Impact of the loss of expression of prion protein on the trafficking of the CD44 in glioblastoma stem cells

• Grant number: 18/04968-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): June 01, 2018
• Effective date (End): November 30, 2019
• Field of knowledge: Biological Sciences - Biology
• Principal Investigator: Marilene Hohmuth Lopes
• Grantee: Rodrigo Nunes Alves
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Among all types of glioma, the most aggressive form (stage IV/IV) is Glioblastoma Multiforme (GMB), related to the lowest survival rate amongst patients. This type of tumor has a specific cell population called glioblastoma stem-cells (GSCs), which are essential to the proliferation, capability of invasion and also directly related to the low rates of the chemotherapy. Thus, the GSCs rises as a potential new target of therapies and our group aims to identify and study markers of these cellular population, specially the prion protein (PrPC), a membrane glycoprotein that contains a GPI-anchor involved in the maintenance of the stemness of these cells. Indeed, the PrPC can act as a scaffold protein, recruiting other proteins to the same membrane microdomain, the lipid rafts, to trigger the intracellular signal transduction mediating a series of biological and molecular processes. Amongst these already known molecules, the CD44 protein, a transmembrane glycoprotein that acts hyaluronic acid receptor (HA), has an important role in cellular migration and stands out as a possible ligand of PrPC. CD44 is coexpressed with PrPC in GSCs and the depletion of each one individually results in the decrease of maintenance, proliferation and invasion of the tumor. In light of these findings, the main goal of this study is to identify the role of the prion protein in the localization and trafficking of CD44 to better understand the metabolism of the GSCs, specifically the stemness maintenance. In order to do this, loss-of-function studies will be conducted using PrPC knockout (K.O.) GSCs generated by the CRISPR/Cas9 technique and already available in the laboratory. Localization and intracellular trafficking of CD44 will be done by immunophenotyping and biochemical assays in wild-type cells vs PrPC K.O. cells. Thus, we want to use this knowledge regarding PrPC and its membrane partners (including CD44) as an alternative treatment to glioblastoma, shedding light on the development of new strategies to decrease resistance and increase the survival rate of the patient.