casein-kinase-ii and Neoplasms

CK2 (casein kinase 2) is a serine/threonine protein kinase that is ubiquitous in eukaryotic cells and plays important roles in a variety of cellular functions, including cell growth, apoptosis, circadian rhythms, DNA damage repair, transcription, and translation. CK2 is involved in cancer pathogenesis and the occurrence of many diseases. Therefore, targeting CK2 is a promising therapeutic strategy. Although many CK2-specific small-molecule inhibitors have been developed, only CX-4945 has progressed to clinical trials. In recent years, novel CK2 inhibitors have gradually become a research hotspot, which is expected to overcome the limitations of traditional inhibitors. Herein, we summarize the structure, biological functions, and disease relevance of CK2 and emphatically analyze the structure-activity relationship (SAR) and binding modes of small-molecule CK2 inhibitors. We also discuss the latest progress of novel strategies, providing insights into new drugs targeting CK2 for clinical practice.

Topics: Antineoplastic Agents; Casein Kinase II; Drug Discovery; Humans; Neoplasms; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases

Protein kinase CSNK2 (CK2) is a pleiotropic serine/threonine kinase frequently dysregulated in solid and hematologic malignancies. To consolidate a wide range of biological and clinically oriented data from this unique kinase in cancer, this systematic review summarises existing knowledge from in vitro, in vivo and pre-clinical studies on CSNK2 across 24 different human cancer types. CSNK2 mRNA transcripts, protein levels and activity were found to be routinely upregulated in cancer, and commonly identified phosphotargets included AKT, STAT3, RELA, PTEN and TP53. Phenotypically, it frequently influenced evasion of apoptosis, enhancement of proliferation, cell invasion/metastasis and cell cycle control. Clinically, it held prognostic significance across 14 different cancers, and its inhibition in xenograft experiments resulted in a positive treatment response in 12. In conjunction with commentary on preliminary studies of CSNK2 inhibitors in humans, this review harmonises an extensive body of CSNK2 data in cancer and reinforces its emergence as an attractive target for cancer therapy. Continuing to investigate CSNK2 will be crucial to advancing our understanding of CSNK2 biology, and offers the promise of important new discoveries scientifically and clinically.

Topics: Apoptosis; Casein Kinase II; Cell Cycle Checkpoints; Cell Proliferation; Humans; Neoplasms

CK2 is a constitutively active Ser/Thr protein kinase which phosphorylates hundreds of substrates. Since they are primarily related to survival and proliferation pathways, the best-known pathological roles of CK2 are in cancer, where its targeting is currently being considered as a possible therapy. However, CK2 activity has been found instrumental in many other human pathologies, and its inhibition will expectably be extended to different purposes in the near future. Here, after a description of CK2 features and implications in diseases, we analyze the different inhibitors and strategies available to target CK2, and update the results so far obtained by their in vivo application.

Topics: Casein Kinase II; Drug Delivery Systems; Humans; Neoplasm Proteins; Neoplasms; Protein Kinase Inhibitors

CK2 is a constitutively active protein kinase that assuring a constant level of phosphorylation to its numerous substrates supports many of the most important biological functions. Nevertheless, its activity has to be controlled and adjusted in order to cope with the varying needs of a cell, and several examples of a fine-tune regulation of its activity have been described. More importantly, aberrant regulation of this enzyme may have pathological consequences, e.g. in cancer, chronic inflammation, neurodegeneration, and viral infection. Our review aims at summarizing our current knowledge about CK2 regulation. In the first part, we have considered the most important stimuli shown to affect protein kinase CK2 activity/expression. In the second part, we focus on the molecular mechanisms by which CK2 can be regulated, discussing controversial aspects and future perspectives.

Topics: Animals; Casein Kinase II; Humans; Inflammation; Neoplasm Proteins; Neoplasms; Signal Transduction; Virus Diseases

The Protein kinase CK2 (formerly known as casein kinase 2) is a highly conserved serine/ threonine kinase\ overexpressed in various human carcinomas and its high expression often correlates with poor prognosis. CK2 protein\ is localized in the nucleus of many tumor cells and correlates with clinical features in many cases. Increased expression\ of CK2 in mice results in the development of various types of carcinomas (both solids and blood related tumors, such\ as (breast carcinoma, lymphoma, etc), which reveals its carcinogenic properties. CK2 plays essential roles in many key\ biological processes related to carcinoma, including cell apoptosis, DNA damage responses and cell cycle regulation.\ CK2 has become a potential anti-carcinoma target. Various CK2 inhibitors have been developed with anti-neoplastic\ properties against a variety of carcinomas. Some CK2 inhibitors have showed good results in in vitro and pre-clinical\ models, and have even entered in clinical trials. This article will review effects of CK2 and its inhibitors on common\ carcinomas in in vitro and pre-clinical studies.

Topics: Animals; Antineoplastic Agents; Casein Kinase II; Disease Management; Humans; Molecular Targeted Therapy; Neoplasms; Prognosis

Protein kinase CK2, formerly referred to as casein kinase II, is a serine/threonine kinase often found overexpressed in solid tumors and hematologic malignancies that phosphorylates many substrates integral to the hallmarks of cancer. CK2 has emerged as a viable oncology target having been experimentally validated with different kinase inhibitors, including small molecule ATP-competitors, synthetic peptides, and antisense oligonucleotides. To date only two CK2 inhibitors, CIGB-300 and CX-4945, have entered the clinic in phase 1-2 trials. This review provides information on CIGB-300, a cell-permeable cyclic peptide that inhibits CK2-mediated phosphorylation by targeting the substrate phosphoacceptor domain. We review data that support the concept of CK2 as an anticancer target, address the mechanism of action, and summarize preclinical studies showing antiangiogenic and antimetastatic effects as well as synergism with anticancer drugs in preclinical models. We also summarize early clinical research (phase 1/2 trials) of CIGB-300 in cervical cancer, including data in combination with chemoradiotherapy. The clinical data demonstrate the safety, tolerability, and clinical effects of intratumoral injections of CIGB-300 and provide the foundation for future phase 3 clinical trials in locally advanced cervical cancer in combination with standard chemoradiotherapy.

Topics: Animals; Antineoplastic Agents; Casein Kinase II; Clinical Trials as Topic; Humans; Neoplasms; Peptides, Cyclic; Phosphorylation; Protein Kinase Inhibitors; Xenograft Model Antitumor Assays

CK2 and AKT display a high degree of cross-regulation of their respective functions, both directly, through physical interaction and phosphorylation, and indirectly, through an intense cross-talk of key downstream effectors, ultimately leading to sustained AKT activation. Being CK2 and AKT attractive targets for therapeutic intervention, here we would like to emphasize how AKT and CK2 might influence cell fate through their complex isoform-specific and contextual-dependent cross-talk, to the extent that such functional interplay should be considered when devising therapies that target one or both these key signaling kinases.

Topics: Animals; Antineoplastic Agents; Casein Kinase II; Gene Expression Regulation, Neoplastic; Humans; Molecular Targeted Therapy; Neoplasms; Phosphorylation; Protein Isoforms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction

The conventional term 'casein kinase' (CK) denotes three classes of kinases - CK1, CK2 and Golgi-CK (G-CK)/Fam20C (family with sequence similarity 20, member C) - sharing the ability to phoshorylate casein in vitro, but otherwise unrelated to each other. All CKs have been reported to be implicated in human diseases, and reviews individually dealing with the druggability of CK1 and CK2 are available. Our aim is to provide a comparative analysis of the three classes of CKs as therapeutic targets.. CK2 is the CK for which implication in neoplasia is best documented, with the survival of cancer cells often relying on its overexpression. An ample variety of cell-permeable CK2 inhibitors have been developed, with a couple of these now in clinical trials. Isoform-specific CK1 inhibitors that are expected to play a beneficial role in oncology and neurodegeneration have been also developed. In contrast, the pathogenic potential of G-CK/Fam20C is caused by its loss of function. Activators of Fam20C, notably sphingolipids and their analogs, may prove beneficial in this respect.. Optimization of CK2 and CK1 inhibitors will prove useful to develop new therapeutic strategies for treating cancer and neurodegenerative disorders, while the design of potent activators of G-CK/Fam20C will provide a new tool in the fields of bio-mineralization and hypophosphatemic diseases.

Topics: Animals; Casein Kinase I; Casein Kinase II; Drug Design; Extracellular Matrix Proteins; Humans; Hypophosphatemia; Molecular Targeted Therapy; Neoplasms; Neurodegenerative Diseases; Protein Kinase Inhibitors

The PH domain-containing casein kinase 2 interacting protein-1 (CKIP-1, also known as PLEKHO1) acts as a scaffold protein mediating interactions with multiple proteins, including CK2α, CPα, AP-1/c-Jun, Akt, ATM, IFP35/Nmi and Smurf1. CKIP-1 functions through different ways, such as plasma membrane recruitment, transcriptional activity modulation and posttranscriptional modification regulation. Moreover, the subcellular localization of CKIP-1 is determined by several key amino acids in a cell type dependent style, and the nucleus/plasma membrane shuttle of CKIP-1 is regulated by different cell stresses. As an adaptor protein, CKIP-1 is involved in various important signaling pathways, controlling cell growth, apoptosis, differentiation, cytoskeleton and bone formation. Strikingly, CKIP-1 has been recently demonstrated to be a promising target for treatment of osteoporosis in rat models. In addition, more evidences suggest that CKIP-1 might also function as a potential tumor suppressor.

Topics: Animals; Bone Diseases; Carrier Proteins; Casein Kinase II; Cell Membrane; Cell Nucleus; Humans; Intracellular Signaling Peptides and Proteins; Neoplasms; Signal Transduction

The transcription factor Twist plays vital roles during embryonic development through regulating/controlling cell migration. However, postnatally, in normal physiological settings, Twist is either not expressed or inactivated. Increasing evidence shows a strong correlation between Twist reactivation and both cancer progression and malignancy, where the transcriptional activities of Twist support cancer cells to disseminate from primary tumours and subsequently establish a secondary tumour growth in distant organs. However, it is largely unclear how this signalling programme is reactivated or what signalling pathways regulate its activity. The present review discusses recent advances in Twist regulation and activity, with a focus on phosphorylation-dependent Twist activity, potential upstream kinases and the contribution of these factors in transducing biological signals from upstream signalling complexes. The recent advances in these areas have shed new light on how phosphorylation-dependent regulation of the Twist proteins promotes or suppresses Twist activity, leading to differential regulation of Twist transcriptional targets and thereby influencing cell fate.

