CIGB-300, an anti-CK2 peptide, inhibits angiogenesis, tumor cell invasion and metastasis in lung cancer models

Recent Advances in the Discovery of CK2 Inhibitors

CK2 is a vital enzyme that phosphorylates a large number of substrates and thereby controls many processes in the body. Its upregulation was reported in many cancer types. Inhibitors of CK2 might have anticancer activity, and two compounds are currently under clinical trials. However, both compounds are ATP-competitive inhibitors that may have off-target side effects. The development of allosteric and dual inhibitors can overcome this drawback. These inhibitors showed higher selectivity and specificity for the CK2 enzyme compared to the ATP-competitive inhibitors. The present review summarizes the efforts exerted in the last five years in the design of CK2 inhibitors.

Angiotensin-converting enzyme inhibitor promotes angiogenesis through Sp1/Sp3-mediated inhibition of notch signaling in male mice

Angiogenesis is a critical pathophysiological process involved in organ growth and various diseases. Transcription factors Sp1/Sp3 are necessary for fetal development and tumor growth. Sp1/Sp3 proteins were downregulated in the capillaries of the gastrocnemius in patients with critical limb ischemia samples. Endothelial-specific Sp1/Sp3 knockout reduces angiogenesis in retinal, pathological, and tumor models and induced activation of the Notch1 pathway. Further, the inactivation of VEGFR2 signaling by Notch1 contributes to the delayed angiogenesis phenotype. Mechanistically, endothelial Sp1 binds to the promoter of Notch1 and inhibits its transcription, which is enhanced by Sp3. The proangiogenic effect of ACEI is abolished in Sp1/Sp3-deletion male mice. We identify USP7 as an ACEI-activated deubiquitinating enzyme that translocated into the nucleus binding to Sp1/Sp3, which are deacetylated by HDAC1. Our findings demonstrate a central role for endothelial USP7-Sp1/Sp3-Notch1 signaling in pathophysiological angiogenesis in response to ACEI treatment.

CIGB-300 Anticancer Peptide Differentially Interacts with CK2 Subunits and Regulates Specific Signaling Mediators in a Highly Sensitive Large Cell Lung Carcinoma Cell Model

Large cell lung carcinoma (LCLC) is one form of NSCLC that spreads more aggressively than some other forms, and it represents an unmet medical need. Here, we investigated for the first time the effect of the anti-CK2 CIGB-300 peptide in NCI-H460 cells as an LCLC model. NCI-H460 cells were highly sensitive toward CIGB-300 cytotoxicity, reaching a peak of apoptosis at 6 h. Moreover, CIGB-300 slightly impaired the cell cycle of NCI-H460 cells. The CIGB-300 interactomics profile revealed in more than 300 proteins that many of them participated in biological processes relevant in cancer. Interrogation of the CK2 subunits targeting by CIGB-300 indicated the higher binding of the peptide to the CK2α' catalytic subunit by in vivo pull-down assays plus immunoblotting analysis and confocal microscopy. The down-regulation of both phosphorylation and protein levels of the ribonuclear protein S6 (RPS6) was observed 48 h post treatment. Altogether, we have found that NCI-H460 cells are the most CIGB-300-sensitive solid tumor cell line described so far, and also, the findings we provide here uncover novel features linked to CK2 targeting by the CIGB-300 anticancer peptide.

Competition between electrostatic interactions and halogen bonding in the protein-ligand system: structural and thermodynamic studies of 5,6-dibromobenzotriazole-hCK2α complexes

CK2 is a member of the CMGC group of eukaryotic protein kinases and a cancer drug target. It can be efficiently inhibited by halogenated benzotriazoles and benzimidazoles. Depending on the scaffold, substitution pattern, and pH, these compounds are either neutral or anionic. Their binding poses are dictated by a hydrophobic effect (desolvation) and a tug of war between a salt bridge/hydrogen bond (to K68) and halogen bonding (to E114 and V116 backbone oxygens). Here, we test the idea that binding poses might be controllable by pH for ligands with near-neutral pK_a, using the conditionally anionic 5,6-DBBt and constitutively anionic TBBt as our models. We characterize the binding by low-volume Differential Scanning Fluorimetry (nanoDSF), Isothermal Calorimetry (ITC), Hydrogen/Deuterium eXchange (HDX), and X-ray crystallography (MX). The data indicate that the ligand pose away from the hinge dominates for the entire tested pH range (5.5-8.5). The insensitivity of the binding mode to pH is attributed to the perturbation of ligand pK_a upon binding that keeps it anionic in the ligand binding pocket at all tested pH values. However, a minor population of the ligand, detectable only by HDX, shifts towards the hinge in acidic conditions. Our findings demonstrate that electrostatic (ionic) interactions predominate over halogen bonding.

