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Updated: Jan 19, 2026
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Published on: June 27, 2025
Systematically Mitigating the p38α Activity of Triazole-based BET Inhibitors
Angela S Carlson1, Huarui Cui1, Anand Divakaran1
1Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States.
Abstract:
The Bromodomain and Extra Terminal (BET) family of proteins recognize post-translational N-ε-acetylated lysine modifications, regulating transcription as "reader" proteins. Bromodomain inhibitors are interesting targets for the development of potential cancer, inflammation, and heart disease treatments. Several dual kinase-bromodomain inhibitors have been identified by screening kinase inhibitor libraries against BET proteins. Although potentially useful from a polypharmacology standpoint, multitarget binding complicates deciphering molecular mechanisms. This report describes a systematic approach to mitigating kinase activity in a dual kinase-bromodomain inhibitor based on a 1,2,3-triazole-pyrimidine core. By modifying the triazole substituent and altering the pyrimidine core, this structure-activity relationship study enhanced BET activity while reducing the p38α kinase activity >90,000-fold. A BRD4-D1 cocrystal structure indicates that the 1,2,3-triazole is acting as a N-ε-acetylated lysine mimic. A BRD4 sensitive cell line, MM.1S, was used to demonstrate activity in cells, which is further supported by reduced c-Myc expression.
Insights
Researchers developed a novel bromodomain inhibitor by modifying a 1,2,3-triazole-pyrimidine core. This enhanced BET protein activity while significantly reducing p38α kinase activity, offering a more selective approach for potential therapies.
Area of Science:
- Medicinal Chemistry
- Molecular Biology
- Drug Discovery
Background:
- Bromodomain and Extra Terminal (BET) proteins are epigenetic "readers" that regulate transcription via acetylated lysine recognition.
- BET inhibitors show therapeutic potential in cancer, inflammation, and heart disease.
- Existing dual kinase-bromodomain inhibitors complicate mechanistic studies due to polypharmacology.
Purpose of the Study:
- To systematically mitigate kinase activity in dual kinase-bromodomain inhibitors.
- To enhance selectivity towards BET proteins while reducing off-target kinase inhibition.
- To validate the mechanism of action and cellular activity of the developed inhibitor.
Main Methods:
- Structure-activity relationship (SAR) study focused on modifying a 1,2,3-triazole-pyrimidine core.
- Systematic chemical modifications of the triazole substituent and pyrimidine core.
- Biochemical assays to quantify BET protein and p38α kinase activity; BRD4-D1 cocrystallography; cellular assays using MM.1S cell line.
Main Results:
- Chemical modifications significantly enhanced BET activity.
- p38α kinase activity was reduced by over 90,000-fold, demonstrating high selectivity.
- Cocrystal structure revealed the 1,2,3-triazole moiety mimics N-ε-acetylated lysine.
- Cellular assays confirmed activity in a BRD4-sensitive cell line (MM.1S) with reduced c-Myc expression.
Conclusions:
- A systematic SAR approach successfully yielded a highly selective BET inhibitor with minimal kinase activity.
- The developed inhibitor acts as an N-ε-acetylated lysine mimic, targeting BET proteins effectively.
- This selective inhibitor provides a valuable tool for mechanistic studies and potential therapeutic development.
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