Detection and quantification of extracellular microRNAs in medulloblastoma

Abstract

Aim: Medu lloblastoma (MB) is the most common malignant brain tumor in children. The crucial role of extracellular-microRNAs (ex-miRNAs) in cancer has been widely recognized; however, their role in MB remains unknown. This study aimed to investigate MB-driven ex-miRNAs. Methods: Microarray analysis was used to disclose the identity and quantity of key miRNAs excreted in culture-medium (CM) of 3 human MB cell lines and cere brospinal fl uid (CSF) of brain tumors (including MB) and leukemia patients. MiRNA expression was validated by quantitative reverse transcription polymerase chain reaction. Results: We have demonstrated that the 3 MB cell lines tested commonly expressed 1,083 miRNAs in their spent CM. Among them, 57 miRNAs were specifi c to the CM of metastasis-related cell lines which represents the aggressive group 3 and group 4 MB subtypes. A signifi cant number (1,254) of ex-miRNAs were identifi ed in the CSF of a MB patient. Eighty-six of these miRNAs were found to be differentially expressed in this patient's CSF compared with controls. Interestingly, 3 metastasis-associated miRNAs over-represented in CM of metastasis-related MB cell lines were found to be signifi cantly enriched in the CSF of the MB patient. Conclusion: Although more samples are required to fully verify these results, our work provides the fi rst evidence for the presence of a signifi cant amount of miRNAs excreted extracellularly by MB cells and raises the possibility that, in the near future, miRNAs could be probed in CSF of MB patients and serve as novel biological markers.

Fluids and flows in brain cancer and neurological disorders

“…(Weber et al, 2010). A number of clinical studies have shown that heightened expression of specific miRNAs is closely associated with malignant tumors, in particular the miRNAs contained in the CSF of brain tumor patients show promise as diagnostic biomarkers (Grotzer et al, 2015;R. Shi et al, 2015).…”

“…Circulating miRNAs exist in almost all human body fluids including blood, serum, urine, saliva, tears, and CSF ( Weber et al, 2010 ). A number of clinical studies have shown that heightened expression of specific miRNAs is closely associated with malignant tumors, in particular the miRNAs contained in the CSF of brain tumor patients show promise as diagnostic biomarkers ( Grotzer et al, 2015 ; R. Shi et al, 2015 ). One study in particular identified that metastatic tumor miRNA (i.e., miRNA-125a, miRNA-125b and miRNA-1290) was over-expressed in CSF samples, corresponding to expression levels in the tumor.…”

MicroRNAs in Cerebrospinal Fluid as Biomarkers in Brain Tumor Patients

“…Zajímavé je, že c-miRNA jsou vysoce stabilní a odolávají extrémním podmínkám, jako je aktivita ribonukleáz, opakované zmrazování, var, nízké a vysoké pH nebo i skladování při pokojové teplotě [13]. Deregulované hladiny miRNA v CSF jsou podle nedávných studií také asociovány s maligními nádory CNS [14][15][16][17][18][19][20]. Například hladina miR-21 u pacientů s gliomy dokázala rozlišit nádorové vzorky CSF s vyšší citlivostí a specificitou než hladiny miR-21 detekované v krevní plazmě [21].…”