RESUMO
OBJECTIVES: As a member of miR-29 family, miR-29a can act as either oncogene or tumor suppressor. However, its expression patterns in acute myeloid leukemia (AML) are controversial according to previous studies. Thus, the aim of this study was to determine the expression and clinical significance of miR-29a in pediatric AML. METHODS: Expression levels of miR-29a in bone marrow mononuclear cells were detected by real-time quantitative PCR in a cohort of 106 patients with newly diagnosed pediatric AML. The prognostic values of miR-29a in pediatric AML were also analyzed. RESULTS: Compared with normal controls, we demonstrated a significantly decreased expression of miR-29a in the bone marrow of pediatric AML patients (P<0.001). The expression levels of miR-29a were significantly lower in French-American-British classification subtype M7 than in other subtypes (P<0.001) and differed significantly across cytogenetic risk groups (P=0.002) with high miR-29a expression among those with favorable karyotypes. Moreover, low miR-29a expression was significantly associated with shorter relapse-free (P<0.001) and overall (P=0.008) survival in pediatric AML patients. Cox proportional hazards multivariate analysis of the univariate predictors identified cytogenetic risk and miR-29a expression as independent prognostic factors for relapse-free survival and overall survival. More interestingly, the prognostic value of miR-29a expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics. CONCLUSION: Our data indicate for the first time that the down-regulation of miR-29a was associated with advanced clinical features and poor prognosis of pediatric AML patients, suggesting that miR-29a down-regulation may be used as an unfavorable prognostic marker in pediatric AML.
