CKAP4 silencing impairs growth and survival of esophageal adenocarcinoma cells in vitro

Background Esophageal adenocarcinoma (EAC) is the predominant histologic subtype of esophageal cancer in Western countries and has a poor prognosis. Cytoskeleton-associated protein 4 (CKAP4), a transmembrane receptor involved in proliferation, migration, and signaling, has been implicated in several cancers, but its role in EAC remains unclear. We investigated CKAP4 expression and cellular changes associated with CKAP4 depletion in EAC cell models. Methods CKAP4 expression was characterized using an in vitro Barrett’s esophagus (BE) model of EAC progression. CKAP4 was silenced by siRNA in OE33 and OE19 EAC cells. Functional and molecular effects were assessed, and transcriptional changes were analyzed by RNA sequencing. Results CKAP4 expression varied across Barrett’s neoplastic progression, with highest total expression in dysplastic cells and marked surface overexpression in OE33, OE19, and FLO-1 EAC cells. CKAP4 depletion reduced CKAP4 mRNA and protein, altered cell morphology, decreased viability and proliferation, and increased apoptosis. AKT phosphorylation was reduced in OE19 cells and MAPK phosphorylation in OE33 cells, whereas ß-catenin and GSK3ß activity remained unchanged. CKAP4 silencing increased surface expression of adhesion molecules, including integrins α5/ß1 in OE33 cells. RNA sequencing identified >500 differentially expressed genes enriched in immune-related pathways, indicating immune-related transcriptional changes. Conclusion CKAP4 is a functionally relevant, surface-overexpressed protein in Barrett’s-associated EAC. These findings define cellular and transcriptional changes associated with CKAP4 depletion in EAC cells in vitro and support further mechanistic and preclinical investigation; therapeutic and biomarker relevance in EAC remains to be established.