Towards a better molecular understanding and safer drug therapies: The importance of stereoselectivity in genetically polymorphic drug membrane transporters of the solute carrier family

• Applicant: Dr. Muhammad Rafehi
• Subject Area: Pharmacology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437446827

• Final Report Year: 2024

Final Report Abstract

Approximately half of the small-molecule drugs on the market are racemic mixtures composed of two stereoisomers. It has been well-established for many years that these enantiomers can differ both in terms of receptor affinities as well as enzymatic metabolism. The pharmacokinetics of drugs are also determined by transport proteins, and differences in substrate translocation between enantiomers can lead to differing plasma concentrations, tissue distribution, and elimination rates. However, the extent of this has so far been barely addressed. Thus, the purpose of this project has been a comprehensive in vitro investigation of the effects of stereoselectivity on drug transport and how this may vary with genetic polymorphism as well as on the inhibition of membrane transporters. The focus has been on cation transporters with comparisons between polyspecific transporters of the SLC22A- (organic cation transporters, OCTs) and SLC47A- (multidrug and toxin extrusion proteins, MATEs) families and the high-affinity monoamine neurotransmitter transporters of the SLC6A-family. Overall, stereoselectivity in drug transport was moderate to low for OCTs 1-3, with some notable exceptions at OCT2 and OCT3. Common genetic variants of OCT1 and OCT2 did not cause considerable differences in enantiopreference. The SLC6A-transporters NET, DAT, and SERT also exhibited mostly minor stereoselectivity, which was unexpected given the higher substrate selectivity of these high-affinity transporters. With respect to stereoselectivity in transporter inhibition, a similar pattern was observed in that it appears to be more important for OCT2 and OCT3 than for OCT1 but that, with certain exceptions, effects are mostly minor. Even NET and SERT, for which pure enantiomers are used as antidepressants, showed only moderate differences between the enantiomers of inhibitors. In summary, this project has shown that the importance of stereoselectivity depends on the respective transporter and substrate combination, and that strong differences and even opposite enantiopreference exist between closely related transporters. Given the modest stereoselective effects for most of the studied drugs, significant clinical consequences are unlikely. However, further investigations on chiral transporter substrates and inhibitors, particularly in combination with structural analyses, will improve our general understanding of substrate recognition, translocation, and transporter inhibition.

Publications

• Stereoselective transport by organic cation transporters. Greifswalder Transporttage 2019, September 2019 (oral presentation)
  Brockmöller, J.; Jensen, O. & Rafehi, M.
  
• Stereoselective uptake of fenoterol and atenolol by the organic cation transporter 1. 4th German Pharm-Tox Summit in Stuttgart, Feb 2019
  Jensen, O.; Rafehi, M. & Brockmöller, J.
  
• Stereoselective cell uptake of adrenergic agonists and antagonists by organic cation transporters. Biochemical Pharmacology, 171, 113731.
  Jensen, Ole; Rafehi, Muhammad; Tzvetkov, Mladen V. & Brockmöller, Jürgen
  
• Cellular Uptake of Psychostimulants – Are High- and Low-Affinity Organic Cation Transporters Drug Traffickers?. Frontiers in Pharmacology, 11.
  Jensen, Ole; Rafehi, Muhammad; Gebauer, Lukas & Brockmöller, Jürgen
  
• Overlap and Specificity in the Substrate Spectra of Human Monoamine Transporters and Organic Cation Transporters 1, 2, and 3. International Journal of Molecular Sciences, 22(23), 12816.
  Gebauer, Lukas; Jensen, Ole; Neif, Maria; Brockmöller, Jürgen & Dücker, Christof
  
• Tracing the stereoselectivity of organic cation transporter 1: New insights from modelling and mutagenesis studies. Greifswalder Transporttage 2021, September 2021 (oral presentation)
  Gebauer, L.; Murugan, N. A.; Jensen, O.; Brockmöller, J. & Rafehi, M.
  
• Molecular basis for stereoselective transport of fenoterol by the organic cation transporters 1 and 2. Biochemical Pharmacology, 197, 114871.
  Gebauer, Lukas; Arul, Murugan N.; Jensen, Ole; Brockmöller, Jürgen & Rafehi, Muhammad
  
• Relationships between Inhibition, Transport and Enhanced Transport via the Organic Cation Transporter 1. International Journal of Molecular Sciences, 23(4), 2007.
  Jensen, Ole; Gebauer, Lukas; Brockmöller, Jürgen & Dücker, Christof
  
• Stereoselectivity in drug membrane transport by organic cation transporters. 12th Transport Colloquium at Schloß Rauischholzhausen, May 2022 (oral presentation)
  Rafehi, M.; Gebauer, L. & Brockmöller J.
  
• Stereoselectivity in the inhibition of SLC22 organic cation transporters 1, 2, and 3 and comparison to other cation transporters. The Spectra of Life: Dimensional Breadth in Biological Research, 24th EMBL PhD Symposium in Heidelberg, December 2022 (poster)
  Gebauer, L.; Brockmöller, J. & Rafehi, M.
  
• Stereoselectivity in the Membrane Transport of Phenylethylamine Derivatives by Human Monoamine Transporters and Organic Cation Transporters 1, 2, and 3. Biomolecules, 12(10), 1507.
  Gebauer, Lukas; Rafehi, Muhammad & Brockmöller, Jürgen
  
• Stereoselectivity in the monoamine transport by human monoamine transporters and organic cation transporters 1, 2 and 3. German Pharm-Tox Summit, online due to pandemic, March 2022 (poster)
  Gebauer, L.; Rafehi, M. & Brockmöller, J.
  
• Substrates and Inhibitors of the Organic Cation Transporter 3 and Comparison with OCT1 and OCT2. Journal of Medicinal Chemistry, 65(18), 12403-12416.
  Gebauer, Lukas; Jensen, Ole; Brockmöller, Jürgen & Dücker, Christof
  
• Combined and independent effects of OCT1 and CYP2D6 on the cellular disposition of drugs. Biomedicine & Pharmacotherapy, 161, 114454.
  Gebauer, Lukas; Dücker, Christof; Jensen, Ole & Brockmöller, Jürgen
  
• Stereoselective Inhibition of High- and Low-Affinity Organic Cation Transporters. Molecular Pharmaceutics, 20(12), 6289-6300.
  Gebauer, Lukas; Jensen, Ole; Rafehi, Muhammad & Brockmöller, Jürgen
  
• Stereoselectivity in Cell Uptake by SLC22 Organic Cation Transporters 1, 2, and 3. Journal of Medicinal Chemistry, 66(23), 15990-16001.
  Gebauer, Lukas; Jensen, Ole; Rafehi, Muhammad & Brockmöller, Jürgen
  
• Stereoselectivity in drug membrane transport. Frontiers in Medicinal Chemistry in Vienna, April 2023 (poster)
  Rafehi, M.; Stefan, S. M.; Gebauer, L. & Brockmöller, J.
  
• The importance of stereoselectivity in drug membrane transporter inhibition. 8th German Pharm-Tox Summit in Ulm, March 2023 (poster)
  Gebauer, L.; Brockmöller, J. & Rafehi, M.
  
• Target repurposing unravels avermectins and derivatives as novel antibiotics inhibiting energy‐coupling factor transporters (ECFTs). Archiv der Pharmazie, 357(9).
  Haupenthal, Jörg; Rafehi, Muhammad; Kany, Andreas M.; Lespine, Anne; Stefan, Katja; Hirsch, Anna K. H. & Stefan, Sven Marcel