Fig. 5

Suppression of Dickkopf-1 (DKK1) by overexpression of microRNA-218-5p (miR-218) or silencing of roundabout1 (ROBO1). a At the protein level, transfection of rheumatoid arthritis (RA)-fibroblast-like synovial cells (FLS) (n = 4) with precursor miR-218 (pre-miR-218) for 48 h decreased DKK1 protein production in the culture supernatant compared to scrambled RNA transfected controls, as determined by ELISA. Graphs represent optical density (OD) value; each mean amount of DDK1 protein are as follows; scrambled control: pre-miR-218 1.17 ng/ml:0.76 ng/ml, scrambled control: anti-miR-218 1.58 ng/ml:1.65 ng/ml, respectively. b At the mRNA level, transfection of RA-FLS (n = 4) with pre-miR-218 for 48 h decreased DKK1 expression compared to scrambled RNA transfected controls, as determined by SYBR green real-time PCR analysis. c Secretion of DKK1 from RA-FLS (n = 4) was decreased after transfection with ROBO1-specific small interfering RNA (siRNA) compared to the scrambled RNA transfected controls, as determined by ELISA. Graphs represent OD value; each mean amount of DDK1 protein are as follows; scrambled control: siROBO1.28 ng/ml:1.09 ng/ml, respectively. Values are presented as means ± SEM: *p < 0.05 versus scrambled RNA-transfected controls, as determined by Student’s paired t test