Roles of miRNAs in regulating the differentiation and maturation of myeloid-derived suppressor cells

Abstract

Myeloid-derived suppressor cells (MDSCs) accumulate in tumor-bearing hosts and play an essential role in tumor-associated immunosuppression, which hampers effective immunotherapeutic approaches. MicroRNAs (miRNAs) are short noncoding RNAs that negatively regulate target gene expression at the posttranscriptional level. miRNAs are involved in regulating cell proliferation, differentiation and maturation, and abnormal expression and function of miRNAs are recognized in various human diseases. Accumulating evidence shows that various miRNAs modulate the development and differentiation of myeloid cells, which implies their possible role in the differentiation of MDSCs into mature myeloid cells. Our recent studies have found that the classical myeloid differentiation related gene runt-related transcription factor 1 (Runx1) and target nuclear factor 1/A (NFI-A) are modulated during the differentiation and maturation of MDSCs while six miRNAs are found to possibly regulate these two targets by miRNA array analysis. Thus, we hypothesize that the predicted miRNAs may modulate the target genes to regulate the differentiation and maturation of MDSCs. Further studies will provide a novel potential approach for tumor immunotherapy.