Abstract 5311: Lipidomic profiling of extracellular vesicles derived from cancer cell lines: Lipid species as potential biomarkers and cellular uptake enhancers
Authors: Salazar Ruben R. Lopez , Bustamante Prisca , Zouggari Chaymaa , Chen Yunxi , Tsering Thupten , Stiharu Ion , Mounier Catherine , Nerguizian Vahe , Burnier Julia 
Published: April 2023

Introduction: Extracellular vesicles (EVs) are lipid bilayer-made particles shed by cells to the extracellular space. They carry different cargo proteins, nucleic acids, and other metabolites. EVs play a role in disseminating cancer to distant organs by communicating with the tumor microenvironment to prepare the metastatic niche and also through horizontal transfer of oncogenic traits to recipient cells. The EV surface, which includes proteins and lipids, plays a role in organotropism and cellular uptake. While proteins have been extensively characterized, lipids have not been explored sufficiently. This work aims to evaluate EV lipids as potential biomarkers and their role in enhancing cellular uptake.

Methods: To detect which lipid species (LS) were differentially expressed, we used two cell models of liver metastatic cells: colorectal cancer (HT29) and uveal melanoma (MP41, MP46, MEL 270, OMM 2.5) cell lines. Colon (CCD18-Co) and fibroblast (BJ) immortalized non-cancerous cells were used as controls. EVs were isolated from culture media by ultrafiltration using 100 kDa units filters. Lipids were extracted by methyl-tert-butyl ether for high-throughput lipidomics. High-resolution ‘shotgun’ mass spectrometry was performed. Data was analyzed using LipidView software (SCIEX), and the lipid % normalized was reported. MarkerView (SCIEX) was used to perform Principal Component Analysis. The LS segregating cancerous vs. non-cancerous cells were identified. To evaluate the influence on cellular uptake, we used liposomes as EV models with lipid formulations containing the segregating LS to compare them with naturally occurring lipids and EVs using Incucyte live cell imaging.

Results: We identified four LS that segregated EV subpopulations. PE 34:1 and PS 36:1 divided cancerous vs non-cancerous cells, uveal melanoma cells were segregated by PE 36:2, and normal colon cells were segregated by LPC 18:0. We validated the effect of PS 36:1 in cellular uptake by producing liposomes with a lipid formulation resembling the lipid profile of naturally occurring EVs lipid profile with an artificially high DOPS concentration (17% of the total molar ratio). We determined that human hepatocytes preferentially internalized liposomes made of naturally occurring EVs, followed by the ones with a high concentration of DOPS and lastly by a control EV lipid formulation.

Conclusion: This study identified EV LS that segregated cancerous, normal, and melanoma cell lines. We showed that LS could be used to distinguish cell populations. Moreover, we demonstrated that LS alone influences cellular uptake and that adding the segregating LS to lipid formulations in excess effects cellular uptake. These results pave the way to identify EV lipid biomarkers and better understand EV based cancer dissemination.

Citation Format: Ruben R. Lopez Salazar, Prisca Bustamante, Chaymaa Zouggari, Yunxi Chen, Thupten Tsering, Ion Stiharu, Catherine Mounier, Vahe Nerguizian, Julia Burnier. Lipidomic profiling of extracellular vesicles derived from cancer cell lines: Lipid species as potential biomarkers and cellular uptake enhancers. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5311.