissue have important implications for glycan biomarker discovery.
Department of Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, Sydney, Australia.
Jenny H L
JH
Chik
School of Molecular Bioscience, University of Sydney, Sydney, Australia.
Jerry
J
Zhou
Department of Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, Sydney, Australia.
Edward S X
ES
Moh
School of Molecular Bioscience, University of Sydney, Sydney, Australia.
Richard
R
Christopherson
Department of Medicine, Royal North Shore Hospital, University of Sydney, Australia.
Stephen J
SJ
Clarke
Department of Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, Sydney, Australia; Australian Proteome Analysis Facility, Macquarie University, Sydney, Australia.
Mark P
MP
Molloy
Department of Chemistry and Biomolecular Sciences, Faculty of Science, Macquarie University, Sydney, Australia. Electronic address: nicki.packer@mq.edu.au.
Nicolle H
NH
Packer
D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005700:Galactosyltransferases / Q000235:genetics / Q000378:metabolism*; D054794:Glycomics; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D008297:Male; D009077:Mucins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*
D014408:Biomarkers, Tumor; D009077:Mucins; D009363:Neoplasm Proteins; C505293:C1GALT1 protein, human; D005700:Galactosyltransferases; D012799:Sialyltransferases; C038525:CMP-N-acetylneuraminate-alpha-N-acetylgalactosaminide alpha-2,6-sialyltransferase
Biomarkers; Colorectal cancer; Glycosylation; Glycosyltransferases; Mucins