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Antimicrob Agents Chemother. 2017 Mar 24;61(4). pii: e01725-16. doi: 10.1128/AAC.01725-16. Print 2017 Apr.

Tenofovir Disoproxil Fumarate Is a New Substrate of ATP-Binding Cassette Subfamily C Member 11.

Author information

1
Pharmacy Program in Biopharmaceutical Sciences, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand.
2
Department of Pharmacology and Toxicology, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand CHINPAISAL_C@su.ac.th.
3
Department of Health and Related Informatics, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand.

Abstract

Tenofovir disoproxil fumarate (TDF), a nucleotide reverse transcriptase inhibitor, after conversion to tenofovir (TFV), is mainly eliminated by glomerular filtration and active tubular secretion. The major adverse effect of tenofovir is nephrotoxicity; however, the exact mechanism remains poorly understood. In this study, the ATP-binding cassette subfamily C member 11 (ABCC11; multidrug resistance protein 8 [MRP8]) transporter, which is abundant in proximal tubular cells, was demonstrated to act as an efflux transporter of tenofovir. Real-time PCR (RT-PCR) and indirect immunofluorescence assays were used to determine MRP8 overexpression in a continuous cell line. Tenofovir accumulations were assessed by cytotoxicity, cellular transport, and vesicular uptake assays. Substrate specificity was confirmed using MK-571, an MRP-specific inhibitor, and methotrexate, which served as a known substrate. Intracellular and intravesicular concentrations of tenofovir were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The 50% cytotoxic concentration (CC50) of TDF in MRP8-overexpressing cells was 4.78 times higher than that of parental cells. Transport assays also showed that the intracellular accumulation of tenofovir in MRP8-overexpressing cells was 55 times lower than that in parental cells and was partly reversed by MK-571. Similarly, an "inside-out" vesicular uptake assay, using Sf9 inverted membrane vesicles to allow measuring of accumulation of the substrates into the vesicles, demonstrated a higher intravesicular concentration of tenofovir in MRP8-overexpressing vesicles than in Sf9 insect control vesicles. These effects were effectively reversed by increasing concentrations of the specific inhibitor MK-571. In conclusion, tenofovir is a new substrate of the MRP8 transporter. An alteration in the activity of this efflux pump may increase the intracellular accumulation of tenofovir in proximal renal tubular cells.

KEYWORDS:

ABCC11; ATP-binding cassette subfamily C11; MRP8 transporter; methotrexate; nephrotoxicity; tenofovir; tenofovir disoproxil fumarate

PMID:
28167562
PMCID:
PMC5365707
DOI:
10.1128/AAC.01725-16
[Indexed for MEDLINE]
Free PMC Article

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