31P MRS of human tumor cells: effects of culture media and conditions on phospholipid metabolite concentrations.

31P magnetic resonance spectroscopy has been used to determine phosphate metabolite profiles in five human tumor cell lines in culture and as solid tumor xenografts in nude mice. Significant differences between cell lines, in particular in their phospholipid metabolite levels, were observed. The largest differences between metabolite profiles in vivo and in culture were observed for cell lines which exhibit low phosphoethanolamine levels in culture. One of these lines, the colon carcinoma CX-1, was studied in more detail in both incubated and perfused DMEM cultures with variation of the concentrations of glucose, choline and ethanolamine. Highly significant alterations of phospholipid metabolite concentrations and UDP-hexoses (primarily UDP-GlcNAc and UDP-GalNAc) were observed as a function of the precursor concentrations, culture time or perfusion time. A strong interaction between phospholipid metabolic pathways and UDP-hexose pathways could be demonstrated.