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Massive apoptotic cell death in chemically induced rat urinary bladder carcinomas following in situ HSVtk electrogene
Masa-Aki Shibata1, Taisuke Horiguchi, Junji Morimoto
1Department of Anatomy and Biology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka 569-8686, Japan.
Background:
Gene delivery in current gene therapy studies relies largely on recombinant viral vectors. However, the safety of this method is still under investigation. The effectiveness of in vivo electrogene transfer as a means of gene therapy for rat bladder cancers using the herpes simplex virus 1 thymidine kinase (HSVtk) gene in combination with ganciclovir (GCV) was therefore investigated.
Methods:
The killing effects of HSVtk/GCV therapy were evaluated in transitional cell carcinoma (TCC) cells in vitro and in vivo. In animal experiments, electrogene transfer of HSVtk into N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced rat bladder tumors was conducted followed by GCV administration.
Results:
In vitro studies demonstrated that approximately 50-70% of the TCC cells died as a result of transfection with pHSVtk and GCV administration and that this treatment was associated with decreased DNA synthesis and elevated activities of caspase-3, -8 and -9. A significantly decreased mitochondrial membrane potential was also noted in TCC cells given pHSV tk + GCV. A direct single injection of HSVtk into bladder tumors using in vivo electrogene transfer followed by GCV i.p. administration resulted in significant increases in the levels of apoptosis and histopathological necrosis accompanied by marked inflammation. Active caspase-3 was strongly expressed in the cell death areas of the TCC in rats given pHSVtk/GCV therapy.
Conclusions:
In vivo electrogene transfer results in efficient gene transfer in BBN-induced rat bladder tumors and the HSVtk/GCV prodrug system induces significant cell death which appears to be, at least, mediated via the mitochondrial apoptotic pathway.
Insights
In vivo electrogene transfer effectively delivered the herpes simplex virus 1 thymidine kinase (HSVtk) gene into rat bladder tumors. This gene therapy approach, combined with ganciclovir (GCV), significantly induced cancer cell death via apoptosis.
Area of Science:
- Oncology
- Gene Therapy
- Molecular Biology
Background:
- Current gene therapy predominantly uses viral vectors, raising safety concerns.
- Investigating alternative gene delivery methods is crucial for advancing cancer treatment.
- Electrogene transfer offers a potentially safer and effective gene delivery strategy.
Purpose of the Study:
- To evaluate the efficacy of in vivo electrogene transfer for gene therapy in rat bladder cancers.
- To assess the combined therapeutic effect of the herpes simplex virus 1 thymidine kinase (HSVtk) gene and ganciclovir (GCV).
Main Methods:
- Utilized in vitro and in vivo models of transitional cell carcinoma (TCC).
- Performed electrogene transfer of the HSVtk gene into N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced rat bladder tumors.
- Administered ganciclovir (GCV) post-gene transfer for prodrug activation.
Main Results:
- In vitro: HSVtk/GCV treatment led to 50-70% TCC cell death, reduced DNA synthesis, and increased caspase activity.
- In vivo: Electrogene transfer with HSVtk/GCV induced significant apoptosis, necrosis, and inflammation in rat bladder tumors.
- Observed decreased mitochondrial membrane potential and elevated caspase-3 expression in treated TCC cells.
Conclusions:
- In vivo electrogene transfer facilitates efficient gene delivery to rat bladder tumors.
- The HSVtk/GCV system effectively induces cancer cell death, at least partly through the mitochondrial apoptotic pathway.