Fig. 9
BRD9 activation mediates acquired resistance to IMiDs. A. Proteomics analysis of NCI-H929 cells that were resistant to pomalidomide (Pom-R). B. Western blot analysis of BRD9 in NCI-H929 and RPMI-8226 cells that were resistant to lenalidomide (Len-R) and pomalidomide (Pom-R), respectively. C. qPCR analysis of the indicated gene expression associated BRD9 in NCI-H929 and RPMI-8226 cells that were resistant to lenalidomide (Len-R) and pomalidomide (Pom-R), respectively, compared with parental NCI-H929 cells. Error bars denote standard deviations (independent experiments, n = 3). **p < 0.01 (t-test). D. Effects of pomalidomide (Pom), lenalidomide (Len), I-BRD9 or drug combination on viability of NCI-H929 cells that were resistant to pomalidomide (NCI-H929Pom − R, left) and lenalidomide (NCI-H929Len − R, right), respectively. Data shown are a representative graph of three independent experiments; mean ± SD of triplicates. E-F. Effects of BRD9 overexpression on MM cell lines in response to pomalidomide treatment. WB analysis was conducted to detect BRD9 expression in MM cells that were stably transfected with empty vector (EV) or BRD9 (E). The effects of empty vector, BRD9 overexpression on the IC50 of pomalidomide are shown in the bar graph (F). Error bars denote standard deviations (independent experiments, n = 3). **p < 0.01 (t-test). G. Effect of pomalidomide (Pom), MGD-28, I-BRD9 or drug combination on viability of NCI-H929 cells. Data shown are a representative graph of three independent experiments; mean ± SD of triplicates. H. Three-dimensional synergy score heatmaps for pomalidomide (Pom, left) or MGD-28 (right) plus I-BRD9 combination in NCI-H929 cells calculated using SynergyFinder. I-J. NOD/SCID nude mice transplanted with NCI-H929Pom − R cells were orally administrated with single agent I-BRD9, pomalidomide (Pom), MGD-28 and vehicle as well as combinational treatment of I-BRD9 + Pom and I-BRD9 + MGD-28 for 24 days. The change of NCI-H929Pom − R tumor volume (I) and change of body weight (J) of all mice in each group were shown (n = 7). Data are mean ± SD, ns (no significance), **p < 0.01 (one-way ANOVA). K. Representative images of Ki67-IHC staining in harvested tumors from each group in (I) are shown. Scale bars represent 50 mm