Abstract 2370: The role of extracellular vesicles in the glioblastoma tumor microenvironment
Authors: Russo Marissa 
Published: April 2023

Abstract
Glioblastoma (GBM) is the most malignant form of gliomas and is the most common and lethal primary brain tumor in adults. Within the tumor, there is a subtype of cells deemed brain tumor initiating cells (BTICs), which contribute to tumor progression, therapy resistance, and tumoral heterogeneity. The tumor microenvironment, surrounding tumors, contains an ecosystem of cells in which BTICs can interact with and further promote tumor progression. In the lateral wall of the lateral ventricles, the neurogenic niche of the subventricular zone (SVZ), contains neural stem cells (NSCs) that self-renew and generate highly migratory neural progenitor cells (NPCs). Interestingly, GBM tumors proximal to the SVZ are more proliferative, migratory, and negatively impact the survival of patients. We have previously observed that the presence of GBM induces reciprocal changes to the SVZ altering its neurogenic capacity and resulting in a more proliferative tumor. BTICs share the similar self-renewal capacity to NPCs and may exert intercellular communication resulting in increase malignancy features. However, the exact mechanisms of how GSCs communicate with NPCs is not well understood. Cancer cells release higher amounts of extracellular vesicles (EVs) than non-malignant cells. Cancer EVs help communicate with other nearby cells, leading to promotion of tumorigenesis. EVs are a heterogenous group of cell-derived membranous structures that serve as means of intercellular communication, allowing for cells to exchange proteins, lipids, RNA, and other genetic material. They can be further characterized into two main subtypes, small EVs, that range from 30-150nm, and large EVs, that range from 50-1000nm. EVs derived from gliomas or non-glioma cells in the tumor microenvironment are involved in tumor cell proliferation, invasion, malignancy, and drug resistance. The overarching goal of this project is to characterize BTIC-derived small EV cargo to identify proteins and RNAs that modify the GBM tumor microenvironment. We hypothesize that GBM-derived small extracellular vesicles alter the phenotype of non-cancer cells in the tumor microenvironment through distinct cargo contained in small extracellular vesicles. The results of these experiments will help us to elucidate what exact small EV cargo impacts the tumor microenvironment, with the potential of revealing possible therapeutic targets for GBM.The optimized protocol gives us the ability to enrich our desired EV population of small EVs from BTICs. BTIC-derived small EVs influence recipient NPCs by significantly upregulating markers for stemness, tumor aggressiveness, and invasion, as well as increasing NPC migration. Future experiments will include trying to establish a cell-specific labeling system in vitro to label EVs from BTICs, to allow for direct co-culture of BTICs with NPCs and other cells in the tumor microenvironment.
Citation Format: Marissa Russo. The role of extracellular vesicles in the glioblastoma tumor microenvironment [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 2370.