ABSTRACT
Protein kinase CK2 is a potential drug target for many diseases including cancer and inflammation disorders. The crystal structure of clinical candidate CX-4945 1 with CK2 revealed an indirect interaction with the protein through hydrogen bonding between the NH of the 3-chlorophenyl amine and a water molecule. Herein, we investigate the relevance of this hydrogen bond by preparing several novel tricyclic derivatives lacking a NH moiety at the same position. This SAR study allowed the discovery of highly potent CK2 inhibitors.
Subject(s)
Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Casein Kinase II/antagonists & inhibitors , Quinolines/chemistry , Casein Kinase II/chemistry , Cell Line, Tumor , Chemistry, Pharmaceutical/methods , Crystallography, X-Ray/methods , Drug Design , Drug Screening Assays, Antitumor , Humans , Inhibitory Concentration 50 , Models, Chemical , Models, Molecular , Protein Conformation , Quinolines/chemical synthesis , Structure-Activity RelationshipABSTRACT
In this article we describe the preclinical characterization of 5-(3-chlorophenylamino) benzo[c][2,6]naphthyridine-8-carboxylic acid (CX-4945), the first orally available small molecule inhibitor of protein CK2 in clinical trials for cancer. CX-4945 was optimized as an ATP-competitive inhibitor of the CK2 holoenzyme (Ki = 0.38 nM). Iterative synthesis and screening of analogs, guided by molecular modeling, led to the discovery of orally available CX-4945. CK2 promotes signaling in the Akt pathway and CX-4945 suppresses the phosphorylation of Akt as well as other key downstream mediators of the pathway such as p21. CX-4945 induced apoptosis and caused cell cycle arrest in cancer cells in vitro. CX-4945 exhibited a dose-dependent antitumor activity in a xenograft model of PC3 prostate cancer model and was well tolerated. In vivo time-dependent reduction in the phosphorylation of the biomarker p21 at T145 was observed by immunohistochemistry. Inhibition of the newly validated CK2 target by CX-4945 represents a fresh therapeutic strategy for cancer.
Subject(s)
Casein Kinase II/antagonists & inhibitors , Naphthyridines/therapeutic use , Prostatic Neoplasms/drug therapy , Protein Kinase Inhibitors/therapeutic use , Small Molecule Libraries/therapeutic use , Xenograft Model Antitumor Assays , Administration, Oral , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Casein Kinase II/metabolism , Caspase 3/metabolism , Caspase 7/metabolism , Cell Cycle/drug effects , Cell Line, Tumor , Humans , Immunohistochemistry , Male , Mice , Naphthyridines/chemistry , Naphthyridines/pharmacology , Phenazines , Phosphorylation/drug effects , Prostatic Neoplasms/enzymology , Prostatic Neoplasms/pathology , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Small Molecule Libraries/administration & dosage , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology , Structure-Activity RelationshipABSTRACT
Herein we chronicle the discovery of CX-4945 (25n), a first-in-class, orally bioavailable ATP-competitive inhibitor of protein kinase CK2 in clinical trials for cancer. CK2 has long been considered a prime cancer drug target because of the roles of deregulated and overexpressed CK2 in cancer-promoting prosurvival and antiapoptotic pathways. These biological properties as well as the suitability of CK2's small ATP binding site for the design of selective inhibitors, led us to fashion novel therapeutic agents for cancer. The optimization leading to 25n (K(i) = 0.38 nM) was guided by molecular modeling, suggesting a strong binding of 25n resulting from a combination of hydrophobic interactions, an ionic bridge with Lys68, and hydrogen bonding with the hinge region. 25n was found to be highly selective, orally bioavailable across species (20-51%) and efficacious in xenograft models. The discovery of 25n will allow the therapeutic targeting of CK2 in humans for the first time.
