Fiber-knob modifications enhance adenoviral tropism and gene transfer in malignant glioma.
BACKGROUND
Malignant gliomas remain refractory to Ad5-mediated gene therapy due to deficiency of the coxsackie adenovirus receptor on tumor cells. The purpose of this study was to evaluate whether changes in adenoviral tropism can enhance gene transfer in the context of malignant glioma.


METHODS
We have identified several receptors that are over-expressed on tumor cells and created a series of pseudotyped Ad5 vectors that recognize these receptors: Ad5-RGD which binds alpha(v)beta3/alpha(v)beta5 integrins; Ad5/3 which contains adenovirus serotype 3 knob and binds to CD46; Ad5-Sigma which incorporates the reovirus sigma knob and binds to junctional adhesion molecule-1; and Ad5-pk7 which contains the polylysine motif and binds heparan sulfate proteoglycans. We also investigated the Ad5-CAV1 vector, which contains the knob of canine adenovirus type 1, a virus previously shown to infect glioma via an unknown mechanism. In this study, we compared these modified vectors for their ability to promote the expression of luciferase transgene both in vitro and in vivo.


RESULTS
Our results indicate that all five modified vectors attained higher mean luciferase activity vs. control. Among them, Ad5-CAV1 and Ad5-pk7 attained the highest transduction efficiency independent of different tumor lines or infection time. Ad5-Sigma and Ad5-pk7 also demonstrated the least nonspecific infection in normal human astrocytes. Most importantly, Ad5-pk7 achieved 1000-fold increased transgene expression in human glioma xenografts in vivo.


CONCLUSIONS
These results indicate that modifications of adenoviral tropism can enhance gene transfer in tumors that are poorly susceptible to adenoviral vectors and warrant further development of Ad5-pk7 for glioma gene therapy.
Zheng
Sophy
S
Division of Neurosurgery, University of Chicago, Chicago, Illinois 60637, USA.
Ulasov
Ilya V
IV
Han
Yu
Y
Tyler
Matthew A
MA
Zhu
Zeng B
ZB
Lesniak
Maciej S
MS
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D001932:Brain Neoplasms / Q000737:chemistry / Q000628:therapy*; D036022:Capsid Proteins / Q000032:analysis; D045744:Cell Line, Tumor; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D005910:Glioma / Q000737:chemistry / Q000628:therapy*; D006801:Humans; D008099:Liver / Q000737:chemistry; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D051379:Mice; D016513:Mice, SCID; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism; D014161:Transduction, Genetic / Q000379:methods*; D019076:Transgenes; D023041:Xenograft Model Antitumor Assays
D036022:Capsid Proteins; D011956:Receptors, Cell Surface; C018315:hexon capsid protein, Adenovirus; D008156:Luciferases