Novel system uses probasin-based promoter, transcriptional silencers and amplification loop to induce high-level prostate expression.
BACKGROUND
Despite several effective treatment options available for prostate cancer, it remains the second leading cause of cancer death in American men. Thus, there is a great need for new treatments to improve outcomes. One such strategy is to eliminate cancer through the expression of cytotoxic genes specifically in prostate cells by gene therapy vectored delivery. To prevent systemic toxicity, tissue- and/or cancer-specific gene expression is required. However, the use of tissue- or cancer-specific promoters to target transgene expression has been hampered by their weak activity.


RESULTS
To address this issue, we have developed a regulation strategy that includes feedback amplification of gene expression along with a differentially suppressible tetracycline regulated expression system (DiSTRES). By differentially suppressing expression of the tetracycline-regulated transcriptional activator (tTA) and silencer (tTS) genes based on the cell origin, this leads to the activation and silencing of the TRE promoter, respectively. In vitro transduction of LNCaP cells with Ad/GFPDiSTRES lead to GFP expression levels that were over 30-fold higher than Ad/CMV-GFP. Furthermore, Ad/FasL-GFPDiSTRES demonstrated cytotoxic effects in prostate cancer cells known to be resistant to Fas-mediated apoptosis.


CONCLUSIONS
Prostate-specific regulation from the DiSTRES system, therefore, serves as a promising new regulation strategy for future applications in the field of cancer gene therapy and gene therapy as a whole.
Woraratanadharm
Jan
J
Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, USA. jworara@genphar.com <jworara@genphar.com>
Rubinchik
Semyon
S
Yu
Hong
H
Dong
John Y
JY
D000727:Androgen-Binding Protein / Q000235:genetics*; D045744:Cell Line, Tumor; D005246:Feedback; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D020868:Gene Silencing; D018390:Gene Targeting / Q000379:methods*; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008297:Male; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D021141:Nucleic Acid Amplification Techniques; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000628:therapy; D015202:Protein Engineering; D014157:Transcription Factors / Q000235:genetics*
D000727:Androgen-Binding Protein; D009363:Neoplasm Proteins; D014157:Transcription Factors; C027519:probasin