Subject(s)
Antineoplastic Agents/chemical synthesis , Casein Kinase II/antagonists & inhibitors , Naphthyridines/chemical synthesis , Adenosine Triphosphate/metabolism , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Binding, Competitive , Biological Availability , Cell Line, Tumor , Dogs , Drug Screening Assays, Antitumor , Humans , Hydrogen Bonding , Hydrophobic and Hydrophilic Interactions , Mice , Mice, Inbred ICR , Mice, Nude , Models, Molecular , Naphthyridines/chemistry , Naphthyridines/pharmacology , Neoplasm Transplantation , Phenazines , Rats , Structure-Activity Relationship , Transplantation, HeterologousABSTRACT
Malignant transformation and maintenance of the malignant phenotype depends on oncogenic and non-oncogenic proteins that are essential to mediate oncogene signaling and to support the altered physiologic demands induced by transformation. Protein kinase CK2 supports key prosurvival signaling pathways and represents a prototypical non-oncogene. In this study, we describe CX-4945, a potent and selective orally bioavailable small molecule inhibitor of CK2. The antiproliferative activity of CX-4945 against cancer cells correlated with expression levels of the CK2α catalytic subunit. Attenuation of PI3K/Akt signaling by CX-4945 was evidenced by dephosphorylation of Akt on the CK2-specific S129 site and the canonical S473 and T308 regulatory sites. CX-4945 caused cell-cycle arrest and selectively induced apoptosis in cancer cells relative to normal cells. In models of angiogenesis, CX-4945 inhibited human umbilical vein endothelial cell migration, tube formation, and blocked CK2-dependent hypoxia-induced factor 1 alpha (HIF-1α) transcription in cancer cells. When administered orally in murine xenograft models, CX-4945 was well tolerated and demonstrated robust antitumor activity with concomitant reductions of the mechanism-based biomarker phospho-p21 (T145). The observed antiproliferative and anti-angiogenic responses to CX-4945 in tumor cells and endothelial cells collectively illustrate that this compound exerts its antitumor effects through inhibition of CK2-dependent signaling in multiple pathways. Finally, CX-4945 is the first orally bioavailable small molecule inhibitor of CK2 to advance into human clinical trials, thereby paving the way for an entirely new class of targeted treatment for cancer.
Subject(s)
Casein Kinase II/antagonists & inhibitors , Inflammatory Breast Neoplasms/drug therapy , Naphthyridines/pharmacology , Pancreatic Neoplasms/drug therapy , Protein Kinase Inhibitors/pharmacology , Administration, Oral , Animals , Biological Availability , Cell Line, Tumor , Endothelial Cells/cytology , Endothelial Cells/drug effects , Female , HeLa Cells , Humans , Inflammatory Breast Neoplasms/blood supply , Inflammatory Breast Neoplasms/enzymology , Mice , Naphthyridines/pharmacokinetics , Neovascularization, Pathologic/drug therapy , Neovascularization, Pathologic/metabolism , Neovascularization, Pathologic/pathology , Pancreatic Neoplasms/blood supply , Pancreatic Neoplasms/enzymology , Phenazines , Protein Kinase Inhibitors/pharmacokinetics , Random Allocation , Xenograft Model Antitumor AssaysABSTRACT
This letter details the attenuation of hERG in a class of Akt inhibitors through heteroatom insertions into aromatic rings. The development of a cell-active dual Akt 1 and 2 inhibitors devoid of hERG activity is discussed using structure-activity relationships.
Subject(s)
Enzyme Inhibitors/pharmacology , Ether-A-Go-Go Potassium Channels/chemistry , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Allosteric Regulation , Allosteric Site , Chemistry, Pharmaceutical/methods , Drug Design , ERG1 Potassium Channel , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Ether-A-Go-Go Potassium Channels/metabolism , Humans , Inhibitory Concentration 50 , Models, Chemical , Structure-Activity RelationshipABSTRACT
This article describes the details of our synthetic studies toward the complex marine alkaloid sarain A. Various strategies were conceived, setbacks encountered, and solutions developed, ultimately leading to a successful enantioselective total synthesis. Our route to (+)-sarain A features a number of key steps, including an asymmetric Michael addition to install the C4'-C3'-C7' stereotriad, an enoxysilane-N-sulfonyliminium ion cyclization to set the C3 quaternary carbon stereocenter, and assemble the diazatricycloundecane core, a ring-closing metathesis to construct the 13-membered ring, an intramolecular Stille coupling to fashion the unsaturated 14-membered macrocycle, and a late-stage installation of the tertiary amine-aldehyde proximity interaction.
Subject(s)
Bridged-Ring Compounds/chemical synthesis , Alkaloids/chemical synthesis , Alkaloids/chemistry , Alkanes/chemical synthesis , Animals , Bridged-Ring Compounds/chemistry , Cyclization , Models, Molecular , Porifera , StereoisomerismABSTRACT
Structure-activity relationship studies leading to the discovery of novel mGlu5 receptor antagonists are described. These compounds show high in vitro potency, have good in vivo receptor occupancy, and a reasonable intravenous pharmacokinetic profile.
Subject(s)
Excitatory Amino Acid Antagonists/pharmacology , Pyridines/pharmacology , Receptors, Metabotropic Glutamate/antagonists & inhibitors , Excitatory Amino Acid Antagonists/pharmacokinetics , Pyridines/pharmacokinetics , Receptor, Metabotropic Glutamate 5ABSTRACT
Pyrimidine methyl anilines as potent and selective mGlu2 potentiators are described. Findings from the structure-activity-relationship investigations are discussed.
