Specific microribonucleic acids (miRNAs) that are present in cerebrospinal fluid (CSF) can serve as biomarkers for particular brain malignancies and disease activity.

The level of individual microRNAs can be assayed in CSF and could help identify glioblastoma and metastatic brain cancers, and reflect disease activity and response to therapy.

Scientists at Brigham and Women's Hospital (Boston MA, USA) studied 118 patients with different types of brain cancers and showed that miRNA profiling of CSF can be used to determine the presence of glioblastoma, the most common and lethal type of brain tumor. The test utilizes miRNAs, which are tiny RNA molecules that provide excellent biomarkers for various conditions, and whose levels can be accurately measured in body fluids simply and inexpensively.

The levels of individual miRNAs in CSF and tumors were determined by TaqMan miRNA assays from Applied Biosystems (Carlsbad, CA, USA). Total RNA was used in 6 µL reverse transcription (RT) reactions with specific miRNA RT probes, prior to TaqMan real time polymerase chain reactions (qRT-PCR), that were performed in duplicates. The scientists chose a few candidate miRNAs based on prior knowledge about their expression profiles in normal brain versus various brain cancers and other tissues. Moreover, important pleiotropic roles of their top candidates miR-10b and miR-21 in gliomagenesis are well established.

The investigators concluded that are several advantages of using miRNAs as biomarkers for brain cancer compared with other biomarkers, such as messenger RNA (mRNA) and proteins. MiRNAs are highly stable, and their detection by qRT-PCR is quantitative, extremely sensitive, requiring only nanograms of starting RNA material, highly specific, and reproducible. The same process can be used to detect the presence of cancer that started in another part of the body and spread to the brain, and furthermore, the process can also be used to monitor the tumor as it is treated.

Anna M. Krichevsky, PhD, the principal author, said, "We are excited about the potential that this test has to ease the process of detecting and monitoring brain tumors. The test needs to be further developed before it is used in a clinical setting, but I expect it could be particularly valuable for patients who are not surgical candidates due to the tumor's size or location, or due to an underlying medical condition." The study was published on April 4, 2012, in the journal Neuro-Oncology.

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Brigham and Women's Hospital
Applied Biosystems