Potent and Selective CK2 Kinase Inhibitors with Effects on Wnt Pathway Signaling in Vivo

Abstract

ABSTRACT:The Wnt pathway is an evolutionarily conserved and tightly regulated signaling network with important roles in embryonic development and adult tissue regeneration. Impaired Wnt pathway regulation, arising from mutations in Wnt signaling components, such as Axin, APC, and β-catenin, results in uncontrolled cell growth and triggers oncogenesis. To explore the reported link between CK2 kinase activity and Wnt pathway signaling, we sought to identify a potent, selective inhibitor of CK2 suitable for proof of concept studies in vivo. Starting from a pyrazolo[1,5-a]pyrimidine lead (2), we identified compound 7h, a potent CK2 inhibitor with picomolar affinity that is highly selectivity against other kinase family enzymes and inhibits Wnt pathway signaling (IC 50 = 50 nM) in DLD-1 cells. In addition, compound 7h has physicochemical properties that are suitable for formulation as an intravenous solution, has demonstrated good pharmacokinetics in preclinical species, and exhibits a high level of activity as a monotherapy in HCT-116 and SW-620 xenografts. KEYWORDS: CK2 kinase, pyrazolo[1,5-a]pyrimidine, Wnt, β-catenin T he serine/threonine protein kinase CK2 is a constitutively active heterotetrameric complex composed of two catalytic (α or α′) and two regulatory (β) subunits, 1 which has emerged as an attractive drug discovery target in oncology. 2 Researchers from Cylene have recently advanced CX-4945, a selective, orally available inhibitor of CK2 into the clinic for treatment of patients with solid tumors and hematological malignancies. 3 Among its diverse functions, CK2 interacts with and regulates multiple components of the Wnt pathway, an evolutionarily conserved signaling network that regulates embryonic development and the regeneration of intestinal epithelial cells. 4 Certain cancers, including colorectal carcinoma (CRC), arise due to gene mutations among constituents of the Wnt pathway, including the CK2 substrates dishevelled (Dvl), APC, and β-catenin. 5 Inhibition of CK2, either by RNA knockdown or with small molecules, decreases β-catenin−Tcfmediated transcription of Wnt target genes such as survivin and leads to cell death and apoptosis in a range of CRC lines. 6,7 In addition, elevated levels of CK2 activity have been reported in CRC tissue samples and expression levels correlate with poor prognosis in CRC patients. 8,9 Taken together, these data illustrate the potential utility of CK2 inhibitors in CRC and other cancers characterized by aberrant Wnt pathway activity.We sought to identify a potent, selective inhibitor of CK2 kinase for hypothesis testing in vivo using preclinical models of CRC. An early probe from our previously described series of ATP-competitive pyrazolo[1,5-a]pyrimidine-derived inhibitors of CK2 (1, 2; Figure 1) was used to assess the link between CK2 inhibition and Wnt signaling. 10 Treatment of DLD-1(APC mutant) cells with 2 inhibits β-catenin phosphorylation and decreases Wnt-mediated gene transcription as shown in a Luciferase reporter assay in APC

The CK2 inhibitor CX4945 reverses cisplatin resistance in the A549/DDP human lung adenocarcinoma cell line

“…CK2 exerts a variety of biological functions, including enhancing growth (18), angiogenesis (19), invasion and metastasis (19,20) in various human tumour xenografts, including lung cancer (19), urothelial cancer (21), mesothelioma (22), hepatocellular cancer (23) and gastric cancer (24), as well as participating in the regulation of different signaling pathways. Previous findings suggested CK2 as a positive regulator of Wnt signaling (25,26); however, to the best of our knowledge, its association with cisplatin resistance in lung cancer cells remains to be elucidated. Previous reports have indicated that the inhibition of dishevelled-2 (DVL-2; the most abundant isoform of the mammalian DVL family) can re-sensitize cisplatin-resistant lung cancer cells by downregulating Wnt/β-catenin signaling (27,28).…”

“…Activation of the Wnt/β-catenin pathway leads to cisplatin resistance in lung cancer (13)(14)(15). Moreover, CK2 is a positive regulator of Wnt signaling (25,26). Therefore, we hypothesized that Wnt signaling might be associated with cisplatin resistance in lung cancer cells; however, the role of CK2 in cisplatin resistance in lung cancer cells, as well as the potential underlying mechanism, remained unknown.…”

Death‐associated protein kinase (DAPK) family modulators: Current and future therapeutic outcomes

“…Even though this class of compounds is the most potent known DAPK1 inhibitors to date, the stability and reactivity issues of the benzylidene‐5‐oxazolone core in biological systems can restrict their use clinically urging for the development of clinically acceptable inhibitors …”

Defining the Neural Kinome: Strategies and Opportunities for Small Molecule Drug Discovery to Target Neurodegenerative Diseases

“…We prepared a small library of pyrazolopyrimidines based upon a literature compound that was reported to have DYRK2 activity. 53 We profiled this library using the cell-based DYRK2 nanoBRET assay 68 and we were able to identify AZ-G as meeting the criteria to be named a DK tool for DYRK2 (IC50 = 160 nM). Details about the DYRK2 nanoBRET assay and DK tool can be found at https://darkkinome.org/kinase/DYRK2.…”