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Variable efficiency of the thymidine kinase/ganciclovir system in human glioblastoma cell lines: implications for
F G Sturtz1, K Waddell, J Shulok
1Progenitor Inc., Menlo Park, CA 94025, USA.
Abstract:
The gene therapy strategy using the hsvl-thymidine kinase gene (TK) and ganciclovir (GCV) injections that has been used for treating human glioblastomas has not been as effective as expected after the first animal experiments. A better understanding of the different steps involved in this treatment, like gene transfer, gene expression, and sensitivity of the recipient cells, is needed. After proposing sensitivity criteria for the TK/GCV system and for the bystander effect, based on the levels of GCV that can be reached in vivo, we studied seven human glioblastoma cell lines (U87, U118, U251, SNB19, SNB75, SF295, SF539) for their sensitivity to the TK/GCV system. We also studied their in vitro bystander effect and their in vitro transfectability using LipofectAMINE as a transfection enhancer. Among six human glioblastoma cell lines stably transfected with the TK gene, five were sensitive to TK/GCV, and two had a good in vitro bystander effect. The in vitro transfectability of the cell lines tested was low (< or = 1%) compared to that of an established animal cell line, C6 rat glioma, in which 20-30% of the cells can be transfected routinely. According to this in vitro analysis, most of the glioblastoma cell lines should be sensitive to the TK/GCV system, but there is an urgent need for agents to increase transfection efficiency.
Insights
Gene therapy using the herpes simplex virus thymidine kinase (TK) gene and ganciclovir (GCV) shows promise for glioblastoma. Most tested cell lines were sensitive to TK/GCV, but low transfection efficiency remains a challenge.
Area of Science:
- Oncology
- Gene Therapy
- Molecular Biology
Background:
- The herpes simplex virus thymidine kinase (TK) gene and ganciclovir (GCV) gene therapy approach for human glioblastomas has shown suboptimal efficacy post-initial animal studies.
- A deeper comprehension of gene transfer, expression, and recipient cell sensitivity is crucial for improving this therapeutic strategy.
Purpose of the Study:
- To evaluate the sensitivity of seven human glioblastoma cell lines to the TK/GCV system.
- To assess the in vitro bystander effect and transfectability of these glioblastoma cell lines.
- To establish sensitivity criteria for the TK/GCV system and bystander effect based on achievable in vivo GCV levels.
Main Methods:
- Seven human glioblastoma cell lines (U87, U118, U251, SNB19, SNB75, SF295, SF539) were tested for sensitivity to the TK/GCV system.
- In vitro bystander effect and transfectability were evaluated using LipofectAMINE as a transfection enhancer.
- Sensitivity criteria were proposed based on in vivo GCV concentrations.
Main Results:
- Five out of six human glioblastoma cell lines, stably transfected with the TK gene, demonstrated sensitivity to TK/GCV.
- Two cell lines exhibited a notable in vitro bystander effect.
- In vitro transfectability of the tested glioblastoma cell lines was low (≤1%), significantly lower than the C6 rat glioma cell line (20-30%).
Conclusions:
- Most glioblastoma cell lines analyzed in vitro are predicted to be sensitive to the TK/GCV gene therapy system.
- There is a critical need for enhanced transfection agents to improve the efficiency of gene delivery in glioblastoma treatment.
- Improving transfection efficiency is essential for the successful clinical application of TK/GCV gene therapy for glioblastomas.