Hypoxia- and radiation-activated Cre/loxP 'molecular switch' vectors for gene therapy of cancer
Hypoxia- and radiation-activated Cre/loxP 'molecular switch' vectors for gene therapy of cancer
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DOI：
10.1038/sj.gt.3302640
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发表时间：
2006-02-01
期刊：
影响因子：
5.1
通讯作者：
Scott, SD
中科院分区：
文献类型：
--
作者：
Greco, O;Joiner, MC;Scott, SD
尽管肿瘤缺氧是一个重要的负性预后因素，但它可以用于基因治疗。为了最大限度地靶向肿瘤块内，我们已经开发了合成基因启动子，其含有来自促红细胞生成素（Epo）基因的低氧响应元件（HRE）以及来自早期生长反应（Egr）1基因的辐射响应CArG元件。此外，为了实现自杀基因单纯疱疹病毒胸苷激酶（HSVtk）的高和持续表达，我们的基因治疗载体包含基于Cre/loxP重组的表达扩增系统或“分子开关”。在暴露于缺氧和/或辐射的人神经胶质瘤和乳腺癌细胞中，HRE/CArG启动子快速激活Cre重组酶表达，导致选择性和持续的HSVtk合成。在与前药更昔洛韦（GCV;通过HSVtk转化为细胞毒素）孵育后测量转染的肿瘤细胞的杀伤。在体外，与直接驱动HSVtk表达的相同诱导型启动子相比，开关载体实现了更高和更有选择性的GCV介导的毒性。在裸鼠中植入的肿瘤异种移植物中，HRE/CArG开关诱导显著的生长延迟和肿瘤根除。总之，低氧和辐射激活的“分子开关”载体是一个有前途的策略，为实体瘤的靶向和有效的基因治疗。
Although a significant negative prognostic factor, tumor hypoxia can be exploited for gene therapy. To maximize targeting within the tumor mass, we have developed synthetic gene promoters containing hypoxia-responsive elements (HREs) from the erythropoietin (Epo) gene as well as radiation-responsive CArG elements from the early growth response (Egr) 1 gene. Furthermore, to achieve high and sustained expression of the suicide gene herpes simplex virus thymidine kinase (HSVtk), our gene therapy vectors contain an expression amplification system, or 'molecular switch', based on Cre/loxP recombination. In human glioma and breast adenocarcinoma cells exposed to hypoxia and/or radiation, the HRE/CArG promoter rapidly activated Cre recombinase expression leading to selective and sustained HSVtk synthesis. Killing of transfected tumor cells was measured after incubation with the prodrug ganciclovir ( GCV; converted by HSVtk into a cytotoxin). In vitro, higher and more selective GCV-mediated toxicity was achieved with the switch vectors, when compared with the same inducible promoters driving HSVtk expression directly. In tumor xenografts implanted in nude mice, the HRE/ CArG-switch induced significant growth delay and tumor eradication. In conclusion, hypoxia-and radiation-activated 'molecular switch' vectors represent a promising strategy for both targeted and effective gene therapy of solid tumors.