BACKGROUND: MicroRNAs (miRNAs) are small (19-22-nt) single-stranded noncoding 
RNA molecules whose deregulation of expression can contribute to human disease 
including the multistep processes of carcinogenesis in human. Circulating miRNAs 
are emerging biomarkers in many diseases and cancers such as type 2 diabetes, 
pulmonary disease, colorectal cancer, and gastric cancer among others; however, 
defining a plasma miRNA signature in acute myeloblastic leukemia (AML) that 
could serve as a biomarker for diagnosis or in the follow-up has not been done 
yet.
METHODS: TaqMan miRNA microarray was performed to identify deregulated miRNAs in 
the plasma of AML patients. Quantitative real-time RT-PCR was used to validate 
the results. Receiver-operator characteristic (ROC) curve analysis was conducted 
to evaluate the diagnostic accuracy of the highly and significantly identified 
deregulated miRNA(s) as potential candidate biomarker(s).
RESULTS: The plasma expression level of let-7d, miR-150, miR-339, and miR-342 
was down-regulated whilst that of let-7b, and miR-523 was up-regulated in the 
AML group at diagnosis compared to healthy controls. ROC curve analyses revealed 
an AUC (the areas under the ROC curve) of 0.835 (95% CI: 0.7119- 0.9581; 
P<0.0001) and 0.8125 (95% CI: 0.6796-0.9454; P=0.0005) for miR-150, and miR-342 
respectively. Combined ROC analyses using these 2 miRNAs revealed an elevated 
AUC of 0.86 (95% CI: 0.7819-0.94; P<0.0001) indicating the additive effect in 
the diagnostic value of these 2 miRNAs. QRT-PCR results showed that the 
expression level of these two miRs in complete remission AML patients resembled 
that of healthy controls.
CONCLUSIONS: Our findings indicated that plasma miR-150 and miR-342 are novel 
important promising biomarkers in the diagnosis of AML. These novel and 
promising markers warrant validation in larger prospective studies.