Analysis of the X-ray induced changes in lipids extracted from hepatocarcinoma cells by means of ATR-FTIR spectroscopy

Radiation therapy, particularly X-ray-based treatment, is widely used against cancer due to its ability to induce cell death, hence local tumor control Recently, increasing attention has been devoted to the role of lipid metabolism in the radiation-induced response of tumor cells. This study utilized Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy to examine the role of lipids in the response of hepatocarcinoma (HepG2) cells to X-ray radiation. Infrared spectra were acquired from lipids extracted from HepG2 cells exposed to different X-ray doses (0, 2, and 6 Gy). Results showed that X-ray exposure causes shifts in the peak positions in infrared spectra indicating biochemical changes in lipid components. The phosphate group asymmetric stretching band shifted to higher wave numbers in the 2 and 6 Gy exposed samples, likely due to alterations in membrane fluidity. The 2-Gy exposure led a reduction of sphingolipid, phospholipid, and fatty acid contributions that can be probably ascribed to apoptosis processes. The 6-Gy exposure triggered also changes in sphingolipid content potentially linked to increased lipid peroxidation supported by higher carbonyl contribution. This peroxidation results in smaller lipid fragments and various degradation products. The changes in sphingolipids are also confirmed by the analysis of different ratios between the areas of selected bands and the results of a mass spectroscopy investigation carried out on the same samples.