NMR-SPECTROSCOPY ANALYSIS OF PHOSPHORUS METABOLITES AND THE EFFECT OF ADRIAMYCIN ON THESE METABOLITE LEVELS IN AN ADRIAMYCIN-SENSITIVE AND ADRIAMYCIN-RESISTANT HUMAN SMALL-CELL LUNG-CARCINOMA CELL-LINE

P-31 nuclear magnetic resonance (NMR) spectra of cells and of cell extracts revealed high levels of phosphorylcholine (PC) and phosphocreatine (PCr) in an adriamycin-resistant human small cell lung carcinoma cell line (GLC4/ADR) and the adriamycin-sensitive parental cell line (GLC4). PCr levels in extracts of GLC4/ADR were increased compared to extracts of GLC4. We estimated that 11% of the total intracellular ATP is not bound to Mg2+ in both cell lines. This value corresponded to an intracellular free Mg2+ of 0.30 mM. The effects of different adriamycin concentrations, 0.05, 1 and 30-mu-M for GLC4 and 1, 30 and 200-mu-M for GLC4/ADR, on the phosphorus metabolite levels in continuously perfused cells were monitored. Significant differences between GLC4 and GLC4/ADR included: (a) a strong increase in the beta-ATP level in the presence of 30-mu-M adriamycin in GLC4 only, followed by a fast decrease after 5 h of perfusion. (b) a less dramatic increase in the PC level in GLC4/ADR and an unchanged ATP level in the presence of increasing adriamycin concentrations. (c) an increased GPC level in GLC4/ADR in the presence of adriamycin. The changes in PC and GPC levels in the presence of adriamycin suggested that the phospholipid turnover was increased in GLC4/ADR and could be stimulated in the presence of adriamycin. In both cell lines, PCr levels decreased faster than the ATP levels after adriamycin treatment. Thus, biochemical markers for adriamycin resistance can be detected with NMR spectroscopy. However, more studies are necessary to obtain parameters to distinguish drug-sensitive from drug-resistant tumours in patients by NMR spectroscopy.