19F磁共振波谱分析CD基因在人结肠癌细胞的表达

为了研究¹⁹F-NMR波谱分析胞嘧啶脱氨酶（CD）基因在人结肠癌细胞中表达的可行性，通过逆转录病毒介导方法，将编码大肠杆菌的CD基因转染到人结肠癌细胞系SW1116. 通过RT-PCR、MTT方法和¹⁹F-NMR波谱分析了CD基因在人结肠癌细胞中的表达状况. 结果显示转基因的肿瘤细胞SWCD₂中表达CD基因，对前药5-氟胞嘧啶（5-FC）的敏感性较亲本肿瘤细胞SW1116明显增高，50%细胞生长抑制率（IC₅₀）为66 μmol/L, 而SW1116 细胞IC₅₀为16 mmol/L. ¹⁹F-NMR波谱分析显示，转导CD基因细胞在774 μmol/L 5-FC浓度培养24 h后的样品，在δ -91.7和δ -93.3显示了2个双峰，分别是5-FC和5-氟尿嘧啶(5-FU)的¹⁹F-NMR的信号，提示5-FU是SWCD₂细胞内的CD酶催化5-FC的代谢产物. 这些结果表明¹⁹F-NMR分析是一种能够用于检测CD基因在人结肠癌细胞中表达的新方法，它将有助于对临床基因治疗方案实施监测. 

ANALYSIS OF EXPRESSION OF CYTOSINE DEAMINASE GENE IN COLON CANCER CELLS WITH 19F MAGNETIC RESONANCE SPECTROSCOPY

To investigate the feasibility of using¹⁹F-NMR spectroscopy to monitor cytosine deaminase (CD) transgene expression in human colon cancer cell line. The SW1116 cell line was transfected with a gene coding for CD from-E.coli- by the retroviral mediated method. The assessment of the expression of CD gene in the colon cancer cell line was carried out by RT-PCR, MTT assay of drug sensitivity to 5-FC and ¹⁹F-NMR spectroscopy. The results indicate that the transgenic SWCD₂ cell line was more sensitive to the prodrug 5-fluorcytosine (5-FC) (IC₅₀=66μmol/L) as compared to the parent cancer cells SW1116 (IC₅₀=16 mmol/L). After incubation of the cultured CD⁺ cells in 774 μmol/L 5-FC for 24 h, ¹⁹F-NMR spectra of the intact cells showed two broad resonances corresponding to 5-FC (taken up into cell chemical shift relative to trifluoroacetate of δ-91.7) and 5-FC produced by the action of CD (chemical shif of δ-93.3), respectively. These results demonstrated the feasibility of using ¹⁹F-NMR spectroscopy to noninvasively monitor CD gene expression in human colon cancer cells. This capability provides a new approach for measuring gene expression that will be useful in clinical gene therapy trials.