Cancer Stem Cells and Glioblastoma: Time for Innovative Biomarkers of Radio-Resistance?

SIMPLE SUMMARY: Glioblastoma (GB) is characterized by a high level of resistance to radiotherapy. Recent studies focused attention on the importance of cancer stem cells (CSC) as elements that influence not only the growth of GB but also its resistance to available treatments. Therefore, stem cells’ radiosensitivity has become an important area of investigation. In this context, biomarkers of stemness (namely, the ability of a cell to perpetuate its lineage, give rise to differentiated cells, and interact with its environment to maintain a balance between quiescence, proliferation, and regeneration) seem to play an important role. The aim of this review is to summarize findings both on stem cells’ radiosensitivity and on biomarkers of stemness, in order to evaluate their relevance in this field. ABSTRACT: Despite countless papers in the field of radioresistance, researchers are still far from clearly understanding the mechanisms triggered in glioblastoma. Cancer stem cells (CSC) are important to the growth and spread of cancer, according to many studies. In addition, more recently, it has been suggested that CSCs have an impact on glioblastoma patients’ prognosis, tumor aggressiveness, and treatment outcomes. In reviewing this new area of biology, we will provide a summary of the most recent research on CSCs and their role in the response to radio-chemotherapy in GB. In this review, we will examine the radiosensitivity of stem cells. Moreover, we summarize the current knowledge of the biomarkers of stemness and evaluate their potential function in the study of radiosensitivity.