Advances in exosome-related biomarkers for glioblastoma: Basic research and clinical application

Abstract

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. The median survival rate of GBM patients is approximately 14 months and tumor recurrence is almost inevitable. With the increased use of immunotherapy, immune response and edema found on posttreatment magnetic resonance imaging (MRI) may be misinterpreted as tumor progression. Distinguishing the true radiographic progression from pseudo-progression by MRI is often difficult. Peripheral biomarkers are needed to identify the true tumor recurrence and evaluate therapy response. Exosomes isolated from both blood and cerebrospinal fluid are cargo containers utilized by eukaryotic cells to exchange biomolecules such as proteins, mRNA, and microRNA (miRNA). These biomolecules participate in cell-cell communication, cell migration, angiogenesis, and tumor growth. Isolation of RNA (including miRNA) from exosomes can yield a greater concentration compared with circulating mRNA directly taken from body fluid as molecules within exosomes are not degraded by nucleases and proteases. Not only are exosomes a novel approach to biomarker detection, but they may also provide potential therapeutic interventional targets. In addition, exosomes are critical in miRNA replacement therapy as they can act as a carrier for anticancer drug delivery. This review focuses on the advances in basic research of exosome-related potential biomarkers and discusses their potential application in the diagnosis, prognosis, and treatment of GBM.