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Antimicrobial Agents and Chemotherapy, July 2001, p. 2082-2091, Vol. 45, No. 7
Departments of
Oncology1 and
Medicine,2 Johns Hopkins University
School of Medicine, Baltimore, Maryland 21231
Received 27 January 2000/Returned for modification 7 April
2000/Accepted 25 April 2001
The presence of Epstein-Barr virus (EBV) in the tumor cells of some
EBV-associated malignancies may facilitate selective killing of these
tumor cells. We show that treatment of an EBV+ Burkitt's
lymphoma cell line with 5-azacytidine led to a dose-dependent induction
of EBV lytic antigen expression, including expression of the viral
thymidine kinase (TK) and phosphotransferase (PT). Azacytidine
treatment for 24 h modestly sensitized the cell line to all nucleosides
tested. To better characterize EBV TK with regard to various nucleoside
analogues, we expressed EBV TK in stable cell clones. Two EBV
TK-expressing clones were moderately sensitive to high doses of
acyclovir and penciclovir (PCV) (62.5 to 500 µM) and to lower doses
of ganciclovir (GCV) and bromovinyldeoxyuridine (BVdU) (10 to 100 µM)
compared to a control clone and were shown to phosphorylate GCV.
Similar experiments in a transient overexpression system showed more
killing of cells transfected with the EBV TK expression vector than of
cells transfected with the control mutant vector (50 µM GCV for 4 days). A putative PT was also studied in the transient transfection
system and appeared similar to the TK in phosphorylating GCV and
conferring sensitivity to GCV, but not in BVdU- or PCV-mediated cell
killing. Induction of EBV kinases in combination with agents such as
GCV merits further evaluation as an alternative strategy to gene
therapy for selective killing of EBV-infected cells.
0066-4804/01/$04.00+0 DOI: 10.1128/AAC.45.7.2082-2091.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Induction of Epstein-Barr Virus Kinases To
Sensitize Tumor Cells to Nucleoside Analogues
*
Corresponding author. Mailing address: 1650 Orleans
St., Cancer Research Building, Rm 389, Baltimore, MD 21231. Phone:
(410) 955-5617. Fax: (410) 955-0961. E-mail:
rambind{at}jhmi.edu.
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