Abstract 2668: Pancreatic cancer cell extracellular vesicles drive the unfolded protein response in recipient normal pancreas cells
Authors: Hinzman Charles Phillip , Bansal Shivani , Li Yaoxiang , Iliuk Anton , Trevino Jose , Banerjee Partha , Cheema Amrita 
Published: July 2021

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second leading cause of cancer-related deaths by 2030. The 5-year survival rate remains low, hovering ~9%. A key driver of poor patient outcomes is late-stage diagnosis of disease. Currently, no diagnostics exist to identify indolent disease. A better understanding of the complex tumor microenvironment in PDAC is needed for discerning disease etiology and progression. Extracellular vesicles (EVs) are nanometer sized lipid-bilayer particles released from cells of all tissue types, which carry an array of biomolecules. EVs mediate a myriad of cancer progression events including tumor proliferation, angiogenesis, immune escape, and metastasis. Their role in PDAC tumorigenesis, however, is largely unknown. In this study we report on the effects of PDAC cell derived EVs on normal pancreatic epithelial cells.

Results: We treated normal pancreas cells with pancreas cancer cell derived EVs (cEVs). Global gene expression analysis identified 376 differentially expressed genes (DEGs) enriched for genes in the aminoacyl-tRNA biosynthesis, tRNA aminoacylation, ATF4 and ATF6 signaling pathways. Gene ontology analysis identified enrichment in biological processes associated with endoplasmic reticulum (ER) stress, NF-kB signaling and DNA damage response. Lipid synthesis was severely altered, with decreased expression in several cholesterol, sterol, and acetyl-CoA pathways. Transcription factor analysis identified enrichment of CHOP/DDIT3 target motifs, as well as targets of XBP1, ATF6 and ATF4. Unfolded protein response (UPR) and ER stress genes in our dataset were significantly upregulated, including DDIT3, NFYB, ATF6 and ATF4. We validated upregulation of UPR/ER stress in these cells using qPCR and luciferase activity assays. Multi-omics characterization of EVs isolated from PDAC and normal cell lines showed distinct biochemical profiles. This analysis identified potential mediators of UPR/ER stress enriched in cEVs, including proteins which regulate protein trafficking and ubiquitination, lipid species esterified to palmitic acid and metabolites which regulate tRNA charging.

Conclusions: We show that cEVs induce significant gene expression changes within recipient normal pancreatic cells and likely induce ER stress, leading to an UPR. Long-term UPR/ER stress can impact a variety of cancer hallmarks, including angiogenesis, genome stability, inflammation, metastasis, and drug resistance. ER stress has been shown to mediate progression of pancreatic intraepithelial neoplasia (PanIN) to PDAC. These results highlight a potential role of EVs in mediating cellular messages from pancreatic cancer cells to alter the function of recipient normal cells, aiding disease onset and progression. Further studies are ongoing to identify key mediators within cEVs for the induction of UPR/ER stress.

Citation Format: Charles Phillip Hinzman, Shivani Bansal, Yaoxiang Li, Anton Iliuk, Jose Trevino, Partha Banerjee, Amrita Cheema. Pancreatic cancer cell extracellular vesicles drive the unfolded protein response in recipient normal pancreas cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2668.