Specific microRNAs Are Altered in Chronic Myelomonocytic Leukemia – A PCR Validated Microarray Study.
Mehdi Nassiri, Anupama Tewari, Magdalena Czader. Indiana University School of Medicine, Indianapolis
Background: Chronic myelomonocytic leukemia (CMML) remains a heterogeneous group of diseases with variable patient outcomes and no well-defined targeted therapy. We studied microRNA (miRNA) expression profiles and their relation to the diagnostic and clinical parameters in CMML, and compared it to global miRNA expression in normal reference bone marrow samples.
Design: Bone marrow samples from 22 patients with CMML were studied. Seventeen patients presented with CMML-1 and 5 with CMML-2 (defined by WHO criteria; blasts less than 5% in peripheral blood and less than 10% of bone marrow differential count). Nine cases had total WBC count of less than 13x109/L. All cases were negative for BCR-ABL1 translocation. Microarray studies were performed using Agilent human miRNA microarrays (version 1.0) containing probes for 470 human and 64 human viral miRNAs cataloged in the Sanger database v9.1. Selected miRNA were validated using Quantitative real-time PCR using ABI TaqMan microRNA assay.
Results: Using unsupervised hierarchical clustering, CMML cases could be classified into two different groups with patterns of miRNA expression distinct from normal bone marrows. There was an overlap in miRNA expression profiles between groups of CMML based on blast percentage (CMML-1 vs. CMML-2), dysplastic vs. proliferative features (WBC <13x109/L vs. >13x109/L) and presence or absence of cytogenetic abnormalities. Twenty seven miRNAs were significantly different between normal bone marrow samples vs. CMML-1 and -2. The following miRNAs showed predictive power in select CMML subtypes: hsa-miR-519b (in CMML-1 vs. 2); hsa-miR-15b and hsa-miR-432 (CMML with WBC of < and > than 13x109/L) and hsa-miR-223 (comparing CMML with and without cytogenetic abnormalities). Both hsa-miR-15b and hsa-miR-223 showed reproducible difference among selected groups by real time PCR.
Conclusions: Significantly different miRNA profiles were seen in CMML as compared to normal reference bone marrows. In addition, two distinct subgroups of CMML were identified by the miRNA expression profiles. We further validated the specific microRNAs by real- time PCR. Our finding might imply that biologic differences are not well represented by current histopathologic classification, since few miRNAs were different among known categories.
Monday, February 28, 2011 2:30 PM
Platform Session: Section B, Monday Afternoon