Cerebrospinal fluid microRNAs as diagnostic biomarkers in brain tumors

Cerebrospinal fluid (CSF) is a body fluid that has many important functions and is in direct contact with the extracellular environment of the central nervous system (CNS). CSF serves as both the communication channel allowing the distribution of various substances among the CNS cells and the storage facility for the waste products these cells release. For these reasons, CSF is a potential source of diagnostic biomarkers of many CNS diseases, including brain tumors. Recent studies have revealed that CSF also contains circulating microRNAs (miRNAs), short non-coding RNAs that have been described as biomarkers in many cancers. However, CSF miRNAs are difficult to detect, which is why researchers face major challenges, including technological difficulties in its detection and its lack of standardization. Therefore, this review aims (i) to highlight the potential of CSF miRNAs as diagnostic, prognostic and predictive biomarkers in brain tumors, and (ii) to summarize technological approaches for detection of CSF miRNAs.