Waldenström’s macroglobulinemia (WM) is an incurable B cell malignancy characterized by the accumulation of IgM secreting clonally related bone marrow lymphoplasmacytic cells (LPC) including CD19+ B-cells and CD138+ plasma cells. Despite intense research efforts, the pathogenetic basis for this disease remains to be clarified. MicroRNAs are small noncoding RNAs that regulate the expression of protein-coding genes by inducing translational inhibition and through cleavage of targeted transcripts by partial or complete base pairing. We therefore evaluated the expression of 384 microRNAs in CD19+ and CD138+ sorted bone marrow lymphoplasmacytic from 13 untreated WM patients, and compared their expression profiling to analogous lymphoplasmacytic cells taken from the bone marrows of 13 healthy donors. Data obtained from microRNA arrays was analyzed using SDS, RQ manager, R and dChip softwares. Relative expression was calculated using the comparative Ct method through RQ manager and dChip softwares. Of the 384 microRNAs evaluated in CD19+ patient cells, miR-192, -125b, -21, -155 demonstrated significant upregulation, whereas miR-181c, -572, and -650 were significantly down regulated compared to healthy donor CD19+ bone marrow cells (p<0.05). Analysis of bone marrow derived CD138+ cells from WM patients demonstrated significant upregulation in miR-192, -193b, -17-3p, -585, -148b, whereas miR-29c, -155, -126, -148a, -125a, -181d, -30a-3p, let-7b, let-7c were downregulated in comparison to healthy donor CD138+ bone marrow cells (p<0.05). Importantly, characterization of the modulated microRNAs found in these studies demonstrated a critical role in growth and survival pathways through modulation of several genes including HOX, BCL-2 and c-myc. Taken together, these studies demonstrate significant differences in microRNA expression between comparable WM and healthy donor lymphoplasmacytic cell populations, and identify aberrancies in microRNAs with a pivotal role in the growth and survival of B-cells.

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