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Determination of Slow-Binding HDAC Inhibitor Potency and Subclass Selectivity
Carlos Moreno-Yruela1, Christian A Olsen1
1Center for Biopharmaceuticals and Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
ACS Medicinal Chemistry Letters
|May 19, 2022
Summary
Selective HDAC inhibitors like entinostat and RGFP966 exhibit slow-binding kinetics, impacting potency and selectivity assessments. Thorough kinetic analysis is crucial for developing reliable histone deacetylase (HDAC) probes.
Area of Science:
- Biochemistry and Molecular Biology
- Pharmacology and Drug Discovery
Background:
- Histone deacetylases (HDACs) 1-3 are critical regulators of chromatin structure and gene expression.
- HDACs 1-3 are therapeutic targets for cancer, immune disorders, and neurodegeneration.
- A lack of selective pharmacological tools hinders the study of individual HDAC roles.
Purpose of the Study:
- To compare the potencies and selectivities of slow-binding HDAC inhibitors using discontinuous and continuous assays.
- To investigate the kinetic mechanisms of entinostat and RGFP966.
Main Methods:
- Enzyme inhibition assays (discontinuous and continuous) were employed to measure inhibitor potencies and selectivities.
- Kinetic analysis was performed to characterize the binding mechanisms of entinostat and RGFP966.
Main Results:
- Entinostat, a clinical candidate, inhibits HDACs 1-3 via a two-step slow-binding mechanism with lower potencies than previously reported.
- RGFP966, marketed as an HDAC3-selective probe, is a slow-binding inhibitor with nanomolar inhibitor constants against HDACs 1-3.
- Slow-binding kinetics can lead to delayed enzyme-inhibitor equilibration, affecting assay readouts.
Conclusions:
- The study reveals that entinostat and RGFP966 exhibit slow-binding kinetics, necessitating careful interpretation of their potencies and selectivities.
- These findings underscore the importance of thorough kinetic investigations for the development of selective HDAC probes and pharmacological tools.
