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Adenovirus-mediated suicide gene therapy for experimental bladder cancer
M A Sutton1, S A Berkman, S H Chen
1Scott Department of Urology, Baylor College of Medicine, Houston, TX 77030, USA.
Objectives:
To determine the feasibility, safety, and efficacy of suicide gene therapy using adenoviral-mediated herpes simplex virus thymidine kinase gene (HSV-tk) and the prodrug ganciclovir (GCV) in a murine model of human transitional cell carcinoma.
Methods:
We used a replication-defective adenoviral construct containing the beta-galactosidase gene (ADV/Rous sarcoma virus [RSV]-beta-gal) as a control or ADV/RSV-tk as the therapeutic vector under the transcriptional control of the RSV long-terminal repeat promoter. Transduction efficiency was assessed in vitro by infection of MBT-2 cells with ADV/RSV-beta-gal at various multiplicities of infection (MOI) utilizing 5-bromo-4-chlor-3-indolyl-beta-D-galactoside (X-gal) staining. Sensitivity of MBT-2 cells to the therapeutic vector was determined after infection with ADV/RSV-tk with or without GCV. Subcutaneous tumors were established in syngeneic C3H/He female mice with 5 x 10(5) MBT-2 cells. Optimal dosing of ADV/RSV-tk was determined by direct percutaneous tumor injection with increasing viral doses and treatment with GCV. Treatment efficacy, long-term survival, and toxicity were determined in separate, similar, controlled experiments.
Results:
In vitro studies indicated greater than 95% transduction 96 hours after inoculation at an MOI of 3000 and a greater than 95% cell death rate with RSV-tk + GCV at an MOI of 61 or greater. In vivo experiments demonstrated an optimal viral dose of 3 x 10(8) plaque-forming units (pfu) and a greater than fourfold reduction in tumor growth for the animals treated with ADV/RSV-tk compared with control animals (P = 0.0013). Toxicity was limited to histologic evidence of hepatitis with ADV/RSV-tk doses greater than 3 x 10(8) pfu + GCV. Long-term survival of treatment animals was significantly increased over that of control animals (59%, P = 0.0001).
Conclusions:
ADV/RSV-tk with GCV treatment results in efficient gene transfer in vitro and provides effective therapy in experimental murine bladder cancer by significantly inhibiting tumor growth and improving host survival.
Insights
Suicide gene therapy using adenoviral-mediated herpes simplex virus thymidine kinase gene (HSV-tk) and ganciclovir (GCV) effectively inhibited tumor growth and improved survival in a murine bladder cancer model.
Area of Science:
- Oncology
- Gene Therapy
- Virology
Background:
- Transitional cell carcinoma is a common form of bladder cancer.
- Suicide gene therapy offers a potential therapeutic strategy for cancer treatment.
- Adenoviral vectors are widely used for gene delivery in preclinical cancer models.
Purpose of the Study:
- To evaluate the feasibility, safety, and efficacy of adenoviral-mediated suicide gene therapy using herpes simplex virus thymidine kinase gene (HSV-tk) and ganciclovir (GCV).
- To assess this therapy in a murine model of human transitional cell carcinoma.
Main Methods:
- Utilized a replication-defective adenoviral construct (ADV/RSV-tk) for gene transfer.
- Assessed in vitro transduction efficiency and cancer cell death.
- Determined optimal viral dosing and treatment efficacy in a murine bladder cancer model.
- Monitored long-term survival and toxicity.
Main Results:
- Achieved >95% transduction efficiency and >95% cancer cell death in vitro.
- Demonstrated a significant reduction in tumor growth (fourfold) in vivo (P = 0.0013).
- Observed significantly increased long-term survival in treated animals (59%, P = 0.0001).
- Identified dose-limiting toxicity (hepatitis) at doses >3 x 10(8) pfu.
Conclusions:
- Adenoviral-mediated HSV-tk and GCV treatment is an effective suicide gene therapy for experimental murine bladder cancer.
- The therapy demonstrates efficient gene transfer, significant tumor growth inhibition, and improved host survival.
- Further investigation into optimizing dosage and minimizing toxicity is warranted.