A first generation inhibitor of human Greatwall kinase, enabled by structural and functional characterisation of a minimal kinase domain construct.
Ocasio, C.A., Rajasekaran, M.B., Walker, S., Le Grand, D., Spencer, J., Pearl, F.M., Ward, S.E., Savic, V., Pearl, L.H., Hochegger, H., Oliver, A.W.(2016) Oncotarget 7: 71182-71197
- PubMed: 27563826 
- DOI: https://doi.org/10.18632/oncotarget.11511
- Primary Citation of Related Structures:  
5LOH - PubMed Abstract: 
MASTL (microtubule-associated serine/threonine kinase-like), more commonly known as Greatwall (GWL), has been proposed as a novel cancer therapy target. GWL plays a crucial role in mitotic progression, via its known substrates ENSA/ARPP19, which when phosphorylated inactivate PP2A/B55 phosphatase. When over-expressed in breast cancer, GWL induces oncogenic properties such as transformation and invasiveness. Conversely, down-regulation of GWL selectively sensitises tumour cells to chemotherapy. Here we describe the first structure of the GWL minimal kinase domain and development of a small-molecule inhibitor GKI-1 (Greatwall Kinase Inhibitor-1). In vitro, GKI-1 inhibits full-length human GWL, and shows cellular efficacy. Treatment of HeLa cells with GKI-1 reduces ENSA/ARPP19 phosphorylation levels, such that they are comparable to those obtained by siRNA depletion of GWL; resulting in a decrease in mitotic events, mitotic arrest/cell death and cytokinesis failure. Furthermore, GKI-1 will be a useful starting point for the development of more potent and selective GWL inhibitors.
Organizational Affiliation: 
Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, UK.