探索红外光谱监测肿瘤细胞凋亡的可行性及初步分析。 采用结肠癌细胞系SW620作为诱导细胞模型, MTT法确定最优5-FU诱导浓度, 无血清饥饿培养协同细胞周期阻滞在G1和S期, 傅里叶显微红外光谱仪(FTIR) 联合流式细胞仪(FCM)对SW 620细胞和凋亡的SW 620细胞12 h、 早期凋亡(24 h)和晚期凋亡(48 h)的峰位、 相对峰强等指标进行比较分析。 光谱分析结果显示SW 620对比凋亡细胞有以下特征: (1)与脂类相关谱带1 740 cm-1相对峰强比I1 740/I1 460明显降低(p<0.05), 表明凋亡细胞中脂类相对含量增多。 (2)与氨基酸残基相关谱带1 410 cm-1, I1 460/I1 460在凋亡早期和晚期明显升高(p<0.05), 与丝、 苏氨基酸相关谱带1 120 cm-1 向高波数移动, I1 120/I1 460明显升高(p<0.05), 表明凋亡细胞中DNA双螺旋解链, 氨基酸残基增多。 (3)DNA的反对称伸缩1 240 cm-1向高波数移动, 表明凋亡细胞中核酸分子构象发生改变。 (4)与核酸多糖1 040 cm-1相关谱带在凋亡的24和48 h出现, 向高波数移动, I1 040/I1 460在凋亡晚期降低(p<0.05)。 初步研究结果表明傅里叶变换红外光谱分析可能成为实时无创监测肿瘤化疗的有效方法。

The aim of the present study was to evaluate Fourier transform infrared spectroscopy (FTIR) monitoring of biochemical changes in apoptosis cells. Different concentrations of 5-fluorouracil (5-FU) treated colon cancer cell lines SW620 were used to determine the optimum concentration of 5-FU IC50 by means of MTT assay. Cell starvation and 5-Fu synergistic cell cycle arrest was in G1 and S phase. FTIR combined with flow cytometry was applied to analysis of SW 620 cells and SW620 cells treated with 5-FU for 12h, 24h (early apoptosis) and 48 h (late apoptosis) respectively. The peak position and the intensity of all bands were measured and comparison was made between the SW620 and apoptotic SW620 cells. Apoptosis cells have following characteristics compared with SW620 cells (1) The band at 1 740 cm-1 is an CO stretching vibration. Changes in these bands can reflect lipid changes, and relative peak intensity ratio I1 740/I1 460 significantly increased (p<0.05), indicating that the relative contents of lipid in apoptosis cells increased. (2) The band at the 1 410 cm-1 peak represents that C-H stretching related was increased to amino acid residues and shifted to higher wave numbers compared to other groups. I1 410/I1 460 at early and late death phase was significantly increased, which suggests that the relative contents of amino acid residues in apoptosis cells increased (p<0.05). New vibrational bands at 1 120 cm-1 appeared at 24 h and increased at 48 h compared with other groups. The 1 120 cm-1 absorption band is mainly due to ser, serine and threonine C-O(H) stretching vibration, and I1 120/I1 460 significantly increased (p<0.05), indicating that the relative quantity of amino acid residues in apoptosis cells increased due to that DNA unwinds the double helix. (3) 1 240 cm-1 is mainly due to the asymmetric stretching modes of phosphodiester groups shifting to higher wave number, illustrating that nucleic acid conformation was changed in apoptosis cells. (4) The band 1 040 cm-1 associated with polysaccharide appeared at 24 and 48 h, meanwhile shifted to higher wave number, suggesting that polysaccharide decreased in late apoptotic cells, and I1 040/I1 460 increased at late stage apoptosis, indicating that the relative content of polysaccharide in apoptosis cells increased. The authors’ results suggest that FTIR applied to monitoring SW620 cells apoptosis may be as a potential diagnostic tool for cancer chemotherapy monitoring.