High
glucose consumption due to Warburg effect is one of the metabolic hallmarks of
cancer. Consequently,
glucose antimetabolites, such as 2-deoxy-glucose (2DG), can induce substantial growth inhibition of
cancer cells. However, the inhibition of metabolic pathways is not the sole effect of 2DG on
cancer cells. As
mannose-mimetic molecule, 2DG is believed to interfere with normal glycosylation of
proteins in cells. Here, we address how 2DG influences protein glycosylation in
cancer cells and discuss possible implications of the consequences of this influence. In detail, six
colorectal cancer cell lines were examined for alterations of protein glycosylation by measuring
monosaccharide incorporation into cellular
glycoproteins and cell surface glycosylation by
lectin FACS. A significant increase in
mannose incorporation was observed on treatment with 2DG (1 mM for 48 h), which was also reflected by an increased binding of the
mannose-binding lectin Concanavalin A in FACS analysis. This phenomenon, which could be reversed by external addition of
mannose, was not caused by 2DG-mediated
mannosidase inhibition, as shown by pulse-chase experiments, arguing in favor of the hypothesis that 2DG directly influenced the incorporation of
mannose. Increased
mannose content was generally observed in cellular
glycoproteins, including
glycoproteins isolated from the plasma membrane fraction. Our results indicate that 2DG at low doses, which have only a limited metabolism-related effect on glycosylation, induces a strong increase in
mannose incorporation into cellular
glycoproteins. On the other hand, higher 2DG concentrations (10 and 20 mM) led to a significant decrease of absolute
mannose incorporation accompanied by a dramatically reduced
protein synthesis rate. 2DG-induced alterations of glycosylation may represent a novel mechanism potentially explaining the varied effects of 2DG on
cancer cells. Moreover, 2DG treatment may open a path toward novel diagnostic and
cancer therapeutic approaches, which specifically target altered glycoantigen structures induced by 2DG.