Electronic Thesis and Dissertation Repository


Master of Science




David W Litchfield


Protein kinase CK2 is a constitutively active serine/threonine kinase that is overexpressed in several human cancers, and by virtue of the vast number of putative substrates in the phosphoproteome, is implicated in the regulation of numerous cellular processes. Consequently, CK2 is an emerging therapeutic target with many CK2 inhibitors having been developed. An example of one such inhibitor is the clinical stage compound CX-4945. Although highly selective for CK2, the ATP competitive CX-4945 has demonstrated affinity for other kinases. Unique features of the catalytic pocket of CK2 have allowed for the development of inhibitor refractory mutants, which have since been stably integrated into tetracycline inducible osteosarcoma cell lines. A mass spectrometry-based phosphoproteomic workflow was used in conjunction with inhibitor refractory cell lines to study the impact of CK2 inhibition on the phosphoproteome, and potentially identify off-targets of the clinical compound CX-4945. In response to CX-4945 treatment the inhibitor refractory mutant recovered phosphorylation at several sites, revealing potential novel substrates of CK2. Phosphoproteomic analysis also revealed potential off-targets of CX-4945. This investigation provides valuable insight into the role played by CK2 in cellular signaling and provides a platform for downstream targeted proteomic analysis of CK2