CIRCULATING MICRORNAS IN PLASMA OF PATIENTS WITH MYELODYSPLASTIC SYNDROMES

Background
Myelodysplastic syndromes (MDS) represent a wide range of hematopoietic stem cell disorders characterized by ineffective hematopoiesis, peripheral blood cytopenias, and a tendency to evolve into acute myeloid leukemia. MicroRNAs (miRNAs) are short endogenous non-coding RNA molecules that play an essential role in the regulation of gene expression at post-transcriptional levels. Existence of miRNAs has been recognized not only in the intracellular environment but it has recently been shown that these molecules are also present in a wide variety of body fluids, including blood plasma. Cell free miRNAs (referred to as circulating miRNAs) have been repeatedly proved to function as new promising semi-invasive diagnostic markers of various types of cancer but only little information is known about their deregulation in MDS.

Aims
In this study, we focus on alteration of miRNA levels circulating in plasma of MDS patients with the emphasis on differences between low and high risk disease.

Methods
Peripheral blood plasma was collected from 40 patients with untreated primary MDS and from 10 healthy, age-matched donors with no medical history. Written informed consent was obtained from all tested subjects in accordance with the Institutional Review Board. Total RNA was extracted from plasma using Qiagen miRNeasy mini kit. Agilent Human miRNA Microarrays were used to assess the amount of 2,006 human miRNAs in blood plasma from 13 MDS patients and 6 healthy donors. The microarray results were confirmed in the complete set of samples by RT-qPCR.

Results
Statistical analyses identified significant differences in a plasma profile of circulating miRNAs between different study groups. In MDS, 19 down-regulated and 25 up-regulated miRNAs were detected compared to healthy controls. Some hematopoiesis and/or oncology-associated miRNAs were found in the list of deregulated molecules, e.g. down-regulation of miR-92a-3p, miR-142-3p/5p, miR-320a/b/d/e, and miR-451a, and up-regulation of miR-150-5p, miR-188-5p, and miR-548q. Low-risk and high-risk groups of patients significantly differed in levels of several miRNAs, namely in reduction of miR-185-5p and miR-4306 and elevation of miR-548q, miR-623, miR-4707-5p, miR-4721, and miR-4739 in high-risk patients.

Summary
Expression profiling of plasma miRNAs in patients with MDS revealed several miRNAs with altered levels gradually changing within the disease progression, suggesting that circulating miRNAs may be new candidate molecular markers for monitoring of the disease.

This work was supported by the grant NT13847-4 from the Ministry of Health of the Czech Republic. 

Keyword(s): Microarray analysis, Myelodysplasia, Plasma

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