The Role of Protein Kinase CK2 in Development and Disease Progression: A Critical Review

Protein kinase CK2 (CK2) is a ubiquitous holoenzyme involved in a wide array of developmental processes. The involvement of CK2 in events such as neurogenesis, cardiogenesis, skeletogenesis, and spermatogenesis is essential for the viability of almost all organisms, and its role has been conserved throughout evolution. Further into adulthood, CK2 continues to function as a key regulator of pathways affecting crucial processes such as osteogenesis, adipogenesis, chondrogenesis, neuron differentiation, and the immune response. Due to its vast role in a multitude of pathways, aberrant functioning of this kinase leads to embryonic lethality and numerous diseases and disorders, including cancer and neurological disorders. As a result, CK2 is a popular target for interventions aiming to treat the aforementioned diseases. Specifically, two CK2 inhibitors, namely CX-4945 and CIBG-300, are in the early stages of clinical testing and exhibit promise for treating cancer and other disorders. Further, other researchers around the world are focusing on CK2 to treat bone disorders. This review summarizes the current understanding of CK2 in development, the structure of CK2, the targets and signaling pathways of CK2, the implication of CK2 in disease progression, and the recent therapeutics developed to inhibit the dysregulation of CK2 function in various diseases.

The synergistic therapeutic effect of imatinib and protein kinase CK2 Inhibition correlates with PI3K-AKT activation in gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Casein kinase 2 (CK2) has been reported to be involved in several cellular processes in multiple cancers. However, the role of CK2 in GIST remains unclear.

AIM

We aimed to investigate the combinatorial treatment of imatinib (IM) and CK2 inhibition on the progression of GISTs.

METHODS

GIST biopsies and adjacent normal tissues were collected from patients. GIST882 and GIST48 cell lines were subjected to investigate the effect of IM and CK2 inhibition in GIST cells. CCK-8 assay, Caspase-3 activity assay, western blotting, and flow cytometry analysis were employed in the present investigation.

RESULTS

Our results showed that CK2 was highly expressed in GIST biopsies, and inhibition of CK2 resulted in decrease in cell viability and increase in apoptosis of GIST cells. Moreover, the combination treatment with CX-4945 (CX) and IM resulted in a more significant decrease in cell viability and increase in cell apoptosis compared with mono-treatment. Mechanistically, the combination treatment influenced the activation of the PI3K/AKT pathway. The activation of the PI3K/AKT pathway reversed the synergistic impacts of the combined treatment on cell viability and apoptosis.

CONCLUSION

Our results demonstrated that inhibition of CK2 combined with IM exhibited a synergistic anti-cancer effect on GIST cells through inactivation of the PI3K/AKT pathway.

Novel Angiogenic Regulators and Anti-Angiogenesis Drugs Targeting Angiogenesis Signaling Pathways: Perspectives for Targeting Angiogenesis in Lung Cancer

Lung cancer growth is dependent on angiogenesis. In recent years, angiogenesis inhibitors have attracted more and more attention as potential lung cancer treatments. Current anti-angiogenic drugs targeting VEGF or receptor tyrosine kinases mainly inhibit tumor growth by reducing angiogenesis and blocking the energy supply of lung cancer cells. However, these drugs have limited efficiency, raising concerns about limited scope of action and mechanisms of patient resistance to existing drugs. Therefore, current basic research on angiogenic regulators has focused more on screening carcinogenic/anticancer genes, miRNAs, lncRNAs, proteins and other biomolecules capable of regulating the expression of specific targets in angiogenesis signaling pathways. In addition, new uses for existing drugs and new drug delivery systems have received increasing attention. In our article, we analyze the application status and research hotspots of angiogenesis inhibitors in lung cancer treatment as a reference for subsequent mechanistic research and drug development.

