Hsieh Ya-Ju, Liu Ren-Shyan, Hwu Luen, Ke Chien Chih, Wang Fu Hui, Wang Hsin-Ell, Chen Fu-Du
School of Medical Technology and Engineering, Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei City, Taiwan, ROC.
Anticancer Res. 2007 May-Jun;27(3B):1571-9.
To specifically target malignant cells, cancer gene therapy needs to combine highly selective gene delivery with highly specific gene expression. In this study, hepatitis B virus (HBV) enhancer II was combined with alpha-fetoprotein (AFP) promoter which selectively controls the Cre/loxP system in hepatoma.
pE4luc, pE4Tk, EIIAPA-Cre and E4CMV-STOP-Tk constructs and AFP promoter combined with HBV enhancer were constructed and transfected into HepG2, HeLa and NIH-3T3 cell lines.
The E4 enhancer showed the highest luciferase gene expression at a dose range of 5 approximately 7 Gy after 60 hours irradiation. The EIIAPA chimeric promoter which controls the Cre/loxP system provided high specificity only to the hepatoma cells. In addition, the E4 response to radiation encoded more Herpes simplex virus thymidine kinase (HSV1-Tk) protein and killed more tumor cells.
The chimeric EIIAPA promoter can precisely control the Cre/loxP switch and the radiation effect on the EIIAPA-Cre and E4CMV-STOP-Tk system shows promising results in terms of cell survival of hepatocellular carcinoma (HCC).
为了特异性靶向恶性细胞，癌症基因治疗需要将高度选择性的基因传递与高度特异性的基因表达相结合。在本研究中，乙型肝炎病毒（HBV）增强子II与甲胎蛋白（AFP）启动子相结合，该启动子可在肝癌中选择性地控制Cre/loxP系统。
构建了pE4luc、pE4Tk、EIIAPA-Cre和E4CMV-STOP-Tk构建体以及与HBV增强子结合的AFP启动子，并将其转染到HepG2、HeLa和NIH-3T3细胞系中。
E4增强子在60小时照射后5至7 Gy的剂量范围内显示出最高的荧光素酶基因表达。控制Cre/loxP系统的EIIAPA嵌合启动子仅对肝癌细胞具有高特异性。此外，E4对辐射的反应编码了更多的单纯疱疹病毒胸苷激酶（HSV1-Tk）蛋白并杀死了更多的肿瘤细胞。
嵌合的EIIAPA启动子可以精确控制Cre/loxP开关，并且EIIAPA-Cre和E4CMV-STOP-Tk系统对辐射的效应在肝细胞癌（HCC）的细胞存活方面显示出有前景的结果。
