title: Intercellular delivery of thymidine kinase prodrug activating enzyme by the herpes simplex virus protein, VP22.
abstract: We demonstrate that fusion proteins consisting of the herpes simplex virus (HSV) transport protein VP22 linked in frame to HSV thymidine kinase (tk) retain the ability to be transported between cells. In vivo radiolabelling experiments and in vitro assays show that the fusion proteins also retain tk activity. When transfected COS cells, acting as a source of the VP22-tk chimera, were co-plated on to gap junction-negative neuroblastoma cells, ganciclovir treatment induced efficient cell death in the recipient neuroblastoma cell monolayer. No such effect was observed with COS cells transfected with tk alone. Tumours established in mice with neuroblastoma cell lines expressing VP22-tk regressed upon administration of ganciclovir. Furthermore tumours established from 50:50 mixtures of VP22-tk transduced and nontransduced cells also regressed while no significant effect was observed in similar experiments with cells transduced with tk alone. VP22 mediated transport may thus have application in a clinical setting to amplify delivery of the target protein in enzyme-prodrug protocols.
authors.affiliation: Department of Medicine, Huddinge Hospital, Karolinska Institute, Sweden.
authors.forename: M S
authors.initials: MS
authors.lastname: Dilber
authors.forename: A
authors.initials: A
authors.lastname: Phelan
authors.forename: A
authors.initials: A
authors.lastname: Aints
authors.forename: A J
authors.initials: AJ
authors.lastname: Mohamed
authors.forename: G
authors.initials: G
authors.lastname: Elliott
authors.forename: C I
authors.initials: CI
authors.lastname: Smith
authors.forename: P
authors.initials: P
authors.lastname: O'Hare
mesh_terms: D000818:Animals; D000963:Antimetabolites / Q000627:therapeutic use; D019556:COS Cells; D015774:Ganciclovir / Q000627:therapeutic use; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D009369:Neoplasms / Q000628:therapy*; D011355:Prodrugs / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D013937:Thymidine Kinase / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics*
chemical_list: D000963:Antimetabolites; D011355:Prodrugs; D011993:Recombinant Fusion Proteins; D015678:Viral Structural Proteins; C073413:herpes simplex virus type 1 protein VP22; D013937:Thymidine Kinase; D015774:Ganciclovir