Research Development, Optimization and Modifications of Anti-cancer Peptides

Anti-cancer peptides play an important role in the area of cancer inhibition. A variety of anti- cancer peptides have emerged through the extraction and structural modification of peptides from biological tissues. This review provides the research background of anti-cancer peptides, the introduction of the mechanism of anti-cancer peptides for inhibition of cancers, the discovery and development along with optimization and modifications of these peptides in the clinical application. In conclusion, it can be said that anti-cancer peptides will play a major role in the future oncologic clinic.

Chemical probes targeting the kinase CK2: a journey outside the catalytic box

CK2 is a protein kinase that plays important roles in many physio-pathological cellular processes. As such, the development of chemical probes for CK2 has received increasing attention in the past decade with more than 40 lead compounds developed. In this review, we aim to provide the reader with a comprehensive overview of the chemical probes acting outside the highly-conserved ATP-site developed to date. Such probes belong to different classes of molecules spanning from small molecules to peptides, act with a range of mechanisms of action and some of them present themselves as promising tools to investigate the biology of CK2 and therefore develop therapeutics for many disease areas including cancer and COVID-19.

Tuning the Anti-Angiogenic Effect of the P15 Peptide Using Cyclic Trypsin Inhibitor Scaffolds

Angiogenesis is important for tumor growth, and accordingly, targeting angiogenesis has become an important pathway for antitumor therapy. A novel proapoptotic peptide, CIGB-300 (P15-Tat), has been shown to be involved in the casein kinase II phosphorylation pathway, conferring it with antiangiogenic activity. Cyclic peptides have been widely used as scaffolds in drug design studies due to their high stability and favorable biopharmaceutical properties. Here, we chose two very stable cyclic trypsin inhibitors, MCoTI-II and SFTI-1, as frameworks to incorporate the bioactive epitope P15 into various backbone loops. NMR studies revealed that all re-engineered analogs had similar secondary structures to their native cyclic frameworks. One key analog, MCoP15, displayed significant improvement for inhibiting human umbilical vein endothelial cell migration, was nontoxic, and had higher stability than the P15 epitope alone. Overall, the results show the value of P15 being engineered into cyclic trypsin inhibitor scaffolds for improving antiangiogenic activity and stability. More broadly, the study highlights the versatility of cyclic peptide frameworks in drug design for antiangiogenic therapies.

Protein kinase CK2: a potential therapeutic target for diverse human diseases

CK2 is a constitutively active Ser/Thr protein kinase, which phosphorylates hundreds of substrates, controls several signaling pathways, and is implicated in a plethora of human diseases. Its best documented role is in cancer, where it regulates practically all malignant hallmarks. Other well-known functions of CK2 are in human infections; in particular, several viruses exploit host cell CK2 for their life cycle. Very recently, also SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been found to enhance CK2 activity and to induce the phosphorylation of several CK2 substrates (either viral and host proteins). CK2 is also considered an emerging target for neurological diseases, inflammation and autoimmune disorders, diverse ophthalmic pathologies, diabetes, and obesity. In addition, CK2 activity has been associated with cardiovascular diseases, as cardiac ischemia-reperfusion injury, atherosclerosis, and cardiac hypertrophy. The hypothesis of considering CK2 inhibition for cystic fibrosis therapies has been also entertained for many years. Moreover, psychiatric disorders and syndromes due to CK2 mutations have been recently identified. On these bases, CK2 is emerging as an increasingly attractive target in various fields of human medicine, with the advantage that several very specific and effective inhibitors are already available. Here, we review the literature on CK2 implication in different human pathologies and evaluate its potential as a pharmacological target in the light of the most recent findings.

How can a traffic light properly work if it is always green? The paradox of CK2 signaling

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.

Protein kinase CK2 inhibition as a pharmacological strategy

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.

Protein kinase 2 (CK2): a potential regulator of immune cell development and function in cancer

Protein kinase CK2, formally known as casein kinase II, is ubiquitously expressed and highly conserved serine/threonine or tyrosine kinase enzyme that regulates diverse signaling pathways responsible for cellular processes (i.e., cell proliferation and apoptosis) via interactions with over 500 known substrates. The enzyme's physiological interactions and cellular functions have been widely studied, most notably in the blood and solid malignancies. CK2 has intrinsic role in carcinogenesis as overexpression of CK2 subunits (α, α`, and β) and deregulation of its activity have been linked to various forms of cancers. CK2 also has extrinsic role in cancer stroma or in the tumor microenvironment (TME) including the immune cells. However, very few research studies have focused on extrinsic role of CK2 in regulating immune responses as a therapeutic alternative for cancer. The following review discusses CK2's regulation of key signaling events [Nuclear factor kappa B (NF-κB), Janus kinase/signal transducer and activators of transcription (JAK/STAT), Hypoxia inducible factor-1alpha (HIF-1α), Cyclooygenase-2 (COX-2), Extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK), Notch, Protein kinase B/AKT, Ikaros and Wnt] that can influence the development and function of immune cells in cancer. Potential clinical trials using potent CK2 inhibitors will facilitate and improve the treatment of human malignancies.

