Abstract 2015: The Aurora kinases are a potential therapeutic target in Ewing sarcoma
Authors: McNae Molly , Roundhill Elizabeth A. , Burchill Susan A. , Bayliss Richard W. 
Published: June 2022

The poor survival rates and limited treatment options for patients with relapsed/metastatic Ewing sarcoma (ES) highlights the need for more personalized targeted therapeutic approaches. In this project, we have investigated the prognostic potential of Aurora kinase expression in ES patients and evaluated the activity of Aurora kinase inhibitors in ES cell lines and patient derived cultures.

The prognostic value of Aurora kinase A (AURKA), Aurora kinase B (AURKB) and Aurora kinase C (AURKC) was determined through interrogation of the online GSE17618 dataset using Cox models and Kaplan Meier plots. RNA seq data was obtained from the CCRG dataset for expression analysis (Roundhill et al., 2021, Cell Oncol, 44(5), 1065-85). Viable cell number was determined using the trypan blue exclusion assay on the Vi-CELL XR. Cells were treated with increasing concentrations of inhibitor (Table 1) or DMSO vehicle control for 48h. Protein was extracted after 48h for western blotting.

In ES patients, high RNA expression of AURKA and AURKB is associated with a 5- and 3-fold increased risk of death respectively (n=42). Risk of an event was increased 3- or 2-fold with high expression of AURKA or AURKB respectively (n=42). High AURKC expression was not prognostic. Expression of AURKA and AURKB was confirmed at the RNA level in ES cell lines and patient derived cultures, and at the protein level in cell lines. Aurora kinase inhibitors (Table 1) decreased viable cell number of ES cell lines and patient derived cultures. Western blotting confirmed a decrease in AURKA and MYC-C expression with increasing concentration of inhibitor. AMG900 was the most potent inhibitor in TC32 cells (Table 1) and decreased viable cell number of patient derived cultures (n=5, p&lt;0.01).

High expression of AURKA or AURKB mRNA predicts poor outcome for ES patients. Inhibitors of these kinases reduce viable cell number of both ES cell lines and patient derived cultures. We are currently investigating the mechanism of action.

Table 1. Summary of the effect of Aurora kinase inhibitors in TC32 ES cells. Aurora Kinase Inhibitor Concentration Range Used (nM) Target Kinases(IC50, nM) EC50 TC32 Cells (nM) (n=3) P value (EC50 AMG900 vs EC50 another inhibitor) References AMG900 1.25-50 AurA (5), AurB (4), AurC (1) + 10 kinases 1.57 N/A Payton et al., 2010, Cancer Res, 70(23), 9846-54 MLN8237 5-300 AurA (1.2), AurB (396.5) + 22 kinases 29.48 0.0468 Manfredi et al., 2011, Clin Cancer Res, 17(24), 7614-24 CCT137690 5-300 AurA (15), AurB (25), AurC (19) + 3 kinases 97.56 0.0004 Bavetsias et al., 2010, J Med Chem, 53(14), 5213-28 LY3295668 31.25-1000 AurA (0.8) AurB (1038)AurC (98) + 2 kinases Not able to calculate N/A Gong et al., 2019, Cancer Discov, 9(2), 248-263 EC50 values were calculated by nonlinear regression (GraphPad PRISM). Statistical differences between EC50 of AMG900 and the EC50 of other inhibitors were evaluated using two-way ANOVA and Tukey’s multiple comparisons test. IC50 - half maximal inhibitory concentration, EC50 - half maximal effective concentration

Citation Format: Molly McNae, Elizabeth A. Roundhill, Susan A. Burchill, Richard W. Bayliss. The Aurora kinases are a potential therapeutic target in Ewing sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2015.