Exploring the role of inflammation in the malignant transformation of low-grade gliomas

Studies of inflammatory mediators have established the tumor micro-environment as a driver of oncogenesis. This inflammatory milieu often precedes cancer, however recent data also point to the ability of oncogenic changes to induce inflammatory responses that are later harnessed by the tumor to survive and proliferate. In this review, we propose that the IDH1 mutation, present in the majority of low-grade gliomas (LGGs), initiates an inflammatory cascade that is ultimately hijacked by the tumor. Glioma infiltrating macrophages and microglia (GIMs) are polarized to the M2 phenotype, subverting the host's adaptive immune response, and fostering a tumor milieu ripe for angiogenesis, migration, and metastasis. As data continue to expand the role of inflammation in low-grade gliomas, new molecular pathways may emerge as therapeutic targets that offer a window of opportunity to intervene before the malignant transformation (MT) of LGGs occurs. (C) 2016 Elsevier B.V. All rights reserved.