Topics: Acrocephalosyndactylia; Animals; Casein Kinase II; Gene Expression Regulation, Neoplastic; Humans; Neoplasm Invasiveness; Neoplasms; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Twist-Related Protein 1; Ventricular Remodeling

Topics: Animals; Casein Kinase II; Cell Line, Tumor; Humans; Neoplasms; Protein Kinase Inhibitors

CK2 is a pleiotropic, ubiquitous and constitutively active protein kinase, localized in both cytosolic and nuclear compartments, where it catalyzes the phosphorylation of hundreds of proteins. CK2 is generally described as a tetramer composed of two catalytic (α and/or α') and two regulatory subunits (β), however, the free α/α' subunits are catalytically active by themselves. CK2 plays a key role in several physiological and pathological processes and has been connected to many neoplastic, inflammatory, autoimmune and infectious disorders. In the last 20 years, several inhibitors of CK2 have been discovered though only one of these, CX-4945, has recently entered into Phase II clinical trials as potential anticancer drug.. The main objective of the present review is to describe the development of CK2 activity modulators over the years according to the timeline of their patent registration.. CK2 was discovered in 1954, but the first patent on CK2 modulators was deposited only 50 years later, in 2004. However, in the last 5 years an increasing number of patents on CK2 inhibitors have been registered, reflecting an increased interest in this kind of drug candidates and their possible therapeutic applications.

Topics: Animals; Antineoplastic Agents; Casein Kinase II; Clinical Trials, Phase II as Topic; Drug Design; Humans; Neoplasms; Patents as Topic; Protein Kinase Inhibitors

Gene alterations affecting elements of PI3K signaling pathway do not appear to be sufficient to explain the extremely high frequency of PI3K signaling hyperactivation in leukemia. It has been known for long that PTEN phosphorylation at the C-terminal tail, in particular by CK2, contributes to the stabilization and simultaneous inhibition of this critical tumor suppressor. However, direct evidence of the involvement of this mechanism in cancer has been gathered only recently. It is now known that CK2-mediated posttranslational, non-deleting, inactivation of PTEN occurs in T-ALL, CLL and probably other leukemias and solid tumors. To explore this knowledge for therapeutic purposes remains one of the challenges ahead.

Topics: Animals; Casein Kinase II; Cell Survival; Humans; Leukemia; Mutation; Neoplasms; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Signal Transduction

Execution of the mitochondrial death signaling is paramount to an effective response of cancer cells to chemotherapeutic intervention. Therefore, factors that inhibit the engagement of the mitochondrial amplification pathway, such as the expression of the anti-apoptotic proteins of the Bcl2 family or inactivation of inducers of mitochondrial permeability, play a critical role in the acquisition of the resistant phenotype. Protein kinase CK2 (CK2) is a ubiquitous serine/threonine kinase that is highly conserved in eukaryotic cells. This multifunctional protein kinase has been shown to impact cell growth and proliferation, as numerous growth-related proteins are substrates of CK2. More importantly, experimental evidence linking increased expression and activity of the kinase to human cancers, underscores the relevance of CK2 biology to cellular transformation and carcinogenesis. Of note, among the many cellular substrates of CK2 are proteins involved in the efficient execution of the mitochondria-dependent cell death signaling, such as Bid, caspase-2, ARC and others. Supporting this, recent reports have demonstrated that genetic manipulation of CK2 expression as well as pharmacological inhibition of its enzymatic activity sensitizes cancer cells to apoptotic stimuli. Due to the critical regulatory role that this kinase plays in cell fate determination in cancer cells, there is a tremendous increase in activity geared at the development of CK2-specific therapies. Here we provide a brief review of CK2-mediated inhibition of mitochondrial death signaling in cancer cells and its implications for the design of novel target specific therapeutic strategies.

Topics: Animals; Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Proliferation; Drug Delivery Systems; Drug Design; Humans; Mitochondria; Neoplasms

CK2 denotes a pleiotropic, constitutively active protein kinase whose abnormally high level in many cancer cells is held as an example of "non oncogene addiction". A wide spectrum of cell permeable, fairly specific ATP site-directed CK2 inhibitors are currently available which are proving useful to dissect its biological functions and which share the property of inducing apoptosis of cancer cells with no comparable effect on their "normal" counterparts. One of these, CX-4945, has recently entered clinical trials for the treatment of advanced solid tumors, Castelman's disease and multiple myeloma. The solution of a wide range of 3D structures of inhibitors bound to the catalytic subunits of CK2 reveals that their efficacy substantially relies on hydrophobic interactions within a cavity which is smaller than in other protein kinases. Accordingly the potency of tetra-halogenated benzimidazoles increases upon replacement of chlorine by bromine and, even more, by iodine, and decreases if two unique bulky side chains on CK2 (Val66 and Ile174) are mutated to alanines. Many CK2 inhibitors have been tested on a panel of more than 60 kinases providing Promiscuity Scores useful to evaluate their selectivity, the lowest value (9.47), denoting highest selectivity, being displayed by quinalizarin. The observation that CK2 inhibitors with medium/high promiscuity scores share the ability to inhibit a group of protein kinases as effectively as CK2 discloses the possibility of using their scaffolds for the rational development of selective inhibitors of these kinases, with special reference to PIMs, DYRKs, HIPK2, PKD and ERK8.

Topics: Adenosine Triphosphate; Antineoplastic Agents; Casein Kinase II; Humans; Neoplasms; Protein Kinase Inhibitors; Structure-Activity Relationship

At variance with most oncogenic protein kinases whose malignancy is generally due to genetic alterations conferring constitutive activity, CK2 is a highly pleiotropic Ser/Thr protein kinase naturally endowed with constitutive activity and lacking gain-of-function mutants. Nonetheless CK2 is abnormally elevated in a wide variety of tumors and there is strong evidence that it operates as a cancer driver by creating a cellular environment favorable to neoplasia: notably, CK2 plays a global role as an anti-apoptotic and pro-survival agent, it enhances the multi-drug resistance (MDR) phenotype, it assists the chaperone machinery which protects the "onco-kinome" and it promotes neo-angiogenesis. Based on this scenario we propose that the implication of CK2 in neoplasia is an example of "non oncogene addiction", i.e. over reliance of the perturbed cellular signaling network on high CK2 level for its own maintenance. Consistent with this, an ample spectrum of diverse types of cancer cells have been already shown to rely on high CK2 level for their survival, as judged from their response to specific CK2 inhibitors and silencing of endogenous CK2 catalytic subunits. Remarkably, among these are cells whose cancer phenotype arises from the genetic alteration of onco-kinases (e.g. Abl and Alk) different from CK2 and insensitive to the CK2 inhibitors used in those experiments. Based on these premises, CK2 could represent a "multi-purpose" target for the treatment of different kinds of tumors.

Topics: Animals; Casein Kinase II; Catalytic Domain; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Mutation; Neoplasms; Neovascularization, Pathologic; Protein Kinase Inhibitors

Protein kinase CK2 is an unfavorable pronostic marker in several cancers and has consequently emerged as a relevant therapeutic target. Several classes of ATP-competitive inhibitors have been identified, showing variable effectiveness. The molecular architecture of this multisubunit enzyme could offer alternative strategies to develop small molecule inhibitors targeting different surfaces of the kinase. Polyoxometalates were identified as original CK2 inhibitors targeting key structural elements located outside the active site. In addition, the CK2 subunit interface represents an exosite distinct from the catalytic cavity that can be targeted by peptides or small molecules to achieve functional effects.

Topics: Animals; Biomarkers, Tumor; Casein Kinase II; Catalytic Domain; Humans; Neoplasms; Protein Synthesis Inhibitors; Tungsten Compounds

Casein Kinase II (CK2) is a ubiquitous serine/threonine kinase that is highly conserved in eukaryotic cells. CK2 has been shown to impact cell growth and proliferation, as numerous growth-related proteins are substrates of CK2. More importantly, experimental evidence linking increased expression and activity of CK2 to human cancers underscores the relevance of CK2 biology to cellular transformation and carcinogenesis. Due to the critical regulatory role CK2 plays in cell fate determination in cancer cells, there is a tremendous interest in the development of CK2-specific therapies. Supporting this, recent reports have demonstrated that genetic manipulation of CK2 expression as well as pharmacological inhibition of its enzymatic activity sensitizes cancers to apoptotic stimuli. Here we provide a succinct account of the biology of CK2, its cellular substrates, its pro-survival and pro-proliferation activity, and highlight evidence for its involvement in human cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Growth Processes; Cell Transformation, Neoplastic; Drug Design; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Humans; Neoplasms

Elevated levels of protein kinase CK2 (formerly casein kinase 2 or II) have long been associated with increased cell growth and proliferation both in normal and cancer cells. The ability of CK2 to also act as a potent suppressor of apoptosis offers an important link to its involvement in cancer since deregulation of both cell proliferation and apoptosis are among the key features of cancer cell biology. Dysregulated CK2 may impact both of these processes in cancer cells. All cancers that have been examined show increased CK2 expression, which may also relate to prognosis. The extensive involvement of CK2 in cancer derives from its impact on diverse molecular pathways controlling cell proliferation and cell death. Downregulation of CK2 by various approaches results in induction of apoptosis in cultured cell and xenograft cancer models suggesting its potential as a therapeutic target.

Topics: Animals; Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Humans; Neoplasm Transplantation; Neoplasms; Protein Kinase Inhibitors; Signal Transduction; Transplantation, Heterologous

Protein kinase CK2 (formerly referred to as casein kinase II) is an evolutionary conserved, ubiquitous protein kinase. There are two paralog catalytic subunits, i.e. alpha (A1) and alpha' (A2). The alpha and alpha' subunits are linked to two beta subunits to produce a heterotetrameric structure. The catalytic alpha subunits are distantly related to the CMGC subfamily of kinases, such as the Cdk kinases. There are some peculiarities associated with protein kinase CK2, which are not found with most other protein kinases: (i) the enzyme is constitutively active, (ii) it can use ATP and GTP and (iii) it is found elevated in most tumors investigated and rapidly proliferating tissues. With the elucidation of the structure of the catalytic subunit, it was possible to explain why the enzyme is constitutively active [1] and why it can bind GTP [2]. Considerable information on the potential roles of CK2 in various disease processes including cancer has been gained in recent years, and the present review may help to further elucidate its aberrant role in many disease states. Its peculiar structural features [3-9] may be advantageous in designing tailor-made compounds with the possibility to specifically target this protein kinase [10]. Since not all the aspects of what has been published on CK2 can be covered in this review, we would like to recommend the following reviews; (i) for general information on CK2 [11-18] and (ii) with a focus on aberrant CK2 [19-22].

Topics: Casein Kinase II; Humans; Neoplasms; Nervous System Diseases; Protein Subunits; Signal Transduction

CK2 is probably the most pleiotropic Ser/Thr protein kinase with hundreds of endogenous substrates already known, which are implicated in a variety of cellular functions. At variance with most protein kinases whose activity is turned on only in response to specific stimuli, and whose genetic alterations often underlie pathological situations, CK2 is not susceptible to tight regulation and there are no mutations known to affect its constitutive activity. Nevertheless an abnormally high level of CK2 is invariably found in tumours, and solid arguments have accumulated suggesting that CK2 plays a global pro-survival function, which under special circumstances creates a cellular environment particularly favourable to the development and potentiation of the tumour phenotype. Therefore any strategy aimed at attenuating CK2 activity may represent a "master key" for the treatment of different neoplastic diseases. Waiting for the clarification of the epigenetic mechanisms promoting the rise of CK2 in cells predisposed to develop a tumour phenotype, a useful pharmacological aid can come from the improvement of a number of fairly potent and selective CK2 inhibitors already available.

