High throughput screening (HTS)

Developers

A. Persidis, K. R. Oldenburg, A. Del Rio etc.

Description of the technology

Testing of drugs in laboratory and clinical trials on drugs follow the complex process of «candidates’" preparation. In this process, various methods are used — from the stage of selection of the target molecule that plays the key role in the pathogenesis — to the stage of ligand selection (ligand is a chemical compound that must bind with the target molecule, inhibiting or enhancing its biological functions).

One of the methods, which are used to select ligands for the specified target, is selection of the appropriate ligand from large databases of chemical compounds (such databases are usually called ‘libraries’). The method of the high throughput screening (HTS) is used so as to hasten the process of selection. Thus, the high throughput screening is one of the stages of drug development.

High throughput screening can be virtual (in silico — performed on the computer) and experimental (in vitro — performed in the laboratory).

As input data for the virtual screening, three-dimensional models of protein and ligand molecules are used. During molecular docking, scientists select mutual geometrical arrangement of molecules that minimize Gibbs free energy for that molecular system. Then they calculate so-called valuation function which demonstrates a bonding force at the chosen arrangement of molecules. The process is repeated for the given set of ligands; only those ligands are chosen for the following (physical) experiments, which were predicted to have the best bonding force. The chosen ligands become hit compounds.

Experimental screening is a conveyer procedure where huge amount of chemical compounds are checked for affinity or activity to special test system imitating biological one. Being «industrial» procedure, screening must meet the requirements of effectiveness, cost and time needed to perform one operation, so experimental screening is performed on robotic installations which are able to work in the round-the-clock and year-round mode. Screening is classified as a high throughput one when it allows to check 100,000 compounds on a certain type of activity daily.

The principle of the experimental screening is rather simple: following a given program, a robot pipets compounds (or a mixture of compounds) being investigated into plates containing a test system (for example, immobilized target or whole cells modified in a special manner). It should be noted that a single plate can contain thousands of «holes» with the test system, and the volume of such a hole can be extremely small, as well as the volume of the sample introduced. Then data from the plate are read off; this process shows which holes have exhibited biological activity and which ones have not. Depending on the used technology, a detector can read off radioactive signal, fluorescence, bioluminescence, radiation polarization and many other parameters. Compounds showed activity above the prescribed value during that experiment become hit compounds.

Hit compounds selected during the high throughput screening are chemically modified in order to improve their medicinal properties. This process is called optimization. After that, preclinical and clinical trials on a drug start.

Practical application

High throughput screening is one of the stages in the development of new drugs. This technology allows to select hit compounds from huge libraries of chemical compounds. Some hit compounds can become drug compounds.

This technology is already on the market.

Laboratories

• Chemical Diversity Research Institute, Khimki, Moscow region (Russian Federation)
• High Throughput Screening Core Facility, Centre for Integrative Biology, University of Trento, Trento (Italy)
• Charles River Laboratories, Wilmington, Massachusetts (USA)
• Sigma-Aldrich, Munich (Germany)
• Scripps Florida, The Scripps Research Institute (TSRI), La Jolla, California (USA)

Links

Publications

• Walters, W. Patrick, Matthew T. Stahl, and Mark A. Murcko. «Virtual screening-an overview." Drug Discovery Today 3.4 (1998): 160–178.
• Jorge Moura Barbosa, Armenio, and Alberto Del Rio. «Freely accessible databases of commercial compounds for high-throughput virtual screenings." Current topics in medicinal chemistry 12.8 (2012): 866–877.
• Zhang, Ji-Hu, Thomas DY Chung, and Kevin R. Oldenburg. «A simple statistical parameter for use in evaluation and validation of high throughput screening assays." Journal of biomolecular screening 4.2 (1999): 67–73.
• Gupta, Piyush B., et al. «Identification of selective inhibitors of cancer stem cells by high-throughput screening." cell 138.4 (2009): 645–659.
• de Wildt, Ruud MT, et al. «Antibody arrays for high-throughput screening of antibody-antigen interactions." Nature biotechnology 18.9 (2000): 989–994.