CXCR4 and Glioblastoma.

This article focuses on the possible application of antagonists of the G-protein coupled chemokine receptor, CXCR4, for the treatment of glioblastoma and summarises the evidence for CXCR4 antagonism being a viable therapeutic approach. Particular attention is paid to the role of this receptor in cancer stem cell biology, and the maintenance of CXCR4 expression by the glioblastoma key driver mutations. The expression of the CXCR4 receptor, and of its ligand stromal derived factor 1 (SDF-1, CXCL12), is maintained by intracellular pathways via positive feedback loops, and is associated with the epithelial mesenchymal transition (EMT) and the generation and self-renewal of cancer stem cells. SDF-1 and CXCR4 also play a role in the generation and maintenance of the perivascular stem cell niche which contains these cancer stem cells. The available data suggest that most, if not all, glioblastoma cancer stem cells rely on CXCR4 mediated signalling to maintain their phenotype. SDF-1 and CXCR4 are alsoinvolved in many other aspects of brain tumour biology including resistance to radio- and chemotherapy, the migration of cancer cells through the brain, the generation of the tumour blood supply and the recruitment of vascular progenitor cells. These properties suggest that a CXCR4 antagonist would help in the control of this disease.