Preclinical efficacy of CIGB-300, an anti-CK2 peptide, on breast cancer metastasic colonization

CK2 is a serine/threonine kinase that is overexpressed in breast cancer and its inhibition is associated to reduced tumor growth and disease progression. CIGB-300 is an antitumor peptide with a novel mechanism of action, since it binds to protein kinase CK2 catalytic subunit alpha and to CK2 substrates thus preventing the enzyme activity. Our aim was to evaluate the potential therapeutic benefits of CIGB-300 on breast cancer disease using experimental models with translational relevance. We demonstrated that CIGB-300 reduces breast cancer cell growth in MDA-MB-231, MCF-7 and F3II cells, exerting a pro-apoptotic action and cell cycle arrest. We also found that CIGB-300 decreased cell adhesion, migration and clonogenic capacity of malignant cells. Effect on experimental breast cancer lung metastasis was evaluated after surgical removal of primary F3II tumors or after tail vein injection of tumor cells, also we evaluated CIGB-300 effect on spontaneous lung metastasis in an orthotopic model. Systemic CIGB-300 treatment inhibited breast cancer colonization of the lung, reducing the size and number of metastatic lesions. The present preclinical study establishes for the first time the efficacy of CIGB-300 on breast cancer. These encouraging results suggest that CIGB-300 could be used for the management of breast cancer as an adjuvant therapy after surgery, limiting tumor metastatic spread and thus protecting the patient from distant recurrence.

Nucleophosmin in Its Interaction with Ligands

Nucleophosmin (NPM1) is a mainly nucleolar protein that shuttles between nucleoli, nucleoplasm and cytoplasm to fulfill its many functions. It is a chaperone of both nucleic acids and proteins and plays a role in cell cycle control, centrosome duplication, ribosome maturation and export, as well as the cellular response to a variety of stress stimuli. NPM1 is a hub protein in nucleoli where it contributes to nucleolar organization through heterotypic and homotypic interactions. Furthermore, several alterations, including overexpression, chromosomal translocations and mutations are present in solid and hematological cancers. Recently, novel germline mutations that cause dyskeratosis congenita have also been described. This review focuses on NPM1 interactions and inhibition. Indeed, the list of NPM1 binding partners is ever-growing and, in recent years, many studies contributed to clarifying the structural basis for NPM1 recognition of both nucleic acids and several proteins. Intriguingly, a number of natural and synthetic ligands that interfere with NPM1 interactions have also been reported. The possible role of NPM1 inhibitors in the treatment of multiple cancers and other pathologies is emerging as a new therapeutic strategy.

Protein Kinase CK2 in Cancer Energetics

Protein kinase CK2 (formerly known as casein kinase 2) is abnormally elevated in many cancers. This may increase tumor aggressiveness through CK2-dependent phosphorylation of key proteins in several signaling pathways. In this work, we have compiled evidence from the literature to suggest that CK2 also modulates a metabolic switch characteristic of cancer cells that enhances resistance to death, due to either drugs or to a microenvironment deficient in oxygen or nutrients. Concurrently, CK2 may help to preserve mitochondrial activity in a PTEN-dependent manner. PTEN, widely recognized as a tumor suppressor, is another CK2 substrate in the PI3K/Akt signaling pathway that promotes cancer viability and aerobic glycolysis. Given that CK2 can regulate Akt as well as two of its main effectors, namely mTORC1 and β-catenin, we comprehensively describe how CK2 may modulate cancer energetics by regulating expression of key targets and downstream processes, such as HIF-1 and autophagy, respectively. Thus, the specific inhibition of CK2 may lead to a catastrophic death of cancer cells, which could become a feasible therapeutic strategy to beat this devastating disease. In fact, ATP-competitive inhibitors, synthetic peptides and antisense oligonucleotides have been designed as CK2 inhibitors, some of them used in preclinical models of cancer, of which TBB and silmitasertib are widely known. We will finish by discussing a hypothetical scenario in which cancer cells are "addicted" to CK2; i.e., in which many proteins that regulate signaling pathways and metabolism-linked processes are highly dependent on this kinase.

