LNA-mediated anti–miR-155 silencing in low-grade B-cell lymphomas

miR-155 acts as an oncogenic miR in B-cell lymphoproliferative disorders, including Waldenstrom macroglobulinemia (WM) and chronic lymphocytic leukemia, and is therefore a potential target for therapeutic intervention. However, efficient targeting of miRs in tumor cells in vivo remains a significant challenge for the development of miR-155–based therapeutics for the treatment of B-cell malignancies. In the present study, we show that an 8-mer locked nucleic acid anti–miR-155 oligonucleotide targeting the seed region of miR-155 inhibits WM and chronic lymphocytic leukemia cell proliferation in vitro. Moreover, anti–miR-155 delivered systemically showed uptake in the BM CD19+ cells of WM-engrafted mice, resulting in the up-regulation of several miR-155 target mRNAs in these cells, and decreased tumor growth significantly in vivo. We also found miR-155 levels to be elevated in stromal cells from WM patients compared with control samples. Interestingly, stromal cells from miR-155–knockout mice led to significant inhibition of WM tumor growth, indicating that miR-155 may also contribute to WM proliferation through BM microenvironmental cells. The results of the present study highlight the therapeutic potential of anti–miR-155–mediated inhibition of miR-155 in the treatment of WM.