摘要
目的:构建由Egr-1启动子驱动HSV-TK基因表达的重组质粒,通过放射诱导调控HSV-TK基因的肿瘤靶向表达,以提高肺癌基因治疗的选择性和有效性。方法:利用基因重组方法构建tgEgr-HyTK表达载体;脂质体介导转染肺癌A549、SHG44细胞系,给以不同剂量γ射线照射,观察照射前后各时相点肺癌细胞HSV-TK表达情况;以及不同浓度前药GCV作用下肺癌细胞相对存活率的变化。结果:γ射线可诱导HSV-TK基因在被转染肺癌细胞表达显著增强,呈剂量依赖性;照射后3h HSV-TK基因表达增强,于第8小时达峰值,第36小时恢复至照射前水平。经放射诱导后,tgEgr-HyTK转染肺癌细胞对GCV的敏感性明显升高(P<0.05);进一步发现,HSV-TK/GCV系统对放射线有较明显的增敏作用。放射和HSV-TK/GCV在肿瘤杀伤作用上存在明显协同效应。结论:利用Egr-1启动子调控HSV-TK基因的肿瘤靶向性表达,是一种高效、特异的肺癌基因治疗新策略。
Objective A strategy was designed for suicide gene therapy in conjunction with irradiation therapy, by constructing a plasmid tgEgr-HyTk in which HSV-TK gene was driven by the early growth response gene 1 ( Egr-1) promoter, in order to improve the efficacy and selectivity of gene therapy for lung carcinoma. Methods The radio-inducible suicide gene was constructed by insertion of Egr-1 promoter upstream of the the HSV-TK gene.The expression of HSV-TK in lung carcinoma cell lines A549 & SHG44 which were infected with tgEgr-HyTk and exposed to different doses of γ-ray irradiation at every post-radiation time point were analyzed, and the relative survival rate of cells in presence of prodrug ganciclovir(GCV) was tested. Results Expression of HSV-TK gene in lung carcinoma cells infected with tgEgr-HyTK plasmids was markedly increased in a radiation dose-dependent manner, with a peak at 8 hour post irradiation. An in vitro gene therapy experiment showed that tgEgr-HyTK transduced lung carcinoma cells became highly sensitive to GCV after irradiation, but not without irradiation. In addition,a 'radiosensitization effect' and the synergistic effect for killing lung carcinoma cells were also demonstrated by combination therapy with the HSV-TK/GCV system and irradiation. Con-clusions Tumor targeted expression of HSV-TK gene under the control of a radioinducible promoter represents a novel strategy for safe and effective gene therapy of lung carcinoma and might have wide application in the future.
出处
《肿瘤防治杂志》
2003年第1期51-55,共5页
China Journal of Cancer Prevention and Treatment
基金
国家教育部高等学校骨干教师资助项目(GG13173)
关键词
肺肿瘤
病理学
辐射效应
基因疗法
lung neoplasms/pathology
tumor cells, cultured/radiation effects
gene therapy
recombination, genetic
