title: Gene expression in intrahepatic tumors through DNA recombination by a replication-activated adenovirus vector.
abstract: One strategy for improving selectivity of gene therapy is the use of a replication-activated adenovirus vector that mediates transgene expression specifically in tumor cells through homologous recombination of viral genomes. In this study, we compared replication-activated adenovirus containing inverted repeats (Ad.IR-BG) with IR-deficient virus (Ad.BG) for selective gene expression in hepatocellular carcinoma and colon carcinoma metastases in the liver. We found that Ad.IR-BG conferred specific gene expression in both carcinoma cells, with minimal expression in hepatocytes and colon epithelial cells. This occurred through viral DNA recombination in Ad.IR-BG-infected tumor cells but not in normal cells. Hydroxyurea, which blocks DNA replication, inhibited DNA recombination and beta-gal expression in Ad.IR-BG-infected but not Ad.BG-infected tumor cells. Finally, systemic injection of Ad.IR-BG into tumor xenografts in nude mice significantly improved selectivity of gene expression in tumors with minimal expression in normal tissues. Viral DNA recombination, which was absent in normal liver, was detected in Ad.IR-BG-infected tumors but not in Ad.BG-infected tissue. These findings demonstrated that replication-activated adenovirus can mediate tumor-specific gene expression through viral DNA recombination, which is otherwise deficient in normal cells.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Xiao W
authors.initials: XW
authors.lastname: Huang
authors.forename: Andre
authors.initials: A
authors.lastname: Lieber
authors.forename: Zhao Y
authors.initials: ZY
authors.lastname: Tang
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.forename: Mary P
authors.initials: MP
authors.lastname: Moyer
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000628:therapy; D004247:DNA / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000628:therapy; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D004279:DNA, Viral; D004247:DNA; D001616:beta-Galactosidase; D006918:Hydroxyurea