Updates in Microglial Research with Respect to Brain Cancer

Abstract

Microglia resides in the microenvironment of the central nervous system (CNS) and is thought to play a key role in the development and progression of brain cancer. This is because it was shown that microglia comprised a large portion of the total brain tumour mass. Besides, the origin of microglia cells in brain tumours is worth understanding as it is important to distinguish the resident macrophages from the circulating macrophages when discussing the pathology of brain tumours. Activated microgliosis has been linked to increased inflammatory mediators like cytokines, growth factors, matrix metalloproteinases (MMPs) and many more, which would facilitate tumourigenesis. Brain tumour cells also proliferate under the influence of signalling pathways, such as the toll-like receptor 2 signals. Vascular endothelial growth factor (VEGF) which is an angiogenic factor aids in the growth of tumour cells. Brain cancer cells rely on suppressing the effector arm of immune system to evade attacks by downregulating major histocompatibility complexes (MHC) class II molecules and inducing the conversion of microglia to an immunosuppressive phenotype. Glioblastoma stem cells (GSCs) that give rise to brain cancers communicate with microglia cells, which determines their growth and invasion potential. Understanding the molecular interactions of brain cancer and microglia cells would help unlock novel treatments via means of immunotherapy, immunosuppressants and utilising microglia cells to deliver nanoparticle drugs to effectively target and treat brain cancer.