Aptamer modification improves the adenoviral transduction of malignant glioma cells

Adenovirus has shown increasing promise in the gene-viral therapy for glioblastoma, a treatment strategy that relies on the delivery of viruses or transgenes into tumor cells. However, targeting of adenovirus to human glioblastoma remains a challenge due to the low expression level of coxsackie and adenovirus receptor (CAR) in glioma cells. Aptamers are small and highly structured single-stranded oligonucleotides that bind at high affinity to a target molecule, and are good candidates for targeted imaging and therapy. In this study, to construct an aptamer-modified Ad5, we first genetically modified the HVR5 of Ad hexon by biotin acceptor peptide (BAP), which would be metabolically biotinylated during production in HEK293 cells, and then attached the biotin labeled aptamer to the modified Ad through avidin–biotin binding. The aptamers used in this study includes AS1411 and GBI-10. The former is a DNA aptamer that can bind to nucleolin, a nuclear matrix protein found on the surface of cancer cells. The latter is a DNA aptamer that can recognize the extracellular matrix protein tenascin-C on the surface of human glioblastoma cells. To examine if aptamer-modification of the hexon protein could improve the adenoviral transduction efficiency, a glioblastoma cell line, U251, was transduced with aptamer-modified Ads. The transduction efficiency of AS1411- or GBI-10-modified Ad was approximately 4.1-fold or 5.2-fold higher than that of the control. The data indicated that aptamer modified adenovirus would be a useful tool for cancer gene therapy.