Overexpression of microRNA-21 in peripheral blood mononuclear cells of patients with B-cell non-Hodgkin's lymphoma is associated with disease stage and treatment outcome.

We wished to assess the association between microRNA-21 (miR-21) and disease stage and treatment outcome in patients with B-cell non-Hodgkin's Lymphoma (B-NHL).A total of consecutive 128 patients with B-NHL were enrolled; 30 healthy individuals served as controls. qPCR assay was utilized to quantify expression levels of miR-21 in peripheral blood mononuclear cells (PBMC; Ficoll isolation protocol). Expression of the miR-21 target, phosphatase and tensin homolog (PTEN), was assessed by Western blot analysis.miR-21 was overexpressed in PBMC of patients with B-NHL (p < 0.05 vs. healthy individuals). Furthermore, miR-21 expression levels were significantly higher in patients with the stage III/IV B-NHL (p < 0.05 vs. stage I/II B-NHL). After chemotherapy, miR-21 expression levels were significantly decreased in patients in complete remission and became comparable to those of healthy individuals. Also, miR-21 expression levels were lower in patients treated with chemotherapy combined with rituximab. There was a negative association between miR-21 overexpression and post-chemotherapy survival rates of the patients. Expression of PTEN was significantly lower in patients with B-NHL (p < 0.05 vs. healthy individuals).Overexpression of miR-21 is associated with disease stage and treatment outcome of B-NHL. This potentially involves negative modulation of PTEN.