Recent Advances in Peptide-Based Approaches for Cancer Treatment

BACKGROUND

Peptide-based pharmaceuticals have recently experienced a renaissance due to their ability to fill the gap between the two main classes of available drugs, small molecules and biologics. Peptides combine the high potency and selectivity typical of large proteins with some of the characteristic advantages of small molecules such as synthetic accessibility, stability and the potential of oral bioavailability.

METHODS

In the present manuscript we review the recent literature on selected peptide-based approaches for cancer treatment, emphasizing recent advances, advantages and challenges of each strategy.

RESULTS

One of the applications in which peptide-based approaches have grown rapidly is cancer therapy, with a focus on new and established targets. We describe, with selected examples, some of the novel peptide-based methods for cancer treatment that have been developed in the last few years, ranging from naturally-occurring and modified peptides to peptidedrug conjugates, peptide nanomaterials and peptide-based vaccines.

CONCLUSION

This review brings out the emerging role of peptide-based strategies in oncology research, critically analyzing the advantages and limitations of these approaches and the potential for their development as effective anti-cancer therapies.

Enhanced antitumour efficacy of functionalized doxorubicin plus schisandrin B co-delivery liposomes via inhibiting epithelial-mesenchymal transition

Non-small cell lung cancer (NSCLC) is a malignant cancer characterized by easy invasion, metastasis and poor prognosis, so that conventional chemotherapy cannot inhibit its invasion and metastasis. Doxorubicin (DOX), as a broad-spectrum antitumour drug, cannot be widely used in clinic because of its poor targeting, short half-life, strong toxicity and side effects. Therefore, the aim of our study is to construct a kind of PFV modified DOX plus schisandrin B liposomes to solve the above problems, and to explore its potential mechanism of inhibiting NSCLC invasion and metastasis. The antitumour efficiency of the targeting liposomes was carried out by cytotoxicity, heating ablation, wound healing, transwell, vasculogenic mimicry channels formation and metastasis-related protein tests in vitro. Pharmacodynamics were evaluated by tumour inhibition rate, HE staining and TUNEL test in vivo. The enhanced anti-metastatic mechanism of the targeting liposomes was attributed to the downregulation of vimentin, vascular endothelial growth factor, matrix metalloproteinase 9 and upregulation of E-cadherin. In conclusion, the PFV modified DOX plus schisandrin B liposomes prepared in this study provided a treatment strategy with high efficiency for NSCLC.

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

Lung cancer negatively impacts global health, and the incidence of non-small cell lung cancer (NSCLC) is highest among all forms of lung cancer. Chemotherapy failure mainly occurs due to drug resistance; however, the associated molecular mechanism remains unclear. Casein kinase II (CK2), which plays important roles in the occurrence, development and metastasis of many tumours, regulates Wnt signaling by modulating β-catenin expression. In the present study the effects of the CK2 inhibitor, CX4945 on cisplatin [or cis-diamminedichloroplatinum (II); (DDP)]-resistant A549 cells (A549/DDP) were investigated to elucidate the underlying molecular mechanism. A549/DDP cells were divided into four groups (blank control, CX4945, cisplatin and CX4945+cisplatin). Cisplatin resistance was 5.16-fold greater in A549/DDP cells compared with that in A549 cells, with an optimal cisplatin concentration of 5 µg/ml. Moreover, levels of CK2, dishevelled-2 (DVL-2) phosphorylated (p) at Ser143 (p-DVL-2^Ser143), and major Wnt-signaling proteins were significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels further increased following cisplatin treatment (P<0.05), whereas these levels significantly decreased in A549 cells after cisplatin treatment (P<0.05). Additionally, multidrug-resistance-associated protein 1 and lung resistance protein expression was significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels increasing further in A549/DDP (P<0.05) but not A549 cells upon cisplatin treatment (P>0.05). In addition, reduced expression of resistance proteins in A549/DDP cells was accompanied by a decline in the 50% growth inhibition after CX4945 pre-treatment. Furthermore, levels of p-DVL-2^Ser143 and major Wnt-signaling proteins decreased significantly after treatment of A549/DDP cells with CX4945+cisplatin, whereas DVL-2 and p-DVL-2^Thr224 levels remained unchanged. Additionally, significant elevations in apoptosis rates in the CX4945+cisplatin group relative to the control and cisplatin-only groups, was observed (P<0.001). These results suggested that inhibiting Wnt/β-catenin signaling with CX4945, which attenuates levels of drug-resistance-associated proteins and induces apoptosis, might reverse cisplatin resistance in NSCLC.

