Alpha Protein Kinase 2 Promotes Esophageal Cancer via Integrin Alpha 11

Abstract

Background. As a common disease around the world, esophageal cancer (EC) primarily includes two subclasses: esophageal adenocarcinoma and esophageal squamous cell carcinoma. Mortality has been rising over the years; hence, exploring the mechanism of EC development has become critical. Among the alpha protein kinases, alpha protein kinase 2 (ALPK2) presumably has a connection with EC, but it has never been revealed before. Methods. In this study, IHC analysis was used for ALPK2 expression quantification in ES tissues. TE-1 and Eca-109, which are both human EC cell lines, were used for in vitro analysis of cell proliferation, migration, apoptosis, and colony formation. Results. ALPK2 was found to have an abundant expression within EC tissues ( $P<0.001$ ), as well as in the two selected human EC cell lines ( $P<0.05$ ). The data showed that ALPK2 depletion suppressed EC cell proliferation, migration, and colony formation, meanwhile stimulating apoptosis ( $P<0.001$ ). The in vivo experiments also displayed inhibitory effects caused by ALPK2 depletion on EC tumorigenesis ( $P<0.001$ ). It was further validated that ALPK2 depletion made the phosphorylation of Akt and mTOR, as well as CDK6 and PIK3CA levels downregulated ( $P<0.001$ ). Mechanistically, we identified integrin alpha 11 (ITGA11) as a downstream gene of ALPK2 regulating EC. More importantly, we found that ITGA11 elevation promoted cell proliferation and migration and rescued the suppression effects caused by ALPK2 depletion ( $P<0.001$ ). Conclusions. ALPK2 promotes esophageal cancer via integrin its downstream gene alpha 11; ALPK2 can potentially act as a target for the treatment of EC.