Topics: Adenosine Triphosphate; Animals; Antineoplastic Agents; Casein Kinase II; Enzyme Inhibitors; Humans; Neoplasms; Structure-Activity Relationship; Substrate Specificity

Protein kinase CK2 is a ubiquitous, essential, and highly pleiotropic protein kinase whose abnormally high constitutive activity is suspected to underlie its pathogenic potential in neoplasia and other diseases. A number of structurally unrelated CK2 inhibitors, tested on a variety of cells derived from tumours, including lymphomas, leukaemias, multiple myeloma and prostate carcinoma, display a pro-apoptotic effect which is roughly proportional to their in vitro inhibitory potency. In the present review we summarize the most recent discovery of potent and selective CK2 inhibitors and their prospective as future anticancer agents.

Topics: Animals; Antineoplastic Agents; Binding Sites; Casein Kinase II; Humans; Models, Molecular; Molecular Structure; Neoplasms; Protein Kinase Inhibitors

CK2 is a highly conserved protein serine/threonine kinase that is ubiquitously distributed in eukaryotes, constitutively active and has been implicated in multiple cellular functions, as well as in tumorigenesis and transformation. Elevated CK2 activity has been associated with the malignant transformation of several tissues and is associated with aggressive tumor behaviour. While the precise roles of CK2 in tumorigenesis remain incompletely understood, mounting evidence suggests a role for CK2 in the protection of cells from apoptosis via the regulation of tumor suppressor and oncogene activity. Consequently, CK2 has emerged as a potential therapeutic target, and strategies to inhibit CK2 have been ongoing in pre-clinical trials. This review will focus on published evidence highlighting the molecular mechanisms by which CK2 functions in the promotion of tumorigenesis, as well as review current strategies being used to inhibit CK2.

Topics: Animals; Apoptosis; Casein Kinase II; Cell Transformation, Neoplastic; Humans; Neoplasms; NF-kappa B; Oncogenes; Protein Kinase Inhibitors; Signal Transduction; Tumor Suppressor Proteins; Wnt Proteins

Topics: Animals; Apoptosis; Casein Kinase II; Down-Regulation; Humans; Neoplasms

Protein kinase CK2 is a highly ubiquitous and conserved protein serine/threonine kinase that has been found to be involved not only in cell growth and proliferation, but also in suppression of apoptosis. CK2 is capable of dynamic intracellular shuttling in response to a variety of signals. It is localized in both the nucleus and cytoplasm in normal cells, but is particularly predominant in the nuclear compartment in cancer cells. CK2 has been found to be uniformly dysregulated in all the cancers that have been examined. Downregulation of CK2 by chemical or molecular methods promotes apoptosis in cells. We have shown that antisense CK2alpha is particularly potent in inducing apoptosis in cancer cells in culture as well as in xenograft models of cancer such as prostate cancer and squamous cell carcinoma of head and neck. The antisense CK2alpha oligodeoxynucleotide (ODN) mediates tumor cell death in a dose- and time-dependent manner such that at an appropriate concentration of the antisense, a complete resolution of the xenograft tumor is observed. Interestingly, normal and benign cells (in culture as well as in vivo) demonstrate a relative resistance to the antisense CK2alpha ODN treatment, which raises the possibility of a significant therapeutic window for this therapy. Further, novel approaches such as the delivery of antisense CK2alpha ODN encapsulated in sub-50-nm tenascin nanocapsules have become available for its targeting specifically in cancer cells. Our studies minimize generally held concerns regarding suitability of CK2 as a target for cancer therapy and provide the first encouraging results for potential future application of this approach for cancer therapy.

Topics: Antineoplastic Agents; Apoptosis; Capsules; Casein Kinase II; Down-Regulation; Humans; Neoplasms; Oligonucleotides, Antisense; Signal Transduction; Tenascin

Recent studies have generated sufficient information to warrant a consideration of protein kinase CK2 as a potential target for cancer therapy. CK2 is a ubiquitous and highly conserved protein serine/threonine kinase that has long been considered to play a role in cell growth and proliferation. It is essential for cell survival, and considerable evidence suggests that it can also exert potent suppression of apoptosis in cells. This is important since the cancer phenotype is characterized by deregulation of not only proliferation but also of apoptosis. In normal cells, the level of CK2 appears to be tightly regulated, and cells resist a change in their intrinsic level of CK2. However, in all the cancers that have been examined an elevation of CK2 has been observed. Further, it appears that modest deregulation in the CK2 expression imparts a potent oncogenic potential to the cells. Disruption of CK2 by treatment of cells with antisense CK2 results in induction of apoptosis in a time and dose-dependent manner. Thus, we propose that down-regulation of CK2 by employing specific strategies to deliver antisense CK2 in vivo could have a potential role in cancer therapy.

Topics: Animals; Casein Kinase II; Cell Survival; DNA-Binding Proteins; Down-Regulation; Enzyme Inhibitors; Humans; Neoplasms; Protein Serine-Threonine Kinases

Protein kinase CK2 appears to interact with different signaling pathways and therefore represents the prototype of a multifunctional protein kinase. The enzyme is highly expressed in most cancers and this higher expression has been tentatively correlated with the involvement of CK2 in the promotion of specific phases of the cell cycle. This review summarizes our current knowledge on how CK2 may also contribute to tumorigenesis through its direct interaction with the cell-survival circuitry.

Topics: Animals; Apoptosis; Casein Kinase II; Cell Cycle; Cell Survival; Humans; Neoplasm Proteins; Neoplasms; Protein Serine-Threonine Kinases

Protein kinase CK2 (formerly known as casein kinase 2) is a serine/threonine protein kinase whose functions have been under investigation for over three decades, leading to the recognition that it interacts with several signaling pathways. Recent demonstrations of signal-mediated dynamic localization of CK2 and the identification of new signaling targets for it have converged to indicate an unexpected function for this protein kinase: cell survival. Here, we summarize our emerging knowledge about how CK2 might participate in the transduction of survival signals.

Topics: Animals; Caenorhabditis elegans; Casein Kinase II; Cell Division; Cell Survival; Crystallography, X-Ray; Humans; Models, Biological; Models, Molecular; Neoplasms; Protein Serine-Threonine Kinases; Saccharomyces cerevisiae; Signal Transduction

Protein kinase CK2 (previously known as casein kinase II) is a protein serine/threonine kinase that has been implicated in cell growth and proliferation. The focus of this review is on the apparent role of CK2 in cancer. Studies from several laboratories have shown a dysregulated expression of the kinase in tumors. Nuclear matrix and chromatin appear to be key sites for signaling of the CK2 activity in relation to cell growth. Several types of growth stimuli produce a common downstream response in CK2 by enhancing its nuclear shuttling. The neoplastic change is also associated with changes in intracellular localization of the kinase so that a higher nuclear localization is observed in tumor cells compared with normal cells. Experimental studies suggest that dysregulated expression of the alpha subunit of CK2 imparts an oncogenic potential in the cells such that in cooperation with certain oncogenes it produces a profound enhancement of the tumor phenotype. Recent studies have provided evidence that overexpression of CK2 in tumor cells is not simply a reflection of tumor cell proliferation alone but additionally may reflect the pathobiological characteristics of the tumor. Of considerable interest is the possibility that CK2 dysregulation in tumors may influence the apoptotic activity in those cells. Approaches to interfering with the CK2 signal may provide a useful means for inducing tumor cell death.

Topics: Adenocarcinoma; Animals; Apoptosis; Carcinoma, Squamous Cell; Casein Kinase II; Cell Nucleus; Chromatin; Head and Neck Neoplasms; Humans; Immunohistochemistry; Male; Neoplasms; Nuclear Matrix; Prostatic Neoplasms; Protein Serine-Threonine Kinases; Signal Transduction

Many stimuli play a role in influencing the structure and function of chromatin and nuclear matrix through post-translational modifications of the component proteins in these dynamic structures. We propose that the protein serine/threonine kinase CK2 (formerly casein kinase II) is one such agent that is involved in signal transduction in the nuclear matrix and chromatin in response to a variety of stimuli. Protein kinase CK2 appears to undergo rapid modulations in its association with nuclear matrix and nucleosomes in response to mitogenic signals and is involved in the phosphorylation of a variety of intrinsic proteins in these structures depending on the state of genomic activity. In addition, its association or loss from the nuclear matrix may also influence the apoptotic activity in the cell. CK2 has been found to be dysregulated in virtually all the neoplasias examined and nuclear association appears to be an important facet of its expression in tumor cells. We hypothesize that CK2 provides a functional paradigm linking the nuclear matrix and chromatin structures. Identification of precise loci of action of CK2 in these structures and how they influence the morphological appearance of the nucleus under normal and abnormal growth conditions would be an important future direction of investigation. J. Cell. Biochem. Suppl. 35:130-135, 2000. Published 2001 Wiley-Liss, Inc.

Topics: Animals; Casein Kinase II; Cell Division; Cell Nucleus; Humans; Neoplasms; Protein Serine-Threonine Kinases; Signal Transduction; Tumor Cells, Cultured

Protein kinase CK2 is a pleiotropic, ubiquitous and constitutively active protein kinase that can use both ATP and GTP as phosphoryl donors with specificity for serine/threonine residues in the vicinity of acidic amino acids. Recent results show that the enzyme is involved in transcription, signaling, proliferation and in various steps of development. The tetrameric holoenzyme (alpha2beta2) consists of two catalytic alpha-subunits and two regulatory beta-subunits. The structure of the catalytic subunit with the fixed positioning of the activation segment in the active conformation through its own aminoterminal region suggests a regulation at the transcriptional level making a regulation by second messengers unlikely. The high conservation of the catalytic subunit from yeast to man and its role in the tetrameric complex supports this notion. The regulatory beta-subunit has been far less conserved throughout evolution. Furthermore the existence of different CK2beta-related proteins together with the observation of deregulated CK2beta levels in tumor cells and the reported association of CK2beta protein with key proteins in signal transduction, e.g. A-Raf, Mos, pg90rsk etc. are suggestive for an additional physiological role of CK2beta protein beside being the regulatory compound in the tetrameric holoenzyme.

Topics: Animals; Casein Kinase II; Cell Differentiation; Cell Division; Humans; Neoplasms; Protein Serine-Threonine Kinases

Protein kinase CK2 (also termed casein kinase-2 or -II) is a ubiquitous Ser/Thr-specific protein kinase required for viability and for cell cycle progression. CK2 is especially elevated in proliferating tissues, either normal or transformed, and the expression of its catalytic subunit in transgenic mice is causative of lymphomas. CK2 is highly pleiotropic: more than 160 proteins phosphorylated by it at sites specified by multiple acidic residues are known. Despite its heterotetrameric structure generally composed by two catalytic (alpha and/or alpha') and two non catalytic beta-subunits, the regulation of CK2 is still enigmatic. A number of functional features of the beta-subunit which could cooperate to the modulation of CK2 targeting/activity will be discussed.

