IMiD1 inhibits NF-κB activity and enhances the effectiveness of Dex and PS-341 in MM.

(A) Quantification of the DNA binding activity of the transcriptional factor NF-κB in MM.1S cells treated with or without 1 μM IMiD1 for 48 hours, 1 μM Dex for 24 hours, or both, after normalization for cellular protein. Data shown (mean ± SD) are representative of 3 experiments. (B) Combined proapoptotic effect of IMiD1 with Dex in MM.1S cells. Cells were pretreated with or without 1 μM IMiD1 for 24 hours, and then Dex (0.25 μM) was added for an additional 48 hours. IMiD1 potentiated the apoptotic effect of Dex. Data shown (mean ± SD) are representative of 3 experiments. (C) Combined proapoptotic effect of IMiD1 with PS-341 in MM.1S cells. Cells were pretreated with or without 1 μM IMiD1 for 48 hours, and subtoxic concentrations of PS-341 (3 or 5 nM) were added for an additional 24 hours. IMiD1 potentiated the apoptotic effect of PS-341. Data shown (mean ± SD) are representative of 3 experiments. (D) Combined proapoptotic effect of IMiD1 with PS-341 in primary MM cells. Cells were pretreated with or without 1 μM IMiD1 for 48 hours, and a subtoxic concentration of PS-341 (3 nM) was added for an additional 24 hours. IMiD1 potentiated the apoptotic effect of PS-341. Data shown (mean ± SD) are representative of 3 experiments.