MicroRNAs Differentiate Between Primary and Metastatic Brain Tumors

MicroRNAs were used to differentiate between primary and metastatic tumors of the brain.

MicroRNAs (miRNAs) are naturally occurring, small RNAs that act as master regulators and have the potential to form the basis for a new class of diagnostics and therapeutics. MicroRNAs have been shown to have different expression profiles in various pathological conditions. These differences provide a novel diagnostic strategy for many diseases.

A study conducted by Rosetta Genomics' (Rehovot, Israel) scientist Nitzan Rosenfeld and colleagues from five different Israeli medical centers demonstrated microRNAs' potential to act as effective biomarkers that could be applied in a diagnostic test to identify primary tumors in patients with brain cancer. The study results, published in the June 8, 2008 online edition of Brain Pathology, describe the development and validation of microRNA expression profiles for characterization of brain malignancies.

MicroRNA expression was measured in RNA extracted from hundreds of formalin-fixed, paraffin-embedded (FFPE) samples of brain primary tumors and other tissues, as well as 60 samples of metastatic brain tumors. Two microRNAs, miR-92b and miR-9/9*, were found to be significantly over-expressed in brain primary tumors, and may represent potential biomarkers for the identification of these tumors. The study demonstrated, based on a blinded test set, that the overall sensitivity and specificity of this classifier are approximately 90%.

The study authors wrote: "By considering the expression of only these two microRNAs, it is possible to distinguish between primary and metastatic brain tumors with very high accuracy. These microRNAs thus represent excellent biomarkers for brain primary tumors. Previous reports have found that hsa-miR-92b and hsa-miR-9/hsa-miR-9* are expressed more strongly in developing neurons and brain than in adult brain. Thus, their specific over-expression in brain primary tumors supports a functional role for these microRNAs or a link between neuronal stem cells and brain tumorigenesis.”


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