A novel single tetracycline-regulative adenoviral vector for tumor-specific Bax gene expression and cell killing in vitro and in vivo.
Using a binary adenoviral system, we recently showed that the human telomerase reverse transcriptase (hTERT) promoter induces tumor-specific Bax gene expression. However, the strong cytotoxicity of Bax and other pro-apoptotic genes to packaging 293 cells has so far hindered construction of the desired single adenoviral vectors expressing toxic genes. We report here the construction of a single bicistronic adenoviral vector for tumor-specific Bax expression. The vector (Ad/gBax) utilizes the Tet-Off system and expresses a GFP/Bax fusion protein for easy detection. The hTERT promoter drives the expression of tTA, a transactivator capable of binding to TRE (tetracycline-responsive element) in the absence of tetracycline, which in turn induces expression of the GFP-Bax gene. The addition of tetracycline in 293 cells blocks the binding of tTA to TRE and substantially inhibits GFP-Bax expression and toxicity, thus allowing the packaging and production of Ad/gBax. Our data show that Ad/gBax could drive the high expression of GFP-Bax in tumor cells but not in normal cells and mouse tissues. Furthermore, the expression of GFP-Bax fusion protein elicited tumor-specific apoptosis in a variety of human cancer cells in vitro and in vivo at a level comparable to that induced by the binary system. Thus, Ad/gBax may become a potent therapeutic agent for the treatment of cancers.
Gu
Jian
J
Section of Thoracic Molecular Oncology, Department of Thoracic and Cardiovascular Surgery, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX 77030, USA.
Zhang
Lidong
L
Huang
Xuefeng
X
Lin
Tongyu
T
Yin
Min
M
Xu
Kai
K
Ji
Lin
L
Roth
Jack A
JA
Fang
Bingliang
B
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D017209:Apoptosis; D002455:Cell Division; D004268:DNA-Binding Proteins; D015316:Genetic Therapy; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006801:Humans; D007202:Indicators and Reagents / Q000032:analysis; D007700:Kinetics; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins / Q000032:analysis; D019098:Telomerase / Q000235:genetics; D013752:Tetracycline / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; C494827:Bax protein, mouse; D004268:DNA-Binding Proteins; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins; D051028:bcl-2-Associated X Protein; D049452:Green Fluorescent Proteins; D019098:Telomerase; D013752:Tetracycline