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目的探讨温热疗法能否增强前药5-氟胞嘧啶(5-fluorocytosine,5-FC)对转染组织特异性胞嘧啶脱氨基酶(cytosinedeaminase,CD)基因的结肠癌细胞SW480的靶向性杀伤作用及其机制。方法将转染G1CEACDNa之结肠癌SW480细胞接种到96孔细胞培养板中,同时加入含各种浓度梯度的前药5-FC。实验组以水浴加温法在43℃下热处理30min,对照组不加热。第8d去除培养液,以MTT法测定活细胞比率,分析前药5-FC联合温热疗法对转CD基因结肠癌SW480细胞的杀伤作用,并以流式细胞仪分析热化疗对肿瘤细胞周期的影响,透射电镜观察热化疗前后肿瘤细胞形态学改变。结果实验组细胞的杀伤率明显高于对照组(P<0.05,t=2.403,n=9);流式细胞仪检测显示实验组S期细胞比例明显增高(P<0.001,t=7.158,n=6);透射电镜观察下显示实验组细胞膜微绒毛消失,边缘变平直,细胞核皱缩,染色质聚集在核模下。结论温热疗法能明显提高转CD基因结肠癌SW480细胞对前药5-FC的敏感性;两者联用能使转CD基因结肠癌SW480细胞产生S期阻滞,从而促进细胞凋亡。
Objective To investigate whether hyperthermia can enhance the targeting of 5-fluorocytosine (5-FC) to human colon cancer cell line SW480 transfected with tissue-specific cytosine deaminase (CD) Killing effect and its mechanism. Methods The colon cancer SW480 cells transfected with G1CEACDNa were inoculated into 96-well cell culture plates, and 5-FC containing various concentrations of prodrugs was added. The experimental group was heated at 43 ℃ for 30 minutes with water bath warming method, while the control group was not heated. On the 8th day, the culture medium was removed and the ratio of viable cells was determined by MTT assay. The killing effect of pro-drug 5-FC combined with warming therapy on SW480 cells transfected with CD gene was analyzed. The effect of thermo-chemotherapy on cell cycle The morphological changes of tumor cells before and after thermochemotherapy were observed by transmission electron microscope. Results The cytotoxicity of the experimental group was significantly higher than that of the control group (P <0.05, t = 2.403, n = 9). Flow cytometry showed that the proportion of cells in the experimental group was significantly increased = 6). Transmission electron microscopy showed that the microvilli in the experimental group disappeared, the edges became flat, the nucleus was shrunk and the chromatin gathered in the nucleus. Conclusion The thermotherapy can significantly improve the sensitivity of CD4 colon cancer SW480 cells to prodrug 5-FC. The combination of the two can induce S phase arrest in SW480 cells and promote cell apoptosis.