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Updated: Dec 17, 2025
12:26
Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
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Bromodomain-Containing Protein BRD4 Is Hyperphosphorylated in Mitosis
Ranran Wang1, June F Yang1, Flora Ho1
1Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Cancers
|June 25, 2020
Summary
BRD4 phosphorylation by CDK1 drives resistance to BET inhibitors in cancer. Inhibiting CDK1 alongside BET inhibitors synergistically kills resistant cancer cells, offering a new therapeutic strategy.
Area of Science:
- Epigenetics
- Cancer Biology
- Molecular Oncology
Background:
- BRD4 is a key epigenetic regulator of gene transcription and proliferation, implicated in various cancers.
- BET inhibitors (BETis) targeting BRD4 are in clinical trials, but cancer resistance is a significant challenge.
- BRD4 phosphorylation enhances its chromatin binding and oncogene expression, potentially contributing to BETi resistance.
Purpose of the Study:
- To investigate the role of BRD4 phosphorylation by CDK1 in BET inhibitor resistance.
- To identify CDK1 phosphorylation sites on BRD4.
- To evaluate dual CDK1 and BET inhibition as a strategy to overcome BETi resistance.
Main Methods:
- Utilized CRISPR/Cas9 gene editing to create a non-phosphorylatable BRD4 mutant.
- Investigated BRD4 phosphorylation by CDK1, particularly during mitosis.
- Assessed the impact of CDK1-mediated phosphorylation on BETi resistance in cancer cells.
- Examined the synergistic effects of combined CDK1 and BET inhibition.
Main Results:
- Identified CDK1 as the kinase responsible for BRD4 hyperphosphorylation during mitosis and mapped key phosphorylation sites.
- Demonstrated that CDK1-mediated BRD4 phosphorylation contributes to BET inhibitor resistance.
- Showed that overactive CDK1 in cancer can lead to sustained BRD4 hyperphosphorylation, reinforcing its oncogenic functions and conferring resistance.
- Found that simultaneous inhibition of CDK1 and BET is synergistic in eliminating BETi-resistant cancer cells.
Conclusions:
- CDK1-mediated BRD4 phosphorylation is a critical mechanism underlying BET inhibitor resistance in cancer.
- Targeting CDK1 in combination with BET inhibitors offers a promising strategy to overcome resistance and enhance treatment efficacy in BRD4-associated cancers.
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