大肠癌细胞的双自杀基因治疗

目的探讨腺病毒介导的双自杀基因对大肠癌细胞的杀伤作用及其放射增敏作用。方法用重组的腺病毒载体感染大肠癌细胞株SW480,用RT-PCR方法检测CD(cytosine deaminase)-TK(thymidine kinase)融合基因的表达,单独或联合给予前体药物GCV和5-FC后,用MTT法测定双自杀基因对大肠癌细胞的体外杀伤效应,用克隆形成实验分析感染有自杀基因的大肠癌细胞的放射增敏作用。结果感染有自杀基因的大肠癌细胞,在给予前体药物后,细胞的存活率明显下降,联合给予GCV和5-FC细胞的存活率较单独给GCV或5-FC存活率明显降低(χ2=30.371,P<0.01);联合使用5-FC和GCV时,CD-TK自杀基因的旁观者效应最明显(P<0.01);使用GCV和(或)5-FC能增加感染有自杀基因的大肠癌细胞对照射的敏感性,在联合使用前体药物时更为明显(P<0.01)。结论CD-TK双自杀基因体系对大肠癌细胞具有显著的杀伤作用和放射增敏作用,证明双自杀基因系统具有临床应用价值。

Effect and clinical significance of double suicide gene therapy on colorectal carcinoma cells

Objective To investigate the killing effect and radiosensitization of double suicide gene mediated by adenovirus on colorectal carcinoma cells.Methods Colorectal carcinoma cell line,SW480,was transfected with adenovirus expression vector containing CD(cytosine deaminase) and TK(thymidine kinase) fusion gene.The expression of CD-TK fusion gene was detected by RT-PCR.The toxic effect of GCV,5-FC,and both of them on infected cells were determined by MTT assay.The radiosensitization of double suicide gene was evaluated by clonogenic assay.Results After using the prodrugs,the survival rate of colorectal carcinoma cells significantly decreased.When using GCV and 5-FC together,the cytotoxicity and bystander effect was significantly superior to single prodrug(P<0.01).Both GCV and 5-FC sensitized colorectal carcinoma cells to the toxic effect of radiation,and greater radiosensitization was achieved when both prodrugs were used simultaneously.Conclusion CD-TK double suicide gene has significant killing effect and radiosensitization on colorectal carcinoma in vitro.The results demonstrate the therapeutic potential of CD-TK double suicide gene system.