Antiangiogenic activity of 2-deoxy-D-glucose

Background

During tumor angiogenesis, endothelial cells (ECs) are engaged in a number of energy consuming biological processes, such as proliferation, migration, and capillary formation. Since glucose uptake and metabolism are increased to meet this energy need, the effects of the glycolytic inhibitor 2-deoxy-D-glucose (2-DG) on in vitro and in vivo angiogenesis were investigated.

Methodology/Principal Findings

In cell culture, 2-DG inhibited EC growth, induced cytotoxicity, blocked migration, and inhibited actively forming but not established endothelial capillaries. Surprisingly, 2-DG was a better inhibitor of these EC properties than two more efficacious glycolytic inhibitors, 2-fluorodeoxy-D-glucose and oxamate. As an alternative to a glycolytic inhibitory mechanism, we considered 2-DG''s ability to interfere with endothelial N-linked glycosylation. 2-DG''s effects were reversed by mannose, an N-linked glycosylation precursor, and at relevant concentrations 2-DG also inhibited synthesis of the lipid linked oligosaccharide (LLO) N-glycosylation donor in a mannose-reversible manner. Inhibition of LLO synthesis activated the unfolded protein response (UPR), which resulted in induction of GADD153/CHOP and EC apoptosis (TUNEL assay). Thus, 2-DG''s effects on ECs appeared primarily due to inhibition of LLOs synthesis, not glycolysis. 2-DG was then evaluated in two mouse models, inhibiting angiogenesis in both the matrigel plug assay and the LH_BETAT_AG transgenic retinoblastoma model.

Conclusions/Significance

In conclusion, 2-DG inhibits endothelial cell angiogenesis in vitro and in vivo, at concentrations below those affecting tumor cells directly, most likely by interfering with N-linked glycosylation rather than glycolysis. Our data underscore the importance of glucose metabolism on neovascularization, and demonstrate a novel approach for anti-angiogenic strategies.     

N-Alkyl derivatives of 2-amino-2-deoxy-D-glucose

Mono- and di-N-alkylated derivatives of 1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-beta-D-glucose (alkyl=methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl) were synthesised by the reductive alkylation of per-O-acetyl-d-glucosamine. (N-ethyl, N-propyl, N-butyl, N-pentyl and N-hexyl)-1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-beta-D-glucoses were deacetylated in order to attempt an enzymatic phosphorylation. All products were characterised by means of IR, NMR and MS spectra. N-Ethyl- and N-pentyl-d-glucosamines were found to exhibit weak antifungal activity.     

Antimorphogenic effects of 2-deoxy-D-glucose in Candida albicans

Abstract 2-Deoxy- d -glucose (dGlc) is able to inhibit both N -acetyl-hexosamine-induced chlamydosporogenesis and N -acetyl-glucosamine- or proline-induced germ-tube formation in Candida albicans . This inhibition is exerted also at dGlc concentrations which do not affect growth in the yeast form and do not reduce either the uptake or the incorporation of N-acetyl- d -glucosamine (GlcNAc) into yeast or hyphal cell material. Inhibition of germtube formation by dGlc does not occur in serum and is fully reversed by glucose. It is suggested that dGlc acts as a potent antimorphogenic effector in C. albicans .     

High-affinity transport and phosphorylation of 2-deoxy-D-glucose in synaptosomes

2-Deoxy-d -glucose (2 DG) entered synaptosomes (from rat brain) by a high-affinity, Na⁺-independent glucose transport system with a K_m, of 0.24 mM. 3-O-methyl-glucose, D-glucose, and phloretin were competitive inhibitors of 2-DG transport with K_i's of 7 mM, 64 μM, and 0·75 μM, respectively. Insulin was without effect. 2-DG uptake was also saturable at high substrate concentrations with an apparent low affinity K_m, of 75 mM, where the K_l, for glucose was 17.5 mM. We are not certain whether the rate-limiting step for the low-affinity uptake system is attributable to transport or phosphorylation. However, the high-affinity glucose transport system probably is a special property of neuronal cell membranes and could be useful in helping to distinguish separated neurons from glial cells.     

Effect of 2-deoxy-D-glucose on hypothalamic-pituitary-thyroid axis in rats

The intraperitoneal administration to rats of 500 mg/kg body weight of 2-deoxy-D-glucose, an analog of glucose which produces intracellular glucopenia with rise in extracellular fluid glucose concentration, is followed by a significant though transient reduction of hypothalamic TRH content, observed at 15 and 25 minutes after drug administration. A subsequent increase in serum thyrotropin followed by that of triiodothyronine concentration was also observed. These findings indicate that the neuroglucopenia induced by 2-deoxy-D-glucose may play a role in the regulating the hypothalamic-pituitary-thyroid axis.     

Transport and metabolism of 2-deoxy-D-glucose by Rhodotorula glutinis

2-Deoxy-D-glucose transport by Rhodotorula glutinis is an active process. The intracellular concentration of free deoxyglucose after 15 min incubation of Rhodotorula cells with this sugar was 230 times the extracellular concentration. Although cell extracts at this time contained more 2-deoxy-D-glucose 6-phosphate than deoxyglucose, pulse-labelling experiments demonstrated that deoxyglucose is transported as the free sugar and subsequently phosphorylated. After transport, Rhodotorula cells metabolize deoxyglucose. The major metabolites during 30-90 min incubations were determined to be 2-deoxy-D-glucose 6-phosphate, 2-deoxy-D-glucitol, 2-deoxy-D-gluconate and 2,2'-dideoxy-alpha, alpha'-trehalose. Rhodotorula glutinis also degrades deoxyglucose to CO2. The concentrations of intermediates in this pathway were too low to detect and resolve in extracts of control cells. In 2,4-dinitrophenol-poisoned cells, however, it appears that deoxyglucose degradation is restricted largely to loss of C-1 as CO2 and it was possible to identify 1-deoxy-D-ribulose 5-phosphate as an intermediate presumably arising from metabolism of deoxyglucose by the oxidative portion of the hexose monophosphate pathway.