Chloroquine and Hydroxychloroquine, as Proteasome Inhibitors, Upregulate the Expression and Activity of Organic Anion Transporter 3

Recent Advances on the Regulations of Organic Anion Transporters

The organic anion transporter (OAT) family of over 10 members within the solute carrier (SLC) superfamily of membrane proteins plays critical roles in facilitating the flux of negatively charged molecules in and out of cell membranes. These anionic molecules include various endogenous and exogenous compounds such as signaling molecules, nutrients, metabolites, toxins, and drugs. Therefore, OATs actively contribute to the systemic homeostasis and efficacy of therapeutics. This article provides a brief overview on recent advances in the understanding of the regulatory mechanisms that control the expression and activity of OATs in both health and diseases.

Role of Transporters and Enzymes in Metabolism and Distribution of 4-Chlorokynurenine (AV-101)

4-Chlorokynurenine (4-Cl-KYN, AV-101) is a prodrug of a NMDA receptor antagonist and is in clinical development for potential CNS indications. We sought to further understand the distribution and metabolism of 4-Cl-KYN, as this information might provide a strategy to enhance the clinical development of this drug. We used excretion studies in rats, in vitro transporter assays, and pharmacogenetic analysis of clinical trial data to determine how 4-Cl-KYN and metabolites are distributed. Our data indicated that a novel acetylated metabolite (N-acetyl-4-Cl-KYN) did not affect the uptake of 4-Cl-KYN across the blood-brain barrier via LAT1. 4-Cl-KYN and its metabolites were found to be renally excreted in rodents. In addition, we found that N-acetyl-4-Cl-KYN inhibited renal and hepatic transporters involved in excretion. Thus, this metabolite has the potential to limit the excretion of a range of compounds. Our pharmacogenetic analysis found that a SNP in N-acetyltransferase 8 (NAT8, rs13538) was linked to levels of N-acetyl-4-Cl-KYN relative to 4-Cl-KYN found in the plasma and that a SNP in SLC7A5 (rs28582913) was associated with the plasma levels of the active metabolite, 7-Cl-KYNA. Thus, we have a pharmacogenetics-based association for plasma drug level that could aid in the drug development of 4-Cl-KYN and have investigated the interaction of a novel metabolite with drug transporters.