Cell and membrane lipid analysis by proton magnetic resonance spectroscopy in five breast cancer cell lines.

The lipid composition of five human breast cancer cell lines (MCF-7, T47D, ZR-75-1, SKBR3 and MDA-MB231) was assessed by proton magnetic resonance spectroscopy (MRS) in whole cells and membrane-enriched fractions. The proportions of the three main lipid resonances in 1D spectra were different for each cell line. These resonances included mobile methyl and methylene functions from fatty acids of triglycerides and phospholipids and N-trimethyl from choline of phospholipids. T47D and ZR-75-1 cells presented a high methylene/methyl ratio (6.02 +/- 0.35 and 6.28 +/- 0.90). This ratio was significantly lower for SKBR3, MCF-7 and MDA-MB231 cells (2.76 +/- 0.22, 2.27 +/- 0.57 and 1.39 +/- 0.39). The N-trimethyl/methyl ratio was high for MDA-MB231 and SKBR3 cells (1.38 +/- 0.54 and 0.86 +/- 0.32), but lower for MCF-7, T47D and ZR-75-1 cells (0.49 +/- 0.11, 0.16 +/- 0.07 and 0.07 +/- 0.03). 2D COSY spectra confirmed these different proportions in mobile lipids. From 1D spectra obtained on membrane preparations, T47D and ZR-75-1 were the only cell lines to retain a signal from mobile methylene functions. These differences might be related to the heterogeneity found for several parameters of these cells (tumorigenicity, growth rate, hormone receptors); an extended number of cases from fresh samples might enable clinical correlations.

Effect of pressure overload on cardiac Ca2+ antagonist binding sites of guinea pig. Comparison with the adaptational response of the hypertrophied rat heart.

STUDY OBJECTIVE: The aim was to determine if the adaptational process of the cardiac calcium channel to pressure overload observed in rat heart also occurs in species characterised by a higher sensitivity to external calcium than in the rat. This adaptation occurs via a maintained density of dihydropyridine receptors and calcium current in hypertrophied rat heart. DESIGN: The guinea pig was chosen and the dissociation constant (Kd), association and dissociation rate constants (k+1,k-1), and maximal number (Bmax) of the dihydropyridine receptors were measured through binding of [3H]PN 200-110 to crude sarcolemma fractions from control and hypertrophied guinea pig left ventricle. EXPERIMENTAL MATERIAL: Hypertrophy of the left ventricle was obtained by stenosis of the abdominal aorta in guinea pigs. MEASUREMENTS AND MAIN RESULTS: Hypertrophy reached at least 50% in 15% of the surviving animals. No significant differences in the binding of [3H]PN 200-110 to the dihydropyridine receptor were observed between control and hypertrophied left ventricle microsomal preparations: Kd = 1.59(SEM 0.22) and 1.17(0.36) nM; Bmax = 225(18) and 213(4) fmol.mg-1 of protein; k-1 = 2.30(0.26) and 2.00(0.13) min-1 x 10(-2); k+1 = 3.8(0.7) and 3.5(0.3) nM-1.min-1 x 10(-2) respectively. CONCLUSIONS: In guinea pig as in rat, the total number of dihydropyridine receptors per left ventricle increased proportionately to the hypertrophy. This is consistent with an unchanged density of the cardiac Ca2+ channels in the hypertrophied guinea pig heart as previously shown in hypertrophied rat heart.