Identification of small molecule inhibitors of the Aurora-A/TPX2 complex

// Italia Anna Asteriti 1, * , Frederick Daidone 2, * , Gianni Colotti 1 , Serena Rinaldo 2 , Patrizia Lavia 1 , Giulia Guarguaglini 1, † and Alessandro Paiardini 3, † 1 Institute of Molecular Biology and Pathology, CNR National Research Council, Sapienza University of Rome, 00185, Rome, Italy 2 Department of Biochemical Sciences, Sapienza University of Rome, 00185, Rome, Italy 3 Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy * These authors are co-first authors for this work † These authors are co-last authors for this work Correspondence to: Alessandro Paiardini, email: alessandro.paiardini@uniroma1.it Giulia Guarguaglini, email: giulia.guarguaglini@uniroma1.it Keywords: Aurora-A kinase, TPX2, protein-protein interactions, small molecule inhibitors, anti-cancer therapy Received: October 12, 2016 Accepted: February 22, 2017 Published: March 31, 2017 ABSTRACT Aurora kinases are a family of cell division regulators that govern the correct assembly of a bipolar mitotic spindle and the fidelity of chromosome segregation. Their overexpression is associated with genomic instability and aneuploidy, and is frequently observed in cancer. Accordingly, competitive inhibitors targeting Aurora kinase activity at the ATP-binding site are being investigated for therapeutic purposes. Despite promising pre-clinical data, these molecules display moderate effects in clinical trials and incomplete selectivity, either against distinct family members, or other kinases. As an alternative approach, protein-protein interaction inhibitors targeting mitotic kinases and their activators can be exploited to achieve increased specificity of action. In this study, a virtual screening of small molecules led to the identification of 25 potential inhibitors of the interaction between Aurora-A and its activator TPX2. In vitro experiments confirmed that 4 hits bind Aurora-A in the low micromolar range and compete for TPX2 binding. Immunofluorescence assays showed that 2 compounds also yield lowered Aurora-A activity and spindle pole defects in cultured osteosarcoma cells. The identified protein-protein interaction inhibitors of the Aurora-A/TPX2 complex might represent lead compounds for further development towards pioneering anti-cancer drugs and provide the proof-of-concept for a new exploitable strategy to target mitotic kinases.