Anaerobic bacteria as a gene delivery system that is controlled by the tumor microenvironment
Anaerobic bacteria as a gene delivery system that is controlled by the tumor microenvironment
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DOI：
10.1038/sj.gt.3300468
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发表时间：
1997-08-01
期刊：
影响因子：
5.1
通讯作者：
Brown, JM
中科院分区：
文献类型：
--
作者：
Lemmon, MJ;vanZijl, P;Brown, JM
癌症基因治疗的一个基本障碍是实体肿瘤的抗癌基因产物的特异性传递。虽然有几种策略可以在载体直接导入肿瘤后控制基因表达，但目前还没有专门针对实体肿瘤的系统传递系统。非致病性的专性厌氧菌梭状芽胞杆菌在实验中被用作抗癌药物，因为它们在系统应用后在实体肿瘤的缺氧区域选择性生长。在本报告中，我们进一步描述了一种新的癌症基因治疗方法，其中基因工程梭菌被用作肿瘤特异性载体来传递抗肿瘤基因。我们已经将一种大肠杆菌硝基还原酶的基因引入到一种有毒的抗癌药物中，这种基因已知可以激活无毒的前药CB 1954。这些梭菌产生的硝基还原酶能提高cb1954体外杀伤肿瘤细胞的能力，达到22倍。为了证明这种方法对肿瘤靶向的特异性，我们静脉注射了灭活的贝氏弧菌孢子形式，该孢子形式在过渡到繁殖状态时将表达大肠杆菌硝基还原酶基因。在静脉注射失活梭菌孢子后的前5天，10个肿瘤中有10个检测到硝基还原酶活性，表明从孢子到生殖状态的快速转变。含有不含大肠杆菌硝基还原酶基因的梭状芽孢的肿瘤缺乏硝基还原酶活性。最重要的是，在静脉注射含有梭菌的硝基还原酶后，在正常小鼠组织的大量调查中未发现大肠杆菌硝基还原酶蛋白，这强烈表明梭菌等专性厌氧细菌可以作为高度特异性的基因传递载体用于癌症治疗。
A fundamental obstacle in gene therapy for cancer treatment is the specific delivery of an anticancer gene product of a solid tumor. Although several strategies exist to control gene expression once a vector is directly introduced into a tumor, as yet no systemic delivery system exists that specifically targets solid tumors. Nonpathogenic, obligate anaerobic bacteria of the genus Clostridium have been used experimentally as anticancer agents because of their selective growth in the hypoxic regions of solid tumors after systemic application. In this report we further describe a novel approach to cancer gene therapy in which genetically engineered clostridia are used as tumor-specific vectors for the delivery of antitumor genes. We have introduced into a strain of C. beijerinckii the gene for an E. coli nitroreductase known to activate the nontoxic prodrug CB 1954 to a toxic anticancer drug. Nitroreductase produced by these clostridia enhanced the killing of tumor cells in vitro by CB 1954, by a factor of 22. To demonstrate the specificity of this approach far tumor targeting we intravenously injected the inactive spore form of C. beijerinckii, which upon transition to a reproductive state will express the E. coli nitroreductase gene. Nitroreductase activity was detectable in 10 of 10 tumors during the first 5 days after intravenous injection of inactive clostridial spores, indicating a rapid transition from spore to reproductive state. Tumors harboring clostridial spores which did not possess the E. coli nitroreductase gene were devoid of nitroreductase activity. Most importantly, E. coli nitroreductase protein was not found in a large survey of normal mouse tissues following intravenous injection of nitroreductase containing clostridia, strongly suggesting that obligate anaerobic bacteria such as clostridia can be utilized as highly specific gene delivery vectors for cancer therapy.