Topics: Amino Acid Sequence; Animals; Casein Kinase II; Cell Division; Humans; Mice; Mice, Transgenic; Molecular Sequence Data; Neoplasms; Protein Conformation; Protein Serine-Threonine Kinases; Substrate Specificity

Long non-coding RNAs (lncRNAs) play important biological roles. Here, the roles of the lncRNA

Topics: Caloric Restriction; Casein Kinase II; Cell Line; Cellular Senescence; Down-Regulation; Fibroblasts; Gene Knockdown Techniques; HCT116 Cells; Humans; Lipopolysaccharides; MCF-7 Cells; MicroRNAs; Neoplasms; Potassium Channels, Voltage-Gated; Reactive Oxygen Species; Senescence-Associated Secretory Phenotype

Targeting immune checkpoints such as programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) has transformed cancer treatment, with durable clinical responses across a wide range of tumor types. However, a high percentage of patients fail to respond to anti-PD-1/PD-L1 treatment. A greater understanding of PD-L1 regulation is critical to improving the clinical response rate of PD-1/PD-L1 blockade. Here, we demonstrate that PD-L1 is phosphorylated and stabilized by casein kinase 2 (CK2) in cancer and dendritic cells (DC). Phosphorylation of PD-L1 at Thr285 and Thr290 by CK2 disrupted PD-L1 binding with speckle-type POZ protein, an adaptor protein of the cullin 3 (CUL3) ubiquitin E3 ligase complex, protecting PD-L1 from CUL3-mediated proteasomal degradation. Inhibition of CK2 decreased PD-L1 protein levels by promoting its degradation and resulted in the release of CD80 from DC to reactivate T-cell function. In a syngeneic mouse model, combined treatment with a CK2 inhibitor and an antibody against T-cell immunoglobulin mucin-3 (Tim-3) suppressed tumor growth and prolonged survival. These findings uncover a mechanism by which PD-L1 is regulated and suggest a potential antitumor treatment option to activate DC function by blocking the CK2-PD-L1 pathway and inhibiting Tim-3.. This work identifies a role for CK2 in immunosuppression by phosphorylation and stabilization of PD-L1, identifying CK2 inhibition as an immunotherapeutic approach for treating cancer.

Topics: Animals; B7-H1 Antigen; Casein Kinase II; Dendritic Cells; Hepatitis A Virus Cellular Receptor 2; Humans; Mice; Neoplasms; Phosphorylation; Programmed Cell Death 1 Receptor

Topics: Casein Kinase II; Humans; Neoplasms; NF-kappa B; Protein Serine-Threonine Kinases; Signal Transduction; Tumor Microenvironment

CK2 is a Ser/Thr protein kinase overexpressed in many cancers. It is usually present in cells as a tetrameric enzyme, composed of two catalytic (α or α') and two regulatory (β) subunits, but it is active also in its monomeric form, and the specific role of the different isoforms is largely unknown. CK2 phosphorylates several substrates related to the uncontrolled proliferation, motility, and survival of cancer cells. As a consequence, tumor cells are addicted to CK2, relying on its activity more than healthy cells for their life, and exploiting it for developing multiple oncological hallmarks. However, little is known about CK2 contribution to the metabolic rewiring of cancer cells. With this study we aimed at shedding some light on it, especially focusing on the CK2 role in the glycolytic onco-phenotype. By analyzing neuroblastoma and osteosarcoma cell lines depleted of either one (α) or the other (α') CK2 catalytic subunit, we also aimed at disclosing possible pro-tumor functions which are specific of a CK2 isoform. Our results suggest that both CK2 α and α' contribute to cell proliferation, survival and tumorigenicity. The analyzed metabolic features disclosed a role of CK2 in tumor metabolism, and suggest prominent functions for CK2 α isoform. Results were also confirmed by CK2 pharmacological inhibition. Overall, our study provides new information on the mechanism of cancer cells addiction to CK2 and on its isoform-specific functions, with fundamental implications for improving future therapeutic strategies based on CK2 targeting.

Topics: Casein Kinase II; Cell Line, Tumor; Glycolysis; Humans; Isoenzymes; Neoplasm Proteins; Neoplasms

Casein kinase 2 (CK2) is highly expressed in cancer and has been considered a potential therapeutic target. Wells and colleagues developed and characterized the new CK2 inhibitor SGC-CK2-1. Unexpectedly, this potent and highly selective chemical probe does not show broad antiproliferative activity in cancer cells.

Topics: Casein Kinase II; Humans; Neoplasms; Protein Kinase Inhibitors

A large number of secondary metabolites have been isolated from the filamentous fungus

Topics: Benzofurans; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Cell Survival; Humans; Neoplasms; Protein Kinase Inhibitors; Spiro Compounds; Stachybotrys

Methuosis has been described as a distinctive form of cell death characterized by the displacement of large fluid-filled vacuoles derived from uncontrolled macropinocytosis. Its induction has been proposed as a new strategy against cancer cells. Small molecules, such as indole-based calchones, have been identified as methuosis inducers and, recently, the CK2 inhibitor CX-4945 has been shown to have a similar effect on different cell types. However, the contribution of protein kinase CK2 to methuosis signalling is still controversial. Here we show that methuosis is not related to CK2 activity since it is not affected by structurally unrelated CK2 inhibitors and genetic reduction/ablation of CK2 subunits. Interestingly, CX-5011, a CK2 inhibitor related to CX-4945, behaves as a CK2-independent methuosis inducer, four times more powerful than its parental compound and capable to promote the formation on enlarged cytosolic vacuoles at low micromolar concentrations. We show that pharmacological inhibition of the small GTPase Rac-1, its downregulation by siRNA treatment, or the over-expression of the dominant-negative mutated form of Rac-1 (Rac-1 T17N), impairs CX-5011 ability to induce methuosis. Furthermore, cell treatment with CX-5011 induces a durable activation of Rac-1 that persists for at least 24 h. Worthy of note, CX-5011 is able to promote macropinocytosis not only in mammalian cells, but also in an in-vivo zebrafish model. Based on these evidences, CX-5011 is, therefore, proposed as a potential promising compound for cancer therapies for its dual efficacy as an inhibitor of the pro-survival kinase CK2 and inducer of methuosis.

Topics: Casein Kinase II; Cell Death; CRISPR-Cas Systems; Gene Editing; Hep G2 Cells; Humans; Indoles; Neoplasms; Pinocytosis; Pyrimidines; Quinolines; rac1 GTP-Binding Protein; Vacuoles

Protein kinase CK2, a pleiotropic and constitutively active kinase, is strictly involved in different diseases, especially in cancer. Many efforts have been carried out to develop specific CK2 inhibitors and recently, it has been evidenced that ferulic acid (FA) represents a promising, albeit cell impermeable, CK2 inhibitor. In the present study, the potential of a nanotechnological approach to cope with intracellular CK2 regulation was explored. Surface-Active Maghemite Nanoparticles (SAMNs), coupling magnetism with photoluminescence, a new feature of SAMNs here described for the first time, were chosen as dual imaging nanocarrier for FA. The self-assembled nanodevice (SAMN@FA) displayed a significant CK2 inhibitory activity in vitro. Moreover, effective cellular internalization of SAMN@FA in cancer cells was proved by direct visualization of the photoluminescent nanocarrier by confocal microscopy and was corroborated by phosphorylation levels of endogenous CK2 targets. The proposed trimodal nanodevice, representing the first example of cellular CK2 nano-inhibition, paves the way for novel active nanocarriers as appealing theranostic tool for future biomedical applications.

Topics: Casein Kinase II; Coumaric Acids; Drug Carriers; HEK293 Cells; HeLa Cells; Humans; Nanoparticles; Neoplasm Proteins; Neoplasms; Protein Kinase Inhibitors

Protein kinase CK2 alpha (CK2α) is involved in the development of multiple malignancies. Overexpression of Y-box binding protein 1 (YBX1) is related to tumor proliferation, drug resistance, and poor prognosis. Studies have demonstrated that both CK2 and YBX1 could regulate the PI3K/AKT pathway. In addition, we predicted that CK2 might be the upstream kinase of YBX1 through the Human Protein Reference Database (HPRD). Herein, we hypothesize that CK2 may interact with YBX1 and they regulate the PI3K/AKT signaling pathway together. Expressions of CK2α and YBX1 in cancer cell lines were evaluated by immunoblotting. The results showed that CK2α could regulate the expression of YBX1 at the transcriptional level, which is dependent on its enzymatic activity. Synergistic effects of PI3K/AKT pathway inactivation could be observed through combined inhibition of CK2α and YBX1, and YBX1 was required for CK2α-induced PI3K/AKT pathway activation. Further results demonstrated that CK2α could interact with YBX1 and PI3K/AKT antagonist decreased cell resistance to doxorubicin induced by co-activation of CK2α and YBX1. These results indicated that combined inhibition of CK2α and YBX1 showed synergistic effects in inactivating the PI3K/AKT signaling pathway and may be one of the mechanisms involved in tumor growth and migration.

Topics: Casein Kinase II; Cell Movement; Cell Proliferation; Doxorubicin; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; HeLa Cells; Hep G2 Cells; Humans; Neoplasms; Oncogene Protein v-akt; Phosphatidylinositol 3-Kinases; Protein Binding; Signal Transduction; Y-Box-Binding Protein 1

Protein kinase CK2 has emerged as an attractive cancer therapeutic target. Previous studies have highlighted the challenge of optimizing CK2 ATP-competitive inhibitors that have low druggability due to their polycyclic ring scaffolds. Therefore the development of novel inhibitors with non-polycyclic scaffolds emerges as a promising strategy for drug discovery targeting CK2. In this current study, based on the similar predicted binding poses of the linear 2-propenone scaffold of isoliquiritigenin with that of the polycyclic inhibitor CX-4945, a series of 2-propenone derivatives containing an amine-substituted five-membered heterocycle and a benzoic acid were designed, synthesized and evaluated for their in vitro CK2 inhibition and anti-cancer activity. Compound 8b was found to be the most potent CK2 inhibitor (IC

Topics: Alkenes; Antineoplastic Agents; Casein Kinase II; Cell Proliferation; Drug Design; Hep G2 Cells; Humans; Molecular Docking Simulation; Neoplasms; Protein Kinase Inhibitors; Structure-Activity Relationship

We investigated the intracellular metabolic fluxes of protein kinase CK2-activating (Cα OE) cells and role of lactate dehydrogenase A (LDHA) as a contributor of tumorigenesis after reprogrammed glucose metabolism. Facilitated aerobic glycolysis was confirmed via isotope tracer analysis, in which

Topics: Aerobiosis; Animals; Casein Kinase II; Cell Cycle; Cell Line, Tumor; Cell Movement; Cell Proliferation; Citric Acid Cycle; Glucose; Glycolysis; Humans; Lactate Dehydrogenases; Mice; Neoplasms; Pyruvic Acid; Xenograft Model Antitumor Assays

Although it has historically been studied in the context of cancer, recent literature has highlighted the importance of the highly conserved serine/threonine kinase casein kinase II (CK2) in inflammatory disorders. Most strikingly, CK2 is a major regulator of the Th17-Treg axis relevant to many T cell-driven autoimmune disorders including multiple sclerosis (MS).

