title: Replication-deficient adenovirus induces host topoisomerase I activity: implications for adenovirus-mediated gene expression.
abstract: Replication-deficient adenoviruses are useful vectors for the transfer of therapeutic transgenes to malignant and non-malignant tissues. Yet their clinical application is limited by the potential toxicity of viral infection and the transient nature of transgene expression. Although transgene expression from adenovirus vectors is initially higher than expression of transgenes transduced by other viral or non-viral vectors, it is often insufficient to generate a significant therapeutic effect. We addressed this issue by searching for DNA-targeted viral-induced host responses potentially restricting transgene expression. Nuclear protein extracts from livers of rats systemically infected with replication-deficient adenovirus exhibited enhanced topoisomerase I activity compared with extracts from uninfected animals. Consequently, the inhibition of topoisomerase I by the anti-cancer drug topotecan greatly enhanced transgene expression in adenovirus-infected hepatic cells, colon cancer and prostate cancer cell cultures, mouse liver, human ex vivo tumor specimens, and mouse tumor in vivo. The enhancement could not be ascribed to non-specific genotoxic stress, cell death, or cell-cycle perturbation. These findings are significant for gene therapy as they reveal novel aspects of the host anti-adenovirus response and set the stage for the development of a rational molecular-pharmacological approach to increase the effectiveness, and safety, of adenovirus-mediated cancer therapeutics.
authors.affiliation: Department of Surgery, Hadassah University Medical Center, Jerusalem, Israel. gzamir@md.huji.ac.il
authors.forename: Gideon
authors.initials: G
authors.lastname: Zamir
authors.forename: Evelyne
authors.initials: E
authors.lastname: Zeira
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Gelman
authors.forename: Abraham
authors.initials: A
authors.lastname: Shaked
authors.forename: Kim M
authors.initials: KM
authors.lastname: Olthoff
authors.forename: Ahmed
authors.initials: A
authors.lastname: Eid
authors.forename: Eithan
authors.initials: E
authors.lastname: Galun
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000096:biosynthesis*; D003673:Defective Viruses / Q000235:genetics* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000201:enzymology / Q000235:genetics / Q000628:therapy; D051381:Rats; D011917:Rats, Inbred Lew; D059004:Topoisomerase I Inhibitors; D019772:Topotecan / Q000494:pharmacology; D014161:Transduction, Genetic
chemical_list: D017931:DNA Primers; D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D019772:Topotecan; D004264:DNA Topoisomerases, Type I