Emerging role for USP1 in glioblastoma stem cell maintenance and radioresistance: a potential target for glioblastoma therapy

Glioblastoma (GBM) is the most common primary brain malignancy with limited treatment options. The standard of care for GBM, including maximal safe resection, radiotherapy, and concomitant and adjuvant temozolomide is currently recommended for all patients (1) but only a small proportion of patients survive 2 years or longer and, eventually, virtually every tumor recurs (2). GBM is characterized by a high degree of intra-tumoral cellular heterogeneity. Recently, genome-wide expression profiling in the context of The Cancer Genome Atlas (TCGA) project has led to the identification of initially three, and then four main subtypes of GBM (3,4), namely proneural (P), mesenchymal (M), neural (N) and proliferative (or classical, C), thus revealing the existence of a profound degree of inter-tumoral cellular heterogeneity.