Topics: Animals; Autoimmune Diseases; Casein Kinase II; Clinical Trials as Topic; Emodin; Humans; Immunity; Immunomodulation; Inflammation; Mice; Molecular Targeted Therapy; Multiple Sclerosis; Naphthyridines; Neoplasms; Phenazines; Signal Transduction; T-Lymphocytes, Regulatory; Th17 Cells

The role of myeloid cells as regulators of tumor progression that significantly impact the efficacy of cancer immunotherapies makes them an attractive target for inhibition. Here we explore the effect of a novel, potent, and selective inhibitor of serine/threonine protein kinase casein kinase 2 (CK2) on modulating myeloid cells in the tumor microenvironment. Although inhibition of CK2 caused only a modest effect on dendritic cells in tumor-bearing mice, it substantially reduced the amount of polymorphonuclear myeloid-derived suppressor cells and tumor-associated macrophages. This effect was not caused by the induction of apoptosis, but rather by a block of differentiation. Our results implicated downregulation of CCAAT-enhancer binding protein-α in this effect. Although CK2 inhibition did not directly affect tumor cells, it dramatically enhanced the antitumor activity of immune checkpoint receptor blockade using anti-CTLA-4 antibody. These results suggest a potential role of CK2 inhibitors in combination therapies against cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Casein Kinase II; CCAAT-Enhancer-Binding Proteins; Cell Differentiation; Cell Line, Tumor; CTLA-4 Antigen; Female; Fetal Blood; Hematopoietic Stem Cells; Humans; Immunotherapy; Macrophages; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Myeloid Cells; Myeloid-Derived Suppressor Cells; Neoplasm Transplantation; Neoplasms; Tumor Microenvironment

As a ubiquitous, highly pleiotropic and constitutively active serine/threonine protein kinase, casein kinase 2 (CK2) is closely associated with tumorigenesis by its overexpression in cancer cells. Here we report several proteolysis targeting chimeras (PROTACs) via "click reaction" to connect a CK2 inhibitor (CX-4945) and pomalidomide for degradation of CK2 protein. Among them, compound 2 degraded CK2 in a dose and time-dependent manner, and kept CK2 at a low basal level by recruiting ubiquitin-proteasome system. The degradation of CK2 resulted in the reduced phosphorylation of Akt and the up-regulation of p53. As a CK2 protein degrader, 2 showed the analogous cytotoxicity to CX-4945 but with a quite different mechanism of action from the CK2 inhibitor, hinting that degradation of CK2 proteins by PROTACs is a potential way for cancer treatments.

Topics: Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Survival; Humans; Neoplasms; Proteasome Endopeptidase Complex; Protein Kinase Inhibitors; Proteolysis; Ubiquitin

A multitude of proteins are aberrantly expressed in cancer cells, including the oncogenic serine-threonine kinase CK2. In a previous report, we found increases in CK2 transcript expression that could explain the increased CK2 protein levels found in tumors from lung and bronchus, prostate, breast, colon and rectum, ovarian and pancreatic cancers. We also found that, contrary to the current notions about CK2, some CK2 transcripts were downregulated in several cancers. Here, we investigate all other cancers using Oncomine to determine whether they also display significant CK2 transcript dysregulation. As anticipated from our previous analysis, we found cancers with all CK2 transcripts upregulated (e.g. cervical), and cancers where there was a combination of upregulation and/or downregulation of the CK2 transcripts (e.g. sarcoma). Unexpectedly, we found some cancers with significant downregulation of all CK2 transcripts (e.g. testicular cancer). We also found that, in some cases, CK2 transcript levels were already dysregulated in benign lesions (e.g. Barrett's esophagus). We also found that CK2 transcript upregulation correlated with lower patient survival in most cases where data was significant. However, there were two cancer types, glioblastoma and renal cell carcinoma, where CK2 transcript upregulation correlated with higher survival. Overall, these data show that the expression levels of CK2 genes is highly variable in cancers and can lead to different patient outcomes.

Topics: Casein Kinase II; Down-Regulation; Humans; Neoplasms; RNA, Messenger; Up-Regulation

A Pt(IV) prodrug, Cx-platin, containing CX-4945 (a CK2 inhibitor) as an axial ligand was designed and prepared by targeting CK2 to disrupt DNA damage response. In vitro study indicated that Cx-platin had superior cytotoxicity to cisplatin against a number of cancer cell lines with distinct CK2-expressed levels, caused CK2-overexpressed cancer cells death via suppressing CK2-mediated DNA damage repair and reversed cisplatin resistance. Mechanistic investigation suggested that the potent antitumor activity of Cx-platin resulted from its major suppression of CK2-phosphorylated MDC1 to combine FHA domain of aprataxin to DNA double strand breaks (DSBs) caused by improved cellular uptakes of Pt and ATM deactivation. Further in vivo tests exhibited that Cx-platin displayed high tumor inhibition rates, increased weight gain, and hardly toxicity effects in contrast to cisplatin.

Topics: Adaptor Proteins, Signal Transducing; Animals; Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; Casein Kinase II; Cell Cycle Proteins; Cisplatin; DNA Damage; DNA Repair; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Combinations; Drug Design; Female; HCT116 Cells; Hep G2 Cells; Humans; Inhibitory Concentration 50; Male; MCF-7 Cells; Mice, Inbred BALB C; Mice, Nude; Molecular Targeted Therapy; Naphthyridines; Neoplasms; Nuclear Proteins; Organoplatinum Compounds; Phenazines; Phosphorylation; Prodrugs; Protein Interaction Domains and Motifs; Protein Kinase Inhibitors; Rats, Sprague-Dawley; Signal Transduction; Time Factors; Trans-Activators; Xenograft Model Antitumor Assays

HPV-16 E7 is one of the key proteins that, by interfering with the host metabolism through many protein-protein interactions, hijacks cell regulation and contributes to malignancy. Here we report the high resolution investigation of the CR3 region of HPV-16 E7, both as an isolated domain and in the full-length protein. This opens the way to the atomic level study of the many interactions in which HPV-16 E7 is involved. Along these lines we show here the effect of one of the key post-translational modifications of HPV-16 E7, the phosphorylation by casein kinase II.

Topics: Amino Acid Sequence; Casein Kinase II; Cell Line; Human papillomavirus 16; Humans; Neoplasms; Nuclear Magnetic Resonance, Biomolecular; Papillomavirus E7 Proteins; Phosphorylation; Protein Interaction Domains and Motifs; Protein Processing, Post-Translational; Protein Structure, Tertiary

Protein kinase CK2 (designated CSNK2) is a constitutively active protein kinase with a vast repertoire of putative substrates that has been implicated in several human cancers, including cancer of the breast, lung, colon, and prostate, as well as hematologic malignancies. On the basis of these observations, CSNK2 has emerged as a candidate for targeted therapy, with two CSNK2 inhibitors in ongoing clinical trials. CX-4945 is a bioavailable small-molecule ATP-competitive inhibitor targeting its active site, and CIGB-300 is a cell-permeable cyclic peptide that prevents phosphorylation of the E7 protein of HPV16 by CSNK2. In preclinical models, either of these inhibitors exhibit antitumor efficacy. Furthermore, in combinations with chemotherapeutics such as cisplatin or gemcitabine, either CX-4945 or CIGB-300 promote synergistic induction of apoptosis. While CSNK2 is a regulatory participant in many processes related to cancer, its potential to modulate caspase action may be particularly pertinent to its emergence as a therapeutic target. Because the substrate recognition motifs for CSNK2 and caspases are remarkably similar, CSNK2 can block the cleavage of many caspase substrates through the phosphorylation of sites adjacent to cleavage sites. Phosphoproteomic strategies have also revealed previously underappreciated roles for CSNK2 in the phosphorylation of several key constituents of DNA damage and DNA repair pathways. Going forward, applications of proteomic strategies to interrogate responses to CSNK2 inhibitors are expected to reveal signatures for CSNK2 inhibition and molecular insights to guide new strategies to interfere with its potential to inhibit caspase action or enhance the susceptibility of cancer cells to DNA damage. Clin Cancer Res; 22(12); 2840-7. ©2016 AACR.

Topics: Adenosine Triphosphate; Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Line, Tumor; DNA Damage; DNA Repair; Humans; Naphthyridines; Neoplasms; Papillomavirus E7 Proteins; Peptides, Cyclic; Phenazines; Phosphorylation; Protein Kinase Inhibitors

Screening for protein kinase CK2 inhibitors of the structural diversity compound library (DTP NCI/NIH) led to the discovery of 4-[(E)-(fluoren-9-ylidenehydrazinylidene)-methyl]benzoic acid (E9). E9 induces apoptotic cell death in various cancer cell lines and upon hypoxia, the compound suppresses CK2-catalyzed HSP90/Cdc37 phosphorylation and induces HIF-1α degradation. Furthermore, E9 exerts a strong anti-tumour activity by inducing necrosis in murine xenograft models underlining its potential to be used for cancer treatment in future clinical studies. Crystal structure analysis of human and maize CK2α in complex with E9 reveals unique binding properties of the inhibitor to the enzyme, accounting for its affinity and selectivity.

Topics: Animals; Benzoates; Blotting, Western; Casein Kinase II; Cell Cycle; Cell Proliferation; Combinatorial Chemistry Techniques; Female; Fluorenes; Fluorescent Antibody Technique; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Immunoenzyme Techniques; Luciferases; Mice; Mice, Nude; Neoplasms; Phosphorylation; Protein Conformation; Protein Kinase Inhibitors; Signal Transduction; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

B23/NPM is a multifunctional nucleolar protein frequently overexpressed, mutated, or rearranged in neoplastic tissues. B23/NPM is involved in diverse biological processes and is mainly regulated by heteroligomer association and posttranslational modification, phosphorylation being a major posttranslational event. While the role of B23/NPM in supporting and/or driving malignant transformation is widely recognized, the particular relevance of its CK2-mediated phosphorylation remains unsolved. Interestingly, the pharmacologic inhibition of such phosphorylation event by CIGB-300, a clinical-grade peptide drug, was previously associated to apoptosis induction in tumor cell lines. In this work, we sought to identify the biological processes modulated by CIGB-300 in a lung cancer cell line using subtractive suppression hybridization and subsequent functional annotation clustering. Our results indicate that CIGB-300 modulates a subset of genes involved in protein synthesis (ES = 8.4, p < 0.001), mitochondrial ATP metabolism (ES = 2.5, p < 0.001), and ribosomal biogenesis (ES = 1.5, p < 0.05). The impairment of these cellular processes by CIGB-300 was corroborated at the molecular and cellular levels by Western blot (P-S6/P-4EBP1, translation), confocal microscopy (JC-1, mitochondrial potential), qPCR (45SrRNA/p21, ribosome biogenesis), and electron microscopy (nucleolar structure, ribosome biogenesis). Altogether, our findings provide new insights on the potential relevance of the CK2-mediated phosphorylation of B23/NPM in cancer cells, revealing at the same time the potentialities of its pharmacological manipulation for cancer therapy. Finally, this work also suggests several candidate gene biomarkers to be evaluated during the clinical development of the anti-CK2 peptide CIGB-300.

