Abstract LB192: AGR2 knockdown reduces cell proliferation and increases endoplasmic reticulum proteotoxic stress in pancreatic cancer

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal solid malignancy with low survival rates due to a dense stroma, abnormal gene expression patterns, and limited treatment options. Anterior gradient 2 (AGR2) is often overexpressed in many cancers, including PDAC. AGR2 belongs to the protein disulfide isomerase family of proteins and is located in the endoplasmic reticulum, where it helps with protein-disulfide isomerase reactions to ensure proper protein folding. However, the molecular mechanisms underpinning AGR2 overexpression in PDAC pathophysiology are not well understood. Gene expression data obtained from the pancreatic adenocarcinoma (PAAD) dataset shows that AGR2 is overexpressed in PDAC tumors compared to normal tissues. We confirmed this gene over-expression in PDAC tumors and multiple pancreatic cancer cell lines using fluorescent microscopy, RT-qPCR, and western blotting. Using stable inducible short hairpin (shRNA) technology, we showed that AGR2 knockdown significantly decreases the viability and colony-forming ability of HPAF-II and PANC-1 cells. Gene Ontology (GO) enrichment analysis revealed that AGR2 knockdown suppresses a host of protein biosynthesis pathways, including protein targeting and localization to the endoplasmic reticulum (ER). Significantly, ER stress was induced in knockdown cells, shown by the activation of unfolded protein response, suggesting an accumulation of unfolded proteins. To determine the effects of unfolded protein accumulation on the ER, we performed transmission electron microscopy. Here, the results show an increase in the ER lumen size of knockdown cells compared to controls. Interestingly, we observed a decrease in mitochondria size and confirmed the increased expression of mitochondria fission proteins DRP1 and MFF. Finally, flow cytometry analysis revealed increased apoptosis in AGR2 knockdown cells compared to controls. Overall, our data provide insights into the role of AGR2 in PDAC tumorigenesis. However, more research is warranted to determine if AGR2 could be a potential therapeutic target. Citation Format: Philip Salu, Katie Reindl. AGR2 knockdown reduces cell proliferation and increases endoplasmic reticulum proteotoxic stress in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB192.