ABSTRACT

MicroRNAs (miRNAs) are a class of small endogenous RNAs that play important regulatory roles by targeting mRNAs for cleavage or translational repression. miRNAs act in diverse biological processes including development, cell growth, apoptosis, and hematopoiesis, suggesting their association with cancer. We determined the miRNA expression profile of chronic and acute lymphocytic leukemias (CLL and ALL) using the TaqMan ® MicroRNA Assays Human Panel (Applied Biosystems). Pooled leukemia samples were compared to pooled CD19 + samples from healthy individuals (calibrator) by the 2 -∆∆Ct method. Total RNA input was normalized based on the Ct values obtained for hsa-miR-30b. The five most highly expressed miRNAs were miR-128b, miR-204, miR-218, miR-331, and miR181b-1 in ALL, and miR-331, miR-29a, miR-195, miR-34a, and miR29c in CLL. To our knowledge, this is the first report associating miR128b, miR-204 and miR-331 to hematological malignancies. The miR-17-92 cluster was also found to be up-regulated in ALL, as previously reported for some types of lymphomas. The differences observed in gene expression levels were validated for miR-331 and miR-128b in ALL and CD19 + samples. These miRNAs were upregulated in ALL, in agreement with our initial results. A brief target analysis was performed for miR-331. One of its putative targets, SOCS1, promotes STAT activation, which is a known mediator of cell proliferation and survival, suggesting the possibility of an association between miR-331 and these processes. This initial screening provided information on miRNA differentially expressed in normal and malignant B-cells that could suggest the potential roles of these miRNAs in hematopoiesis and leukemogenesis.

Autologous hematopoietic SCT (AHSCT) has been investigated in the past as a therapeutic alternative for multiple sclerosis (MS). Despite advances in clinical management, knowledge about mechanisms involved with clinical remission post transplantation is still limited. Abnormal microRNA and gene expression patterns were described in MS and have been suggested as disease biomarkers and potential therapeutic targets. Here we assessed T-and B-cell reconstitution, microRNAs and immunoregulatory gene expression after AHSCT. Early immune reconstitution was mainly driven by peripheral homeostatic proliferation. AHSCT increased CD4 + CD25 hi FoxP3 + regulatory T-cell counts and expression of CTLA-4 and GITR (glucocorticoid-induced TNFR) on CD4 + CD25 hi T cells. We found transient increase in exhausted PD-1 + T cells and of suppressive CD8 + CD28 − CD57 + T cells. At baseline, CD4 + and CD8 + T cells from MS patients presented upregulated miR-16, miR-155 and miR-142-3p and downregulated FOXP3, FOXO1, PDCD1 and IRF2BP2. After transplantation, the expression of FOXP3, FOXO1, PDCD1 and IRF2BP2 increased, reaching control levels at 2 years. Expression of miR-16, miR-155 and miR-142-3p decreased towards normal levels at 6 months post therapy, remaining downregulated until the end of follow-up. These data strongly suggest that AHSCT normalizes microRNA and gene expression, thereby improving the immunoregulatory network. These mechanisms may be important for disease control in the early periods after AHSCT.