Mp. Gamcsik et al., NONINVASIVE DETECTION OF ELEVATED GLUTATHIONE LEVELS IN MCF-7 CELLS RESISTANT TO 4-HYDROPEROXYCYCLOPHOSPHAMIDE, Cancer research, 55(10), 1995, pp. 2012-2016
Native human mammary MCF-7 adenocarcinoma cells and a subline displayi
ng resistance to 4-hydroperoxycyclophosphamide, the chemically activat
ed form of cyclophosphamide, were grown as multicellular spheroids or
on a collagen sponge matrix and perfused for study by P-31 and C-13 nu
clear magnetic resonance spectroscopy, The natural abundance C-13 spec
trum of the perfused cells exhibits well-resolved resonances due to th
e intracellular glutathione (GSH). The resistant cell line shows a hig
her intensity of the GSH C-13 resonances, consistent with the increase
d GSB concentration determined from biochemical assays of extracts, Tr
eatment of the resistant cell line with buthionine sulfoximine selecti
vely diminishes the intensity of the GSH resonances in the C-13 nuclea
r magnetic resonance spectrum.