Expression of
microRNAs is altered in
cancer. Circulating
miRNA level assessed in body fluids commonly reflects their expression in
tumor cells. In
leukemias, however, both leukemic and nonleukemic cells compose circulating
miRNA expression profile of peripheral blood. The latter contribution to extracellular
miRNA pool may result in specific microenvironmental signaling, which promotes proliferation and survival. In our study, we used qT-PCR to assay peripheral blood serum of 22
chronic lymphocytic leukemia (CLL) patients for the expression of 84
miRNAs associated with activation and differentiation of B and T lymphocytes. Results were analyzed regarding the most important prognostic factors. We have found that the general expression of examined
miRNAs in CLL patients was lower as compared to healthy volunteers. Only miR-34a-5p, miR31-5p, miR-155-5p, miR-150-5p, miR-15a-3p, and miR-29a-3p were expressed on a higher level. Alterations of expression observed in CLL patients involved
miRNAs associated both with B and T lymphocyte differentiation and activation. The most important discriminating factors for all functional
miRNA groups were
trisomy 12, CD38 expression, B2M level, WBC, and NOTCH1 gene mutation. Correlation of expression of
miRNAs related to T lymphocytes with prognostic factors proves their supportive function in a leukemic microenvironment. Further studies utilizing a larger test group of patients may warrant the identification of circulating
miRNAs that are key players in intercellular interactions and should be considered in the design of microenvironment-targeted
therapies.