Research ArticleMetabolism

The induction of HAD-like phosphatases by multiple signaling pathways confers resistance to the metabolic inhibitor 2-deoxyglucose

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Science Signaling  03 Sep 2019:
Vol. 12, Issue 597, eaaw8000
DOI: 10.1126/scisignal.aaw8000

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Resisting a metabolic poison

Once imported into cells and phosphorylated, the glucose analog 2-deoxyglucose (2DG) inhibits glycolysis, leading to the proposal of using 2DG as a cancer treatment. Using yeast as a model, Defenouillère et al. investigated how cells become resistant to 2DG. Exposure to 2DG activated several signaling pathways that resulted in the increased expression of the gene encoding the phosphatase Dog2. In contrast, glucose availability transcriptionally repressed DOG2 expression. When overexpressed, a human homolog of Dog2 conferred 2DG resistance to human cells, suggesting that cancer cells with increased abundance of this phosphatase could escape the toxic effects of 2DG.

Abstract

Anti-cancer strategies that target the glycolytic metabolism of tumors have been proposed. The glucose analog 2-deoxyglucose (2DG) is imported into cells and, after phosphorylation, becomes 2DG-6-phosphate, a toxic by-product that inhibits glycolysis. Using yeast as a model, we performed an unbiased mass spectrometry–based approach to probe the cellular effects of 2DG on the proteome and study resistance mechanisms to 2DG. We found that two phosphatases that target 2DG-6-phosphate were induced upon exposure to 2DG and participated in 2DG detoxification. Dog1 and Dog2 are HAD (haloacid dehalogenase)–like phosphatases, which are evolutionarily conserved. 2DG induced Dog2 by activating several signaling pathways, such as the stress response pathway mediated by the p38 MAPK ortholog Hog1, the unfolded protein response (UPR) triggered by 2DG-induced ER stress, and the cell wall integrity (CWI) pathway mediated by the MAPK Slt2. Loss of the UPR or CWI pathways led to 2DG hypersensitivity. In contrast, mutants impaired in the glucose-mediated repression of genes were 2DG resistant because glucose availability transcriptionally repressed DOG2 by inhibiting signaling mediated by the AMPK ortholog Snf1. The characterization and genome resequencing of spontaneous 2DG-resistant mutants revealed that DOG2 overexpression was a common strategy underlying 2DG resistance. The human Dog2 homolog HDHD1 displayed phosphatase activity toward 2DG-6-phosphate in vitro and its overexpression conferred 2DG resistance in HeLa cells, suggesting that this 2DG phosphatase could interfere with 2DG-based chemotherapies. These results show that HAD-like phosphatases are evolutionarily conserved regulators of 2DG resistance.

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