title: Inducible gene expression in tumors colonized by modified oncolytic vaccinia virus strains.
abstract: Exogenous gene induction of therapeutic, diagnostic, and safety mechanisms could be a considerable improvement in oncolytic virotherapy. Here, we introduced a doxycycline-inducible promoter system (comprised of a tetracycline repressor, several promoter constructs, and a tet operator sequence) into oncolytic recombinant vaccinia viruses (rVACV), which were further characterized in detail. Experiments in cell cultures as well as in tumor-bearing mice were analyzed to determine the role of the inducible-system components. To accomplish this, we took advantage of the optical reporter construct, which resulted in the production of click-beetle luciferase as well as a red fluorescent protein. The results indicated that each of the system components could be used to optimize the induction rates and had an influence on the background expression levels. Depending on the given gene to be induced in rVACV-colonized tumors of patients, we discuss the doxycycline-inducible promoter system adjustment and further optimization.
  
  
  OBJECTIVE
  Oncolytic virotherapy of cancer can greatly benefit from the expression of heterologous genes. It is reasonable that some of those heterologous gene products could have detrimental effects either on the cancer patient or on the oncolytic virus itself if they are expressed at the wrong time or if the expression levels are too high. Therefore, exogenous control of gene expression levels by administration of a nontoxic inducer will have positive effects on the safety as well as the therapeutic outcome of oncolytic virotherapy. In addition, it paves the way for the introduction of new therapeutic genes into the genome of oncolytic viruses that could not have been tested otherwise.
authors: Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany Genelux Corporation, San Diego Science Center, San Diego, California, USA js@genelux.com szalay@biozentrum.uni-wuerzburg.de.
authors: Jochen
authors: J
authors: Stritzker
authors: Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany.
authors: Sascha
authors: S
authors: Huppertz
authors: Genelux Corporation, San Diego Science Center, San Diego, California, USA Department of Radiation Oncology, Moores Cancer Center, University of California, San Diego, La Jolla, California, USA.
authors: Qian
authors: Q
authors: Zhang
authors: Genelux Corporation, San Diego Science Center, San Diego, California, USA.
authors: Ulrike
authors: U
authors: Geissinger
authors: Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany Genelux GmbH, Bernried, Germany.
authors: Barbara
authors: B
authors: Härtl
authors: Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany Genelux Corporation, San Diego Science Center, San Diego, California, USA.
authors: Ivaylo
authors: I
authors: Gentschev
authors: Department of Biochemistry, Biocenter, University of Würzburg, Würzburg, Germany Department of Radiation Oncology, Moores Cancer Center, University of California, San Diego, La Jolla, California, USA js@genelux.com szalay@biozentrum.uni-wuerzburg.de.
authors: Aladar A
authors: AA
authors: Szalay
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D000818:Animals; D002522:Chlorocebus aethiops; D004318:Doxycycline / Q000494:pharmacology; D005347:Fibroblasts / Q000473:pathology / Q000821:virology; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D005822:Genetic Vectors; D006367:HeLa Cells; D064593:Heterografts; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D050130:Oncolytic Virotherapy / Q000379:methods*; D050504:Oncolytic Viruses / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014616:Vaccinia virus / Q000235:genetics*; D014779:Virus Replication; D000097573:Red Fluorescent Protein
chemical_list: D004318:Doxycycline; D008156:Luciferases; D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein