Targeting malignant gliomas with a glial fibrillary acidic protein (GFAP)-selective oncolytic adenovirus.
Glial fibrillary acidic protein (GFAP) is an intermediate filament protein abundantly expressed in malignant gliomas. We have constructed a novel oncolytic adenovirus, Ad5-gfa2(B)3-E1, for treatment of these tumors. In this construct, the E1 region is under control of the tissue-specific GFAP promoter (gfa2) with three additional copies of the glial specific 'B' enhancer. Infection of a GFAP-positive cell line with Ad5-gfa2(B)3-E1 resulted in E1A and E1B expression at 75% and 30% of the levels obtained after wtAd5 infection. Q-PCR showed that Ad5-gfa2(B)3-E1 replicated 4.5 times more efficiently in the GFAP-positive than in the GFAP-negative cell lines. Cell viability assays showed efficient elimination of GFAP-positive cells by Ad5-gfa2(B)3-E1, in some cell lines as efficiently as wtAd5, while the elimination was attenuated in GFAP-negative cell lines. When tested in human tumor xenografts in nude mice, Ad5-gfa2(B)3-E1 effectively suppressed the growth of GFAP-positive SNB-19 glial tumors but not of GFAP-negative A549 lung tumors. In Ad5-gfa2(B)3-E1, the E3 region was deleted to create space for future insertion of heterologous therapeutic genes. Experiments with dl7001, an E3-deleted variant of wtAd5, confirmed that the specificity of Ad5-gfa2(B)3-E1 replication was based on the promoter driving E1 and not on the E3 deletion. Strategies to further improve the efficacy of Ad5-gfa2(B)3-E1 for the treatment of malignant gliomas include the insertion of therapeutic genes in E3 or retargeting to receptors that are more abundantly expressed on primary glioma cells than CAR.
Horst
Maarten ter
Mt
Department of Neurology, Erasmus University Medical Center, Rotterdam, The Netherlands.
Brouwer
Eric
E
Verwijnen
Suzanne
S
Rodijk
Mark
M
de Jong
Marion
M
Hoeben
Rob
R
de Leeuw
Bertie
B
Smitt
Peter Sillevis
PS
D000256:Adenoviridae / Q000235:genetics* / Q000502:physiology; D001932:Brain Neoplasms / Q000473:pathology / Q000628:therapy*; D005904:Glial Fibrillary Acidic Protein / Q000037:antagonists & inhibitors*; D005910:Glioma / Q000473:pathology / Q000628:therapy*; D006801:Humans; D016133:Polymerase Chain Reaction; D014779:Virus Replication
D005904:Glial Fibrillary Acidic Protein