FUNCTIONAL DIFFERENCES BETWEEN NSCS AND GSCS IN PROLIFERATION AND QUIESCENCE: THE ROLE OF IRDS

Glioblastoma (GB) is an aggressive brain tumor characterized by cellular heterogeneity and marked resistance to conventional therapies. Neural stem cells (NSCs) and glioblastoma stem cells (GSCs) share key properties, including self-renewal capacity and similar differentiation potentials, which complicates their identification and functional characterization within mixed populations. In this study, we employed Hoechst and PyY staining to isolate and analyze NSC and GSC subpopulations in proliferative and quiescent states, specifically using Hoechst to assess DNA content and PyY to evaluate RNA levels, along with protein assessment via OPP labeling and confocal microscopy. RNA-seq analyses revealed distinct transcriptomic signatures associated with each cellular state: proliferating cells displayed elevated expression of genes related to cell division and mitotic activity, whereas quiescent cells exhibited upregulation of genes associated with quiescence, including the Interferon-Related DNA Damage Resistance Signature (IRDS). Notably, IRDS expression was elevated in quiescent cells of both NSCs and GSCs. While qNSCs demonstrated a robust response to quiescence-inducing signals, many qGSCs retained residual proliferative activity and sustained colony formation under similar conditions. These observations suggest that IRDS may serve a protective role in NSCs, supporting genome integrity and cellular homeostasis, while in GSCs it could contribute to therapy resistance and cellular persistence, reflecting context-dependent functional implications. Collectively, these results highlight the utility of Hoechst and PyY in discriminating cellular states and provide a framework for investigating molecular and functional differences between normal and tumor stem cells. This approach has potential relevance for the development of more targeted and effective therapeutic strategies in GB.