Fructose 2,6-bisphosphate metabolism in Ehrlich ascites tumour cells

Abstract

Cancer cell energy metabolism is characterized by a high glycolytic rate, which is maintained under aerobic conditions. In Ehrlich ascites tumour cells, the concentration of fructose 2,6-bisphosphate (Fru-2,6-P2), the powerful activator of 6-phosphofructo-1-kinase, is tenfold increased. The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2), synthesizing and degrading Fru-2,6-P2, was characterized. The molecular mass is 120 kDa. The dependence of PFK-2 activity on the substrate concentrations is hyperbolic (Km for Fru-6-P = 0.09 mM; Km for ATP = 0.7 mM), while the dependence of the FBPase-2 activity on the concentrations of Fru-2,6-P2 is sigmoidal (K0.5 for Fru-2,6-P2 = 4 microM). The PFK-2/FBPase-2 activity ratio is 1. PFK-2 activity is inhibited by citrate (I0.5 = 0.17 mM) and phosphoenolpyruvate (I0.5 = 0.08 mM) but only weakly by glycerol 3-phosphate (I0.5 = 1.57 mM). In contrast to the liver enzyme, the activity of tumour PFK-2/FBPase-2 is not influenced by the action of cAMP-dependent protein kinase. The kinetic properties as well as ion-exchange chromatography pattern differ from their normal counterparts in liver and muscle. The properties are likely to contribute to the maintenance of the high glycolytic rate in these tumour cells.

Signal Transduction Dynamics of the Protein Kinase-A/Phosphofructokinase-2 System in Saccharomyces cerevisiae

“…It is commonly known that tumor cells characteristically maintain high glycolytic fluxes even in the presence of oxygen, a phenomenon known as Warburg effect (Warburg, 1930;Dills, 1993). Multiple established cancer cell lines (i.e., Ehrlich ascites tumor cells, HeLa cells, HT29 colon adenocarcinoma cells, and Lewis lung carcinoma cells) display markedly high levels of F-2,6-BP, if compared with normal tissue cells (Nissler et al, 1995;Mojena et al, 1985;Denis et al, 1986;Miralpeix et al, 1990;Chesney et al, 1999). Transformation of chick-embryo fibroblasts by retroviruses carrying either the v-src or v-tps oncogenes has been observed to induce F-2,6-BP synthesis and to cause increased glycolytic flux and cell proliferation (Bosca et al, 1986;Chesney et al, 1999).…”

An inducible gene product for 6-phosphofructo-2-kinase with an AU-rich instability element: Role in tumor cell glycolysis and the Warburg effect

“…F2,6BP has been identified to be present in elevated amounts in many cancer cell lines (6,8,9,11). F2,6BP is considered to be the most potent stimulator of glycolysis and acts by allosteric activation of PFK-1, which phosphorylates F6P to produce F1,6BP (3,4).…”

“…Multiple established cancer cell lines (i.e., Ehrlich ascites tumor cells, HeLa cells, HT29 colon adenocarcinoma cells, and Lewis lung carcinoma cells) have markedly elevated levels of F2,6BP when compared with normal tissue cells (6)(7)(8)(9). Transformation of chick-embryo fibroblasts by retroviruses carrying either the v-src or v-fps oncogenes has been observed to induce F2,6BP synthesis and to cause increased glycolytic flux and cell proliferation (10).…”

Balancing glycolytic flux: the role of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatases in cancer metabolism

“…Several studies have demonstrated that some cancer cell lines produce markedly elevated levels of Fru-2,6-P 2 when compared to non-malignant cells [45-47]. One of the important functions of enhanced glucose uptake and glycolysis in cancer cells is to generate metabolic intermediates that are important for cell growth and survival (Figure 4).…”