cThe glucose analog 2-deoxyglucose (2DG) inhibits the growth of Saccharomyces cerevisiae and human tumor cells, but its modes of action have not been fully elucidated. Yeast cells lacking Snf1 (AMP-activated protein kinase) are hypersensitive to 2DG. Overexpression of either of two low-affinity, high-capacity glucose transporters, Hxt1 and Hxt3, suppresses the 2DG hypersensitivity of snf1⌬ cells. The addition of 2DG or the loss of Snf1 reduces HXT1 and HXT3 expression levels and stimulates transporter endocytosis and degradation in the vacuole. 2DG-stimulated trafficking of Hxt1 and Hxt3 requires Rod1/Art4 and Rog3/ Art7, two members of the ␣-arrestin trafficking adaptor family. Mutations in ROD1 and ROG3 that block binding to the ubiquitin ligase Rsp5 eliminate Rod1-and Rog3-mediated trafficking of Hxt1 and Hxt3. Genetic analysis suggests that Snf1 negatively regulates both Rod1 and Rog3, but via different mechanisms. Snf1 activated by 2DG phosphorylates Rod1 but fails to phosphorylate other known targets, such as the transcriptional repressor Mig1. We propose a novel mechanism for 2DG-induced toxicity whereby 2DG stimulates the modification of ␣-arrestins, which promote glucose transporter internalization and degradation, causing glucose starvation even when cells are in a glucose-rich environment.C ells sense and respond to changes in the nutrient supply to ensure optimal cell growth and survival. To achieve this adaptation, cell-signaling cues dictate compensatory alterations in the transcriptome and proteome (1-5). The addition of the glucose analog 2-deoxyglucose (2DG) to cells causes a glucose starvation-like response, inhibiting growth and reducing viability even in the presence of abundant glucose (6, 7). 2DG is taken up and converted to 2-deoxyglucose-6-phosphate (2DG-6P) (8, 9); however, the absence of a hydroxyl group on C-2 prevents the further catabolism of 2DG-6P by phosphoglucose isomerase. Accumulation of 2DG-6P may result in product inhibition of hexokinase, thereby inhibiting glycolysis (10). In Saccharomyces cerevisiae, 2DG reportedly inhibits the biosynthesis of both cell wall polysaccharide and glycoprotein, causing cells to become osmotically fragile (11,12). Whether these are the only means by which 2DG short-circuits normal glucose utilization remains unclear.Addressing this question is of significant clinical importance, because 2DG is a potent inhibitor of cancer cell proliferation. 2DG impedes cancer progression in animal models and continues to be assessed as an anticancer therapeutic (13-16). 2DG selectively inhibits cancerous cells as a result of a key metabolic shift that distinguishes many malignant cells from the surrounding normal tissues. Many tumor cells shunt glucose through the glycolytic pathway and use lactic acid fermentation to generate ATP, a phenomenon first recognized by Otto Warburg (17,18). In spite of the widespread use of 2DG, the mechanism by which it inhibits cell growth remains controversial; it has been reported to generate a dead-end metabolite in 2DG-6P tha...

Aerobic glycolysis is a metabolic pathway utilized by human cancer cells and also by yeast cells when they ferment glucose to ethanol. Both cancer cells and yeast cells are inhibited by the presence of low concentrations of 2-deoxyglucose (2DG). Genetic screens in yeast used resistance to 2-deoxyglucose to identify a small set of genes that function in regulating glucose metabolism. A recent high throughput screen for 2-deoxyglucose resistance identified a much larger set of seemingly unrelated genes. Here, we demonstrate that these newly identified genes do not in fact confer significant resistance to 2-deoxyglucose. Further, we show that the relative toxicity of 2-deoxyglucose is carbon source dependent, as is the resistance conferred by gene deletions. Snf1 kinase, the AMPactivated protein kinase of yeast, is required for 2-deoxyglucose resistance in cells growing on glucose. Mutations in the SNF1 gene that reduce kinase activity render cells hypersensitive to 2-deoxyglucose, while an activating mutation in SNF1 confers 2-deoxyglucose resistance. Snf1 kinase activated by 2-deoxyglucose does not phosphorylate the Mig1 protein, a known Snf1 substrate during glucose limitation. Thus, different stimuli elicit distinct responses from the Snf1 kinase.

No abstract