Topics: Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Energy Metabolism; Humans; Neoplasms; Nuclear Proteins; Nucleophosmin; Peptides, Cyclic; Phosphorylation; Ribosomes

It has been proposed that dual inhibitors of protein kinases CK2 and PIM-1 are tools particularly valuable to induce apoptosis of cancer cells, a property, however, implying cell permeability, which is lacking in the case of selective CK2/PIM-1 inhibitors developed so far. To fill this gap, we have derivatized the scaffold of the promiscuous CK2 inhibitor TBI with a deoxyribose moiety, generating TDB, a selective, cell-permeable inhibitor of CK2 and PIM-1. Here, we shed light on the structural features underlying the potency and narrow selectivity of TDB by exploiting a number of TDB analogs and by solving the 3D structure of the TDB/CK2 complex at 1.25 Å resolution, one of the highest reported so far for this kinase. We also show that the cytotoxic efficacy of TDB is almost entirely due to apoptosis, is accompanied by parallel inhibition of cellular CK2 and PIM-1, and is superior to both those observed combining individual inhibitors of CK2 and PIM-1 and by treating cells with the CK2 inhibitor CX4945. These data, in conjunction with the observations that cancer cells are more susceptible than non-cancer cells to TDB and that such a sensitivity is maintained in a multi-drug resistance background, highlight the pharmacological potential of this compound.

Topics: Benzimidazoles; Casein Kinase II; Cell Line; Cell Line, Tumor; Cell Membrane Permeability; Cell Proliferation; Halogenation; Humans; Kinetics; Models, Molecular; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-pim-1; Structure-Activity Relationship

The apoptotic actions of p53 require its phosphorylation by a family of phosphoinositide-3-kinase-related-kinases (PIKKs), which include DNA-PKcs and ATM. These kinases are stabilized by the TTT (Tel2, Tti1, Tti2) cochaperone family, whose actions are mediated by CK2 phosphorylation. The inositol pyrophosphates, such as 5-diphosphoinositol pentakisphosphate (IP7), are generated by a family of inositol hexakisphosphate kinases (IP6Ks), of which IP6K2 has been implicated in p53-associated cell death. In the present study we report an apoptotic signaling cascade linking CK2, TTT, the PIKKs, and p53. We demonstrate that IP7, formed by IP6K2, binds CK2 to enhance its phosphorylation of the TTT complex, thereby stabilizing DNA-PKcs and ATM. This process stimulates p53 phosphorylation at serine 15 to activate the cell death program in human cancer cells and in murine B cells.

Topics: Animals; Apoptosis; Ataxia Telangiectasia Mutated Proteins; B-Lymphocytes; Binding Sites; Carrier Proteins; Casein Kinase II; DNA-Activated Protein Kinase; DNA-Binding Proteins; Enzyme Stability; HCT116 Cells; HEK293 Cells; Humans; Inositol Phosphates; Intracellular Signaling Peptides and Proteins; Mice, Knockout; Neoplasms; Nuclear Proteins; Phosphorylation; Phosphotransferases (Phosphate Group Acceptor); Proto-Oncogene Proteins c-ets; RNA Interference; Serine; Signal Transduction; Telomere-Binding Proteins; Transfection; Tumor Suppressor Protein p53

Protein kinase CK2 has emerged as a promising candidate for the treatment of a number of cancers. This enzyme is comprised of two catalytic subunits (CK2 and/or CK2α') that form complexes with homodimers of regulatory CK2β subunits. While catalytic and regulatory CK2 subunits are generally expressed at similar levels to form tetrameric complexes, asymmetric expression of CK2 subunits has been associated with various forms of cancer and the enhanced survival of cancer cells. To elucidate mechanisms responsible for regulation of cancer cell survival by CK2, we recently employed computational and experimental strategies that revealed widespread overlap between sites for CK2 phosphorylation and caspase cleavage. Among candidates with overlapping CK2 and caspase cleavage sites was caspase-3 that is phosphorylated by CK2 to prevent its activation by upstream caspases. To elucidate the precise relationship between CK2 and caspase-3, we modulated expression of individual CK2 subunits and demonstrated that CK2α' exhibits a striking preference for caspase-3 phosphorylation in cells as compared to CK2α and that CK2β exhibits the capacity to abolish caspase-3 phosphorylation. Since caspase-3 represents the first CK2 substrate selectively phosphorylated by CK2α' in cells, our work highlights divergent functions of the different forms of CK2. Given the involvement of CK2 in a diverse series of biological events and its association with various cancers, this work has important implications for identifying pathological roles of distinct forms of CK2 that could instruct efforts to selectively target individual CK2 subunits for therapy.

Topics: Amino Acid Sequence; Blotting, Western; Casein Kinase II; Caspase 3; Catalytic Domain; Cell Survival; HeLa Cells; Humans; Immunoprecipitation; Isoenzymes; Molecular Sequence Data; Neoplasms; Phosphorylation; Reverse Transcriptase Polymerase Chain Reaction; Transfection

Drug combination therapies are commonly used for the treatment of cancers to increase therapeutic efficacy, reduce toxicity, and decrease the incidence of drug resistance. Although drug combination therapies were originally devised primarily by empirical methods, the increased understanding of drug mechanisms and the pathways they modulate provides a unique opportunity to design combinations that are based on mechanistic rationale. We have identified protein kinase CK2 as a promising therapeutic target for combination therapy, because CK2 regulates not just one but many oncogenic pathways and processes that play important roles in drug resistance, including DNA repair, epidermal growth factor receptor signaling, PI3K/AKT/mTOR signaling, Hsp90 machinery activity, hypoxia, and interleukin-6 expression. In this article, we show that CX-4945, a clinical stage selective small molecule inhibitor of CK2, blocks the DNA repair response induced by gemcitabine and cisplatin and synergizes with these agents in models of ovarian cancer. Mechanistic studies show that the enhanced activity is a result of inactivation of XRCC1 and MDC1, two mediator/adaptor proteins that are essential for DNA repair and that require phosphorylation by CK2 for their function. These data position CK2 as a valid pharmacologic target for intelligent drug combinations and support the evaluation of CX-4945 in combination with gemcitabine and platinum-based chemotherapeutics in the clinical setting.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Casein Kinase II; Cell Line, Tumor; Checkpoint Kinase 2; DNA Repair; Drug Synergism; Female; Humans; Mice; Naphthyridines; Neoplasms; Ovarian Neoplasms; Phenazines; Phosphorylation; Protein Serine-Threonine Kinases; Random Allocation; Signal Transduction; Xenograft Model Antitumor Assays

Ser/Thr protein kinase CK2 regulates multiple processes that play important roles in the sensitivity of cancer to epidermal growth factor receptor targeting therapeutics, including PI3K-Akt-mTOR signaling, Hsp90 activity, and inhibition of apoptosis. We hypothesized that top-down inhibition of EGFR, combined with lateral suppression of multiple oncogenic pathways by targeting CK2, would create a pharmacologic synthetic lethal event and result in an improved cancer therapy compared to EGFR inhibition alone. This hypothesis was tested by combining CX-4945, a first-in-class clinical stage inhibitor of CK2, with the EGFR tyrosine kinase inhibitor, erlotinib, in vitro and in vivo in models of non-small cell lung carcinoma, NCI-H2170, and squamous cell carcinoma, A431. Our results demonstrate that combination of CX-4945 with erlotinib results in enhanced attenuation of the PI3K-Akt-mTOR pathway. We also observed an increase in apoptosis, synergistic killing of cancer cells in vitro, as well as improved antitumor efficacy in vivo. Taken together, these data position CK2 as a valid pharmacologic target for drug combinations and support further evaluation of CX-4945 in combination with EGFR targeting agents.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; ErbB Receptors; Erlotinib Hydrochloride; Female; Humans; Mice; Naphthyridines; Neoplasms; Phenazines; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Quinazolines; Signal Transduction; TOR Serine-Threonine Kinases

A novel family of potent dual inhibitors of CK2 and the Pim kinases was discovered by modifying the scaffolds of tricyclic Pim inhibitors. Several analogs were active at single digit nanomolar IC(50) values against CK2 and the Pim isoforms Pim-1 and Pim-2. The molecules displayed antiproliferative activity in various cell phenotypes in the low micromolar and submicromolar range, providing an excellent starting point for further drug discovery optimization.

Topics: Antineoplastic Agents; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Drug Discovery; Humans; Inhibitory Concentration 50; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-pim-1

Casein kinase 2 (CK2) is involved in multiple cellular processes such as proliferation, apoptosis, and cell cycle. In particular, its over-expression in human cancers is associated with angiogenesis and tumor progression. As a first orally bioavailable small molecule inhibitor of CK2, CX-4945 exerts anti-proliferative activity in human cancer cells by inhibiting the cell cycle and the PI3K/Akt signaling pathway. Additionally, CX-4945 reduces angiogenesis via blockade of hypoxia-inducible factor-1α transcription and suppresses the inflammatory interleukin-6 production in human breast cancer cells. These effects are supported by results from mouse xenograft model investigations. Here, we discuss the druggability of CX-4945 and its potential to be developed as an anti-cancer drug in clinical trials.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Casein Kinase II; Cell Cycle; Cell Proliferation; Drug Design; Gene Expression Regulation, Neoplastic; Humans; Mice; Naphthyridines; Neoplasms; Neovascularization, Pathologic; Phenazines; Signal Transduction; Xenograft Model Antitumor Assays

CK2 is a pleiotropic protein kinase, which regulates many survival pathways and plays a global anti-apoptotic function. It is highly expressed in tumor cells, and is presently considered a promising therapeutic target. Among the many inhibitors available for this kinase, the recently developed CX-4945 and CX-5011 have proved to be very potent, selective and effective in inducing cell death in tumor cells; CX-4945 has recently entered clinical trials. However, no data are available on the efficacy of these compounds to overcome drug resistance, a major reasons of cancer therapy failure. Here we address this point, by studying their effects in several tumor cell lines, each available as variant R resistant to drug-induced apoptosis, and normal-sensitive variant S. We found that the inhibition of endogenous CK2 was very similar in S and R treated cells, with more than 50% CK2 activity reduction at sub-micromolar concentrations of CX-4945 and CX-5011. A consequent apoptotic response was induced both in S and R variants of each pairs. Moreover, the combined treatment of CX-4945 plus vinblastine was able to sensitize to vinblastine R cells that are otherwise almost insensitive to this conventional antitumor drug. Consistently, doxorubicin accumulation in multidrug resistant (MDR) cells was greatly increased by CX-4945.In summary, we demonstrated that all the R variants are sensitive to CX-4945 and CX-5011; since some of the treated R lines express the extrusion pump Pgp, often responsible of the MDR phenotype, we can also conclude that the two inhibitors can successfully overcome the MDR phenomenon.