Are peptides a solution for the treatment of hyperactivated JAK3 pathways?

While the inactivation mutations that eliminate JAK3 function lead to the immunological disorders such as severe combined immunodeficiency, activation mutations, causing constitutive JAK3 signaling, are known to trigger various types of cancer or are responsible for autoimmune diseases, such as rheumatoid arthritis, psoriasis, or inflammatory bowel diseases. Treatment of hyperactivated JAK3 is still an obstacle, due to different sensibility of mutation types to conventional drugs and unwanted side effects, because these drugs are not absolutely specific for JAK3, thus inhibiting other members of the JAK family, too. Lack of information, in which way sole inhibition of JAK3 is necessary for elimination of the disease, calls for the development of isoform-specific JAK3 inhibitors. Beside this strategy, up to date peptides are a rising alternative as chemo- or immunotherapeutics, but still sparsely represented in drug development and clinical trials. Beyond a possible direct inhibition function, crossing the cancer cell membrane and interfering in disease-causing pathways or triggering apoptosis, peptides could be used in future as adjunct remedies to potentialize traditional therapy and preserve non-affected cells. To discuss such feasible topics, this review deals with the knowledge about the structure-function of JAK3 and the actual state-of-the-art of isoform-specific inhibitor development, as well as the function of currently approved drugs or those currently being tested in clinical trials. Furthermore, several strategies for the application of peptide-based drugs for cancer therapy and the physicochemical and structural relations to peptide efficacy are discussed, and an overview of peptide sequences, which were qualified for clinical trials, is given.

Thiazole- and selenazole-comprising high-affinity inhibitors possess bright microsecond-scale photoluminescence in complex with protein kinase CK2

A previously disclosed protein kinase (PK) CK2-selective inhibitor 4-(2-amino-1,3-thiazol-5-yl)benzoic acid (ATB) and its selenium-containing counterpart (ASB) revealed remarkable room temperature phosphorescence when bound to the ATP pocket of the protein kinase CK2. Conjugation of these fragments with a mimic of CK2 substrate peptide resulted in bisubstrate inhibitors with increased affinity towards the kinase. Attachment of the fluorescent acceptor dye 5-TAMRA to the conjugates led to significant enhancement of intensity of long-lifetime (microsecond-scale) photoluminescence of both sulfur- and selenium-containing compounds. The developed photoluminescent probes make possible selective determination of the concentration of CK2 in cell lysates and characterization of CK2 inhibitors by means of time-gated measurement of photoluminescence.

A meta-analysis and bioinformatics exploration of the diagnostic value and molecular mechanism of miR-193a-5p in lung cancer

Lung cancer is a leading cause of mortality worldwide and despite recent improvements in lung cancer treatments patient mortality remains high. miR-193a-5p serves a crucial role in the initiation and development of cancer; it is necessary to understand the underlying molecular mechanisms of miR-193a-5p in lung cancer, which may enable the development of improved clinical diagnoses and therapies. The present study investigated the diagnostic value of peripheral blood and tissue miR-193a-5p expression using a microarray meta-analysis. Peripheral blood miR-193a-5p was revealed to be upregulated in patients with lung cancer. The pooled area under the curve (AUC) was 0.67, with a sensitivity and specificity of 0.74 and 0.56, respectively. Conversely, the peripheral tissue miR-193a-5p expression in patients with lung cancer was significantly downregulated. The pooled AUC was 0.83, and the sensitivity and specificity were 0.65 and 0.89, respectively. Through bioinformatics analysis, three Kyoto Encyclopedia of Genes and Genomes (KEGG) terms, pathways in cancer, prostate cancer and RIG-I-like receptor signaling pathway, were identified as associated with miR-193a-5p in lung cancer. In addition, in lung cancer, six key miR-193a-5p target genes, receptor tyrosine-protein kinase erbB-2 (ERBB2), nuclear cap-binding protein subunit 2 (NCBP2), collagen α-1(I) chain (COL1A1), roprotein convertase subtilisin/kexin type 9 (PCSK9), casein kinase II subunit α (CSNK2A1) and nucleolar transcription factor 1 (UBTF), were identified, five of which were significantly upregulated (ERBB2, NCBP2, COL1A1, CSNK2A1 and UBTF). The protein expression of ERBB2, NCBP2, COL1A1, CSNK2A1 and UBTF was also upregulated. NCBP2 and CSNK2A1 were negatively correlated with miR-193a-5p. The results demonstrated that miR-193a-5p exhibited opposite expression patterns in peripheral blood and tissue. Upregulated peripheral blood miR-193a-5p and downregulated tissue miR-193a-5p may be promising diagnostic biomarkers in lung cancer. In addition, the KEGG terms pathways in cancer, prostate cancer and RIG-I-like receptor signaling pathway may suggest which pathways serve vital roles in lung cancer by regulating miR-193a-5p. In addition, six genes, ERBB2, COL1A1, PCSK9, UBTF and particularly NCBP2 and CSNK2A1, may be key target genes of miR-193a-5p in lung cancer.

