In vitro studies with two human organic anion transporters: OAT2 and OAT7

Abstract

1. Penciclovir, ganciclovir, creatinine, para-aminohippuric acid (PAH), ketoprofen, estrone 3-O-sulfate (E3S), dehydroepiandrosterone 3-O-sulfate (DHEAS) and cyclic guanosine monophosphate (cGMP) were screened as substrates of human liver organic anion transporters OAT2 and OAT7.

2. For OAT7, high uptake ratios (versus mock transfected HEK293 cells) of 29.6 and 15.3 were obtained with E3S and DHEAS. Less robust uptake ratios (≤3.6) were evident with the other substrates. OAT2 (transcript variant 1, OAT2-tv1) presented high uptake ratios of 30, 13, ∼35, ∼25, 8.5 and 9 with cGMP, PAH, penciclovir, ganciclovir, creatinine and E3S, respectively. No uptake was observed with DHEAS.

3. Although not a substrate of either transporter, ketoprofen did inhibit transfected OAT2-tv1 (IC₅₀ of 17, 22, 23, 24, 35 and 586 μM; creatinine, ganciclovir, penciclovir, cGMP, E3S and prostaglandin F2α, respectively) and penciclovir uptake (IC₅₀ = 27 µM; >90% inhibition) by plated human hepatocytes (PHH).

4. It is concluded that penciclovir and ketoprofen may serve as useful tools for the assessment of OAT2 activity in PHH. However, measurement of OAT7 activity therein will prove more challenging, as high uptake rates are evident with E3S and DHEAS only and both sulfoconjugates are known to be substrates of organic anion transporting polypeptides.

Keywords:

• Inhibition
• ketoprofen
• liver
• OAT2
• OAT7
• organic anion transporter
• penciclovir
• substrate
• transporter

Acknowledgements

The authors would like to thank Falgun Shah, PhD (Pfizer Inc.) for providing the OAT substrate physico-chemical property information (Supplemental Figure 1). Renato J. Scialis, PhD (Pfizer Inc.) is acknowledged for generating the NTCP (taurocholate) and OATP (estrone 3-O-sulfate) HEK293 cell data (Supplemental Table 2). Ellis Bixler (Sekisui XenoTech LLC) and Julie Keefer (Pfizer Inc.) are acknowledged for the evaluation of RIFsv as an inhibitor of OAT7 and LC-MS/MS support (PHH, OAT2-tv1), respectively. Brian Ogilvie (Sekisui XenoTech LLC) is acknowledged for review of the manuscript.

Declaration of interest

No potential conflict of interest was reported by the authors.

Supplementary material available online