Abstract 3177: In vitro cellular inflammation caused by Caco2BBE and HepG2 cells secreted exosomes
Authors: Stetler Jenniffer L. , Canup Brandon SB , Puckett Russell P. , Meng XiangXiao , Qiang Ma , Laroui Hamed 
Published: August 2015

Background: In colon cancer, the majority of metastatic cells end up in the liver. In order to elucidate metastasis migration, a possible road of investigation may lie in exosomes, a biological nanoparticle. Usually, exosomes range from 80-150 nm and medicate cell-to-cell communication. Additionally, exosomes house up to hundred proteins, oligonucleotides, lipids, and receptors that may contribute to affecting the inflammatory response in cancer cell lines. The aim of the study is to show preferential uptake of Caco2BBE exosomes by HepG2 cells under an inflammatory stimulus. Whereas Caco2BBE cells prohibits HepG2 exosomes uptake under an inflammatory stimulus. Methods: Exosomes was isolated by differential centrifugation from Caco2BBE, HepG2, and Raw 264.7 cell culture media stimulated with and without 10 ug/mL of LPS. Once collected, exosomes were characterized for size and charge by dynamic light scatter (DLS), atomic force microscopy (AFM), and transmission electron microcopy (TEM). Additional characterization of exosomes included toxicity as well as fluorescent microscopy to explore the specificity of Coumarin-6 labelled exosomes (C-6 Exo). Finally, the biological effects of exosomes on inflammatory markers in vitro were examined by Western blot and RT-qPCR. Results: The different measurements of exosomes size indicates an average diameter of 70-100 nm. Additionally, the exosomes extracted from each cells were not toxic to any cells. Interestingly, the uptake of C-6 Exo showed a striking find that Caco2BBE cells uptake HepG2 extracted exosomes under normal conditions. Whereas LPS stimulation of Caco2BBE cells prohibits the uptake of HepG2 exosomes. Then conversely, HepG2 cells were taking up Caco2BBE extracted exosomes when stimulated with LPS. These findings correlate with Western blot and RT-qPCR data that shows up-regulation of IL-6, TNFα, and MMP9 by Caco2BBE exosomes on HepG2 cells. Again, the LPS stimulation on HepG2 cells treated with Caco2BBE exosomes causes decrease of IL-6, TNFα, MMP9, and NF-κB. Conclusions: The characterization of these exosomes showed about 100 nm non-toxic particles that effect IL-6, TNF-α, MMP9, and NFκB on HepG2 cells treated with Caco2BBE exosomes. These effects on inflammatory markers mediate the uptake of these exosomes and especially with an inflammatory stimulation such as LPS, which can either prohibit or promote this process. Together, our data could lead to understanding the role of exosomes on the translocation of metastatic cells to the liver and could open a new therapeutics option.

Citation Format: Jenniffer L. Stetler, Brandon SB Canup, Russell P. Puckett, XiangXiao Meng, Ma Qiang, Hamed Laroui. In vitro cellular inflammation caused by Caco2BBE and HepG2 cells secreted exosomes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3177. doi:10.1158/1538-7445.AM2015-3177