PrPC and its ligands in primary cilia dynamics in glioblastoma models

Glioblastoma (GBM) is a highly aggressive and recurrent adult tumor, with therapeutic resistance linked to glioblastoma stem cells (GSCs), which exhibit self-renewal, plasticity, and depend on complex signaling networks often mediated by cell surface proteins. Our group has shown that the cellular prion protein (PrP^C) functions as a scaffold protein in signaling modules related to the GSC phenotype. Notably, PrP^C shares lipid raft domains with integrin α6 (ITGA6), and both proteins are found in primary cilia, microtubule-based organelles that function as hubs for signal transduction, including the Sonic Hedgehog (SHH) pathway, frequently dysregulated in GBM. This study aims to investigate the functional interaction between PrP^C and ITGA6 in the regulation of ciliogenesis and cilia-mediated signaling in GBM. We performed proteomic meta-analysis of GBM patient samples from the PRIDE database and scRNA-seq data from GBMap to assess expression profiles and enriched biological pathways. High ITGA6 expression was associated with proteins involved in cell adhesion and ciliary functions, while high PrP^C expression correlated with pathways linked to microtubule dynamics and neuronal architecture. Shared differentially expressed proteins suggest functional interplay. Additionally, PRNP expression positively correlated with ciliogenesis genes (IFT88, ARL13B) and transcription factors RFX3/RFX4. Confocal microscopy confirmed primary cilia in GBM cell lines. To explore this further, we modulated PrP^C expression in GBM cell lines using lentiviral knockdown and overexpression. Primary cilia biogenesis and morphology were then analyzed by immunofluorescence and confocal imaging. Our results suggest that PrP^C may cooperate with ITGA6 in modulating signaling via primary cilia, revealing potential therapeutic targets for GBM.