Fig. 4

miR-124 inhibits osteoclastogenesis by regulating osteoclast and osteoblast in vitro. a BMMs were cultured in α-MEM containing conditioned medium from MDA-MB-231 cells transfected with miR-124 mimic (miR-124-CM) or NC (NC-CM). Surviving cells were counted at 24 h and 48 h. b Cultured with α-MEM containing conditioned medium from MCF7 cells transfected with miR-124 inhibitor (in-miR-124-CM) or inhibitor NC (NC-CM) reduced the cell viability of BMMS. c and d The effects of miR-124-CM from MDA-MB-231 cells and in-miR-124-CM from MCF7 cells on RANKL-induced mouse BMM differentiation as detected by TRAP staining. Representative images of TRAP staining (original magnification, ×40) were showed in (c) and statistical analyses were showed in (d). Columns show the means of performed experiments in triplicate; bars show SD. e and f Real-time RT-PCR analysis of Cathepsin K, NFATc1, c-fos and TRAP expression in RAW264.7 cells treated with miR-124-CM or NC-CM from MDA-MB-231 cells (e) as well as in RAW264.7 cells treated with in-miR-124-CM or NC-CM from MCF7 cells (f). Gene expression was normalized against β-actin. g and h The effect of miR-124-CM from MDA-MB-231 cells (g) and in-miR-124-CM from MCF7 cells (h) on OPG and RANKL expression in MC3T3-E1 cells. i and j MC3T3-E1 cells were firstly cultured with conditioned medium from MCF7 cells transfected with miR-124 inhibitor or NC, and then conditioned medium of MC3T3-E1 from both groups were collected (MC3T3-E1 with in-miR-124-CM or MC3T3-E1 with NC-CM). BMMs were cultured in α-MEM containing conditioned medium from MC3T3-E1 with in-miR-124-CM or MC3T3-E1 with NC-CM. Representative images of TRAP staining (original magnification, ×40) were showed in (i) and statistical analyses were showed in (j). * P < 0.05, ** P < 0.01 and *** P < 0.001 by two-tailed Student’s t test. Experiments were performed in triplicate and data are shown as mean ± SD