Protein kinase CK2 modulation of pyruvate kinase M isoforms augments the Warburg effect in cancer cells

Protein kinase CK2 is active in cancer cells. Previously, we reported that increased CK2 activity could induce epithelial mesenchymal transition of cancer cells. CK2 also induced epithelial mesenchymal transition in colon cancer cell lines such as HT29 and SW620, and the transitioned cells (CK2α cells) became more proliferative than the controls. We assumed that CK2 could affect cancer cell growth by modulating their energy metabolism. Here, we examined the molecular effects of CK2 on the glucose metabolism of cancer cells. We found that CK2α cells consumed more glucose and produced more lactate than control cells did. An XF glycolysis stress test showed that aerobic glycolysis was augmented up to the cancer cell's maximal glycolytic capacity in CK2α cells. Molecular analysis revealed that pyruvate kinase M1 was downregulated and pyruvate kinase M2 was nuclear localized in CK2α cells. Consequently, the expression and activity of lactate dehydrogenase A (LDHA) were upregulated. Treatment with FX11-a specific LDHA inhibitor-or clustered regularly interspaced short palindromic repeats (CRISPR)-mediated knockout of LDHA inhibited the CK2-driven proliferation of cancer cells. We conclude that CK2 augments the Warburg effect, resulting in increased proliferation of cancer cells.

CIGB-300: A peptide-based drug that impairs the Protein Kinase CK2-mediated phosphorylation

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.

Identification of a Druggable Pathway Controlling Glioblastoma Invasiveness

Diffuse and uncontrollable brain invasion is a hallmark of glioblastoma (GBM), but its mechanism is understood poorly. We developed a 3D ex vivo organotypic model to study GBM invasion. We demonstrate that invading GBM cells upregulate a network of extracellular matrix (ECM) components, including multiple collagens, whose expression correlates strongly with grade and clinical outcome. We identify interferon regulatory factor 3 (IRF3) as a transcriptional repressor of ECM factors and show that IRF3 acts as a suppressor of GBM invasion. Therapeutic activation of IRF3 by inhibiting casein kinase 2 (CK2)-a negative regulator of IRF3-downregulated the expression of ECM factors and suppressed GBM invasion in ex vivo and in vivo models across a panel of patient-derived GBM cell lines representative of the main molecular GBM subtypes. Our data provide mechanistic insight into the invasive capacity of GBM tumors and identify a potential therapy to inhibit GBM invasion.

Inhibition of protein kinase CK2 sensitizes non-small cell lung cancer cells to cisplatin via upregulation of PML

Non-small cell lung carcinoma (NSCLC), a malignancy of lungs, is very aggressive and usually ends up with a dismal prognosis. Cisplatin (CDDP)-based systemic chemotherapy is the main pharmaceutical approach for treating NSCLC, but its effect is discounted by some hitherto unknown reasons. Thus, this study is dedicated to improving the efficacy of CDDP. Our results show that combining use of CDDP with CK2 siRNA or inhibitor is more efficient in suppressing cancer cell growth and promoting apoptosis than use of CDDP alone. The underlying mechanism is that CDDP has two pathways to go: one is that it directly induces apoptosis and the other is that it activates CK2, which suppresses proapoptosis gene promyelocytic leukemia (PML). In conclusion, inhibiting CK2 can enhance sensitivity of CDDP to NSCLC cancer cells through PML.

