A systematic interaction map of validated kinase inhibitors with Ser/Thr kinases

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Protein kinases are crucial in cell signaling; their dysregulation is linked to diseases.
• Kinase inhibitors are vital research tools and therapeutic agents, but their specificity is often poorly understood.
• Systematic studies on kinase inhibitor selectivity across diverse panels are lacking.

Purpose of the Study:

• To systematically evaluate the specificity of 156 validated kinase inhibitors against 60 human Ser/Thr kinases.
• To identify correlations between kinase active-site residues and inhibitor cross-reactivity.
• To uncover potential new clinical applications for kinase inhibitors based on off-target activities.

Main Methods:

• Thermal stability shift assay used to test 156 kinase inhibitors against 60 human Ser/Thr kinases.
• Analysis of ATP-binding site residues to correlate with observed ligand promiscuity.
• X-ray crystallography to determine inhibitor binding modes.
• Cell-based assays to validate therapeutic potential.

Main Results:

• Many inhibitors displayed unexpected cross-reactivities against kinases presumed to be their specific targets.
• Specific combinations of ATP-binding site residues correlated with inhibitor promiscuity.
• Certain kinases were highly sensitive to inhibition by diverse chemical classes, suggesting them as intervention points.
• LY333'531, a PKCbeta inhibitor, also potently inhibited PIM1 kinase, a potential leukemia target.

Conclusions:

• The study reveals significant off-target activities of many kinase inhibitors, impacting their use as research tools and therapeutics.
• Understanding kinase inhibitor cross-reactivity can guide drug development and identify novel therapeutic strategies.
• LY333'531 demonstrates potential for treating leukemia by inhibiting PIM1 kinase, warranting further clinical investigation.