MiR-424 and miR-155 deregulated expression in cytogenetically normal acute myeloid leukaemia: Correlation with NPM1 and FLT3 mutation status

Background: MicroRNA have a central role in normal haematopoiesis and are deregulated in acute myeloid leukaemia (AML). The purpose of the study was to investigate by qRT-PCR the expression of miRNAs involved in myeloid differentiation (miR-424, miR-155, miR-223, miR-17-5p) in 48 patients with cytogenetically normal AML well characterized for NPM1 and/or FLT3 mutations. Three types of normalization were used for the data validation. Findings: We found that miR-424 was down-modulated in AMLs with NPM1mutA regardless of FLT3 status. On the contrary, miR-155 showed up-regulation in patients with FLT3 internal tandem duplications (ITD) with or without NPM1 mutations. No significant associations were found by analyzing miR-223 and miR-17-5p in relation to FLT3 and NPM1 status. Conclusions: This study supports the view that major genetic subsets of CN-AML are associated with distinct miRNA signatures and suggests that miR-424 and miR-155 deregulation is involved in the pathogenesis of CN-AML with NPM1 and FLT3-ITD mutations, respectively.