Abstract 4192: Genome-wide microRNA and functional genomics analysis during differentiation of acute promyelocytic leukemia to granulocytes.
Authors: Dakir El Habib , Satoh Jun-ichi , Mollinedo Faustino 
Published: August 2014

Abstract
MicroRNA (miRNAs) are short noncoding RNAs that play important roles in human diseases, including cancer, and function to regulate gene expression of critical processes, such as apoptosis, cell proliferation and differentiation, by either translational inhibition or mRNA degradation. However, little is known about the role of miRNAs in granulopoiesis and acute myeloid leukemia (AML). We performed genome-wide miRNAs and functional genomics analysis in the acute promyelocytic leukemia (APL) human cell line HL-60 during its differentiation towards granulocytes, by using miRNA microarrays Exiqon platform, quantitative real time polymerase chain reaction (qRT-PCR) and Ingenuity Pathways Analysis(IPA). Among 1279 human miRNAs analyzed, we identified a unique signature of 86 differentially expressed miRNAs between control and DMSO-treated cells (at p&lt;0.05), 51 of them were up-regulated and 35 of were down-regulated, which have not previously identified as regulators of hematopoietic differentiation. Our data showed that miRNA expression profiling revealed distinctive miRNA signatures that correlated with morphological changes in the cell and nucleus, granule formation, and chromatin condensation, all these processes being consistent with neutrophil maturation. Transmission electron microscopy (TEM) showed large mitochondria and revealed the presence of multiple autophagosome-like vacuoles with double-membrane structures in neutrophil-like differentiated cells. Specific miRNAs, such as miR-125a-5p and miR-483-3p, appeared to be associated with chromatin remodeling and nuclear protein expression, such as chromosome condensation (CHC1L) and histone family member X (H1FX), during HL-60 cell differentiation towards granulocytes. We found by gain-of-function experiments that miRNA-125a-5p and miR483-3p promoted granulocytic differentiation of HL-60 leukemic cells as confirmed by nitroblue tetrazolium (NBT) staining and mature myeloid cell marker expression, while miR-17-92 cluster attenuated granulocytic differentiation. Therefore miRNA-125a-5p, miRNA-483-3p up-regulation and miRNA-17-92 cluster down-regulation provide new insight into the mechanism of granulopoiesis. Molecular network analysis of miRNA targetome during APL differentiation showed a regulation by individual miRNAs that constitute a biological network of functionally-associated molecules in human cells, closely linked to pathological events involved in cancer, p53 signaling, gene expression, cellular growth and differentiation. These findings provide unique molecular insights into how APL malignant cells can be differentiated towards terminal neutrophil-like cells, which might lead to the identification of novel molecular targets in leukemia differentiation therapy.
Citation Format: El Habib Dakir, Jun-ichi Satoh, Faustino Mollinedo. Genome-wide microRNA and functional genomics analysis during differentiation of acute promyelocytic leukemia to granulocytes. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4192. doi:10.1158/1538-7445.AM2013-4192