Abstract 1040: Characterization of extracellular vesicles in pancreatic cancer: Changing the way we think about tumorigenesis
Authors: Hinzman Charles P. , Girgis Michael , Li Yaoxiang , Jayatilake Meth , Rajagopal Meena , Banerjee Partha P. , Cheema Amrita K. 
Published: August 2019

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second leading cause of cancer-related deaths by 2030. Patients diagnosed with PDAC have a 5-year survival rate ~9%. Detection of pre-neoplastic lesions has the potential to improve treatment and overall survival in pancreatic cancer (PC) by 4-5 fold. However, there is currently no validated screening test for the non-invasive and accurate detection of early stage PC.

Extracellular vesicles (EVs) arise from invagination of, and secretion from, cells of all tissue types. Their role in mediating PC tumorigenesis however, is just beginning to be studied. We have found that EVs derived from PC cells (cancer-derived EVs, CDEVs), can impart significant phenotypic and metabolic transformational effects on normal human pancreas cells (hTERT-HPNE and H6c7), tantamount to an epithelial-to-mesenchymal transition (EMT). The goal of this study was to characterize the biochemical cargo of EVs toward understanding their role in PC tumorigenesis.

Results: We isolated CDEVs from various established and PDX PC cell lines. After validating enrichment of EV fractions with quantitative ELISA, immunoblot and transmission electron microscopy (TEM), we added CDEVs to culture media of normal cells. We found that CDEVs induce a myriad of changes in normal cells, including significant morphological changes, increased proliferation and an uncharacteristic invasive capability. CDEVs also caused a bioenergetic switch in normal cells, from a quiescent, aerobic profile to a highly energetic and glycolytic profile.

Comparative analyses of CDEVs and normal-derived EVs (NDEVs) using 1H- and 13C-NMR showed significantly different biochemical fingerprints. Interestingly, we found that NDEVs contained more amino acids than CDEVs, while CDEVs contained elevated amounts of urea and lactic acid. We next designed a 13C-isotope labeling flux experiment to trace the fate of carbon metabolized from 13C-glucose fed to cells in culture. Using UHPLC/Q-ToF-MS, we identified several differentially labeled isotopes in CDEVs, particularly surrounding lipid biosynthesis and folate.

Conclusions: Our results indicate that CDEVs confer enormous transformational properties to normal human pancreas cells in vitro. We hypothesize that EVs could impart tumorigenic properties to normal cells in vivo and this influence could unveil novel mechanisms underpinning cancer onset and progression. We show that there are robust biochemical differences between CDEVs and NDEVs. Biochemical characterization of EV cargo can uncover abrogated pathways in which signaling is mediated by EVs. These signals may be detectable before progression of PC to PDAC, leading to the development of assays for earlier diagnosis in patients.

Citation Format: Charles P. Hinzman, Michael Girgis, Yaoxiang Li, Meth Jayatilake, Meena Rajagopal, Partha P. Banerjee, Amrita K. Cheema. Characterization of extracellular vesicles in pancreatic cancer: Changing the way we think about tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1040.