MicroRNA expression in Sézary syndrome: Identification, function and diagnostic potential.. Homo sapiens

MicroRNAs are commonly aberrantly expressed in many cancers. Very little is known of their role in T-cell lymphoma, however. We therefore elucidated the complete miRNome of purified T-cells cells from 21 patients diagnosed with Sézary syndrome (SzS), a rare aggressive primary cutaneous T-cell (CD4+) lymphoma. Unsupervised cluster analysis of microarray data revealed that the microRNA expression profile was distinct from CD4+ T-cell controls and B-cell lymphomas. The majority (104/114) of SzS-associated microRNAs (P 90% of samples. Furthermore, we demonstrate that the down-regulation of intronically encoded miR-342 plays a role in the pathogenesis of SzS by inhibiting apoptosis and describe a novel mechanism of regulation for this microRNA via binding of miR-199a* to its host gene. We also provide the first in vivo evidence for down-regulation of the miR-17-92 cluster in malignancy and demonstrate that ectopic miR-17-5p expression increases apoptosis and decreases cell proliferation in SzS cells. Overall design: CD4+ cells were purified from peripheral blood of 21 Sz patients and compared with 6 healthy controls.