Fig. 5. CBP/p300 inhibition impairs active protein translation, which can be further reduced by azacitidine.

a Representative polysome profile in MOLM-13 treated with 10 µM C646 for 4 h. Polysomal lysates were fractionated by ultracentrifugation on sucrose gradients and the ribosomal RNA content was monitored across the gradient by UV absorbance (260 nm). The polysome abundance was normalized to the baseline absorbance. Data represent the mean ± SEM of three independent experiments. Statistical analysis was performed by two-sided Student’s T-test compared to untreated samples, *p-value = 0.0267. b Median fluorescence intensity of CD34+ cells from healthy donors after 8 h of treatment with increasing concentrations of C646 followed by Protein Synthesis Assay. Data represent the mean ± SEM of five independent experiments. Statistical analysis was performed by unpaired two-sided T-test compared to untreated samples, **p-value < 0.001. c Median fluorescence intensity of MOLM-13 or SKK-1 cells treated for 6 h with DMSO (0.1%), C646 (10 µM), A-485 (1 µM or 2.5 µM) or CCS1477 (1 µM or 2.5 µM) in the absence or presence of AZA (2 or 1 µM) followed by Click-iT™ HPG Alexa Fluor™ 594 assay. Cells treated 1.5 h with cycloheximide (CHX) were used as positive control. d Representative images of median fluorescence intensity of leukemic blast cells from AML patients treated for 3 h with the indicated concentrations of DMSO (0.075%), C646 (7.5 µM), A-485 (1 µM) or CCS1477 (0.25 µM) in the absence or presence of 0.25 µM AZA followed by Click-iT™ HPG Alexa Fluor™ 594 assay. Cells treated 1.5 h with cycloheximide (CHX) were used as positive control. e Mechanistic model suggesting that the synergy between CBP/p300 inhibition and AZA is caused by the reduction of protein synthesis. c, d Data represent the mean ± SEM of at least three independent experiments. Statistical analysis was performed by two-sided Student’s T-test, *p-value < 0.05. Source data are provided as a Source Data file and in Supplementary Data 8.