Topics: Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Survival; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Humans; Naphthyridines; Neoplasms; Phenazines; Protein Kinase Inhibitors; Pyrimidines; Quinolines; Vinblastine

Topoisomerase I (topo I) is required to unwind DNA during synthesis and provides the unique target for camptothecin-derived chemotherapeutic agents, including Irinotecan and Topotecan. While these agents are highly effective anticancer agents, some tumors do not respond due to intrinsic or acquired resistance, a process that remains poorly understood. Because of treatment toxicity, there is interest in identifying cellular factors that regulate tumor sensitivity and might serve as predictive biomarkers of therapy sensitivity. Here we identify the serine kinase, protein kinase CK2, as a central regulator of topo I hyperphosphorylation and activity and cellular sensitivity to camptothecin. In nine cancer cell lines and three normal tissue-derived cell lines we observe a consistent correlation between CK2 levels and camptothecin responsiveness. Two other topo I-targeted serine kinases, protein kinase C and cyclin-dependent kinase 1, do not show this correlation. Camptothecin-sensitive cancer cell lines display high CK2 activity, hyperphosphorylation of topo I, elevated topo I activity, and elevated phosphorylation-dependent complex formation between topo I and p14ARF, a topo I activator. Camptothecin-resistant cancer cell lines and normal cell lines display lower CK2 activity, lower topo I phosphorylation, lower topo I activity, and undetectable topo I/p14ARF complex formation. Experimental inhibition or activation of CK2 demonstrates that CK2 is necessary and sufficient for regulating these topo I properties and altering cellular responses to camptothecin. The results establish a cause and effect relationship between CK2 activity and camptothecin sensitivity and suggest that CK2, topo I phosphorylation, or topo I/p14ARF complex formation could provide biomarkers of therapy-responsive tumors.

Topics: Antineoplastic Agents; Camptothecin; Casein Kinase II; Cell Line, Tumor; DNA Topoisomerases, Type I; Humans; Neoplasms; Phosphorylation; Protein Structure, Tertiary

The inositol pyrophosphate, diphosphoinositol pentakisphosphate, regulates p53 and protein kinase Akt signaling, and its aberrant increase in cells has been implicated in apoptosis and insulin resistance. Inositol hexakisphosphate kinase-2 (IP6K2), one of the major inositol pyrophosphate synthesizing enzymes, mediates p53-linked apoptotic cell death. Casein kinase-2 (CK2) promotes cell survival and is upregulated in tumors. We show that CK2 mediated cell survival involves IP6K2 destabilization. CK2 physiologically phosphorylates IP6K2 at amino acid residues S347 and S356 contained within a PEST sequence, a consensus site for ubiquitination. HCT116 cells depleted of IP6K2 are resistant to cell death elicited by CK2 inhibitors. CK2 phosphorylation at the degradation motif of IP6K2 enhances its ubiquitination and subsequent degradation. IP6K2 mutants at the CK2 sites that are resistant to CK2 phosphorylation are metabolically stable.

Topics: Amino Acid Motifs; Apoptosis; Casein Kinase II; Cell Survival; Enzyme Stability; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; HEK293 Cells; HeLa Cells; Humans; Insulin Resistance; Neoplasms; Phosphorylation; Phosphotransferases (Phosphate Group Acceptor); Proto-Oncogene Proteins c-akt; Signal Transduction; Tumor Suppressor Protein p53; Ubiquitination; Up-Regulation

The molecular chaperone Heat Shock Protein 90 (Hsp90) is essential for the function of various oncoproteins that are vital components of multiple signaling networks regulating cancer cell proliferation, survival, and metastasis. Hsp90 chaperone function is coupled to its ATPase activity, which can be inhibited by natural products such as the ansamycin geldanamycin (GA) and the resorcinol radicicol (RD). These compounds have served as templates for development of numerous natural product Hsp90 inhibitors. More recently, second generation, fully synthetic Hsp90 inhibitors, based on a variety of chemical scaffolds, have also been synthesized. Together, 18 natural product and synthetic Hsp90 inhibitors have entered clinical trial in cancer patients. To successfully develop Hsp90 inhibitors for oncology indications it is important to understand the factors that influence the susceptibility of Hsp90 to these drugs in vivo. We recently reported that Casein Kinase 2 phosphorylates a conserved threonine residue (T22) in helix-1 of the yeast Hsp90 N-domain both in vitro and in vivo. Phosphorylation of this residue reduces ATPase activity and affects Hsp90 chaperone function. Here, we present additional data demonstrating that ATP binding but not N-domain dimerization is a prerequisite for T22 phosphorylation. We also provide evidence that T22 is an important determinant of Hsp90 inhibitor sensitivity in yeast and we show that T22 phosphorylation status contributes to drug sensitivity in vivo.

Topics: Casein Kinase II; Clinical Trials as Topic; Drug Design; Drug Resistance; Fungal Proteins; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Molecular Chaperones; Molecular Targeted Therapy; Neoplasms; Phosphorylation; Resorcinols; Threonine; Yeasts

At variance with protein kinases expressed by oncogenes, CK2 is endowed with constitutive activity under normal conditions, and no CK2 gain-of-function mutants are known. Its amount, however, is abnormally high in malignant cells where it appears to be implicated in many of the cell biology phenomena associated with cancer. These observations can be reconciled assuming that tumor cells develop an overdue reliance ("non-oncogene addiction") on abnormally high CK2 level. While the potential of this latter to generate an environment favorable to neoplasia is consistent with the global antiapoptotic and prosurvival role played by CK2, it is not clear what is determining accumulation of CK2 in cells "predisposed" to become malignant. Exploiting the apoptosis sensitive (S) or resistant (R) CEM cell model, characterized by sharply different CK2 levels, we have now correlated the level and degradation rate of CK2 to those of the chaperone proteins Hsp90 and Cdc37. We show in particular that persistence of high CK2 level in R-CEM, as opposed to S-CEM, is accompanied by the presence of an immunospecific form of Cdc37 not detectable in S-CEM and refractory to staurosporine-induced degradation.

Topics: Casein Kinase II; Humans; Models, Biological; Molecular Chaperones; Neoplasms; Phosphoproteins; Protein Stability; Proteome

Topics: Animals; Biocatalysis; Biology; Casein Kinase II; Cell Nucleus; Cell Survival; Humans; Medicine; Neoplasms; Plants; Protein Kinase Inhibitors; Saccharomyces cerevisiae; Signal Transduction

Protein kinase 2 (CK2) is a potential target, and the coumarins were identified as the attractive CK2 inhibitors. In this study, two models (CoMFA and CoMSIA) were established, and their reliabilities were supported by statistical parameters. From the CoMFA and CoMSIA models, the hydrophobic and hydrogen bonds play very important roles in the interactions between inhibitors and CK2, which were confirmed sufficiently by molecular docking. Furthermore, the binding mode of the inhibitors at the active sites of CK2 was also investigated by docking study. The hydroxyl at the position R(5) is more important for coumarins inhibitors because it forms hydrogen bonds not only with Lys68 as hydrogen acceptor but also with H(2) O as hydrogen donor. In addition, hydroxyl can make electrostatic interactions with electropositive Lys68 residue. The large group at the R(6) position is not conducive to inhibitor dock into the groove of the binding site of CK2. When there is nitro group, the electrostatic interaction between ligand and receptor is enhanced significantly, and the nitro oxygen can form hydrogen bonds with the backbone NH of Lys68 and Asp175 simultaneously. The results obtained from molecular modeling techniques not only provide the models to predict the activity of inhibitors but also lead to a better understanding of the interactions between inhibitors and CK2, which will be very helpful for drug design.

Topics: Antineoplastic Agents; Casein Kinase II; Coumarins; Drug Design; Enzyme Inhibitors; Humans; Models, Molecular; Neoplasms; Protein Binding; Quantitative Structure-Activity Relationship

5-(3-Chlorophenylamino)benzo[c][2,6]naphthyridine-8-carboxylic acid (CX-4945), the first clinical stage inhibitor of protein kinase CK2 for the treatment of cancer, is representative of a new class of CK2 inhibitors with K(i) values in the low nanomolar range and unprecedented selectivity versus other kinases. Here we present the crystal structure of the complexes of CX-4945 and two analogues (CX-5011 and CX-5279) with the catalytic subunit of human CK2. Consistent with their ATP-competitive mode of inhibition, all three compounds bind in the active site of CK2 (type I inhibitors). The tricyclic scaffold of the inhibitors superposes on the adenine of ATP, establishing multiple hydrophobic interactions with the binding cavity. The more extended scaffold, as compared to that of ATP, allows the carboxylic function, shared by all three ligands, to penetrate into the deepest part of the active site where it makes interactions with conserved water W1 and Lys-68, thus accounting for the crucial role of this negatively charged group in conferring high potency to this class of inhibitors. The presence of a pyrimidine in CX-5011 and in CX-5279 instead of a pyridine (as in CX-4945) ring is likely to account for the higher specificity of these compounds whose Gini coefficients, calculated by profiling them against panels of 102 and/or 235 kinases, are significantly higher than that of CX-4945 (0.735 and 0.755, respectively, vs 0.615), marking the highest selectivity ever reported for CK2 inhibitors.

Topics: Casein Kinase II; Catalytic Domain; Cell Survival; Crystallography, X-Ray; Humans; Hydrophobic and Hydrophilic Interactions; Models, Molecular; Naphthyridines; Neoplasms; Phenazines; Protein Kinase Inhibitors; Pyrimidines; Quinolines

Due to its physiological role into promoting cell survival and its dysregulation in most cancer cells, protein kinase CK2 is a relevant physiopathological target for development of chemical inhibitors. We report the discovery of azonaphthalene derivatives, as a new family of highly specific CK2 inhibitors. First, we demonstrated that CK2 inhibition (IC50= 0.4 µM) was highly specific, reversible and non ATP-competitive. Small Angle X-ray Scattering experiments showed that this inhibition was due to large conformational change of CK2α upon binding of these inhibitors. We showed that several compounds of the family were cell-potent CK2 inhibitors promoting cell cycle arrest of human glioblastoma U373 cells. Finally, in vitro and in vivo assays showed that these compounds could decrease U373 cell tumor mass by 83 % emphasizing their efficacy against these apoptosis-resistant tumors. In contrast, Azonaphthalene derivatives inactive on CK2 activity showed no effect in colony formation and tumor regression assays. These findings illustrate the emergence of nonclassical CK2 inhibitors and provide exciting opportunities for the development of novel allosteric CK2 inhibitors.. CK2 is an emerging therapeutic target and ATP-competitive inhibitors have been identified. CK2 is endowed with specific structural features providing alternative strategies for inhibition.. Azonaphthalene compounds are allosteric CK2 inhibitors showing antitumor activity.. CK2 may be targeted allosterically.. These inhibitors provide a foundation for a new paradigm for specific CK2 inhibition.

