Publications

1992

1. Tamoxifen induced changes in MCF7 human breast cancer: In vitro and in vivo studies using nuclear magnetic resonance spectroscopy and imaging

   FURMAN E., RUSHKIN E., Margalit R., Bendel P. & Degani H. (1992) Journal of Steroid Biochemistry and Molecular Biology. 43, 1-3, p. 189-195  Abstract

   The effects of 17β-estradiol versus tamoxifen on the growth and metabolism of MCF7 human breast cancer cells, in culture and in tumors implanted in nude mice, were studied by ³¹P and ¹³C nuclear magnetic resonance spectroscopy and by proton magnetic resonance imaging. In culture, the content of the phosphate metabolites including nucleoside triphosphates (NTP), phosphomonoesters, phosphodiesters and inorganic phosphate (Pi) were not affected by tamoxifen treatment. However, in the presence of estrogen the rate of glucose consumption and lactate production via glycolysis (270 and 280 fmol/cell · h, respectively) were twice that of tamoxifen treated cells. Estrogen rescue of tamoxifen treated cells indicated that glycolysis induction occurs at the early stages of the hormonal response. The in vivo studies included recording of proton images that provided an accurate measure of tumor size and distribution of tumor cells, necrotic regions and stromal tissue. Tamoxifen caused enhanced necrosis extending from the center of the tumor during the first two days of treatment (12 h to 6 days). This was followed by growth of reparative tissue along with tumor regression. Tamoxifen also modified the content of the phosphate metabolites, increasing markedly (P

2. The application of ¹³C NMR to the characterization of phospholipid metabolism in cells

   RONEN S. & Degani H. (1992) Magnetic Resonance in Medicine. 25, 2, p. 384-389  Abstract

   ³¹P and ³¹C NMR spectroscopy of lipid extracts of T47D human breast cancer spheroids and the use of ¹³Clabeled lipid precursors [3¹³C ] serine, [1,2¹³C] ethanolamine, and [1,2¹³C]choline enabled us to determine the rate of ¹³C incorporation into the major phospholipids and to show that the synthesis of phosphatidylethanolarnine in T47D cells is via both the CDPethanolamine pathway and serine decarboxylation, with the extent of each depending on the concentration of ethanolamine in the medium. In the presence of low ethanolamine (3.4 μ M), both pathways contribute in equal proportions, while in the presence of high ethanolamine, the CDPethanolamine pathway predominates. © 1992 Academic Press, Inc.
3. Gene dosage and down's syndrome: Metabolic and enzymatic changes in PC12 cells overexpressing transfected human liver-type phosphofructokinase

   Elson A., Bernstein Y., Degani H., Levanon D., Ben-Hur H. & Groner Y. (1992) Somatic Cell and Molecular Genetics. 18, 2, p. 143-161  Abstract

   Down's syndrome (DS) is a human genetic disease caused by triplication of the distal third of chromosome 21 and overexpression of an unknown number of genes residing in it. The gene for the liver-type subunit of phosphofructokinase (PFKL), a key glycolytic enzyme, maps to this region and the product is overproduced in DS erythrocytes and fibroblasts. These facts, together with abnormalities which occur in DS glycolysis, make PFKL overexpression a candidate for causing some aspects of the DS phenotype. A cellular model for examining the consequences of PFKL overexpression in DS was constructed by transfecting rat PC12 cells with the human PFKL cDNA. Phosphofructokinase (PFK) isolated from PFKL-overexpressing clones was more inhibited by ATP and citrate and less activated by fructose-6-phosphate than control PFK; similar results were obtained when PFK preparations from DS and control fibroblasts were compared. In vivo NMR measurements determined that cells overexpressing PFKL performed glycolysis 40% faster than controls. These results show that overexpression of PFKL is the cause for altered biochemical regulatory characteristics of PFK in DS fibroblasts and can result in enhancement of glycolysis rates. It is also shown that increased gene dosage can exert its influence not merely by enhancing the amounts of gene products but also by altering their biochemical nature.
4. Lipid metabolism in large T47D human breast cancer spheroids: ³¹P- and ¹³C-NMR studies of choline and ethanolamine uptake

   RONEN S., RUSHKIN E. & Degani H. (1992) Biochimica et Biophysica Acta - Molecular Basis of Disease. 1138, 3, p. 203-212  Abstract

   ³¹P- and ¹³C-NMR were used to determine the kinetics of choline and ethanolamine incorporation in T47D clone 11 human breast cancer cells grown as large (300 μm) spheroids. Spheroids were perfused inside the spectrometer with 1,2-¹³C-labelled choline or ethanolamine (0.028 mM) and the buildup of labeled phosphorylcholine (PC) or phosphorylethanolamine (PE) was monitored. To analyze the NMR kinetic data, it was assumed that each signal represents a weighted average of signal from the proliferating and non-proliferating compartments of the large spheroid. The average ATP pool size was 4±1 fmol/cell compared to 8±1 fmol/cell in small (150 μm) proliferating spheroids (P -1) was not significantly altered, but the rate of the enzyme was reduced from 1.3 to 0.2-0.5 fmol/(cell h). The pool size of PE in medium containing serum ethanolamine (1.7 μM) was approximately the same (15 fmol/cell) in small and large spheroids. In the presence of high ethanolamine (0.028 mM) the average PE level decreased slightly (11 fmol/cell) and the rate of the enzyme ethanolamine kinase in the non-proliferating fraction was 0.7 fmol/(cell h) versus 1.0 fmol/(cell h) in the proliferating cells (P -) was not significantly altered but the corresponding reaction rate was reduced from 1.4 to 0.2-0.8 fmol/(cell h). The kinetics of choline incorporation did not alter in the presence of 0.028 mM ethanolamine.
5. Foreword by the Guest Editors

   Degani H. & Goldfarb D. (1992) Israel Journal of Chemistry. 32, 2-3, p. I-I  Abstract
6. Correlation of MR imaging and histologic findings in mouse melanoma

   DEJORDY J., Bendel P., HOROWITZ A., Salomon Y. & Degani H. (1992) Jmri-Journal Of Magnetic Resonance Imaging. 2, 6, p. 695-700  Abstract

   M2R melanoma tumors in male C57 black mice were used to correlate magnetic resonance (MR) images with the corresponding histologic slices and to determine if analysis of the achievable correlation can provide a basis for predicting gross histologic features with MR imaging alone. The MR imaging sections obtained at 4.7 T were each 680 μm thick, with an inplane resolution of 195 μm. The distribution of melanin within the histologic slices correlated well with the highsignalintensity regions on the T1weighted images (T1W1s), while these regions had low signal intensity on the T2weighted images (T2WIs), providing evidence that melanin or melaninassociated paramagnetic species are responsible for the observed proton relaxation rate enhancement. Viable melanoma cells typically showed intermediate signal intensity on T2WIs, T1WIs, and protondensity images. Necrosis typically had high signal intensity on T2WIs, T1WIs, and protondensity images. Quantitation of the MR imaging results, followed by statistical analysis, demonstrated statistically significant differences between melaninrich, viablemelanoma, and necrotic regions on MR images.