Multisite control of the Crabtree effect in ascites hepatoma cells.
AS-30D hepatoma cells, a highly oxidative and fast-growing tumor line, showed glucose-induced and fructose-induced inhibition of oxidative phosphorylation (the Crabtree effect) of 54% and 34%, respectively. To advance the understanding of the underlying mechanism of this process, the effect of 5 mM glucose or 10 mM fructose on the intracellular concentration of several metabolites was determined. The addition of glucose or fructose lowered intracellular Pi (40%), and ATP (53%) concentrations, and decreased cytosolic pH (from 7.2 to 6.8). Glucose and fructose increased the content of AMP (30%), glucose 6-phosphate, fructose 6-phosphate and fructose 1,6-bisphosphate (15, 13 and 50 times, respectively). The cytosolic concentrations of Ca2+ and Mg2+ were not modified. The addition of galactose or glycerol did not modify the concentrations of the metabolites. Mitochondria isolated from AS-30D cells, incubated in media with low Pi (0.6 mM) at pH 6.8, exhibited a 40% inhibition of oxidative phosphorylation. The data suggest that the Crabtree effect is the result of several small metabolic changes promoted by addition of exogenous glucose or fructose.
Rodríguez-Enríquez
S
S
Departamento de Bioquímica, Instituto Nacional de Cardiología, México. saren96@hotmail.com
Juárez
O
O
Rodríguez-Zavala
J S
JS
Moreno-Sánchez
R
R
D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001201:Ascites / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D005632:Fructose / Q000494:pharmacology; D005635:Fructosediphosphates / Q000378:metabolism; D005636:Fructosephosphates / Q000378:metabolism; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D019298:Glucose-6-Phosphate / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008113:Liver Neoplasms / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014407:Tumor Cells, Cultured
D005635:Fructosediphosphates; D005636:Fructosephosphates; D006601:Hexoses; D005632:Fructose; D000249:Adenosine Monophosphate; D019298:Glucose-6-Phosphate; C027618:fructose-6-phosphate; D000255:Adenosine Triphosphate; D008274:Magnesium; D005947:Glucose; C029063:fructose-1,6-diphosphate; D010100:Oxygen; D002118:Calcium