[Expression of miR-21 in multiple myeloma and its clinical significance]

This study was aimed to explore the expression of microRNA-21 (miR-21) in multiple myeloma (MM), and its correlation with plasma β2-microglobulin (β2-MG) and staging of MM by Durie-Salmon (D-S) classification. The expression level of miR-21 in bone marrow mono-nuclear cells (BMMNC) of 43 patients with MM and 20 healthy individuals was examined by real-time polymerase chain reaction (real-time PCR), and the correlations among the expression level of miR-21 and related clinical pathologic features, plasma β2-MG and staging of MM by D-S classification were analyzed. The results showed that the expression of miR-21 in BMMNC of MM patients was obviously higher than that in normal controls (P < 0.05). The expression of miR-21 in BMMNC of relapsed/refractory MM patients was obviously higher than that in newly diagnosed MM patients. The expression of miR-21 in MM patients decreased after chemical therapy, especially in effective group (P < 0.05), there was no significant change of miR-21 expression level in ineffective/progressive group before and after chemical therapy (P > 0.05). The expression of miR-21 was related with staging of MM and plasma β2-MG level. It is concluded that the expression levels of miR-21 in BMMNC of MM patients are significantly higher than in normal bone marrow, these data indicated that miR-21 may play an important role in the development of MM. Super expression of miR-21 is positively correlated with level of plasma β2-MG and staging of MM by D-S classification.