Ionizing Radiation-regulated Killing of
Human Hepatoma Cells by Liposome-mediated CDglyTK Gene Delivery
LI Xing-Jun, WANG Ke-Min, XU Yue, Wang Zhong-He1, XIA Ai-Di, CHEN
Shi-Shu, QIAN Guan-Xiang*
( Department of
Biochemistry, Research Center for Human Gene Therapy, Shanghai S econd Medical
University, Shanghai 200025, China; 1Department of Radiology, Shanghai
Ninth Peoples Hospital, Shanghai 200011 , China )
Abstract
EGR-1 gene promoter and CDglyTK gene were used to construct the
pcDNA3-EGR-CDglyTK recombinant vector, in which CDglyTK gene expression was under the
control of EGR-1 gene promoter. Cationic liposome LipofectAMINE was used to transfect plasmids
into human hepatoma 7402 cell line. Subsequently, the transfected cells were treated with different
doses of γ-ray. Northern blot and Western blot showed that ionizing radiation can induce
CDglyTK gene expression drived by EGR-1 promoter,in a dose-dependant manner. There was no
ionizing radiation-inducible effect in pcDNA3-CMV-CDglyTK control group. Ionizing radiation also
markedly enhanced the sensitivity of tumor cells transfected with pcDNA3-EGR-CDglyTK to prodrugs
(GCV/5-FC) in tumor cell killing. The data indicated that EGR-1 promoter was inducible by
ionizing radiation, whereas the CMV promoter was not. There was a synergetic effect between GCV
and 5-FC. The cytotoxic effect of the suicide gene-ionizing radiation combination was stronger than
suicide gene alone or ionizing radiation alone.
Key
words ionizing radiation; CDglyTK gene; EGR-1
gene promoter; cationic liposome
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