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STLC-resistant cell lines as tools to classify chemically divergent Eg5 targeting agents according to their mode of
Rose-Laure Indorato1, Salvatore DeBonis, Frank Kozielski
1Univ. Grenoble Alpes, Institut de Biologie Structurale (IBS), F-38027 Grenoble, France; CEA, DSV, IBS, F-38027 Grenoble, France; CNRS, IBS, F-38027 Grenoble, France.
Abstract:
Determining the mechanism of action of drugs and their target specificity in cells remains a major challenge. Here we describe the use of cell lines expressing two point mutations in the allosteric inhibitor binding pocket of the mitotic kinesin Eg5 (D130A, in the loop L5 region and L214A in helix α3), which following transfection, were selected for their ability to proliferate normally in the presence of STLC, a well known Eg5 inhibitor. The cell lines were used to discriminate the mechanism of action of other chemically distinct small molecule inhibitors of Eg5 that differ in their mode of action. The STLC resistant cells were capable of continuous proliferation in the presence of ATP uncompetitive inhibitors, such as K858 and dimethylenastron, but were still sensitive to ATP competitive inhibitors that are thought to bind to a distinct site on Eg5 than the allosteric binding pocket. The STLC resistant cell lines can therefore be used as a filter to distinguish Eg5 loop L5 binding drugs from drugs binding to other pockets without prior structural information. Additionally, the cells can be used to analyze whether inhibitors of Eg5 are specific to this potential drug target or whether they have additional targets in dividing cells.
Insights
Researchers developed drug-resistant cell lines to identify the specific binding sites of mitotic kinesin Eg5 (Eg5) inhibitors. These cells help distinguish between allosteric and ATP-competitive drugs, aiding in drug discovery and specificity analysis.
Area of Science:
- Cell Biology
- Molecular Pharmacology
- Drug Discovery
Background:
- Determining drug mechanisms and target specificity is crucial but challenging.
- Mitotic kinesin Eg5 (Eg5) is a key target for cancer therapeutics.
- Existing methods for characterizing Eg5 inhibitors have limitations.
Purpose of the Study:
- To develop a novel cell-based system for discriminating Eg5 inhibitor mechanisms of action.
- To differentiate inhibitors based on their binding sites within Eg5.
- To assess the specificity of Eg5 inhibitors in dividing cells.
Main Methods:
- Generation of Eg5 inhibitor-resistant cell lines through targeted mutagenesis (D130A, L214A).
- Selection of cell lines exhibiting normal proliferation in the presence of STLC (an Eg5 inhibitor).
- Assay of STLC-resistant cell proliferation in response to various Eg5 inhibitors (ATP-competitive and uncompetitive).
Main Results:
- STLC-resistant cell lines proliferate in the presence of ATP uncompetitive Eg5 inhibitors (e.g., K858, dimethylenastron).
- These cell lines remain sensitive to ATP-competitive Eg5 inhibitors, suggesting distinct binding sites.
- The resistant cell lines effectively differentiate between drugs targeting the STLC allosteric site and other Eg5 binding pockets.
Conclusions:
- Mutant Eg5 cell lines serve as a valuable filter for classifying Eg5 inhibitors based on their binding mode.
- This approach aids in identifying drugs targeting the Eg5 loop L5 allosteric pocket.
- The cell lines facilitate the assessment of Eg5 inhibitor specificity and potential off-target effects in cellular models.
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