GSE178260
Dual role of Integrin alpha-6 in glioblastoma: supporting stemness in proneural stem-like cells while inducing radioresistance in mesenchymal stem-like cells
Therapeutic resistance after multimodal therapy is the most relevant cause of glioblastoma (GBM) recurrence. Extensive cellular heterogeneity, mainly driven by the presence of GBM stem-like cells (GSC), strongly correlates with patients' prognosis and limited response to therapies. Defining the mechanisms which drive stemness and control responsiveness to therapy in a GSC-specific manner is therefore mandatory. Here we investigated the role of integrin a6 (ITGA6) in controlling stemness and resistance to radiotherapy in proneural and mesenchymal GSCs subtypes. Using cell sorting, gene silencing, RNA-Seq and in vitro assays, we verified that ITGA6 expression seems crucial for proliferation and stemness of proneural GSCs, while it appears not to be relevant in mesenchymal GSCs under basal conditions. However, when challenged with a fractionated protocol of radiation therapy, comparable to that employed in the clinical setting, mesenchymal GSCs turned out to be dependent on integrin a6 for survival. Specifically, GSCs with reduced levels of ITGA6 displayed a clear reduction of DNA-damage response and perturbation of cell cycle pathways. These data indicate that ITGA6 inhibition is able to overcome the radioresistance of mesenchymal GSCs, while it reduces proliferation and stemness in proneural GSCs. Therefore, integrin a6 controls crucial characteristics across GBM subtypes in GBM heterogeneous biology and thus may represent a promising target to improve patient outcomes Overall design: mRNA profiles of MES-GSC CTL or KD for integrin alpha6