[349] MicroRNA Expression in Lymph Node Fine Needle Aspiration Biopsy

Stefan Costinean, Arianna Bottoni, Carlo M Croce, Paul E Wakely. The Ohio State University, Columbus

Background: microRNAs (miRs) are small noncoding RNAs with regulatory roles in the fine tuning of protein expression at the level of posttranscriptional regulation. Since their discovery, miRs have been identified as playing major roles in the regulation of numerous normal biologic processes. Their deregulation was linked to multiple pathologic processes (inflammation and especially cancer). Chronic lymphocytic leukemia (CLL) is one of the most frequent adult leukemias in the Western world. Recently, Croce et al identified the deletion of miR15 as being present in 65% of analyzed CLL cases. Further investigation revealed that so-called “indolent” CLL is most likely to be associated with the deletion of miR15.
Design: We investigated whether miR expression in cells collected using the technique of fine needle aspiration (FNA) could identify a specific genetic signature for different leukemias/lymphomas. FNA was performed on lymph nodes of 15 patients: 8 reactive (lymphoid hyperplasia or inflammation), 1 monoclonal T cell population proliferation, 1 diffuse large B cell lymphoma, 1 follicular lymphoma and 4 CLL. Flow cytometry confirmed the immunophenotype of these lesions. RNA was extracted from all samples with Trizol (Invitrogen, Carlsbad, California) and real time PCR was performed with Taqman probes (Applied Biosystems) for miR146a, miR29a, miR155, miR15 and miR16 - all miRs known to be involved in the pathogenesis of various leukemias/lymphomas, especially CLL. The comparative CT (threshold cycle) method for relative quantitation of gene expression was used to determine miR expression levels.
Results: Extraction of RNA and identification of specific miR expression was possible and adequate in all cases. Of all miRs analyzed, miR15 seemed to best predict the presence of a CLL with an indolent course. Both such CLL samples had a very low level of miR15 amplification, whereas all other samples (including 2 aggressive CLLs) exhibited higher miR15 levels, ranging from twice to > 20 times higher.
Conclusions: MiR expression using FNA samples in non-Hodgkin lymphomas/leukemias is technically possible and can provide important clues not only to possible subtype but also to clinical course. Based on our preliminary results we hypothesize that miR expression can be used together with more classical ancillary techniques (flow cytometry, immunohistochemistry, FISH) to identify and predict the behavior of CLL and possibly other non-Hodgkin lymphomas. It may eventually also be used to monitor a patient's response to treatment.
Category: Cytopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 88, Wednesday Afternoon

 

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