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Published on: March 20, 2026
Fibroblast growth factor-2-retargeted adenoviral vector for selective transduction of primary glioblastoma multiforme
Vinay Gupta1, Weijun Wang, Barbara A Sosnowski
1Department of Pathology, K. Norris Jr. Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90033, USA.
Object:
Adenovirus transduction in gene therapy is dependent on the expression of the coxsackie virus-adenovirus receptor (CAR) for initial binding and on the integrin receptors (avb3, avb5) for viral internalization. Low and variable expression of CAR may be responsible for the low transduction rates seen with native adenoviral vectors. The goal of this study was to demonstrate increased transduction efficiency by retargeting the adenovirus with a fibroblast growth factor (FGF) ligand, FGF-2.
Methods:
The retargeted adenoviruses were used to transduce human glioblastoma multiforme (GBM)-derived ECs (tumor-associated brain endothelial cells [TuBECs]), in which there is minimal CAR expression but a high expression of FGF receptor (FGFR). The results demonstrate that the transduction efficiency of TuBECs can reach as high as 80% when one uses an FGF2-conjugated adenovirus containing green fluorescent protein (FGF2-AdGFP) yet be only 5% when one uses the native adenovirus (AdGFP). The TuBECs were transduced with either a native adenovirus (AdHSV-TK) or a retargeted adenovirus (FGF2-AdHSV-TK), both of which carry the suicide herpes simplex virus-thymidine kinase (HSV-TK) gene. Administered as a cytotoxic prodrug, ganciclovir induced a significant decline in the proliferation rate and increased apoptosis in TuBECs treated with the retargeted adenovirus, compared with its effect on TuBECs treated with the native adenovirus. Increased transduction efficiency was determined by performing GFP-based flow cytometry, and the expression of the TK protein by the retargeted adenovirus was assessed by performing an immunohistochemical analysis focused on HSV-TK. The mechanism of cytotoxicity was determined to be apoptosis by performing a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay.
Conclusions:
Fibroblast growth factor-2-retargeted adenoviral vectors may be used to increase the transduction of GBM-derived endothelial cells, enabling a new and efficient antiangiogenesis strategy for the treatment of malignant gliomas.
Insights
Retargeting adenoviruses with fibroblast growth factor-2 significantly enhances gene therapy for brain tumors. This improved transduction of endothelial cells offers a novel anti-angiogenesis strategy for malignant gliomas.
Area of Science:
- Gene therapy
- Oncology
- Virology
Background:
- Adenovirus transduction efficiency in gene therapy is limited by low coxsackie virus-adenovirus receptor (CAR) expression on target cells.
- Native adenoviral vectors exhibit low and variable transduction rates due to CAR dependency.
- Tumor-associated endothelial cells, such as those in glioblastoma multiforme, often have minimal CAR expression.
Purpose of the Study:
- To improve adenovirus transduction efficiency by retargeting the vector using fibroblast growth factor (FGF).
- To demonstrate enhanced transduction of glioblastoma multiforme-derived endothelial cells (TuBECs) using FGF-2 retargeted adenoviruses.
- To evaluate the therapeutic potential of retargeted adenoviruses for anti-angiogenesis strategies in malignant gliomas.
Main Methods:
- Retargeted adenoviruses conjugated with FGF-2 were used to transduce human glioblastoma multiforme-derived endothelial cells (TuBECs).
- Transduction efficiency was quantified using green fluorescent protein (GFP) expression via flow cytometry.
- Cytotoxicity was assessed by transducing TuBECs with herpes simplex virus-thymidine kinase (HSV-TK) carrying vectors and treating with ganciclovir, followed by apoptosis assays.
Main Results:
- FGF2-conjugated adenovirus achieved up to 80% transduction efficiency in TuBECs, compared to only 5% for native adenovirus.
- Treatment with retargeted adenovirus carrying the HSV-TK gene, followed by ganciclovir, significantly reduced TuBEC proliferation and induced apoptosis.
- Immunohistochemical analysis confirmed HSV-TK expression, and apoptosis was verified by TUNEL assays.
Conclusions:
- Fibroblast growth factor-2 retargeted adenoviral vectors significantly increase transduction of glioblastoma-derived endothelial cells.
- This approach offers a novel and efficient anti-angiogenesis strategy for treating malignant gliomas.
- Retargeting adenoviruses holds promise for enhancing gene therapy delivery to tumors with low CAR expression.
