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A complex adenovirus vector that delivers FASL-GFP with combined prostate-specific and tetracycline-regulated
1Department of Microbiology and Immunology, Medical University of South Carolina, Charlestown, SC 29403, USA
Abstract:
Cell-type-restricted transgene expression delivered by adenovirus vectors is highly desirable for gene therapy of cancer, as it can limit cytotoxic gene expression to tumor cells. However, many tumor- and tissue-specific promoters are weaker than the constitutively active promoters and are thus less effective. To combine cell-type specificity with high-level regulated transgene expression, we have developed a complex adenoviral vector. We have placed the tetracycline transactivator gene under the control of a prostate-specific ARR2PB promoter, and a mouse Tnfsf6 (encoding FASL)-GFP fusion gene under the control of the tetracycline responsive promoter. We have incorporated both expression cassettes into a single construct. We show that FASL-GFP expression from this vector is essentially restricted to prostate cancer cells, in which it can be regulated by doxycycline. Higher levels of prostate-specific FASL-GFP expression were generated by this approach than by driving the FASL-GFP expression directly with ARR2PB. More FASL-GFP expression correlated with greater induction of apoptosis in prostate cancer LNCaP cells. Mouse studies confirmed that systemic delivery of both the prostate-specific and the prostate-specific/tet-regulated vectors was well tolerated at doses that were lethal for FASL-GFP vector with CMV promoter. This strategy should be able to improve the safety and efficacy of cancer gene therapy using other cytotoxic genes as well.
Insights
This study developed a novel adenoviral vector for prostate cancer gene therapy. The vector achieves cell-type-specific, regulated transgene expression, enhancing safety and efficacy for cancer treatment.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- Adenovirus vectors are crucial for cancer gene therapy, but achieving cell-type-specific transgene expression remains a challenge.
- Tumor-specific promoters often exhibit lower activity compared to constitutive promoters, limiting therapeutic potential.
- Developing vectors that combine tissue specificity with high-level, regulated transgene expression is essential for effective cancer treatment.
Purpose of the Study:
- To engineer a complex adenoviral vector for cell-type-restricted and regulated transgene expression in prostate cancer.
- To enhance the safety and efficacy of gene therapy by controlling cytotoxic gene delivery to tumor cells.
Main Methods:
- Developed a dual-expression cassette adenoviral vector.
- Utilized a prostate-specific ARR2PB promoter to control tetracycline transactivator (tTA) expression.
- Employed a tetracycline-responsive promoter to drive FASL-GFP fusion gene expression.
- Evaluated vector performance in prostate cancer cell lines and in mouse models.
Main Results:
- Achieved prostate cancer cell-specific FASL-GFP expression regulated by doxycycline.
- Demonstrated higher expression levels compared to direct ARR2PB promoter-driven expression.
- Observed increased apoptosis induction in LNCaP cells with higher FASL-GFP expression.
- Confirmed well-tolerated systemic delivery in mice, unlike vectors with constitutive promoters.
Conclusions:
- The developed adenoviral vector strategy enables precise control of transgene expression in prostate cancer cells.
- This approach significantly improves the safety and efficacy profile for cancer gene therapy.
- The strategy holds promise for enhancing gene therapy with other cytotoxic agents.