Pharmacokinetics, Pharmacodynamics and Drug MetabolismEnhancement of Zidovudine Transfer to Molt-4 Cells, a Human T-Cell Model, by Dehydroepiandrosterone Sulfate
Section snippets
INTRODUCTION
Zidovudine (AZT), a nucleoside reverse transcriptase inhibitor (NRTI), was one of the first drugs developed to treat human immunodeficiency virus type-1 (HIV-1) infection, and is still recommended for certain patients, especially in pregnancy. To improve the efficacy of antiretroviral therapy with NRTIs, strategies to enhance drug delivery to CD4-positive T cells, the primary target of HIV-1, are required. In particular, the enhancement of influx transporter activity into T cells seems to be a
Chemicals
[3H]AZT (0.47 TBq/mmol), 2′,3′-dideoxyinosine (ddI, [3H]ddI; 1.55 TBq/mmol), [3H]adenosine (0.96 TBq/mmol), [3H]uridine (1.67 TBq/mmol), and [3H] thymidine (2.53 TBq/mmol) were purchased from Moravek Biochemicals, Inc. (Brea, California). All other chemicals were commercial products of analytical grade.
Cell Culture
Molt-4 cells (Lot No. 3984740) were purchased from American Type Cell Culture (Manassas, Virginia). They were cultured in RPMI1640 medium (Sigma, St. Louis, Missouri) supplemented with 10% fetal
Characteristics of Nucleoside Transport in Molt-4 Cells
To characterize the nucleoside uptake mechanism, the effect of NBMPR, a specific inhibitor of ENT, on the uptake of nucleosides in Molt-4 cells was measured. In the untreated control cells, [3H]adenosine uptake was the highest, [3H]AZT and [3H]uridine uptakes were relatively high, and [3H]ddI and [3H]thymidine uptakes were moderate (Fig. 1). [3H]AZT uptake was not inhibited by NBMPR, but was almost completely saturated by an excess of unlabeled AZT (Fig. 1). [3H]ddI and [3H]thymidine uptakes
DISCUSSION
Involvement of the ENT family in uptake of nucleoside and nucleoside analogs by Molt-4 cells was investigated using NBMPR, a well-known ENT-specific inhibitor. Molt-4 cells have been shown to express equilibrative nucleoside transporter 1 (ENT1) and ENT2 mRNAs.17,18 ENT1 is very sensitive to NBMPR and is almost completely inhibited by 0.1 µM NBMPR. ENT2 is less sensitive to NBMPR but is inhibited by 100 µM NBMPR.19 Therefore, we can separate the functions of ENT1 and ENT2 by
Acknowledgements
This study was supported in part by a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science and a grant for the adaptable and seamless technology transfer program through target-driven R&D from the Japan Science and Technology Agency, as well as grants from Suzuken Memorial Foundation, Uehara Memorial Foundation, and Nateglinide Memorial Toyoshima Research and Education Fund.
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