Inhibition of CBP synergizes with the RNA-dependent mechanisms of azacitidine by limiting protein translation

ABSTRACT: The nucleotide analogue azacitidine (AZA) interferes with RNA and DNA metabolism and is currently the best treatment option for a subset of patients with high-risk myelodysplastic syndromes. However, only half of treated patients respond and almost all patients that initially respond eventually relapse. Thus, response-predicting biomarkers and new treatment options are urgently needed to improve the clinical management of these patients. Here, we performed a loss-of-function shRNA screen in combination with AZA treatment in a MDS-derived AML cell line to identify chromatin regulators affecting drug response. We identified the histone acetyl transferase and transcriptional co-activator CBP as a major regulator of AZA sensitivity. Compounds inhibiting the enzymatic activity of CBP synergistically reduced viability of MDS-derived AML cell lines when combined with AZA. Surprisingly, this affect was specific for the RNA-dependent functions of AZA and not observed with the related compound decitabine that is limited to DNA incorporation. The identification of immediate target genes suggested that the effect of CBP inhibition is mediated by downregulation of genes encoding the translational machinery, which could be confirmed in proteomic analysis of nascent proteins. Furthermore, proteins most affected by CBP inhibition include key drivers of cycle progression. Taken together, our results identify a novel synergistic interaction between CBP inhibitors and specifically AZA that warrants further evaluation for the combinatorial treatment of high-risk MDS patients. Beyond the scope of MDS and AZA, we provide novel insight in the function of clinically promising CBP inhibitors that is related to unexpected interference with the translational machinery.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Blood Cell, Leukemia Cell

DISEASE(S): Acute Myeloid Leukemia

SUBMITTER: Joan Josep Bech-Serra  

LAB HEAD: Marcus Buschbeck

PROVIDER: PXD021738 | Pride | 2021-09-22

REPOSITORIES: Pride