Extension of microRNA expression pattern associated with high-risk neuroblastoma.

Clinical behavior of neuroblastoma (NBL) is remarkably heterogeneous, as it ranges from spontaneous regression to aggressive clinical phenotype and death. There is increasing body of evidence demonstrating that microRNAs could be considered the potential biomarkers for clinical applications in NBL. In this report, we focus on molecular characterization of high-risk as well as low-risk and intermediate-risk NBL cases in the context of the microRNA expression profile that is specific for the given risk category of the disease. We investigated a total of 30 NBL patients, out of whom there were 19 patients with low- to intermediate-risk and 11 with high-risk NBLs as defined by the Clinical Oncology Group. We determined the expression profiles of 754 microRNAs (miRNAs), whereas the miRNA expression levels were normalized to RNU44, mean expression levels were calculated, and data were analyzed by use of the microarray biostatistical approaches. We identified the signature of 38 miRNAs differentially expressed between these groups of NBL patients (P < 0.05): 17 miRNAs were upregulated and 21 miRNAs were downregulated in the tumors of high-risk NBL patients. We confirm some of the previous observations and we report several new microRNAs associated with aggressive NBL, both being relevant subjects for further translational validation and functional studies.