Chemo-radio-gene therapy targeted by ionizing radiation using the EGR1 promoter

本研究的目的是利用大肠杆菌胞嘧啶脱氨酶（CD）自杀基因和电离辐射诱导早期生长反应1（EGR 1）启动子，开发一种新的化疗-放基因治疗大肠癌的方法。CD将无毒的5-氟胞嘧啶（5 FC）转化为对人结直肠癌细胞具有抗肿瘤活性的5-氟尿嘧啶（5 FU）。电离辐射诱导包括EGFR 1在内的立即早期基因。因此，EGR 1启动子与CD基因的组合可用于在用5 FC处理时在照射区域中诱导强烈的抗癌活性。预期EGR 1-CD载体通过电离辐射驱动以在哺乳动物细胞中表达CD mRNA。当用EGR 1-CD载体转染结肠直肠癌细胞时，电离辐射诱导CD在结肠直肠癌细胞中表达，并且5 FC转化为对结肠直肠癌细胞具有细胞毒性的5 FU。为此，我们尝试了EGR 1启动子区和细菌CD基因的PCR扩增与报道的引物克隆。使用克隆试剂盒进一步克隆这两个DNA片段。将克隆的DNA片段共插入质粒中以构建用于哺乳动物细胞的表达载体。由于在本研究期间，我们尚未完成两个DNA片段的克隆和EGR 1-CD质粒的构建，因此研究者无法证实EGR 1-CD载体在哺乳动物细胞中的活性。

The purpose of this study was to develop a novel chemo-radio-gene therapy against colorectal cancer using Esherichia coli cytosine deaminase (CD) suicide gene and ionizing radiation-inducible early growth response 1 (EGR1) promoter. The CD converts non-toxic 5-Fluorocytosine (5FC) to 5-Fluorouracil (5FU) that has the anti-tumor activity for human colorectal cancer cells. The ionizing irradiation induces immediate-early genes including the EGR1. Thus, the EGR1 promoter in combination with the CD gene can be used to induce an intense anti-cancer activity in the irradiated field when treated with 5FC. The EGR1-CD vector is expected to be driven by ionizing irradiation to express CD mRNA in mammalian cells. When colorectal carcinoma cells are transfected with the EGR1-CD vector, ionizing irradiation induces CD expression in the transformant cells and 5FC is converted to 5FU that is cytotoxic for colorectal cancer cells. For this purpose, we tried cloning of the EGR1 promoter region and the bacterial CD gene by PCR amplification with the reported primers. The two DNA fragments were further cloned using a cloning kit. The cloned DNA fragments were co-inserted into a plasmid to construct an expression vector for mammalian cells. The investigators could not confirm the activity of EGR1-CD vector in mammalian cells because we have not completed cloning of the two DNA fragments and construction of EGR1-CD plasmid during the research period.