Rodríguez-Enríquez S, Juárez O, Rodríguez-Zavala J S, Moreno-Sánchez R
Departamento de Bioquímica, Instituto Nacional de Cardiología, México.
Eur J Biochem. 2001 Apr;268(8):2512-9. doi: 10.1046/j.1432-1327.2001.02140.x.
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.
AS-30D肝癌细胞是一种高度氧化且生长迅速的肿瘤细胞系，分别显示出葡萄糖诱导和果糖诱导的氧化磷酸化抑制（即克氏效应），抑制率分别为54%和34%。为了深入了解这一过程的潜在机制，测定了5 mM葡萄糖或10 mM果糖对几种代谢物细胞内浓度的影响。添加葡萄糖或果糖会降低细胞内无机磷酸盐（40%）和三磷酸腺苷（53%）的浓度，并降低细胞质pH值（从7.2降至6.8）。葡萄糖和果糖会增加一磷酸腺苷（30%）、6-磷酸葡萄糖、6-磷酸果糖和1,6-二磷酸果糖的含量（分别增加15倍、13倍和50倍）。细胞质中钙离子和镁离子的浓度未发生改变。添加半乳糖或甘油不会改变代谢物的浓度。从AS-30D细胞中分离出的线粒体，在pH值为6.8、无机磷酸盐含量低（0.6 mM）的培养基中孵育时，氧化磷酸化受到40%的抑制。数据表明，克氏效应是添加外源葡萄糖或果糖所引发的若干微小代谢变化的结果。
