Study of the effect of gamma irradiation on cellular metabolism by nuclear magnetic resonance spectroscopy

Abstract

The phenomenon of NMR plays an important role in a number of different scientific and medical fields. Nuclear magnetic resonance has the ability to detect changes in tumour, and cell metabolism caused by both chemotherapy and radiation therapy treatments. This project determined the feasibility of NMR spectroscopy for quantifying the effect of radiation therapy on the cellular metabolite levels o f the MCF-7 cancer cell line. The metabolites were extracted using a freeze-thaw procedure developed for this study, and analyzed by 31P NMR spectroscopy. Phosphorous spectra were normalized to the inorganic phosphate peak height, and relative peak height ratios were calculated for all phosphorous metabolites present. The standard deviations found for peak height ratios were determined by performing a control reproducibility study. It was found that the reproducibility of intra-batch samples was much higher than that of inter-batch samples. The percent error values for intra-batch samples ranged from 2.53 % to 7.98 % throughout the different relative metabolite ratios, and for inter-batch samples, the values ranged from 38.61 % to 49.90 %. The post-irradiation times of 2, 24 and 48 hrs were chosen, and the time of 48 hrs was determined to yield the greatest quantitative change. Considering this, a range of doses (4 to 12Gy) was examined at 48 hrs post-irradiation. Through the qualitative examination of the peak ratios for all of the phosphorous metabolites found in MCF-7 extracts, it was found that a direct correlation exists between the amount of irradiation delivered, and the changes in metabolite intensities for the MCF-7 cell line. Therefore, based on these preliminary results, it has been shown that 31P NMR can be used to monitor the effects of radiation therapy, and potentially, can be used to quantify a dose-response relationship.