OE19

AGR2 Depletion and ER Stress Remodel the OE19 Secretome

The endoplasmic reticulum (ER) chaperone Anterior Gradient 2 (AGR2) is overexpressed in various adenocarcinomas, promoting tumor progression and chemoresistance. However, its exact role in modulating the Unfolded Protein Response (UPR) and remodeling the cancer cell secretome under proteotoxic stress remains poorly understood. Using shRNA-mediated silencing of AGR2 combined with high-throughput LC-MS/MS proteomic analysis in OE19 gastroesophageal junction adenocarcinoma cells, Bourgery, Quentin, et al. profiled the global changes in protein secretion under basal and tunicamycin-induced ER stress conditions.

AGR2 silencing efficiency was confirmed by Western blotting (Fig. 1A), and reduced AGR2 levels also impaired clonogenic growth (Fig. 1B). Secretome profiling by LC-MS/MS of exosome-free conditioned media across four conditions (shCtrl, shAGR2, shCtrl + Tun, shAGR2 + Tun) revealed extensive remodeling of secreted protein profiles. Volcano plot analysis identified 93 differentially secreted proteins under basal conditions and between 93 and 97 under ER stress (Fig. 1C). In both conditions, AGR2 depletion was associated with a predominant increase in protein secretion relative to controls. Principal Component Analysis (PCA) showed clear segregation of the four experimental groups, indicating distinct secretory signatures associated with AGR2 status and ER stress (Fig. 1D). Heatmap analysis further illustrated the differential secretion patterns across conditions and the clustering of secreted proteins (Fig. 1E). Comparative analysis identified a core set of 75 common differentially secreted proteins across conditions. Functional enrichment analysis revealed significant enrichment of pathways involved in hemostasis and extracellular matrix organization, linking AGR2-dependent secretome changes to microenvironmental remodeling (Fig. 1F).