Effects of Genetic Polymorphisms of Cathepsin A on Metabolism of Tenofovir Alafenamide

Soichiro Ito,Miyu Yanai,Takeshi Hirota,Yuki Taya,Ichiro Ieiri,Mai Muto,Eri Watanabe

doi:10.3390/genes12122026

Soichiro Ito, Miyu Yanai + Show 5 more

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https://doi.org/10.3390/genes12122026

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Abstract

Cathepsin A (CatA) is important as a drug-metabolizing enzyme responsible for the activation of prodrugs, such as the anti-human immunodeficiency virus drug Tenofovir Alafenamide (TAF). The present study was undertaken to clarify the presence of polymorphisms of the CatA gene in healthy Japanese subjects and the influence of gene polymorphism on the expression level of CatA protein and the drug-metabolizing activity. Single-strand conformation polymorphism method was used to analyze genetic polymorphisms in healthy Japanese subjects. Nine genetic polymorphisms were identified in the CatA gene. The polymorphism (85_87CTG>-) in exon 2 was a mutation causing a deletion of leucine, resulting in the change of the leucine 9-repeat (Leu9) to 8-repeat (Leu8) in the signal peptide region of CatA protein. The effect of Leu8 on the expression level of CatA protein was evaluated in Flp-In-293 cells with a stably expressed CatA, resulting in the expression of CatA protein being significantly elevated in variant 2 with Leu8 compared with Leu9. Higher concentrations of tenofovir alanine (TFV-Ala), a metabolite of TAF, were observed in the Leu8-expressing cells than in the Leu9-expressing cells using LC/MS/MS. Our findings suggest that the drug metabolic activity of CatA is altered by the genetic polymorphism.

Highlights

Prodrugs have played a very important role in drug development
Previous studies showed that patients with a single nucleotide polymorphism (SNP) of CES1 had lower blood levels of dabigatran and a lower risk of bleeding as a side effect compared with the wild type [3]
We focused on the major transcript variant of Cathepsin A (CatA) in healthy Japanese subjects and investigated the genetic polymorphisms of CatA and their effects on mRNA, protein expression, and metabolic activity

Summary

Introduction

Prodrugs have played a very important role in drug development. The prodrugs were metabolized into active forms with pharmacological activity. Many metabolizing enzymes, such as carboxylesterase (CES), are involved in metabolic activation, and the effect of the polymorphism of these metabolizing enzymes on the drug metabolic activity is very important from the viewpoint of the appropriate use of the drug [2]. Cases in which the genetic polymorphism of the drug-metabolizing enzyme influenced the pharmacokinetics of the prodrug are shown below. Dabigatran etexilate, a prodrug with improved bioavailability of dabigatran, is activated by the hepatic drug-metabolizing enzyme CES1, and exhibits an antithrombin effect. The pharmacokinetics and pharmacological effects of tramadol, a known prodrug, were affected by cytochrome P450 2D6 (CYP2D6) gene polymorphism. The incidence of PM in the Japanese population is extremely low, at less than 1.0%, compared with that in Western populations

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