miRNA-155 knockdown inhibited WM cells in the context of bone marrow microenvironment in vitro. WM cells (miRNA-155 knockdown probe–transfected, control probe–transfected BCWM.1 cells) were harvested at 24 hours after transfection. Nontransfected BCWM.1 cells were used as control (ctrl). (A) Adhesion assay to fibronectin (FN). Control probe–transfected and nontransfected cells showed significant increase in adhesion to FN, compared with BSA, used as control. miRNA-155 knockdown probe–transfected cells showed lower adhesion to FN. (B) Purified cRNA (15 μg) isolated from WM cells (control probe–transfected, miRNA-155 knockdown probe–transfected BCWM.1 cells) was hybridized to HG-U133Plus2.0 GeneChip (Affymetrix). Down-regulation of several genes involved in the adhesion process. Fold change is shown by the intensity of induction (red) or suppression (blue). (C) Transwell migration assay. SDF-1 (30 nM) was placed in the lower chambers and migration was determined after 4 hours. Control probe–transfected and nontransfected cells showed significant migration with SDF-1 30 nM, whereas the miRNA-155 knockdown probe–transfected cells showed minimal migration in response to SDF-1. (D) BCWM.1 cells were cultured for 48 hours in the presence or absence of BMSCs, and cell proliferation was assessed using [3H]-thymidine uptake assay. All data represent mean (±SD) of triplicate experiments.