Universiteit Leiden

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Research project

Determining the kinetic profile of ENT1 inhibitors

Supervisor: Anna Vlachodimou

Daan van der Es

Drug discovery and development is a time-consuming and expensive process. Unfortunately, many potential drugs that produce promising in vitro results fail during in vivo experiments or are withdrawn from clinical trials due to lack of efficacy or safety. This indicates a translational gap between the two types of experiments that leads to loss of time and resources. For that reason, novel concepts are necessary in drug discovery.

Within the last 10 years, several studies have highlighted the importance of receptor-ligand binding kinetics, i.e. association and dissociation of the ligand to and from its target over time, for drug discovery. The traditional paradigm, emphasizing affinity or potency identification under equilibrium conditions, is being complemented with a new one that accentuates ligand-receptor residence time (RT), a measure of the duration of time that a ligand stays in complex with its target.

Membrane transporters are transmembrane proteins that regulate the translocation of small molecules, inorganic ions or other proteins across biological membranes. Their function as gatekeepers of small molecules, as well as their ubiquitous presence in the human body constitute them as potential therapeutic targets. Cardiac glycosides, omeprazole, furosemide and tricyclic antidepressants are several examples of transport protein inhibitors, which are very often prescribed. In addition, transport protein substrates, such as 6-mercaptopurine and acyclovir are highly used in anticancer and antiviral therapies, respectively.

More specifically, this study will focus on the Equilibrative Nucleoside Transporter-1 (ENT1), which is the most abundant nucleoside transporter. It is expressed in all tissues and mediates the facilitative diffusion of nucleoside and nucleoside analogue drugs down to their concentration gradients. ENT1 (over)expression has been linked to a variety of cancers, and therefore, ENT1 inhibitors that diminish transporter activity are proposed as an alternative treatment of cancer. In addition, ENT1 inhibitors can potentially be used in the treatment of ischemic heart disease, stroke, inflammatory diseases and viral infections.

By participating in this project you will work on determining the kinetic profile of ENT1 inhibitors. Various (kinetic) radioligand binding assays will be explored and cell culturing will also be part of the project, as the experiments are performed either on whole cells or cell membrane preparations.


  • Cell culture
  • Radioligand binding assays
  • Functional assays

If you are interested in this project, please contact:

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