Glycobiology Advance Access originally published online on January 3, 2009
Glycobiology 2009 19(4):382-398; doi:10.1093/glycob/cwn149
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O-Glycan inhibitors generate aryl-glycans, induce apoptosis and lead to growth inhibition in colorectal cancer cell lines
3 Department of Clinical Science at South Bristol
4 Department of Chemistry
5 Department of Cellular and Molecular Medicine, University of Bristol, Bristol BS8 1TH, UK
6 Institut für Molekularbiologie und Bioinformatik, Charité Universitätsmedizin Berlin, Arnimallee 22, 14195 Berlin, Germany
7 UMR CNRS/USTL 8576, Glycobiologie Structurale et Fonctionnelle, Bâtiment C9, Université des Sciences et Technologies Lille1, F-59655 Villeneuve d’Ascq Cedex, France
1 To whom correspondence should be addressed: Tel: +44-117-928-4898; Fax: +44-117-925-2736; e-mail: tony.corfield{at}bristol.ac.uk
Received on June 30, 2008; revised on December 12, 2008; accepted on December 13, 2008
Our studies provide direct evidence that O-glycosylation pathways play a role in the regulation of cell growth through apoptosis and proliferation pathways. A series of small molecular weight analogs of the GalNAc-
-1-O-serine/threonine structure based on 1-benzyl-2-acetamido-2-deoxy--O-D-galactopyranoside have been synthesized and tested in the human colorectal cancer cell lines PC/AA/C1/SB10C and HCA7/C29. Three inhibitors, 1-benzyl-2-acetamido-2-deoxy--O-D-galactopyranoside, and the corresponding 2-azido- and C-glycoside analogs were screened in these colorectal cancer cell lines at 0.5 mM and showed induction of apoptosis and downregulation of proliferation. Treatment of both cell lines with inhibitors led to changes in glycosylation detected with peanut lectin. The inhibition of glycosyltransferase activity in cell homogenates from human colorectal mucosal cells and cultured cell lines could be shown. The competitive action of the inhibitors resulted in the intracellular formation of 28 aryl-glycan products which were identified by MALDI and electrospray mass spectroscopy. The structures showed a differential pattern for each of the inhibitors in both cell lines. Gene array analysis of the glycogenes illustrated a pattern of glycosyltransferases that matched the glycan structures found in glycoproteins and aryl-glycans formed in the PC/AA/C1/SB10C cells; however, there was no action of the three inhibitors on glycogene transcript levels. The inhibitors act at both intermediary metabolic and genomic levels, resulting in altered protein glycosylation and aryl-glycan formation. These events may play a part in growth arrest.
Key words: apoptosis / aryl-glycans / benzyl-O-GalNAc / growth inhibition / O-glycans
2 Present address: Department of Organic Chemistry II, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioako Kanpusa. Sarriena auzoa, z/g. 48940 Leioa (Bizkaia) Spain.