缺氧/辐射双敏感性启动子调控HSV-TK表达对肺癌移植瘤的作用  

HSV-TK Gene Therapy of Lung Adenocarcinoma Xenografts Using a Hypoxia/radiation Dual sensitive Promoter

作　　者：王卫东[1] 陈正堂[1] 李德志[1] 段玉忠[1] 王志新[1] 曹正怀[1] 

机构地区：[1]第三军医大学附属新桥医院全军肿瘤中心,重庆400037

出　　处：《癌症》2004年第7期788-793,共6页Chinese Journal of Cancer

基　　金：国家自然科学基金项目(No.30300097)~~

摘　　要：背景与目的放射-基因治疗是近年来国际上肿瘤治疗的新策略,由于实体瘤常处于缺氧状态而对放射敏感性低,放射-基因治疗尚未达理想疗效。本研究拟构建缺氧/辐射双敏感性启动子,增强缺氧条件下放射诱导的HSV-TK表达水平,提高肺癌放射-基因治疗效果。方法利用基因重组构建HRE-Egr启动子及其调控的HSV-TK表达载体;脂质体介导重组质粒转染肺癌A549细胞,分为对照组、放射组(6Gy)、缺氧组(1%氧浓度)和放射合并缺氧组,Northernblot法检测转染细胞中HSV-TK表达,四甲基偶氮唑蓝(MTT)法检测放射、缺氧和GCV处理后的细胞存活率。建立BALB/c裸鼠肺癌移植瘤模型,检测放射合并质粒转染后移植瘤体积变化并计算抑瘤率。结果对照组细胞仅可检测到HyTK的低水平表达(21U),放射组和缺氧组HyTK基因表达水平均显著升高(分别为227U和94U),放射合并缺氧组(769U)显著高于放射组。在缺氧条件下,放射合并GCV处理后细胞存活率为(7.2±1.8)%,显著低于常氧组的(32.7±4.6)%。放射联合GCV可明显抑制HRE-Egr启动子转染肺癌移植瘤,抑瘤率达91.2%。结论HRE-Egr启动子具有辐射/缺氧双重敏感性,并使放射后的HSV-TK表达水平在缺氧下得到显著增强。放射联合HRE-Egr启动子可显著抑制肺癌移植瘤的生长。BACKGROUND & OBJECTIVE: Radio genetic therapy is a novel strategy for cancer treatment; however, a limited success was shown due to lower sensitivity of tumor cells to radiation under hypoxia, which is a unique feature for solid tumors. In order to improve the efficacy of radiogenetic therapy for lung cancer, a hypoxia/radiation dual sensitive promoter was constructed to enhance the expression of HSV TK in transfected cells exposed to radiation under hypoxia. METHODS: The chimeric promoter HRE Egr was generated by insertion of hypoxia response elements (HREs) upstream of the Egr 1 (early growth response gene 1) promoter. HSV TK expression vector was constructed by cloning HRE Egr promoter upstream of HSV TK gene, which was transfected into A549 cells via liposome. The expression of HSV TK in transfected cells exposed to irradiation (6 Gy) and/or hypoxia (1% O2) were analyzed by Northern blot, and the relative survival rate of cells in presence of prodrug ganciclovir (GCV) was tested using MTT method. To examine the efficacy of this HRE Egr TK gene therapy in vivo, the A549 adenocarcinoma xenografts were planted in BALB/c nude mice. The tumor volumes and the suppression rates were assayed in nude mice bearing xenografts infected with plasmids and exposed to radiation. RESULTS: HSV TK gene expression in transfected cells was markedly increased in both radiation (227 U) and hypoxia (94 U) groups compared with control group (21 U). The HSV TK expression (769 U) in transfected cells exposed to radiation under hypoxia is much more higher than the former groups. The survival rate of transfected cells exposed to radiation under hypoxia in the presence of GCV was obviously decreased with comparison of cells under normoxia (7.2%±1.8 % vs 32.7%±4.6 %). HRE Egr promoter transfected tumors regressed significantly after a combination therapy of irradiation and GCV in all mice (n=10), the tumor suppression rates was 91.2%. CONCLUSIONS: The hypoxia/radiation dual sensitive promoter HRE Egr can enhance the HSV TK gene expressio

关 键 词：肺肿瘤 放射-基因治疗 缺氧反应元件 

分 类 号：R734.2[医药卫生—肿瘤] R73.36[医药卫生—临床医学]