Interspecies comparison of putative ligand binding sites of human, rat and mouse P-glycoprotein

Abstract

Prior to the clinical phases of testing, safety, efficacy and pharmacokinetic profiles of lead compounds are evaluated in animal studies. These tests are primarily performed in rodents, such as mouse and rats. In order to reduce the number of animal experiments, computational models that predict the outcome of these studies and thus aid in prioritization of preclinical candidates are heavily needed. However, although computational models for human off-target interactions with decent quality are available, they cannot easily be transferred to rodents due to lack of respective data. In this study, we assess the transferability of human P-glycoprotein activity data for development of in silico models to predict in vivo effects in rats and mouse using a structure-based approach. P-glycoprotein (P-gp) is an ATP-dependent efflux transporter that transports xenobiotic compounds such as toxins and drugs out of cells and has a broad substrate and inhibitor specificity. Being mostly expressed at barriers, it influences the bioavailability of drugs and thus contributes also to toxicity. Comparison of the binding site interaction profiles of human, rat and mouse P-gp derived from docking studies with a set of common inhibitors suggests that the inhibitors share potentially similar binding modes. These findings encourage the use of in vitro human P-gp data for predicting in vivo effects in rodents and thus contributes to the 3Rs (Replace, Reduce and Refine) of animal experiments.

Applicability of free drug hypothesis to drugs with good membrane permeability that are not efflux transporter substrates: A microdialysis study in rats

“…In a recent study by Jain et al, 48 the amino acid sequence of P‐glycoprotein was highly conserved among mice, rats, and humans (> 90%), suggesting a high structural similarity. Comparison of the binding site interaction profiles of human, rat, and mouse P‐gp derived from docking studies with a set of common inhibitors further confirmed that P‐gp of rodents and humans share similar binding modes.…”

Optimization of dose and route of administration of the P‐glycoprotein inhibitor, valspodar (PSC‐833) and the P‐glycoprotein and breast cancer resistance protein dual‐inhibitor, elacridar (GF120918) as dual infusion in rats

“…Fortunately, a high level of substrate overlap and binding sites has been observed between mouse, rat, and human P-gp or BCRP, respectively, allowing for cross-species comparisons. 30,31 Some data exist for loperamide in genetic knockout rats and quinidine, verapamil in genetic knockout mice. Loperamide's in vivo efflux ratio of 17, from co-administration of valspodar, is comparable to, albeit on the lower end of the published genetic knockout A line of equivalency, where the free plasma concentration is equal to the IC 50 , is set at 1.…”

“…P-gp (Mdr1a/b) genetic knockout rodents (mice and rats) are available but published data are limited making direct functional comparison of our chemical knockout protocol to the gold-standard genetic knockout challenging. Fortunately, a high level of substrate overlap and binding sites has been observed between mouse, rat, and human P-gp or BCRP, respectively, allowing for cross-species comparisons 30,31. Some data exist for loperamide in genetic knockout rats and quinidine, verapamil in genetic knockout mice.…”

Propafenone analogue with additional H‐bond acceptor group shows increased inhibitory activity on P‐glycoprotein

“…Due to the unavailability of the crystal structure of human P‐gp, we used our recently published homology model for docking experiments. As can be seen from Figure , both the methoxy analog 4a and the acetyl derivative 4e are positioned in the same way as reported previously for the hydroxy compound 4g .…”

“…This resulted in a data set of 12 ligands. Due to unavailability of the crystal structure of P‐gp, we used the homology model published by Jain et al The protein was prepared using the Protein Preparation Wizard of the Schrödinger Suite (2015) . Hydrogen atoms were added, and optimal protonation states and ASN/GLN/HIS flips were determined.…”