Fourier transform infrared microspectroscopy monitoring of 5-fluorouracil-induced apoptosis in SW620 colon cancer cells.

Colon cancer is associated with a high incidence and a poor prognosis. The aim of the present study was to determine whether Fourier transform infrared (FTIR) microspectroscopy can be used to monitor the chemotherapy drug-induced apoptosis of SW620 colon cancer cells. The 50% inhibitory concentration (IC50) of 5-fluorouracil (5-FU), the main chemotherapeutic agent used for the treatment of colorectal cancer, was determined as the inhibition of growth of the SW620 cells using an MTT assay. Cell starvation and 5-FU treatment synergized to arrest the cells in the G1 and S phases of the cell cycle. FTIR combined with fluorescence activated cell sorting (FACS) analysis were used to analyze the SW620 cells following treatment with 5-FU for 12, 24 and 48 h. The apoptotic cells had several spectral characteristics. The relative peak intensity ratio (I1740/I1460) was significantly increased (P<0.05), the I1740/I1460 ratio, associated with a band of amino acid residues at 1,410 cm−1 was significantly increased at the early and late phases of cell death (P<0.05), the peaks at 1,240 cm−1 increased in wave number, a band at 1,040 cm−1, associated with polysaccharides, appeared at 24 and 48 h and then moved to a higher wave number and the I1040/I1460 ratio increased at the late stage of apoptosis. These results demonstrated that FTIR can be used as a label-free technique to monitor cancer cell apoptosis and to understand the spectral fingerprints of apoptotic cells. This suggested that FTIR spectral features have potential as a powerful tool to monitor cancer cell apoptosis.