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Journal of Virology, June 2000, p. 5320-5328, Vol. 74, No. 11
Gene Therapy
Laboratories1 and Departments of
Pediatrics2 and
Surgery,3 University of Southern
California School of Medicine, and the Department of
Molecular Pharmacology and Toxicology, University of Southern
California School of Pharmacy,4 Los Angeles,
California 90033
Received 9 December 1999/Accepted 1 March 2000
Adhesion receptors expressed on the surfaces of tumor-activated
endothelial cells provide an advantageous locus for targeting gene
therapy vectors to angiogenic tissues and/or tumor vasculature. In this
study, we engineered a series of Asn-Gly-Arg (NGR)-containing congeners
of the presumptive cell binding motif contained within the ninth type
III repeat of fibronectin and displayed these tumor vasculature
targeting motifs (TVTMs) within the context of Moloney murine leukemia
envelope "escort" proteins. Comparative studies of envelope
incorporation into viral particles and evaluation of the cell binding
properties of the targeted vectors revealed critical structural
features, thus identifying a subset of optimal TVTMs. Utilizing a
modified ELISA to evaluate viral binding to target cells, we observed a
significant down-regulation of TVTM-virion binding to human endothelial
cells following sustained (48-h) exposure to VEGF. Normalized for
equivalent titers (106 CFU/ml), as assayed on NIH 3T3
cells, vectors displaying TVTM escort proteins significantly enhanced
the transduction efficiency from 12.2 to 37.4% in human KSY-1
endothelial cell cultures (P < 0.001) and from 0.4 to
4.1% in human umbilical vein endothelial cell (HUVEC) cultures
(P < 0.001). In summary, these studies utilized an
engineering approach to identify a subset of TVTMs that are stably
incorporated as envelope "escort" proteins into retroviral vectors
and that, by functioning to improve the binding efficiency and
transduction of both HUVEC and KSY1 endothelial cells, may have
therapeutic potential for targeting gene delivery to the tumor-associated vasculature.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Incorporation of Tumor Vasculature Targeting Motifs
into Moloney Murine Leukemia Virus Env Escort Proteins Enhances
Retrovirus Binding and Transduction of Human Endothelial
Cells
*
Corresponding author. Mailing address: Department of
Surgery and Gene Therapy Laboratories, University of Southern
California School of Medicine, 1975 Zonal Ave. KAM 300, Los Angeles, CA
90089. Phone: (323) 442-1548. Fax: (323) 442-3618. E-mail:
fhall{at}genome2.hsc.usc.edu.
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