Casabiell X, Zugaza J L, Pombo C M, Pandiella A, Casanueva F F
Department of Medicine, Faculty of Medicine, Santiago de Compostela University, Spain.
Exp Cell Res. 1993 Apr;205(2):365-73. doi: 10.1006/excr.1993.1099.
In EGFR-T17 cells, which express high levels of the epidermal growth factor (EGF) receptor, addition of a saturating dose of EGF (10 nM) leads to an increase in Ins(1,4,5)P3/diacylglycerol and also to cytosolic calcium [Ca2+]i due to both intracellular redistribution and influx from extracellular medium. Pretreatment of cells with cis-unsaturated nonesterified fatty acids such as oleic acid (1 to 100 microM) inhibited EGF-stimulated Ins(1,4,5)P3 generation and Ca2+ release from intracellular stores. Furthermore, such a treatment completely suppress Ca2+ influx in a dose-dependent manner. At doses capable of suppressing such early signals, oleic acid did not alter the process of EGF-mediated internalization of the EGF/EGF-receptor complex, suggesting that [Ca2+]i rise did not mediate receptor internalization. EGF-induced cell proliferation assessed by either thymidine incorporation into DNA, direct cell counting, and microscopic observation was not altered by oleic acid, at doses able to block EGF-mediated early signals. In conclusion, suppression of Ins(1,4,5)P3 generation and [Ca2+]i rises by oleic acid did not alter EGF-receptor internalization nor EGF-induced cell mitosis. Such results suggest that [Ca2+]i rise is not instrumental for EGF-stimulated cell proliferation.
在高表达表皮生长因子（EGF）受体的EGFR-T17细胞中，加入饱和剂量的EGF（10 nM）会导致肌醇-1,4,5-三磷酸（Ins(1,4,5)P3）/二酰基甘油增加，并且由于细胞内重新分布以及从细胞外介质流入，胞质钙[Ca2+]i也会增加。用顺式不饱和非酯化脂肪酸如油酸（1至100 microM）预处理细胞可抑制EGF刺激的Ins(1,4,5)P3生成以及细胞内储存库的Ca2+释放。此外，这种处理以剂量依赖的方式完全抑制Ca2+内流。在能够抑制此类早期信号的剂量下，油酸不会改变EGF介导的EGF/EGF受体复合物内化过程，这表明[Ca2+]i升高并未介导受体内化。通过胸苷掺入DNA、直接细胞计数和显微镜观察评估的EGF诱导的细胞增殖，在能够阻断EGF介导的早期信号的剂量下，不受油酸影响。总之，油酸对Ins(1,4,5)P3生成和[Ca2+]i升高的抑制并未改变EGF受体的内化，也未改变EGF诱导的细胞有丝分裂。这些结果表明，[Ca2+]i升高对EGF刺激的细胞增殖不起作用。