The synthetic peptide CIGB-300 modulates CK2-dependent signaling pathways affecting the survival and chemoresistance of non-small cell lung cancer cell lines

BACKGROUND

Lung cancer is the most frequently diagnosed cancer and the leading cause of cancer-related deaths worldwide. Up to 80% of cancer patients are classified as non-small-cell lung cancer (NSCLC) and cisplatin remains as the gold standard chemotherapy treatment, despite its limited efficacy due to both intrinsic and acquired resistance. The CK2 is a Ser/Thr kinase overexpressed in various types of cancer, including lung cancer. CIGB-300 is an antitumor peptide with a novel mechanism of action, since it binds to CK2 substrates thus preventing the enzyme activity. The aim of this work was to analyze the effects of CIGB-300 treatment targeting CK2-dependent signaling pathways in NSCLC cell lines and whether it may help improve current chemotherapy treatment.

METHODS

The human NSCLC cell lines NCI-H125 and NIH-A549 were used. Tumor spheroids were obtained through the hanging-drop method. A cisplatin resistant A549 cell line was obtained by chronic administration of cisplatin. Cell viability, apoptosis, immunoblotting, immunofluorescence and luciferase reporter assays were used to assess CIGB-300 effects. A luminescent assay was used to monitor proteasome activity.

RESULTS

We demonstrated that CIGB-300 induces an anti-proliferative response both in monolayer- and three-dimensional NSCLC models, presenting rapid and complete peptide uptake. This effect was accompanied by the inhibition of the CK2-dependent canonical NF-κB pathway, evidenced by reduced RelA/p65 nuclear levels and NF-κB protein targets modulation in both lung cancer cell lines, as well as conditionally reduced NF-κB transcriptional activity. In addition, NF-κB modulation was associated with enhanced proteasome activity, possibly through its α7/C8 subunit. Neither the peptide nor a classical CK2 inhibitor affected cytoplasmic β-CATENIN basal levels. Given that NF-κB activation has been linked to cisplatin-induced resistance, we explored whether CIGB-300 could bring additional therapeutic benefits to the standard cisplatin treatment. We established a resistant cell line that showed higher p65 nuclear levels after cisplatin treatment as compared with the parental cell line. Remarkably, the cisplatin-resistant cell line became more sensitive to CIGB-300 treatment.

CONCLUSIONS

Our data provide new insights into CIGB-300 mechanism of action and suggest clinical potential on current NSCLC therapy.

Protein Kinase CK2: Intricate Relationships within Regulatory Cellular Networks

Protein kinase CK2 is a small family of protein kinases that has been implicated in an expanding array of biological processes. While it is widely accepted that CK2 is a regulatory participant in a multitude of fundamental cellular processes, CK2 is often considered to be a constitutively active enzyme which raises questions about how it can be a regulatory participant in intricately controlled cellular processes. To resolve this apparent paradox, we have performed a systematic analysis of the published literature using text mining as well as mining of proteomic databases together with computational assembly of networks that involve CK2. These analyses reinforce the notion that CK2 is involved in a broad variety of biological processes and also reveal an extensive interplay between CK2 phosphorylation and other post-translational modifications. The interplay between CK2 and other post-translational modifications suggests that CK2 does have intricate roles in orchestrating cellular events. In this respect, phosphorylation of specific substrates by CK2 could be regulated by other post-translational modifications and CK2 could also have roles in modulating other post-translational modifications. Collectively, these observations suggest that the actions of CK2 are precisely coordinated with other constituents of regulatory cellular networks.

CK2 in Cancer: Cellular and Biochemical Mechanisms and Potential Therapeutic Target

CK2 genes are overexpressed in many human cancers, and most often overexpression is associated with worse prognosis. Site-specific expression in mice leads to cancer development (e.g., breast, lymphoma) indicating the oncogenic nature of CK2. CK2 is involved in many key aspects of cancer including inhibition of apoptosis, modulation of signaling pathways, DNA damage response, and cell cycle regulation. A number of CK2 inhibitors are now available and have been shown to have activity against various cancers in vitro and in pre-clinical models. Some of these inhibitors are now undergoing exploration in clinical trials as well. In this review, we will examine some of the major cancers in which CK2 inhibition has promise based on in vitro and pre-clinical studies, the proposed cellular and signaling mechanisms of anti-cancer activity by CK2 inhibitors, and the current or recent clinical trials using CK2 inhibitors.