Topics: Animals; Apoptosis; Azo Compounds; Casein Kinase II; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Survival; Female; HeLa Cells; High-Throughput Screening Assays; Humans; Mice; Mice, Nude; Naphthalenes; Neoplasms; Protein Kinase Inhibitors; Structure-Activity Relationship

Besides cardiovascular diseases, cancer represents the major cause of death in developed countries. In many different human tumors, increased activity of serine/threonine protein kinase CK2 has been detected, and recent in vivo studies support a direct involvement of CK2 in tumor progression. Therefore, potent compounds to decrease CK2 activity to a non-pathogenic level would be a promising effort toward an antineoplastic therapy. In this study, an alternative to the established radiometric phosphorylation assay for quantification of CK2 activity was developed. For this purpose, the substrate peptide RRRDDDSDDD was coupled at the C-terminus to the fluorophore EDANS (5-[(2-aminoethyl)amino]naphthalene-1-sulfonic acid) and at the N-terminus to the quencher DABCYL (4-(4-dimethylaminophenylazo)benzoic acid). This resulted in quenched fluorescence of EDANS due to a FRET-based effect. After proteolytic cleavage of the peptide by elastase, the quenching effect was reduced and, as a consequence, fluorescence was increased. Because elastase is supposed to cleave at the S/D site of the peptide, phosphorylation of serine by CK2 hampered substrate binding of elastase and blocked the increase in fluorescence by proteolytic cleavage. This means that the new assay to quantify human CK2 activity is based on the differential accessibility of the proteolytic cleavage site, which is dependent on kinase phosphorylation. It could be used to measure inhibition of the human target in neoplastic diseases by the compounds TBB (4,5,6,7-tetrabromobenzotriazole) and Emodin.

Topics: Casein Kinase II; Emodin; Enzyme Assays; Fluorescence; Fluorescence Resonance Energy Transfer; Humans; Naphthalenesulfonates; Neoplasms; p-Dimethylaminoazobenzene; Pancreatic Elastase; Peptides; Phosphorylation; Protein Kinase Inhibitors; Sensitivity and Specificity; Triazoles

Topics: Calcium-Calmodulin-Dependent Protein Kinase Type 2; Casein Kinase II; Cyclic AMP-Dependent Protein Kinases; Fluorescent Dyes; Heterocyclic Compounds, 3-Ring; Humans; Microfluidic Analytical Techniques; Neoplasms; Phosphorylation; Protein Kinase Inhibitors; Protein Kinases; Proto-Oncogene Proteins c-abl; Rhodamines

At variance with the great majority of protein kinases that become active only in response to specific stimuli and whose implication in tumors is caused by genetic alterations conferring to them unscheduled activity, the highly pleiotropic Ser/Thr-specific protein kinase CK2 is constitutively active even under normal conditions and no gain-of-function CK2 mutants are known. Nevertheless, CK2 level is abnormally high in cancer cells where it is believed to generate an environment favorable to the development of malignancy, through a mechanism denoted as "non-oncogene addiction." This makes CK2 not only an appealing target to counteract different kinds of tumors but also a valuable marker of cells predisposed to undergo neoplastic transformation owing to the presence in them of CK2 level exceeding a critical threshold. Such a prognostic exploitation of CK2 would imply the availability of methods suitable for the reliable, sensitive, and specific quantification of its activity in biological samples and in living cells. The aim of this chapter is to describe a number of procedures applicable to the quantitative determination of CK2 activity and to provide experimental details designed for rendering these assays as sensitive and selective as possible even in the presence of many other protein kinases. The procedures described roughly fall in three categories: (i) in vitro quantification of CK2 activity in crude biological samples and cell lysates; (ii) in-cell assay of endogenous CK2 activity based on the phosphorylation of reporter substrates; (iii) identification of CK2 targets in malignant and normal cells.

Topics: Animals; Casein Kinase II; Cell Line, Tumor; Electrophoresis, Polyacrylamide Gel; Enzyme Assays; Humans; Neoplasms

The alkyloid compound ellipticine derived from the berrywood tree is a topoisomerase II poison that is used in ovarian and breast cancer treatment. In this study, we report the identification of ellipticine derivatives and their tetracyclic angular benzopyridoindole analogues as novel ATP-competitive inhibitors of the protein kinase CK2. In vitro and in vivo assays showed that these compounds have a good pharmacologic profile, causing a marked inhibition of CK2 activity associated with cell cycle arrest and apoptosis in human cancer cells. Further, in vivo assays demonstrate antitumor activity in a mouse xenograft model of human glioblastoma. Finally, crystal structures of CK2-inhibitor complex provide structural insights on the molecular basis of CK2 inhibition. Our work lays the foundation for development of clinically useful CK2 inhibitors derived from a well-studied scaffold with suitable pharmacokinetics parameters.

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Apoptosis; Blotting, Western; Carbazoles; Casein Kinase II; Cell Cycle; Cell Line; Cell Line, Tumor; Cell Survival; Crystallography, X-Ray; Ellipticines; Female; HeLa Cells; Humans; Indoles; Kinetics; Mice; Mice, Nude; Molecular Structure; Neoplasms; Tumor Burden; Xenograft Model Antitumor Assays

Casein kinase 2 (CK2) is dysregulated in various human cancers and is a promising target for cancer therapy. To date, there is no small molecular CK2 inhibitor in clinical trial yet. With the aim to identify novel CK2 inhibitors, we screened a natural product library.. We adopted cell-based proliferation and CK2 kinase assays to screen CK2 inhibitors from a natural compound library. Dose-dependent response of CK2 inhibitors in vitro was determined by a radioisotope kinase assay. Western blot analysis was used to evaluate down stream Akt phosphorylation and apoptosis. Apoptosis was also evaluated by annexin-V/propidium iodide (PI) labeling method using flow cytometry. Inhibition effects of CK2 inhibitors on the growth of cancer and normal cells were evaluated by cell proliferation and viability assays.. Hematein was identified as a novel CK2 inhibitor that is highly selective among a panel of kinases. It appears to be an ATP non-competitive and partially reversible CK2 inhibitor with an IC50 value of 0.55 muM. In addition, hematein inhibited cancer cell growth partially through down-regulation of Akt phosphorylation and induced apoptosis in these cells. Furthermore, hematein exerted stronger inhibition effects on the growth of cancer cells than in normal cells.. In this study, we showed that hematein is a novel selective and cell permeable small molecule CK2 inhibitor. Hematein showed stronger growth inhibition effects to cancer cells when compared to normal cells. This compound may represent a promising class of CK2 inhibitors.

Topics: Adenosine Triphosphate; Apoptosis; Casein Kinase II; Cell Growth Processes; Cell Line, Tumor; Dose-Response Relationship, Drug; HCT116 Cells; HeLa Cells; Hematoxylin; Humans; Lung Neoplasms; Neoplasms; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Substrate Specificity

Topics: Adenosine Triphosphate; Animals; Anions; Anti-Infective Agents; Antineoplastic Agents; Binding Sites; Binding, Competitive; Casein Kinase II; Catalytic Domain; Clinical Trials, Phase II as Topic; Combinatorial Chemistry Techniques; Humans; Metal Nanoparticles; Mice; Models, Molecular; Neoplasm Proteins; Neoplasms; Oxygen Compounds; Protein Conformation; Protein Kinase Inhibitors; Transition Elements; Xenograft Model Antitumor Assays

The development of selective cell-permeable inhibitors of protein kinases whose aberrant activation contributes to cell transformation is a promising approach in cancer treatment. Emodin is a natural anthraquinone derivative that exhibits anti-proliferative effects in various cancer cell lines by efficient induction of apoptosis. The phosphoinositide 3-kinase (PI3K)/AKT pathway has been shown to be central in the promotion of cell survival since the alteration of this signalling cascade is a frequent event in human malignancies. Previous published results indicated that treatment of cells with inhibitors of protein kinase CK2, such as emodin, induces apoptosis and that the anti-apoptotic effect of CK2 is partially mediated by target phosphorylation and up-regulation of AKT by CK2. In the present study, a screening with selected CK2 inhibitors induced a variable response with respect to AKT down-regulation, emodin being the most effective, suggesting that other mechanisms other than the inhibition of CK2 were responsible for the emodin-mediated modulation of AKT. We found that emodin does not directly affect AKT kinase. Furthermore, we show that the down-regulation of AKT is due to the emodin-mediated target inhibition of components of the PI3K pathway, which directly or indirectly affect AKT activity, i.e. the mammalian target of rapamycin and the phosphatase and tensin homolog deleted on chromosome 10, but not the phosphoinositide-dependent kinase 1. Taken together, our results highlight a new mechanism by which emodin exerts anti-cancer activity and suggest the further investigation of plant polyphenols, such as emodin, as therapeutic and preventive agents for cancer therapy.

Topics: Antineoplastic Agents, Phytogenic; Casein Kinase II; Emodin; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; HeLa Cells; Humans; Neoplasms; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction

Protein kinase CK2 is a highly conserved enzyme composed of two catalytic subunits alpha and/or alpha' and two regulatory subunits beta whose activity is elevated in diverse tumour types as well as in highly proliferating tissues. Several results suggest that the overexpression of either CK2 catalytic subunits or the CK2 holoenzyme contributes to cellular transformation. In a similar vein, experiments performed compromising the intracellular expression of CK2 has led to somehow contradictory results with respect to the ability of this enzyme to control survival and apoptosis. To better elucidate the role of CK2 in programmed cell death, we have depleted cells of CK2 catalytic subunits by the application of antisense oligodeoxynucleotides and siRNAs techniques, respectively. Our results indicate that protein kinase CK2 is characterized by an extremely high stability that might be due to its association with other intracellular proteins, enhanced half-life or lower vulnerability towards proteolytic degradation. In addition, we show that despite the effectiveness of the methods applied in lowering CK2 kinase activity in all cells investigated, CK2 might not by itself be sufficient to trigger enhanced drug-induced apoptosis in cells.

Topics: Apoptosis; Casein Kinase II; Catalytic Domain; Cell Transformation, Neoplastic; Flow Cytometry; HCT116 Cells; HeLa Cells; Humans; Jurkat Cells; Neoplasms; Nocodazole; Oligonucleotides, Antisense; Reproducibility of Results; RNA, Messenger; RNA, Small Interfering

Although caspase-2 is believed to be involved in death receptor-mediated apoptosis, the exact function, mode of activation, and regulation of caspase-2 remain unknown. Here we show that protein kinase (PK) CK2 phosphorylates procaspase-2 directly at serine-157. When intracellular PKCK2 activity is low or downregulated by specific inhibitors, procaspase-2 is dephosphorylated, dimerized, and activated in a PIDDosome-independent manner. The activated caspase-2 then processes procaspase-8 monomers between the large and small subunits, thereby priming cancer cells for TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. The processed procaspase-8 that is recruited to death-inducing signaling complex by TRAIL engagement becomes fully activated, and cancer cells undergo apoptosis. PKCK2 activity is low in TRAIL-sensitive cancer cell lines but high in TRAIL-resistant cancer cell lines. Thus, downregulating PKCK2 activity is required for TRAIL-mediated apoptosis to occur in TRAIL-resistant cancer cells. Our data provide novel insights into the regulation, mode of activation, and function of caspase-2 in TRAIL-mediated apoptosis.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Casein Kinase II; Caspase 2; Caspase 8; Caspases; Cell Line, Tumor; Dimerization; Enzyme Activation; Humans; Membrane Glycoproteins; Neoplasms; Phosphorylation; Serine; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha