Pivotal Role of STAT3 in Shaping Glioblastoma Immune Microenvironment

Glioblastoma belongs to the most malignant intracranial tumors characterized by indispensable growth and aggressiveness that highly associates with dismal prognosis and therapy resistance. Tumor heterogeneity that often challenges therapeutic schemes is largely attributed to the complex interaction of neoplastic cells with tumor microenvironment (TME). Soluble immunoregulatory molecules secreted by glioma cells attract astrocytes, circulating stem cells and a range of immune cells to TME, inducing a local production of cytokines, chemokines and growth factors that reprogram immune cells to inflammatory phenotypes and manipulate host's immune response in favor of cancer growth and metastasis. Accumulating evidence indicates that these tolerogenic properties are highly regulated by the constitutive and persistent activation of the oncogenic signal transducer and activator of transcription 3 (STAT3) protein, which impairs anti-tumor immunity and enhances tumor progression. Herein, we discuss current experimental and clinical evidence that highlights the pivotal role of STAT3 in glioma tumorigenesis and particularly in shaping tumor immune microenvironment in an effort to justify the high need of selective targeting for glioma immunotherapy.