Ra. Wing et al., AN INVESTIGATION OF RAT MAMMARY HEALTHY AND R3230AC TUMOR-TISSUES ANDCELLS BY MEANS OF SOLID-STATE C-13 NMR, Solid state nuclear magnetic resonance, 7(3), 1996, pp. 263-269
The first results are shown of a low temperature C-13 solid-state, cro
ss-polarization magic angle spinning (CPMAS) NMR study of R3230AC rat
mammary carcinoma transplanted into female Fischer rats. Intact, healt
hy mammary tissues and tumor tissues, quickly frozen at -78 degrees C
after excision, were examined, as were normal epithelial cells and tum
or cells extracted from these tissues. The experiments were performed
at -100 degrees C and -40 degrees C. The solid-state C-13 NMR spectrum
of the healthy tissue is dominated by the triacylglycerols present in
the adipose tissue. The solid-state spectra of the other compounds di
ffer significantly from the spectrum of the healthy tissue, and are do
minated by the phospholipids and the large molecular weight proteins,
for a major part present in the membranes. The spectra of the tumor ti
ssues and the tumor cells were very similar, in accordance with the fa
ct that the tumor tissues consisted of 80-90% tumor cells. The spectru
m of the normal cells shows the same general features as those of the
tumor tissue and tumor cells, but also exhibits some significant diffe
rences. The main difference at -100 degrees C is that, in the tumor sa
mples, the relative intensity of the resonance line arising at 30 ppm,
which is due to methylene chains, is reduced. At -40 degrees C this i
ntensity is futher reduced in the tumor samples, whereas the spectrum
of the normal cells remains unaltered. It is tentatively concluded tha
t the spectral differences between the normal and the malignant cells
are due to changes in mobilities occurring in the cells after tumorige
nesis, and that compared with normal epithelial cells the tumor cells
contain an increased amount of mobile methylene chains. These differen
ces virtually disappear if the samples are preserved at temperatures e
qual to or above 4 degrees C, emphasizing the importance of sample pre
servation at low temperatures, and hence of the solid-state NMR approa
ch to investigate structures and dynamics in cells before and after tu
mor formation.