Inhibition of miR-155 decreases tumor growth in a xenograft mouse model of WM. Immediately after injection of mCherry-Luc⁺-BCWM1 cells, 6 SCID mice per group were injected with a loading dose of 25 mg/kg of anti–miR-155 or scramble control, followed by weekly maintenance doses of 5 mg/kg of anti–miR-155 or scramble control until mice were killed. (A) Bioluminescent imaging of tumor burden from mice injected with mCherry-Luc⁺-BCWM1 cells at day 0, 14, or 19. (B) Treatment with the anti–miR-155 decreased tumor burden significantly compared with scramble control as evaluated by whole body imaging. Three representative mice from each group are shown. P = .024 at day 14; P = .009 at day 19 (n = 6 per group). Data are shown as means ± SD. *P < .05; **P < .01. (C) mRNA levels of miR-155 targets were detected by qRT-PCR in the BM CD19⁺ cells from mice treated with anti–miR-155 or LNA scramble control. Experiments were performed in triplicate and repeated 3 times. Data are shown as means ± SD. (D-E) Protein levels of the miR-155 target genes MAFB (D) and CEBPβ (E) were detected by immunofluorescent imaging from the femur BM or spleens of mice. Cell nuclei are shown by DAPI staining in blue; mCherry-Luc⁺-BCWM1 cells in red. MAFB or CEBPβ proteins were detected by immunostaining with anti-MAFB or anti-CEBPβ. Scale bar indicates 100 μm.