Metabolic studies of estrogen- and tamoxifen-treated human breast cancer cells by nuclear magnetic resonance spectroscopy

Abstract

The effects of 17 beta-estradiol treatment versus tamoxifen on the metabolism of human breast cancer T47D-clone 11 cells were studied by noninvasive 31P and 13C nuclear magnetic resonance techniques. 31P nuclear magnetic resonance spectra revealed differences between estrogen and tamoxifen treated cells. The steady state content of phosphorylcholine and of the nucleoside diphosphates was higher in the tamoxifen treated cells by 33 and 140%, respectively, relative to estrogen treated cells. The intracellular pH of 7.2 and the content of the nucleoside triphosphates, Pi, phosphocreatine, glycerolphosphorylcholine, and glycerolphosphorylethanolamine and uridine diphosphoglucose remained the same in both treatments. Glucose utilization and subsequent lactate, glutamate, alanine, and glycerol 3-phosphate synthesis were monitored on line following administration of specifically labeled [13C]glucose. In estrogen treated cells the rate of lactate production via glycolysis was 560 fmol/cell/h and the initial rate of 13C labeling of the glutamate pool via the Krebs cycle was 6.8 fmol/cell/h. In the tamoxifen treated cells these rates were 2-fold lower, at 250 and 2.9 fmol/cell/h for lactate and glutamate labeling, respectively. In estrogen treated cells, the calculated content of glutamate (19 fmol/cell), alanine (11 fmol/cell), and glycerol 3-phosphate (8 fmol/cell) was higher than in tamoxifen treated cells, where only glutamate labeling was detected (13 fmol/cell). The observed differences in the in vivo kinetics of glucose metabolism may provide a sensitive measure for detecting the response of human breast cancer cells to estrogen versus tamoxifen treatments.