Non-Tumor Cells within the Tumor Microenvironment-The "Eminence Grise" of the Glioblastoma Pathogenesis and Potential Targets for Therapy

Abstract

Glioblastoma (GBM) is the most common malignancy of the central nervous system in adults. GBM has high levels of therapy failure and its prognosis is usually dismal. The phenotypic heterogeneity of the tumor cells, dynamic complexity of non-tumor cell populations within the GBM tumor microenvironment (TME), and their bi-directional cross-talk contribute to the challenges of current therapeutic approaches. Herein, we discuss the etiology of GBM, and describe several major types of non-tumor cells within its TME, their impact on GBM pathogenesis, and molecular mechanisms of such an impact. We also discuss their value as potential therapeutic targets or prognostic biomarkers, with reference to the most recent works on this subject. We conclude that unless all "key player" populations of non-tumor cells within the TME are considered, no breakthrough in developing treatment for GBM can be achieved.

Keywords: CAFs; CSCs; GBM; TANs; TILs; cancer; cancer stem cells; glioblastoma; novel therapeutic targets; tumor microenvironment.

Figure 1

Different non-tumor cell populations within the GBM TME. Some elements of the figure were created using Server Medical Art figures licensed under a Creative Common Attribution 3.0 Unported License; https://smart.servier.com (accessed on 2 March 2024). Some elements were created with the use of free figures from https://bioicons.com (accessed on 2 March 2024) under a Creative Common license.