Tumor-specific transcriptional targeting of suicide gene therapy.
Transcriptional targeting of gene expression has been plagued by the weakness of tissue-specific promoters. Thus, to increase promoter strength while maintaining tissue specificity, we constructed a recombinant adenovirus containing a binary promoter system with a tumor-specific promoter (CEA; carcinoembryonic antigen) driving a transcription transactivator, which then activates a minimal promoter to express a suicide gene (HSV-tk; herpes simplex virus thymidine kinase). This ADV/binary-tk induced equal or greater cell killing in a CEA-specific manner in vitro compared with the CEA-independent killing of a vector with a constitutive viral promoter driving HSV-tk (ADV/RSV-tk). To monitor adenovirus-mediated HSV-tk gene expression in vivo, we employed noninvasive nuclear imaging using a radioiodinated nucleoside analog ([((1)31)I]-FIAU) serving as a substrate for HSV-tk. [((1)31)I]-FIAU-derived radioactivity accumulated after intratumoral injection of ADV/binary-tk only in the area of CEA-positive tumors with significantly less spread to the adjacent liver tissue than after administration of the universally expressed ADV/RSV-tk. Both viruses exhibited similar antitumor efficacy upon injection of liver metastases. Importantly, in vivo dose escalation studies demonstrated significantly reduced toxicity after intravenous administration of ADV/binary-tk versus ADV/RSV-tk. In summary, the increased therapeutic index of this novel, amplified CEA-driven suicide gene therapy vector is a proof of principle for the powerful enhancement of a weak tissue-specific promoter for effective tumor restricted gene expression.
Qiao
J
J
Institute for Gene Therapy and Molecular Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.
Doubrovin
M
M
Sauter
B V
BV
Huang
Y
Y
Guo
Z S
ZS
Balatoni
J
J
Akhurst
T
T
Blasberg
R G
RG
Tjuvajev
J G
JG
Chen
S-H
SH
Woo
S L C
SL
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001943:Breast Neoplasms / Q000628:therapy*; D002272:Carcinoembryonic Antigen / Q000235:genetics*; D015870:Gene Expression; D018390:Gene Targeting / Q000379:methods*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage; D006367:HeLa Cells; D017405:Herpes Simplex Virus Protein Vmw65 / Q000235:genetics; D006801:Humans; D015552:Injections, Intralesional; D008113:Liver Neoplasms / Q000556:secondary / Q000628:therapy; D051379:Mice; D008807:Mice, Inbred BALB C; D011401:Promoter Regions, Genetic; D015301:Retroviruses, Simian / Q000201:enzymology; D018139:Simplexvirus / Q000201:enzymology; D013937:Thymidine Kinase / Q000235:genetics; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D002272:Carcinoembryonic Antigen; D017405:Herpes Simplex Virus Protein Vmw65; D013937:Thymidine Kinase