Tumor-specific in vivo transfection with HSV-1 thymidine kinase gene using a sindbis viral vector as a basis for prodrug ganciclovir activation and PET Journal Article


Authors: Tseng, J. C.; Zanzonico, P. B.; Levin, B.; Finn, R.; Larson, S. M.; Meruelo, D.
Article Title: Tumor-specific in vivo transfection with HSV-1 thymidine kinase gene using a sindbis viral vector as a basis for prodrug ganciclovir activation and PET
Abstract: One type of gene therapy of tumors, gene-directed enzymeprodrug therapy (GDEPT), holds considerable promise, although practical considerations limit its clinical applicability. These include the lack of acceptable noninvasive methods that are adaptable to humans for selective tumor targeting of the therapeutic genetic material. Sindbis virus is an oncolytic, α-virus that selectively targets tumors through the 67-kDa laminin receptor (LAMR). In this report we describe a novel approach that permits tumor-selective tumor targeting and quantitative in vivo monitoring using PET of a commonly applied GDEPT, based on herpes simplex virus thymidine kinase type 1 (HSVtk) and ganciclovir (GCV). Methods: Sindbis/tk vectors were harvested from the supernatant of in vitro cultures of a packaging cell produced by electroporation of both replicon RNA (SinRep5/tk) and helper RNA (DH-BB) into baby hamster kidney (BHK) cells. The therapeutic effect of GCV was determined by incubation of transfected tumor cells with increasing concentrations of GCV. BHK tumors growing as xenografts in severe combined immunodeficiency disease (SCID) mice were transfected by parenteral administration of the vector. Imaging was performed using small-animal PET at 2 h after injection of 18F fluoro-ethyl- arabinosyluridine (18F-FEAU) and 24 h after the final parenteral injection of Sindbis/tk viral vector. Results: The vector efficiently expresses the HSVtk enzyme in infected tumor cells, both in vitro and in vivo. High levels of HSVtk expression ensure sufficient prodrug GCV conversion and activation for bystander effects that kill the surrounding untransduced tumor cells. Tumor localization of intravenously administered 18F-FEAU after 2 and 3 parenteral vector treatments of Sindbis/tk demonstrated uptake of 1.7 and 3.1 %ID/g (percentage injected dose per gram), respectively. Conclusion: The vector efficiently targets the HSVtk enzyme gene into Sindbis-infected tumor cells. High levels of HSVtk expression ensure sufficient prodrug GCV conversion and activation for bystander effects that killed many surrounding untransduced tumor cells. In addition, the HSVtk activities in tumors can be noninvasively monitored using PET after systemic Sindbis/tk treatments as a basis for determining the levels and tissue distribution of vector, noninvasively in living animals, and for optimizing in vivo transfection rates of tumor. Copyright © 2006 by the Society of Nuclear Medicine, Inc.
Keywords: controlled study; protein expression; unclassified drug; genetics; nonhuman; drug targeting; positron emission tomography; methodology; animal cell; mouse; animal; metabolism; mouse mutant; animals; mice; tumor localization; animal experiment; animal model; in vivo study; antineoplastic activity; in vitro study; tumor xenograft; mice, scid; transfection; gene transfer; viral gene delivery system; rna; chemistry; kidney; genetic transfection; cell culture; kidney tumor; positron-emission tomography; tumor cell; radiopharmaceutical agent; electroporation; therapy effect; thymidine kinase; herpesvirus 1, human; tumor growth; immune deficiency; pet; thymidine kinase 1; herpes simplex virus 1; ganciclovir; scid mouse; prodrug; virus vector; gene transfer techniques; 5 ethyl 2' fluorouracil arabinoside f 18; prodrugs; bystander effect; cricetinae; replicon; in vivo imaging; hamster; drug activation; gene-directed enzyme-prodrug therapy; herpes simplex virus thymidine kinase type 1; sindbis vector; herpes simplex virus thymidine kinase 1; cell strain bhk; sindbis virus
Journal Title: Journal of Nuclear Medicine
Volume: 47
Issue: 7
ISSN: 0161-5505
Publisher: Society of Nuclear Medicine  
Date Published: 2006-07-01
Start Page: 1136
End Page: 1143
Language: English
PUBMED: 16818948
PROVIDER: scopus
DOI/URL:
Notes: --- - "Cited By (since 1996): 24" - "Export Date: 4 June 2012" - "CODEN: JNMEA" - "Source: Scopus"
Citation Impact
MSK Authors
  1. Ronald D Finn
    278 Finn
  2. Pat B Zanzonico
    315 Zanzonico
  3. Steven M Larson
    921 Larson