Cre/loxP system controlled by specific promoter for radiation-mediated gene therapy of hepatoma.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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).
Hsieh
Ya-Ju
YJ
School of Medical Technology and Engineering, Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei City, Taiwan, ROC.
Liu
Ren-Shyan
RS
Hwu
Luen
L
Ke
Chien Chih
CC
Wang
Fu Hui
FH
Wang
Hsin-Ell
HE
Chen
Fu-Du
FD
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000628:therapy*; D002470:Cell Survival; D004742:Enhancer Elements, Genetic / Q000528:radiation effects*; D015774:Ganciclovir / Q000494:pharmacology; D015316:Genetic Therapy / Q000379:methods*; D006367:HeLa Cells; D006515:Hepatitis B virus / Q000235:genetics; D018259:Herpesvirus 1, Human / Q000235:genetics; D006801:Humans; D019426:Integrases / Q000235:genetics*; D008113:Liver Neoplasms / Q000628:therapy*; D051379:Mice; D016513:Mice, SCID; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D011827:Radiation; D013937:Thymidine Kinase / Q000235:genetics; D014162:Transfection; D023041:Xenograft Model Antitumor Assays; D000509:alpha-Fetoproteins / Q000235:genetics
D000998:Antiviral Agents; D000509:alpha-Fetoproteins; D013937:Thymidine Kinase; C045073:Cre recombinase; D019426:Integrases; D015774:Ganciclovir