Fig. 6

c-Myc is a major transcription factor of miR-551b, miR-25 and miR-130b. A Overexpression of c-Myc induced pri-miR-551b, pri-miR-25 and pri-miR-130b and the induction can be inhibited by TAK-981 treatment. MM1S cells were transfected with empty vector (EV) or c-Myc expression plasmid (c-Myc) then treated with 0.1 μM TAK-981 (TAK) or vehicle (Veh) for 24 h. Pri-miR level was measured by q-PCR. B Knockdown of c-Myc decreased miR-551b, miR-25 and miR-130b miR and pri-miR level. MM1S cells were transfected with siRNA targeting c-Myc (siMyc) or non-targeting control (SiCtrl) for 72 h, miR and pri-miR level were determined by qPCR. C RPMI8226 stable cell line was generated with inducible shRNA targeting c-Myc. Dox (5 μg/mL) was added to induce c-Myc knockdown (shMyc+Dox) for 48 h. miRs and pri-miRs levels were measured by qPCR. D ChIP assay identified c-myc binding at the promoter regions of miR-551b, miR-25, and miR-130b. TAK-981 treatment decreases the c-Myc binding occupancy in both MM1S and MM1R cells but Dex only decreases in MM1S cells. ChIP was performed using an anti-c-Myc antibody in MM1S and MM1R cells treated with Vehicle (Veh), 0.1 μM TAK-981 (TAK-981) or 1 μM Dex (Dex). The occupancy was normalized to DNA input and calculated relative to IgG control. Data were analyzed using ANOVA. Data presented as mean ± SD. ns, not significant; *, p < 0.05; **, p < 0.01; ***, p < 0.001. E c-Myc and (F) SAE2 (UBA2) level correlates with miR-551b, miR-25 and miR-130b level in 15 primary MM samples. Pearson correlation analysis was performed. p and r values were labeled