Phosphoproteomic Landscape of AML Cells Treated with the ATP-Competitive CK2 Inhibitor CX-4945.

Mauro Rosales,Osmany Guirola,Arielis Rodríguez-Ulloa,Jacek R Wiśniewski,Yassel Ramos,Silvio E Perea,Yasser Perera,Vladimir Besada,Luis J González,George V Pérez,Katharina Zettl,Ailyn C Ramón

doi:10.3390/cells10020338

Abstract

Casein kinase 2 (CK2) regulates a plethora of proteins with pivotal roles in solid and hematological neoplasia. Particularly, in acute myeloid leukemia (AML) CK2 has been pointed as an attractive therapeutic target and prognostic marker. Here, we explored the impact of CK2 inhibition over the phosphoproteome of two cell lines representing major AML subtypes. Quantitative phosphoproteomic analysis was conducted to evaluate changes in phosphorylation levels after incubation with the ATP-competitive CK2 inhibitor CX-4945. Functional enrichment, network analysis, and database mining were performed to identify biological processes, signaling pathways, and CK2 substrates that are responsive to CX-4945. A total of 273 and 1310 phosphopeptides were found differentially modulated in HL-60 and OCI-AML3 cells, respectively. Despite regulated phosphopeptides belong to proteins involved in multiple biological processes and signaling pathways, most of these perturbations can be explain by direct CK2 inhibition rather than off-target effects. Furthermore, CK2 substrates regulated by CX-4945 are mainly related to mRNA processing, translation, DNA repair, and cell cycle. Overall, we evidenced that CK2 inhibitor CX-4945 impinge on mediators of signaling pathways and biological processes essential for primary AML cells survival and chemosensitivity, reinforcing the rationale behind the pharmacologic blockade of protein kinase CK2 for AML targeted therapy.

Highlights

Protein phosphorylation is an essential post-translational modification in most cellular processes, making of protein kinases promising therapeutic targets for a wide variety of disorders, including cancer [1,2]
In spite of the similar antiproliferative effect attained by CX-4945 in both acute myeloid leukemia (AML) cell lines, our results and previous studies have evidenced that HL-60 cells appears to be less sensitive to CX-4945 induced apoptosis when compared to other AML cell lines (Figure S1A,B) [51]
Selected cells lines represent major AML subtypes, and different niches that can be found in the clinical setting considering its differential sensitivity to casein kinase 2 (CK2) inhibition with CX-4945

Summary

Introduction

Protein phosphorylation is an essential post-translational modification in most cellular processes, making of protein kinases promising therapeutic targets for a wide variety of disorders, including cancer [1,2]. Among the protein kinases involved in cell signaling networks, casein kinase 2 (CK2) is responsible of about 25% of all cell phosphoproteome [3]. CK2 is a constitutively active and ubiquitously expressed Ser/Thr-protein kinase composed of two catalytic subunits (α or its isoform α’) and two regulatory subunits (β) [4]. Concerning CK2 substrates, about one third are involved in gene expression and protein synthesis, while numerous are signaling proteins implicated in cell growth, proliferation, and survival [3,6]. A small number of CK2 substrates are classical metabolic enzymes or associated with some virus life cycle [3]

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