casein-kinase-ii and Cell-Transformation--Neoplastic

Genetic mutations of oncogenes often underlie deranged cell growth and altered differentiation pathways leading to malignant transformation of B-lymphocytes. However, addiction to oncogenes is not the only drive to lymphoid tumor pathogenesis. Dependence on non-oncogenes, which act by propelling basic mechanisms of cell proliferation and survival, has also been recognized in the pathobiology of lymphoid leukemias, lymphomas and multiple myeloma. Among the growing number of molecules that may uphold non-oncogene addiction, a key place is increasingly being recognized to the serine-threonine kinase CK2. This enzyme is overexpressed and overactive in B-acute lymphoblastic leukemia, multiple myeloma, chronic lymphocytic leukemia and non-Hodgkin lymphomas, such as mantle cell, follicular, Burkitt's and diffuse large B-cell lymphomas. In these tumors, CK2 may serve the activity of oncogenes, similar to BCR-ABL and c-MYC, control the activation of critical signaling cascades, such as NF-κB (nuclear factor-κB), STAT3 (signal transducer and activator of transcription 3) and PTEN/PI3K/AKT (phosphatase and tensin homolog protein/phosphoinositide 3-kinase/AKR thymoma), and sustain multiple cellular stress-elicited pathways, such as the proteotoxic stress, unfolded protein and DNA-damage responses. CK2 has also been shown to have an essential role in tuning signals derived from the stromal tumor microenvironment. Not surprisingly, targeting CK2 in lymphoid tumor cell lines or mouse xenograft models can boost the cytotoxic effects of both conventional chemotherapeutics and novel agents, similar to heat-shock protein 90, proteasome and tyrosine kinases inhibitors. In this review, we summarize the evidence indicating how CK2 embodies most of the features of a cancer growth-promoting non-oncogene, focusing on lymphoid tumors. We further discuss the preclinical data of the use of small ATP-competitive CK2 inhibitors, which hold the promise to be additional options in novel drug combinations for the therapy of lymphoid and plasmacellular malignancies.

Topics: Animals; B-Lymphocytes; Biomarkers, Tumor; Casein Kinase II; Cell Proliferation; Cell Survival; Cell Transformation, Neoplastic; Gene Expression Regulation, Neoplastic; Humans; Leukemia, B-Cell; Lymphoma, B-Cell; Oncogenes; Signal Transduction

CK2 is a multitask kinase whose role is essential for a countless number of cellular processes, many of which are critical for blood cell development. A prevailing task for this kinase rests on counteracting programmed cell death triggered by multiple stimuli. CK2 is overexpressed in many solid tumors and in vivo mouse models have proven its tumorigenic potential. Recent data have suggested that CK2 may also have a significant role in the pathogenesis of hematopoietic tumors, such as multiple myeloma, chronic lymphocytic leukemia, acute myelogenous leukemia, acute lymphoblastic leukemia and chronic myeloproliferative neoplasms. CK2 regulates hematopoiesis-associated signaling pathways and seems to reinforce biochemical cascades indispensable for tumor growth, proliferation and resistance to conventional and novel cytotoxic agents. Although its activity is multifold, recent evidence supports the rationale of CK2 inhibition as a therapeutic strategy in solid and hematological tumors and phase-I clinical trials are in progress to test the efficacy of this innovative therapeutic approach. In this review, we will summarize the data supporting CK2 as an oncogenic kinase in blood tumors and we will describe some critical signaling pathways, whose regulation by this protein kinase may be implicated in tumorigenesis.

Topics: Animals; Casein Kinase II; Cell Survival; Cell Transformation, Neoplastic; Hematologic Neoplasms; Humans; Mice; Oncogenes; Signal Transduction

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

CK2 is a highly conserved tetrameric serine/ threonine kinase present in all eukaryotic organisms. It is constitutively active, and appears to be regulated by level of expression and activity, and subcellular localization. In turn, it has been postulated to control the function of many proteins through changes in phosphorylation that affect protein stability, protein-protein interactions, and subcellular localization. Through these mechanisms, CK2 regulates many fundamental cellular properties. An enzyme that carries out such a master regulatory function is likely to be important in organismic development and in cancer. We have shown that overexpression of CK2 catalytic subunits is capable of promoting tumorigenesis, and that loss of CK2 catalytic subunits in development can be lethal. Through studies in cells, mice, and frogs, we and others have identified the Wnt and NF-kappaB pathways as two key signal transduction pathways that are regulated by CK2 activity, in embryonic development and in cancer. These results suggest that inhibiting CK2 could be useful in treating cancer, but dangerous to developing organisms.

