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CD46 represents a target for adenoviral gene therapy of malignant glioma
Ilya V Ulasov1, Matthew A Tyler, Sophy Zheng
1Division of Neurosurgery, University of Chicago, IL 60637, USA.
Abstract:
Malignant gliomas remain refractory to adenovirus serotype 5 (Ad5) gene therapy because of the lack of the primary adenoviral receptor, the coxsackie-adenovirus receptor (CAR), on tumor cells. To bypass the dependence on CAR, we investigated the expression of adenovirus serotype 3 (Ad3) receptor, or CD46, on glioma cells. First, we analyzed the expression of CD46 by RT-PCR on primary and passaged glioma cells. We then performed immunofluorescence studies to examine protein expression of CAR and CD46 on the same tumor lines. Finally, we constructed a replication-defective Ad vector that binds to CD46 and contains a luciferase transgenic cassette in place of the deleted E1 region: Ad5/3 (containing tail/shaft domain of Ad5 and knob domain of Ad3). These vectors were analyzed in vitro and in vivo against malignant glioma and compared with wild-type Ad5 or control vector Ad3/5 (containing tail of Ad5, shaft of Ad3, and knob of Ad5). The chimeric vector Ad5/3 showed a significant increase in the transduction efficiency of glioma tumor cells. At the same time, blocking the CD46 receptor caused a 65% inhibition of adenoviral infection when using Ad5/3. Taken together, these results indicate that CD46 is overexpressed by malignant glioma. Retargeting to the Ad3 receptor enhances gene transfer and offers a novel target for gene therapy of malignant brain tumors.
Insights
Malignant gliomas are difficult to treat with adenovirus serotype 5 (Ad5) gene therapy. Targeting the adenovirus serotype 3 (Ad3) receptor, CD46, significantly enhances gene transfer in glioma cells.
Area of Science:
- Oncology
- Virology
- Gene Therapy
Background:
- Malignant gliomas are challenging for adenovirus serotype 5 (Ad5) gene therapy due to low expression of the coxsackie-adenovirus receptor (CAR).
- Alternative viral receptors are needed to improve Ad5-based gene delivery to glioma cells.
Purpose of the Study:
- To investigate the expression of the adenovirus serotype 3 (Ad3) receptor, CD46, on malignant glioma cells.
- To develop and evaluate a novel Ad5/3 chimeric vector for enhanced gene transfer targeting CD46 in gliomas.
Main Methods:
- RT-PCR and immunofluorescence were used to analyze CD46 and CAR expression on glioma cells.
- A replication-defective Ad5/3 chimeric vector, targeting CD46, was constructed.
- In vitro and in vivo studies compared Ad5/3 vector efficiency against Ad5 and Ad3/5 vectors in malignant glioma models.
Main Results:
- CD46 receptor is significantly overexpressed on malignant glioma cells.
- The Ad5/3 chimeric vector demonstrated a substantial increase in transduction efficiency in glioma cells compared to control vectors.
- Blocking the CD46 receptor inhibited Ad5/3 mediated infection by 65%, confirming CD46 as the primary entry receptor.
Conclusions:
- CD46 is a viable and overexpressed receptor on malignant gliomas, suitable for targeted gene therapy.
- Retargeting adenovirus vectors to CD46 via the Ad3 knob enhances gene transfer efficiency.
- This strategy offers a promising new avenue for gene therapy of malignant brain tumors.
