title: The role of the tumor suppressor p53 in the biogenesis and function of extracellular vesicles.
title: Die Rolle des Tumorsupressors p53 in the Biogenese und Funktion extrazellulärer Vesikel.
titleType: AlternativeTitle
Creators: name: Linder, Manuel
Publisher: name: Philipps-Universität Marburg
Year: 2024
Subjects: Ovarian Cancer
Extrazelluläre vesikel
Medical sciences Medicine
Medizin
p53
EV biogenesis
Fibroblasten
Extracellular vesicles
EV Biogenese
fibroblasts
Ovarialkarzinom
tumor

description: The progression and metastasis of ovarian cancer (OC) relies on the intricate interplay between cancer cells and their surrounding tumor microenvironment (TME). Within this complex ecosystem, various cell types, particularly fibroblasts, play a significant role in facilitating OC invasion and metastasis. The TME also encompasses diverse soluble components, including cytokines or extracellular matrix (ECM) and, notably, extracellular vesicles (EVs). EVs have emerged as critical mediators of cellular communication by transporting and presenting their cargo, including proteins, lipids, and nucleic acids. The complex biogenesis of EVs involves different mechanisms and factors, with recent attention focusing on the tumor protein p53. In the majority of ovarian cancer cases, p53 is mutated, but its potential role as a facilitator of EV biogenesis remains elusive. Therefore, this study aims to further unravel the role of p53 in EV biogenesis and its impact on the TME, with a specific focus on cancer-associated fibroblasts (CAFs).
To address this, I genetically engineered ovarian cancer cell lines (OVCAR8) with a defined p53 status, including lines with a p53 knockout (KO), a p53 wildtype (WT), and two specific hot spot mutations (mutp53; R175H or R273H). The characterization of the secreted EVs revealed no significant differences in particle size and EV marker expression between knockout and mutated cells. Of note, transcriptomic analysis demonstrated higher expression of genes involved in exosome biogenesis, such as ESCRT components, in p53 WT cells, which also released elevated amounts of EVs. Moreover, EVs preferentially transferred WTp53 compared to mutp53 to recipient cells, although it was lower expressed in the respective cells. Treatment of human fibroblast with EVs from p53 wildtype cells and, to a remarkably lesser extent, from p53KO/mutp53 cells induced an inflammatory phenotype. This was shown to be at least partially mediated by NFκB and STAT3 activity. Secretome analysis further confirmed the inflammatory phenotype of wildtype EV-treated fibroblast with the secretion of cytokines and chemokines, such as IL6, CXCL1, and CXCL8. In contrast, EVs from p53KO cells induced a phenotype associated with ECM remodeling, including secretion of COMP, POSTN, and TGFB1. Notably, EV from mutp53 cells did not cause a specific phenotype in fibroblasts. 
In conclusion, our findings indicate that EVs from OC cells expressing p53 wildtype influence the phenotype of human fibroblasts, indicating that p53 directs specific EV cargo loading. These findings provide the basis to further investigate p53 as an essential mediator of EV biogenesis and potentially develop innovative strategies to educate the TME and, specifically, fibroblasts to an anti-tumorigenic phenotype by utilizing p53 wildtype-derived EVs.