Figure 4.

Functional role of miR23b replacement in MM and WM cells. (a) Cell growth of NCI-H929 myeloma cells stably expressing miR-23b (V-miR-23b) or control (V-CNT) was evaluated by [³H]Thymidine uptake at the indicated time. Data are presented as cell growth increase compared with Day 1. (b) Activation of Caspase-3, -8 and -9 was assessed by luminescence assay. (c) To test effects of miR-23b overexpression on the malignant phenotype of MM and WM cells, we measured colony formation in semisolid, methylcellulose media. Representative phase contrast images for H929 colonies formed in semisolid methylcellulose medium at day 21 for V-miR-23b and V-CNT cells are shown in the left panel. In the right panel, graphs depict average colony numbers (mean±s.d.) for NCI-H929 and MWCL1 V-miR-23b and V-CNT cells in methyl cellulose medium at day 21. (d) Transient transfection of miR-23b inhibited cancer cell survival as evaluated by cell titer glow assay, and induced caspase-3 activation as evaluated by luminescence assay. Data are presented as % of control cells. (e) WB analysis confirmed cleavage of caspase-3 and -8 in cells transiently transfected with miR-23b mimics compared with control cells. (f) Growth curve assess tumor size after subcutaneous injection of NCI-H929 myeloma cells transduced with miR-23b or scrambled control virus into the right posterior flank region of SCID mice. Data are shown as mean values±s.d.