Effect of H2O2 induced oxidative stress (OS) on volatile organic compounds (VOCs) and intracellular metabolism in MCF-7 breast cancer cells.

Oxidative stress (OS) refers to the process of oxidative damage caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS) accumulated by the organisms or cells during the process of generating and scavenging oxygen free radicals. In this study, an OS model of MCF-7 cells was constructed through H₂O₂-treatment, which for the first time combined volatile organic compounds (VOCs) and intracellular metabolic analysis for a comprehensive and in-depth study of the OS effect on cell metabolism. The VOCs produced by cells in H₂O₂-treated groups and control groups were extracted with solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometer (GC-MS). Meanwhile, the intracellular metabolites were extracted by methanol and analyzed by GC-MS coupled with silyl-derivatization. The results indicated 15 VOCs and 29 intracellular metabolites were statistically different (p < 0.05) between the H₂O₂-treated groups and the control groups. The VOC biomarkers were mainly linear chain alkanes and branched chain alkanes, and they were up-regulated in cells treated by H₂O₂. The intracellular metabolites with significant changes were mainly fatty acids, amino acids, and organic acids. Most of them, however, were down-regulated under OS state. This study revealed volatile and non-volatile metabolites that influenced by elevated OS in MCF-7 cells, and provided clues for mechanism exploration of exhaled biomarkers, thus promoting the non-invasive prediction of BC.