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Updated: May 12, 2026
Identification of Kinase-substrate Pairs Using High Throughput Screening
Published on: August 29, 2015
High-throughput screening AlphaScreen assay for identification of small-molecule inhibitors of ubiquitin E3 ligase
Dana Ungermannova1, Junglim Lee, Gan Zhang
1Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA.
Abstract:
Decreased levels of cell cycle inhibitor p27(Kip1) due to excessive degradation occur in a variety of aggressive human tumors. Since reduced p27(Kip1) expression has been associated with a poor prognosis in many human cancers and resistance to certain antitumor therapies, elevation of p27(Kip1) expression could improve prognosis and prevent excessive cell proliferation. SCF(Skp2) is one of the major ubiquitin E3 ligases responsible for degradation of p27(Kip1). Ubiquitination of p27(Kip1) also requires a small adaptor protein, Cks1, which facilitates substrate recruitment by bridging the interaction between Skp2 and p27(Kip1). It has been shown previously that a direct interaction between Cks1 and Skp2 is required for p27(Kip1) degradation. Accordingly, perturbation of the Skp2-Cks1 interaction may represent an attractive target for pharmacological intervention. Here we describe a high-throughput AlphaScreen assay for discovering small-molecule inhibitors of the Skp2-Cks1 protein-protein interaction in vitro. Two compounds (NSC689857 and NSC681152) were identified and validated through a structure-activity relationship analysis. Both compounds were also shown to inhibit p27(Kip1) ubiquitination in vitro. These studies demonstrate that disruption of the Skp2-Cks1 interaction provides a viable strategy to prevent p27(Kip1) ubiquitination and may potentially be useful for the control of excessive degradation of this cell cycle inhibitor in tumor cells.
Insights
Researchers identified small molecules that inhibit the Skp2-Cks1 interaction, a key step in degrading the cell cycle inhibitor p27(Kip1). This discovery offers a potential strategy to prevent tumor cell proliferation by stabilizing p27(Kip1) levels.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Decreased levels of the cell cycle inhibitor p27(Kip1) are linked to aggressive human tumors and poor prognosis.
- Excessive degradation of p27(Kip1) by the SCF(Skp2) ubiquitin E3 ligase complex contributes to tumor progression.
- The adaptor protein Cks1 facilitates p27(Kip1) ubiquitination by bridging Skp2 and p27(Kip1).
Purpose of the Study:
- To develop a high-throughput assay for identifying inhibitors of the Skp2-Cks1 protein-protein interaction.
- To discover small molecules that disrupt the Skp2-Cks1 interaction, thereby preventing p27(Kip1) degradation.
- To explore the therapeutic potential of targeting the Skp2-Cks1 interaction for cancer treatment.
Main Methods:
- Development of a high-throughput AlphaScreen assay to screen for inhibitors of the Skp2-Cks1 interaction.
- Identification and validation of small-molecule inhibitors (NSC689857 and NSC681152) using structure-activity relationship analysis.
- In vitro assessment of identified compounds for their ability to inhibit p27(Kip1) ubiquitination.
Main Results:
- Two novel small-molecule compounds, NSC689857 and NSC681152, were identified as inhibitors of the Skp2-Cks1 interaction.
- Structure-activity relationship analysis confirmed the efficacy of these compounds.
- Both identified compounds demonstrated the ability to inhibit p27(Kip1) ubiquitination in vitro.
Conclusions:
- Disrupting the Skp2-Cks1 interaction is a viable strategy to prevent p27(Kip1) ubiquitination.
- Targeting the Skp2-Cks1 interaction may offer a novel therapeutic approach to control tumor cell proliferation.
- Elevating p27(Kip1) levels through inhibition of its degradation could improve cancer prognosis and treatment outcomes.
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