Unfolded Protein Response Is Activated by Aurora Kinase A in Esophageal Adenocarcinoma

SIMPLE SUMMARY: Esophageal cancer is the 6th most common cause of cancer-related deaths in 2018 worldwide, with a 5-year survival rate of around 20%. This study reported that esophageal adenocarcinoma cancer cells take advantage of unfolded protein response to survival. Our data using both in vitro cancer cell models and in vivo mice models discovered, for the first time, that Aurora kinase A hijacks pro-survival unfolded protein response in esophageal adenocarcinoma, promoting the survival of cancer cells under reflux-mediated stress conditions. ABSTRACT: Unfolded protein response (UPR) protects malignant cells from endoplasmic reticulum stress-induced apoptosis. We report that Aurora kinase A (AURKA) promotes cancer cell survival by activating UPR in esophageal adenocarcinoma (EAC). A strong positive correlation between AURKA and binding immunoglobulin protein (BIP) mRNA expression levels was found in EACs. The in vitro assays indicated that AURKA promoted IRE1α protein phosphorylation, activating prosurvival UPR in FLO-1 and OE33 cells. The use of acidic bile salts to mimic reflux conditions in patients induced high AURKA and IRE1α levels. This induction was abrogated by AURKA knockdown in EAC cells. AURKA and p-IRE1α protein colocalization was observed in neoplastic gastroesophageal lesions of the L2-IL1b mouse model of Barrett’s esophageal neoplasia. The combined treatment using AURKA inhibitor and tunicamycin synergistically induced cancer cell death. The use of alisertib for AURKA inhibition in the EAC xenograft model led to a decrease in IRE1α phosphorylation with a significant reduction in tumor growth. These results indicate that AURKA activates UPR, promoting cancer cell survival during ER stress in EAC. Targeting AURKA can significantly reverse prosurvival UPR signaling mechanisms and decrease cancer cell survival, providing a promising approach for the treatment of EAC patients.