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Original Article

Detection and quantifi cation of extracellular microRNAs in
medulloblastoma

Tarek Shalaby , Giulio Fiaschetti , Sylvain Baulande , Nicolas U. Gerber , Martin Baumgartner , Michael A. Grotzer 1
2
1
1
1
1
1 Department of Oncology, University Children’s Hospital Zurich, 8032 Zurich, Switzerland.
2 Department of Biology, PartnerChip CEA, Génopole Campus 2, 91000 Évry, France.
Correspondence to: Prof. Michael A. Grotzer, Department of Oncology, University Children’s Hospital Zurich, Steinwiesstrasse 75CH, 8032
Zurich, Switzerland. E-mail: michael.Grotzer@kispi.uzh.ch
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.

Key words: Medulloblastoma, extracellular-microRNA, pediatric cancer

Introduction Every cancer investigated has a distinct miRNA
signature and deregulated levels of miRNAs have been
Medulloblastoma (MB) is the most common malignant detected in body fl uids of patients, including those
brain tumor in children. Metastatic MB carries a poor with lymphoma, leukemia, [12] colon, [13] breast,
[1]
[14]
[11]
[2]
prognosis. Mechanisms that predict dissemination prostate, [15] ovarian, [16] pancreatic, [17] gastric, [18] and lung
are poorly understood. Recently, several studies have cancer. [19] In the context of brain tumors, recent studies
revealed a critical role for microRNAs (miRNAs) have demonstrated a signifi cant presence of certain
during tumorigenesis and metastasis of several cancers, miRNAs in CSF samples from patients with central
including MB. [3-6]
nervous system lymphoma, glioma, and metastatic
Besides intracellular miRNAs with the traditional brain cancers. [20-22] Recent miRNA profi ling of CSF has
function of translation regulation, there is accumulating enabled early detection of glioblastoma and refl ected
evidence that miRNAs exist extracellularly in body fl uids, disease activity. [22] Therefore, ex-miRNAs may represent
including cerebrospinal fl uids (CSF). [7,8] Several reports important minimally invasive candidate biomarkers
have described that deregulated extracellular-miRNAs in brain tumors. The presence and biological role of
(ex-miRNAs) are closely associated with the clinical ex-miRNAs in MBs, however, remain unknown. This
course of malignant tumors. [9,10] Interestingly, such study was conducted to gain insight into the identity and
deregulation returns to a normal level after tumor quantity of MB-related ex-miRNAs and to speculate on
resection. [7,8] Hence, expression analysis of ex-miRNAs their possible biological function in the context of MB
is of increasing interest for diagnostic and prognostic metastasis.
purposes.
Methods
Access this article online Patient characteristics and CSF
Quick Response Code: CSF samples from patients with MB (n = 2), control
Website:
www.jcmtjournal.com patients with leukemia with no intracranial mass
lesions and/or neurologic disorders (n = 3), CSF
samples from patients with ependymoma (n = 3) and
DOI:
10.4103/2394-4722.157068 glioblastoma (n = 1) that were collected from patients
treated at the University Children’s Hospital of Zürich,

Journal of Cancer Metastasis and Treatment ¦ Volume 1 ¦ Issue 2 ¦ July 15, 2015 ¦ 67