Protein kinases have been established as promising drug targets for treatment of various types of cancers. Small molecule kinase inhibitors have become increasingly important in cancer therapeutics. Currently, more than 33 FDA-approved kinase inhibitors have been used as promising targeted therapeutics, and numerous (>250) inhibitors are in various stages of clinical evaluation. Kinobeads technology in combination with high-resolution MS has emerged a powerful tool to understand the mode of action, to identify new targets, and to characterize potential off-target effects of small molecule kinase inhibitors. In this thesis, a dose-resolved quantitative chemical proteomics approach has been used to understand the mechanism of small molecule kinase inhibitors and to highlight their off-targets.
CDKs are a family of protein kinases that play the most important role in the regulation of cell cycle transitions, and four CDKs (CDK1, CDK2, CDK4, and CDK6) are essential components of the cell cycle machinery with key functions in both human normal cells and in human cancer cells. Over-expression of CDKs is highly related with human cancers, and 14 drugs that target CDKs activity have emerged and have been tested in various stages of clinic. The other CDK inhibitors are still in clinical trials beside FDA approved CDK4/6 inhibitor Palbociclib. This study characterized 14 CDK inhibitors, which include both first- and second-generation CDK inhibitors. These inhibitors were tested using Kinobeads technology in a competitive approach against a large number of kinases, including CDKs and their complex partners. The results of this work show the successful development of a new generation of CDK inhibitors, but they also offer good explanations why CDK inhibitors have not been able to withstand FDA testing in the past.
Salt-inducible kinase 2 (SIK2) has been found to be a potential target in inflammation and autoimmune diseases. In this study, SIK2 has been detected as an off-target by screening 242 small molecule kinase inhibitors through Kinobeads pulldown assay. Notably, treatment of various immune responding models (THP-1, BMDCs, PBMCs, and human DCs) with SIK2 inhibitors particularly induced the production of anti-inflammatory cytokine IL-10 and reduced the production of pro-inflammatory cytokine TNF-α. Anti-TNF-α therapy and IL-10 therapy have been demonstrated to be exploited in various clinical trials for the development of therapies of several inflammatory diseases. Nevertheless, no small molecule kinase inhibitor has shown therapeutic benefits in these therapies. This work provides strong reasons to drive low molecular weight SIK2 inhibitors in the investigation of inflammatory and autoimmune diseases.
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Protein kinases have been established as promising drug targets for treatment of various types of cancers. Small molecule kinase inhibitors have become increasingly important in cancer therapeutics. Currently, more than 33 FDA-approved kinase inhibitors have been used as promising targeted therapeutics, and numerous (>250) inhibitors are in various stages of clinical evaluation. Kinobeads technology in combination with high-resolution MS has emerged a powerful tool to understand the mode of acti...
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