Characterization of 1H NMR detectable mobile lipids in cells from human adenocarcinomas

Magnetic resonance spectroscopy studies are often carried out to provide metabolic information on tumour cell metabolism, aiming for increased knowledge for use in anti-cancer treatments. Accordingly, the presence of intense lipid signals in tumour cells has been the subject of many studies aiming to obtain further insight on the reaction of cancer cells to external agents that eventually cause cell death. The present study explored the relationship between changes in neutral lipid signals during cell growth and after irradiation with gamma rays to provide arrest in cell cycle and cell death. Two cell lines from human tumours were used that were differently prone to apoptosis following irradiation. A sub-G1 peak was present only in the radiosensitive HeLa cells. Different patterns of neutral lipids changes were observed in spectra from intact cells, either during unperturbed cell growth in culture or after radiation-induced growth arrest. The intensities of triglyceride signals in the spectra from extracted total lipids changed concurrently. The increase in lipid peak intensities did not correlate with the apoptotic fate. Modelling to fit the experimental data revealed a dynamic equilibrium between the production and depletion of neutral lipids. This is observed for the first time in cells that are different from adipocytes.