放射诱导的肿瘤特异性嵌合启动子研究

Study of cancer-specific chimeric promoters induced by irradiation

目的将放射敏感性的CArG元件与肿瘤特异性的人端粒酶反转录酶（hTERT）基因启动子相结合，构建新的嵌合启动子。方法构建含不同CArG元件数量的嵌合hTERT启动子，在放射线诱导下（单剂量或分割照射），利用荧光素酶报告基因检测其在肿瘤细胞（HeLa、A549、MHCC97细胞）及正常细胞（hEL细胞）中的活性。结果包含6个CArG元件的hTERT嵌合启动子较含其他数量CArG的嵌合启动子显示了更好的放射诱导性，并在4～6Gy时达到顶峰，而构建的嵌合启动子在正常的hEL细胞中活性很低。在肿瘤细胞中，3次2Gy与单次6Gy剂量照射相比较，报告基因的表达相当。结论包含6个CArG元件的肿瘤特异性嵌合启动子具备良好的放射诱导性，这种嵌合的启动子系统具有肿瘤基因治疗的潜力。

Objective To combine the radio-inducible CArG element with cancer-specific human telomerase reverse transcriptase（hTERT） gcne promoter, and to construct the novel chimeric promoters. Methods The synthetic hTERT promoters containing different number of radio-inducible CArG elements were constructed, and the activities of the promoters in the cancer ceils （ HeLa, A549, and MHCC97 cells） and nomal cells（hEL cells） were detected by using lucifcrase-reporter assays afer the treatment of irradiation（a single or fractionated irradiation dose）. Results Synthetic promoter containing 6 repeated CArG units was better in radio-inducibility than any other promoters containing different number of CArG units, and nearly maximum levels obtained at 4-6 Gy. The very low activities of the chimeric promoters could be detected in normal hEL cells. A similar level of reporter gent expression was observed after 3 fractionated doses of 2 Gy compared with a single close of 6 Gy in cancer cells. Conclusions The cancerspecific chimeric promoter containing 6 CArG elements showes the best radio-response, and the chimeric promoter system has the potential in cancer genc therapy.