MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level and participate in a lot of biological processes. Several studies indicated that miRNAs play an important role in hematopoietic system. It has not been elucidated well about miRNAs involved in cytokine-regulated molecular mechanisms in cellular proliferation and differentiation. We screened specific miRNAs expressed in human leukemia cell lines, UT-7 and its sublines UT-7/GM, UT-7/EPO and UT-7/TPO, which exhibit hematopoietic lineage properties depending on cytokine stimuli by GM-CSF, erythropoietin (EPO), or thrombopoietin (TPO), respectively. The expression profiles of 470 miRNAs in all were analyzed using LNA-based microarray between UT-7/GM, UT-7/EPO and UT-7/TPO cells. The initial microarray data were validated, and specific expressions of several miRNAs were confirmed using quantitative real-time PCR. Especially, the expression levels of miR-188 and 362 clustered on X chromosome were significantly higher in UT-7/EPO cells as compared with those in UT-7, UT-7/GM and UT-7/TPO cells. To assess the effect of EPO on the expression of miR-188 and 362, UT-7/EPO cells were cultured under various concentration of EPO (0 to 10 U/ml) after cytokine withdrawal for 24 hours. Quantification of miRNAs expression by real-time PCR showed that miR-188 and 362 were increased 2- to 20-fold by EPO stimuli, but both expressions were not in dose-dependent manner. Furthermore, the addition of EPO (1 ng/ml) to growth factor-derived UT-7 cells which were cultured for 1 month caused a 4- to 50-fold increase of miR-362 expression; while miR-188 expression was not increased. Similarly, EPO induced the expression of miR-362 in erythroleukemic cell line TF-1. The expression levels of miR-188 and miR-362 were significantly higher in UT-7/EPO with erythrocytic features than UT-7/GM and UT-7/TPO cells, in addition, expressions of both miRNAs were induced by EPO stimuli in UT-7/EPO cells, suggesting that miR-188 and miR-362 are involved in lineage specific molecular mechanisms of erythropoiesis.
Disclosure: No relevant conflicts of interest to declare.