161P - Differential expression of various miRNAs in pediatric cytogenetically normal acute myeloid leukemia (CN-AML).

Dysregulation of various miRNAs has been linked to the initiation and progression of several cancers including acute myeloid leukemia (AML). However, their role in pediatric cytogenetically normal AML (CN-AML) is still unclear. The objective of the present study was to identify deregulated miRNA expression patterns and their correlation with survival outcome in pediatric CN-AML. The study was approved by Institutional Ethical Committee. Informed written consent was taken from all the subjects. Bone marrow (BM) samples from 36 pediatric CN-AML patients and 20 pediatric controls (with solid tumors without BM involvement) were collected and used for isolation of mononuclear cells, genomic DNA and total RNA. Various clinical parameters were accessed and mutation status (NPM1 and FLT3-ITD) determined by PCR. Total RNA from 10 samples (5 CN-AML and 5 controls) was used for global miRNA profiling on Illumina HiSeq2500 platform and data were analysed using bioinformatic pipeline. For all 36 CN-AML patients, cDNA was prepared using TaqMan advanced miRNA cDNA synthesis kit followed by qPCR using TaqMan advanced miRNA assay for selected miRNAs. Global miRNA profiling revealed differential expression of 168 miRNAs of which 66 were upregulated and 102 were downregulated (fold change>1.5, p ≤ 0.05) in pediatric CN-AML patients. Interestingly, 40 miRNAs belonging to human 14q32 miRNA cluster were significantly downregulated in CN-AML patients. The expression of 11 miRNAs selected for qPCR-based validation based on their involvement in signalling pathways in AML (and other cancers), were found to be dysregulated in 36 patients. Most of these miRNAs were found to target genes involved in the initiation and progression of AML. Importantly, there was a significant correlation between expression levels of miR-75, miR-589, miR-4446, miR-889, and miR-654 and survival outcomes like Event-free, Disease-free, and Overall survival. Clinical parameters like TLC, ANC, LDH, Blast percentage were also significantly correlated with survival outcomes. Along with various genetic abnormalities, deregulation in the expression of miRNAs might be an important contributor to the development of pediatric CN-AML. The authors. Department of Biotechnology, Government of India. All authors have declared no conflicts of interest. [ABSTRACT FROM AUTHOR]