Raman spectroscopic analysis of apoptosis of single human gastric cancer cells

A drug (5-FU) was employed to treat the gastric carcinoma cells and induce apoptosis of the cancer cells. Raman spectra obtained from single gastric carcinoma cells and the induced apoptotic cells through scan-excitation mode were used to analyze the effectiveness of the treatment. The major difference of the apoptotic cells from the cancer cells are the reduction in intensities of vibration bands generated by cellular lipids, proteins and nucleic acids. In particular, large intensity reduction in nucleic vibrations at 782, 1092, 1320, 1340, and 1578 cm−1 was observed upon apoptosis of the gastric carcinoma cells. Up to 45% reduction in the magnitude of the 782 cm−1 peak in Raman spectra of the apoptotic cells was observed, which suggests the breakdown of phosphodiester bonds and DNA bases. We showed that the principal components analysis (PCA), a multivariate statistical tool, can be used to distinguish single apoptotic cells and gastric carcinoma cells based on their Raman spectra.