Preclinical Development The Aurora Kinase A Inhibitor MLN8237 Enhances Cisplatin- Induced Cell Death in Esophageal Adenocarcinoma Cells

Esophageal adenocarcinomas are poorly responsive to chemotherapeutics. This study aimed to determine the levels of Aurora kinase A (AURKA) and the therapeutic potential ofMLN8237, an investigational AURKA inhibitor, alone and in combination with cisplatin. Using quantitative real-time PCR, we detected frequent AURKA gene amplification (15 of 34, 44%) and mRNA overexpression (37 of 44, 84%) in esophageal adenocarcinomas (P < 0.01). Immunohistochemical analysis showed overexpression of AURKA in more than two-thirds of esophageal adenocarcinoma tissue samples (92 of 132, 70%; P < 0.001). Using FLO-1, OE19, and OE33 esophageal adenocarinoma cell lines, with constitutive AURKA overexpression and mutant p53, we observed inhibition of colony formation with a single treatment of 0.5 mmol/LMLN8237 (P < 0.05). This effect was further enhanced in combinationwith 2.5 mmol/L cisplatin (P < 0.001). Twenty-four hours after treatment with theMLN8237 orMLN8237 and cisplatin, cell-cycle analyses showed a sharp increase in the percentage of polyploid cells (P < 0.001). This was followed by an increase in the percentage of cells in the sub-G1 phase at 72 hours, concordant with the occurrence of cell death (P < 0.001).Western blot analysis showed higher induction of TAp73b, PUMA, NOXA, cleaved caspase-3, and cleaved PARP with the combined treatment, as compared with a single-agent treatment. Using xenograft models, we showed an enhanced antitumor role for the MLN8237 and cisplatin combination, as compared with single-agent treatments (P < 0.001). In conclusion, this study shows frequent overexpression of AURKA and suggests that MLN8237 could be an effective antitumor agent, which can be combinedwith cisplatin for a better therapeutic outcome in esophageal adenocarcinomas. Mol Cancer Ther; 11(3); 763–74. 2012 AACR.