Identification of a novel microRNA cluster miR-193b-365 in multiple myeloma

There is accumulating evidence that the patterns of altered expression of microRNAs (miRNAs) correlate with distinct types of hematological malignancies. There is also emerging evidence for such miRNAs expression in multiple myeloma (MM), but the identity of the miRNAs that are abnormally expressed in this disease has not been elucidated. In the current study, we examined the miRNAs perturbed in CD138 positive MM cell lines and CD138 positive primary MM cells, using microarray analysis and quantitative real-time PCR. The expression levels in these cells were compared with the expression levels in CD138 positive plasma cells isolated from bone marrows of healthy donors. Our data demonstrate that multiple new miRNAs are commonly up-regulated and down-regulated including a new miRNA cluster, miR-193b-365, composed of two paralogs that were significantly up-regulated in MM. The organization and the sequences of the new miR-193b-365 cluster are highly conserved among vertebrates. Given that dysregulation of miR-193b-365 cluster has not been identified in other hematological malignancies examined to date, our findings suggest that miR-193b-365 cluster is part of the unique miRNA signature in MM.