HDM2 Regulation by AURKA Promotes Cell Survival in Gastric Cancer

Purpose: Suppression of P53 (tumor protein 53) transcriptional function mediates poor therapeutic response in patients with cancer. Aurora kinase A (AURKA) and human double minute 2 (HDM2) are negative regulators of P53. Herein, we examined the role of AURKA in regulating HDM2 and its subsequent effects on P53 apoptotic function in gastric cancer. Experimental Design: Primary tumors and in vitro gastric cancer cell models with overexpression or knockdownofAURKAwereused.TheroleofAURKAinregulatingHDM2andcellsurvivalcoupledwithP53 expression and activity were investigated. Results: Overexpression of AURKA enhanced the HDM2 protein level; conversely, knockdown of endogenousAURKAdecreasedexpressionofHDM2inAGSandSNU-1cells.Dualco-immunoprecipitation assay data indicated that AURKA was associated with HDM2 in a protein complex. The in vitro kinase assay using recombinant AURKA and HDM2 proteins followed by co-immunoprecipitation revealedthatAURKA directly interacts and phosphorylates HDM2 protein in vitro. The activation of HDM2 by AURKA led to inductionofP53ubiquitinationandattenuationofcisplatin-inducedactivationofP53ingastriccancercells. Inhibition of AURKA using an investigational small-molecule specific inhibitor, alisertib, decreased the HDM2 protein level and induced P53 transcriptional activity. These effects markedly decreased cell survival in vitro and xenograft tumor growth in vivo. Notably, analysis of immunohistochemistry on tissue microarraysrevealedsignificantoverexpressionofAURKAandHDM2inhuman gastriccancersamples(P <0.05). Conclusion: Collectively, our novel findings indicate that AURKA promotes tumor growth and cell survivalthroughregulationofHDM2-inducedubiquitinationandinhibitionofP53.ClinCancerRes;20(1); 76–86. � 2013 AACR.