title: In vitro primary cell culture as a physiologically relevant method for preclinical testing of human oncolytic adenovirus.
abstract: Ad[I/PPT-E1A] is an oncolytic adenovirus that specifically kills prostate cells via restricted replication by a prostate-specific regulatory element. Off-target replication of oncolytic adenoviruses would have serious clinical consequences. As a proposed ex vivo test, we describe the assessment of the specificity of Ad[I/PPT-E1A] viral cytotoxicity and replication in human nonprostate primary cells. Four primary nonprostate cell types were selected to mimic the effects of potential in vivo exposure to Ad[I/PPT-E1A] virus: bronchial epithelial cells, urothelial cells, vascular endothelial cells, and hepatocytes. Primary cells were analyzed for Ad[I/PPT-E1A] viral cytotoxicity in MTS assays, and viral replication was determined by hexon titer immunostaining assays to quantify viral hexon protein. The results revealed that at an extreme multiplicity of infection of 500, unlikely to be achieved in vivo, Ad[I/PPT-E1A] virus showed no significant cytotoxic effects in the nonprostate primary cell types apart from the hepatocytes. Transmission electron microscopy studies revealed high levels of Ad[I/PPT-E1A] sequestered in the cytoplasm of these cells. Adenoviral green fluorescent protein reporter studies showed no evidence for nuclear localization, suggesting that the cytotoxic effects of Ad[I/PPT-E1A] in human primary hepatocytes are related to viral sequestration. Also, hepatocytes had increased amounts of coxsackie adenovirus receptor surface protein. Active viral replication was only observed in the permissive primary prostate cells and LNCaP prostate cell line, and was not evident in any of the other nonprostate cells types tested, confirming the specificity of Ad[I/PPT-E1A]. Thus, using a relevant panel of primary human cells provides a convenient and alternative preclinical assay for examining the specificity of conditionally replicating oncolytic adenoviruses in vivo.
authors.affiliation: YCR Cancer Research Unit, Department of Biology, University of York , Heslington, York YO10 5DD, United Kingdom. rea3@york.ac.uk
authors.forename: R E
authors.initials: RE
authors.lastname: Adamson
authors.forename: A A
authors.initials: AA
authors.lastname: Frazier
authors.forename: H
authors.initials: H
authors.lastname: Evans
authors.forename: K F
authors.initials: KF
authors.lastname: Chambers
authors.forename: E
authors.initials: E
authors.lastname: Schenk
authors.forename: M
authors.initials: M
authors.lastname: Essand
authors.forename: R
authors.initials: R
authors.lastname: Birnie
authors.forename: R R
authors.initials: RR
authors.lastname: Mitry
authors.forename: A
authors.initials: A
authors.lastname: Dhawan
authors.forename: N J
authors.initials: NJ
authors.lastname: Maitland
mesh_terms: D000260:Adenoviruses, Human; D000818:Animals; D045744:Cell Line, Tumor; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism / Q000821:virology; D004847:Epithelial Cells / Q000378:metabolism / Q000821:virology; D015870:Gene Expression; D005822:Genetic Vectors; D022781:Hepatocytes / Q000378:metabolism / Q000821:virology; D006801:Humans; D008297:Male; D051379:Mice; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D050130:Oncolytic Virotherapy / Q000379:methods*; D050504:Oncolytic Viruses; D009928:Organ Specificity; D061251:Primary Cell Culture; D011471:Prostatic Neoplasms / Q000473:pathology / Q000628:therapy*; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication
chemical_list: D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D014764:Viral Proteins