Targeting the Glycolytic Enzyme PGK1 to Inhibit the Warburg Effect: A New Strategy for Keloid Therapy.

BACKGROUND: Aerobic glycolysis (the Warburg effect) may play an important role in keloid pathogenesis, which may be aggravated by the hypoxic microenvironment in keloids. Phosphoglycerate kinase 1 (PGK1), a key glycolytic enzyme, is essential for cellular aerobic glycolysis, but its role in keloid formation remains unknown. This study aimed to detect PGK1 expression in keloid tissue and investigate the effects of inhibiting PGK1 expression on keloid fibroblasts (KFbs) under hypoxia and normoxia. METHODS: Normal skin and keloid samples were separated into two parts, one was used for immunohistochemistry, and one for primary cell culture. PGK1 tissue expression was detected by immunohistochemistry. Reverse-transcriptase polymerase chain reaction and Western blotting were used to detect PGK1, GLUT1, LDHA, and COL1 expression, and glucose uptake and lactate production were detected with a microplate reader. Cell proliferation and apoptosis were investigated with IncuCyte and flow cytometry. Cell migration and invasion were detected with Transwell assays. Glycolytic function was explored with the Seahorse XF96 system. RESULTS: Immunohistochemistry showed PGK1 overexpression in keloid tissue compared with normal skin tissue ( P < 0.05). Consistently, PGK1 expression was significantly higher in KFbs than in normal skin fibroblasts (NFbs), and hypoxia stimulated PGK1 expression in KFbs and NFbs ( P < 0.05). PGK1 knockdown significantly inhibited KFb glycolysis, proliferation, migration, invasion, glucose consumption, and lactate production ( P < 0.05). Furthermore, GLUT1, LDHA, and COL1 expression was decreased in KFbs compared with NFbs ( P < 0.05). In addition, suppressing PGK1 may mediate the PI3K/AKT pathway to down-regulate GLUT1, LDHA, and COL1 expression ( P < 0.05). CONCLUSIONS: These findings provide new evidence that suppressing PGK1, inhibiting glycolysis, reduces KFb proliferation, migration, invasion, and type I collagen expression. Targeting PGK1 to inhibit the Warburg effect may be a new therapeutic strategy for keloids. CLINICAL RELEVANCE STATEMENT: This article may provide new suggestions into the pathogenesis and treatment of keloids. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Excretory/secretory products of Fasciola hepatica but not recombinant phosphoglycerate kinase induce death of human hepatocyte cells.

The liver fluke Fasciola hepatica infects a wide range of hosts, and has a considerable impact on the agriculture industry, mainly through infections of sheep and cattle. Further, human infection is now considered of public health importance and is hyperendemic in some regions. The fluke infection causes considerable damage to the hosts' liver. However, the mechanisms of liver destruction have not yet been completely elucidated. In the present report we incubated a human liver cell line in the presence of either F. hepatica excretory/secretory material (FhES) or recombinant phosphoglycerate kinase (FhPGK). Dosedependent cytotoxicity in the presence of FhES was observed, indicating that FhES is capable of killing human hepatocytes, supporting a role for FhES in damaging host liver cells during infection; while treatment with a recombinant intracellular protein - FhPGK, had no impact on cell survival.

Induction of tumor stem cell differentiation--novel strategy to overcome therapy resistance in gastric cancer.

PURPOSE: Metastases are a frequent finding in gastric cancer and are associated with poor prognosis. A recently discovered link between metabolic changes, differentiation, and therapy resistance due to tumor stem cells could depict a novel approach in cancer research and therapy. Phosphoglycerate kinase 1 (PGK1) is a metabolic enzyme and is known to be involved in enabling gastric cancer cells to be invasive and to disseminate. In this study, we investigated if PGK1 is a promising candidate in inducing stem cell differentiation in gastric cancer. MATERIALS AND METHODS: MKN45 gastric cancer cells were used due to their known cancer stem cell population, which is defined by the surface marker CD44. MKN45 cells were separated between CD44+ and CD44- cells and, in equal parts, incubated with shRNA anti-PGK1 using fluorescence-activated cell sorting (FACS) analysis; they were then injected into nude mice to evaluate their tumor growth behavior in vivo. Further, the invasive potential of gastric cancer cells was evaluated in vitro using the xCelligence analyzing system. RESULTS: CD44+ gastric cancer cells treated with and without shRNA anti-PGK1 were capable to cause tumor growth in vivo, whereas tumor growth in CD44+ cells treated with shRNA anti-PGK1 was considerably smaller in comparison with that in CD44+ cells without treatment. CD44- cells did not show any noticeable tumor growth in vivo. By targeting PGK1, the invasive potential of gastric cancer cells was impressively reduced in vitro. In all our cells, which were targeted with shRNA anti-PGK1, we did not find any change that is in accordance with the phenotype of the cells using FACS analysis. CONCLUSIONS: Our findings suggest that targeting the key metabolic enzyme PGK1 in gastric cancer cells may open a new chapter in cancer treatment, which is well worth for further exploration in combination with recent chemotherapy, and might be a promising possibility to overcome therapy resistance in gastric cancer.

Control of glycolysis in cerebral cortex slices.

1. Intracellular concentrations of intermediates and cofactors of glycolysis were measured in guinea-pig cerebral cortex slices incubated under varying conditions. 2. Comparison of mass-action ratios with apparent equilibrium constants for the reactions of glycolysis showed that hexokinase, phosphofructokinase and pyruvate kinase catalyse reactions generally far from equilibrium, whereas phosphoglucose isomerase, aldolase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, adenlyate kinase and creatine phosphokinase are generally close to equilibrium. The possibility that glyceraldehyde 3-phosphate dehydrogenase may catalyse a ;non-equilibrium' reaction is discussed. 3. Correlation of changes in concentrations of substrates for enzymes catalysing ;non-equilibrium' reactions with changes in rates of glycolysis caused by alteration of the conditions of incubation showed that hexokinase, phosphofructokinase, pyruvate kinase and possibly glyceraldehyde 3-phosphate dehydrogenase are subject to metabolic control in cerebral cortex slices. 4. It is suggested that the glycolysis is controlled by two regulatory systems, the hexokinase-phosphofructokinase system and the glyceraldehyde 3-phosphate dehydrogenase-pyruvate kinase system. These are discussed. 5. It is concluded that the rate of glycolysis in guinea-pig cerebral cortex slices is limited either by the rate of glucose entry into the slices or by the hexokinase-phosphofructokinase system. 6. It is concluded that addition of 0.1mm-ouabain to guinea-pig cerebral cortex slices causes inhibition of either glyceraldehyde 3-phosphate dehydrogenase or phosphoglycerate kinase or both, in a manner independent of the known action of ouabain on the sodium- and potassium-activated adenosine triphosphatase.