Deep Sequencing of the Small RNA Transcriptome of Normal and Malignant Human B cells Identifies Hundreds of Novel MicroRNAs: microarray analysis

A role for microRNAs has been recognized in nearly every biological system examined thus far. A complete delineation of their role must be preceded by the identification of all microRNAs present in any system. We elucidated the complete small RNA transcriptome of normal and malignant B cells through deep sequencing of 31 normal and malignant human B cell samples that comprise the spectrum of B cell differentiation and common malignant phenotypes. We identified the expression of 333 known microRNAs, which is over twice the number previously recognized in any tissue type. We further identified the expression of 286 candidate novel microRNAs in normal and malignant B cells. These microRNAs were validated at a high rate (92%) using quantitative PCR and we demonstrated their application in the distinction of clinically relevant subgroups of lymphoma. Here, we analyzed the expression of 100 diffuse large B-cell lymphoma (DLBCL) samples using microarrays. Total RNA was extracted from frozen patient samples. The RNA was labeled, fragmented and hybridized to Human Gene 1.0 ST arrays.