Characterization of the mechanism of zidovudine uptake by rat conditionally immortalized syncytiotrophoblast cell line TR-TBT
Characterization of the mechanism of zidovudine uptake by rat conditionally immortalized syncytiotrophoblast cell line TR-TBT
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DOI：
10.1007/s11095-008-9564-9
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发表时间：
2008-07-01
影响因子：
3.7
通讯作者：
Nakashima, E.
中科院分区：
文献类型：
--
作者：
Sai, Y.;Nishimura, T.;Nakashima, E.
目的。目的：利用本课题组建立的合体滋养层细胞系，研究核苷类逆转录酶抑制剂齐多夫定(AZT)在合体滋养层细胞中的摄取机制。研究了几种转运蛋白抑制剂对tr-TBT 18d-1细胞初始和稳态顶端摄取AZT的影响，以确定所涉及的转运蛋白(S)。AZT的初始吸收是不依赖于钠且可饱和的；K(M)值约为16亩M。硝基苯硫肌苷(NBMPR)、丙磺舒和西咪替丁对AZT的饱和吸收几乎没有影响，表明有机阴离子转运体(OATS和OATPs)、有机阳离子转运体(OCTs)和平衡核苷转运体(Ents)等特征较好的转运体不参与。然而，胸腺嘧啶核苷和2‘-脱氧尿嘧啶核苷强烈抑制AZT摄取。这些结果表明，一种未知的核苷摄取转运体对AZT的摄取负责。环孢菌素A、Ko143和丙磺舒对Tr-TBT 18d-1细胞内AZT的蓄积影响不大，提示转运体介导的AZT外排不是实质性的。我们的结果表明，Tr-TBT 18d-1对AZT的饱和摄取是由一种迄今未知的转运蛋白介导的。
Purpose. To characterize the uptake mechanism of zidovudine (AZT), a nucleoside reverse transcriptase inhibitor, in syncytiotrophoblast cells using the TR-TBT 18d-1 cell line previously established by our group.Materials and Methods. The effects of several transporter inhibitors on the initial and steady-state apical uptake of AZT by TR-TBT 18d-1 were characterized, in order to identify the transporter(s) involved.Results. Initial uptake of AZT was sodium-independent and saturable; the K(m) value was about 16 mu M. Nitrobenzylthioinosine (NBMPR), probenecid and cimetidine each had little effect on the saturable AZT uptake, indicating that well characterized transporters, such as organic anion transporters (OATs and OATPs), organic cation transporters (OCTs) and equilibrative nucleoside transporters (ENTs), are not involved. However, thymidine and 2'-deoxyuridine strongly inhibited AZT uptake. These results suggest that an unidentified nucleoside uptake transporter is responsible for the uptake of AZT. Cyclosporin A, Ko143 and probenecid had little effect on AZT accumulation by TR-TBT 18d-1 cells, suggesting that transporter-mediated efflux of AZT is not substantial.Conclusion. Our results indicate that saturable AZT uptake into TR-TBT 18d-1 is mediated by a so-far-unidentified transporter.