Upregulation of miR-224 predicts poor prognosis in patients with pediatric acute myeloid leukemia

Dysregulation of miR-224 has been shown to be involved in cancer tumorigenesis and progression of several cancer types. However, its expression patterns in tumors are controversial. The aim of this study was to determine the expression and clinical significance of miR-224 in pediatric acute myeloid leukemia (AML). Expression levels of miR-224 in bone marrow mononuclear cells were detected by real-time quantitative PCR in 104 patients with newly diagnosed pediatric AML. The results showed that miR-224 expression was significantly upregulated in the bone marrow of pediatric AML patients when compared with controls (P<0.001). Also, miR-224 upregulation occurred more frequently in French-American-British classification subtype M7 than in other subtypes (P=0.007). Regarding to cytogenetic risk, the levels of miR-224 in pediatric AML patients with unfavorable karyotypes were dramatically higher than those in intermediate and favorable groups (P=0.028). Moreover, Kaplan-Meier analysis showed that pediatric AML patients with high miR-224 expression tended to have shorter disease free and overall survivals. In multivariate analysis stratified for known prognostic variables, high miR-224 expression was identified as an independent prognostic factor for both disease free and overall survivals. In conclusion, our data indicated that the upregulation of miR-224 was associated with advanced clinical features and poor prognosis of pediatric AML patients, suggesting that miR-224 upregulation may serve as an unfavorable prognostic biomarker in pediatric AML.