Objective: To detect the expression of microRNA-223 and analyze its clinical value in B lymphoproliferative disorders.
Methods: Peripheral blood samples (n = 78) and bone marrow samples (n = 9) were collected from patients with chronic lymphocytic leukemia (CLL, n = 53), mantle cell lymphoma (MCL, n = 13), splenic marginal zone lymphoma (SMZL, n = 9) and healthy donors (n = 12) at our hospital from 2003 to 2010. Mononuclear cells were isolated and B cells purified with a CD19(+) magnetic-bead system. Total RNA was extracted from purified CD19(+) cells and the expression of microRNA-223 measured by TaqMan microRNA quantitative polymerase chain reaction (PCR). The clinical data of these patients were collected and their outcomes analyzed with SPSS 16.0 software.
Results: (1) The levels of microRNA-223 in CLL, MCL and SMZL were 4.58 ± 0.62, 4.03 ± 0.54 and 4.63 ± 0.57 respectively. And they were significantly lower than that in normal B cells (5.69 ± 0.60, P < 0.01). The expression of microRNA-223 decreased significantly in MCL versus CLL and SMZL (P < 0.05). There was no statistical difference between CLL and SMZL (P > 0.05). (2) The down-regulation of microRNA-223 was associated with disease aggressiveness in CLL. Patients with unmutated immunoglobulin heavy chain variable region (IgVH) expressed significantly a lower level of microRNA-223 (4.05 ± 0.69 vs 4.67 ± 0.51, P = 0.003). In 13q-negative patients, the expression of microRNA-223 decreased more significantly than that in 13q-positive patients (4.25 ± 0.67 vs 4.76 ± 0.45, P = 0.044). (3) Using receiver operating characteristic (ROC) curve analysis, the microRNA-223 cutoffs were defined according to the IgVH mutational status. The patients were divided into the positive and negative subgroups. The median progression-free survival (PFS) of microRNA-223 positive patient subgroup was 48 months. It was significantly longer than the negative subgroup (P = 0.001). In the microRNA-223 positive subgroup, no patient died at the end of follow-up.
Conclusions: MicroRNA-223 may play an important role in the pathogenesis of B lymphoproliferative disorders. The down-regulation of microRNA-223 is associated with disease aggressiveness and poor prognostic factors in CLL. It may become a new reliable prognostic predictor.