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Updated: Nov 4, 2025
Assays for Validating Histone Acetyltransferase Inhibitors
Published on: August 6, 2020
Discovery of a Potent and Selective Covalent p300/CBP Inhibitor
Anthony Mastracchio1, Chunqiu Lai1, Enrico Digiammarino1
1AbbVie, Inc., 1 North Waukegan Road, North Chicago, Illinois 60064, United States.
Abstract:
Aberrant gene activation driven by the histone acetyltransferases p300 and CREB binding protein (CBP) has been linked to several diseases, including cancers. Because of this, many efforts have been aimed toward the targeting of the closely related paralogues, p300 and CBP, but these endeavors have been exclusively directed toward noncovalent inhibitors. X-ray crystallography of A-485 revealed that both p300 and CBP possess a cysteine (C1450) near the active site, thus rendering covalent inhibition an attractive chemical approach. Herein we report the development of compound 2, an acrylamide-based inhibitor of p300/CBP that forms a covalent adduct with C1450. We demonstrated using mass spectrometry that compound 2 selectively targets C1450, and we also validated covalent binding using kinetics experiments and cellular washout studies. The discovery of covalent inhibitor 2 gives us a unique tool for the study of p300/CBP biology.
Insights
Researchers developed a novel covalent inhibitor, compound 2, targeting p300/CBP enzymes implicated in diseases like cancer. This inhibitor selectively forms a bond with a specific cysteine residue, offering a new tool for studying p300/CBP biology.
Area of Science:
- Biochemistry and Molecular Biology
- Chemical Biology
- Drug Discovery
Background:
- Aberrant histone acetyltransferase (HAT) activity of p300 and CREB binding protein (CBP) is implicated in various diseases, including cancers.
- Existing therapeutic strategies primarily focus on noncovalent inhibitors of p300/CBP.
- Structural insights reveal a reactive cysteine residue (C1450) near the active site of p300/CBP, suggesting covalent inhibition as a viable approach.
Purpose of the Study:
- To develop and characterize a novel covalent inhibitor targeting p300 and CBP.
- To investigate the selectivity and mechanism of action of the developed covalent inhibitor.
- To provide a new chemical tool for exploring p300/CBP biological functions.
Main Methods:
- Design and synthesis of an acrylamide-based covalent inhibitor (compound 2).
- Mass spectrometry to confirm selective targeting of C1450.
- Enzyme kinetics and cellular washout studies to validate covalent binding.
Main Results:
- Compound 2 was successfully developed as an acrylamide-based inhibitor of p300/CBP.
- Mass spectrometry confirmed that compound 2 selectively forms a covalent adduct with C1450.
- Kinetics and cellular studies validated the covalent nature of the inhibition.
Conclusions:
- The development of compound 2 provides a selective covalent inhibitor for p300/CBP.
- This novel inhibitor offers a valuable chemical probe for studying p300/CBP in biological systems.
- Covalent inhibition targeting C1450 represents a promising strategy for modulating p300/CBP activity.
