Prion protein as a stemness regulator in glioblastoma stem cells: its role in the formation and function of multiprotein signaling platforms.

Author(s)

Mariana Brandão Prado

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2023-05-04

Examining board members

Marilene Hohmuth Lopes; Alison Colquhoun; Erico Tosoni Costa; Maria Cristina Rodrigues Rangel

• Advisor: Marilene Hohmuth Lopes

Abstract

Glioblastoma multiforme (GB) is a tumor composed of glial cells, being the most common and malignant type of glioma, with high rates of recurrence and mortality. In addition, certain aspects of GB make its complete physiological removal difficult, such as the fact that it grows in regions of the brain that are difficult to access and its diffuse growth pattern, without determined borders. Studies have shown that GB is maintained by a stem cell-like subpopulation called glioblastoma stem cells (GSCs). These cells self-renew, promote angiogenesis and invasion, and are also chemo- and radio-resistant. Thus, GSCs have significant potential as a therapeutic target for the treatment of glioblastomas. Recent studies have shown that cellular prion protein (PrPC) emerges as a key factor in the maintenance of GB and CTGs. PrPC has an important role as a scaffold protein being able to interact with various membrane and extracellular matrix proteins, forming complexes capable of regular functions different from tumor biology. In this study, we generated PrPC knockout (KO) U87 and U251 cells using the CRISPR-Cas9 method, which are cultured in two different conditions, the monolayer (2D) and the neurosphere (3D), which is enriched with markers of GSCs. Our studies indicate that PrPC is able to regulate CD44 expression and localization, as well as EGFR expression in U87 cells. Furthermore, flow cytometry assays demonstrate that other membrane proteins, such as NOTCH1, 6 integrin and CD133, have reduced expression on the cell surface of KO cells when compared to WT cells. KO cell transcriptome data here reinforce the role of PrPC in modulating GB biology, being able to modulate genes related to cell anticipation, stemness and migration. Indeed, functional assays corroborate these data, demonstrating that the loss of PrPC leads to a decrease in preference, self-renewal and migration in GB. Therefore, the results seen here reinforce the role of PrPC as a key protein in the maintenance of GB and GSCs, and with therapeutic potential. (AU)

• FAPESP's process: 17/26158-0 - Prion protein as stem regulator in glioblastoma stem cells: its role in the formation and function of multiprotein signaling platforms
• Grantee: Mariana Brandão Prado
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)