Topics: Animals; Casein Kinase II; Cell Transformation, Neoplastic; Embryonic Development; Humans; NF-kappa B; Phosphorylation; Signal Transduction; Wnt Proteins

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; Casein Kinase II; Cell Transformation, Neoplastic; DNA-Binding Proteins; Humans; Oncogene Proteins; Protein Binding; Protein Conformation; Protein Serine-Threonine Kinases; Transcription Factors

Topics: Animals; Casein Kinase II; Cattle; Cell Division; Cell Transformation, Neoplastic; Lymphocyte Activation; Lymphoma; Mice; Mice, Transgenic; Protein Serine-Threonine Kinases; Signal Transduction; T-Lymphocytes; Theileria parva; Theileriasis

Dietary supplements such as vitamins and minerals are widely used in the hope of improving health but may have unidentified risks and side effects. In particular, a pathogenic link between dietary supplements and specific oncogenes remains unknown. Here we report that chondroitin-4-sulfate (CHSA), a natural glycosaminoglycan approved as a dietary supplement used for osteoarthritis, selectively promotes the tumor growth potential of BRAF V600E-expressing human melanoma cells in patient- and cell line-derived xenograft mice and confers resistance to BRAF inhibitors. Mechanistically, chondroitin sulfate glucuronyltransferase (CSGlcA-T) signals through its product CHSA to enhance casein kinase 2 (CK2)-PTEN binding and consequent phosphorylation and inhibition of PTEN, which requires CHSA chains and is essential to sustain AKT activation in BRAF V600E-expressing melanoma cells. However, this CHSA-dependent PTEN inhibition is dispensable in cancer cells expressing mutant NRAS or PI3KCA, which directly activate the PI3K-AKT pathway. These results suggest that dietary supplements may exhibit oncogene-dependent pro-tumor effects.

Topics: Animals; Antinematodal Agents; Carcinogens; Casein Kinase II; Cell Proliferation; Cell Transformation, Neoplastic; Chondroitin Sulfates; Dietary Supplements; Drug Resistance, Neoplasm; Female; GTP Phosphohydrolases; HEK293 Cells; HT29 Cells; Humans; Melanoma; Membrane Proteins; Mice; Mice, Inbred NOD; Mice, Nude; Mice, Transgenic; Mutation; NIH 3T3 Cells; Nuclear Proteins; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; PTEN Phosphohydrolase; Signal Transduction; Skin Neoplasms; Transcription Factors; Xenograft Model Antitumor Assays

Upon growth factor stimulation, PAK1 is recruited to the plasma membrane and activated by a mechanism that requires its phosphorylation at Ser-223 by the protein kinase CK2. However, the upstream signaling molecules that regulate this phosphorylation event are not clearly defined. Here, we demonstrate a major role of the CK2α-interacting protein CKIP-1 in activation of PAK1. CK2α, CKIP-1, and PAK1 are translocated to membrane ruffles in response to the epidermal growth factor (EGF), where CKIP-1 mediates the interaction between CK2α and PAK1 in a PI3K-dependent manner. Consistently, PAK1 mediates phosphorylation and modulation of the activity of p41-Arc, one of its plasma membrane substrate, in a fashion that requires PI3K and CKIP-1. Moreover, CKIP-1 knockdown or PI3K inhibition suppresses PAK1-mediated cell migration and invasion, demonstrating the physiological significance of the PI3K-CKIP-1-CK2-PAK1 signaling pathway. Taken together, these findings identify a novel mechanism for the activation of PAK1 at the plasma membrane, which is critical for cell migration and invasion.

Topics: Actin-Related Protein 2-3 Complex; Casein Kinase II; Cell Line; Cell Line, Tumor; Cell Transformation, Neoplastic; Epidermal Growth Factor; Epithelial Cells; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Male; Membrane Microdomains; p21-Activated Kinases; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Prostate; Protein Kinase Inhibitors; Protein Transport; Recombinant Proteins; RNA, Small Interfering; Signal Transduction

Signal transducer and activator of transcription 3 (Stat3) is a transcription factor that is involved in cell survival and proliferation and has been found to be persistently activated in most human cancers mainly through its phosphorylation at Tyr-705. However, the role and regulation of Stat3 Ser-727 phosphorylation in cancer cells have not been clearly evaluated. In our findings, correlation studies on the expression of CK2 and Stat3 Ser-727 phosphorylation levels in human glioma patient samples as well as rat orthotopic tumor model show a degree of negative correlation. Moreover, brain tumor cell lines were treated with various pharmacological inhibitors to inactivate the CK2 pathway. Here, increased Stat3 Ser-727 phosphorylation upon CK2 inhibition was observed. Overexpression of CK2 (α, α' or β subunits) by transient transfection resulted in decreased Stat3 Ser-727 phosphorylation. Stat3 Tyr-705 residue was conversely phosphorylated in similar situations. Interestingly, we found PP2A, a protein phosphatase, to be a mediator in the negative regulation of Stat3 Ser-727 phosphorylation by CK2. In vitro assays prove that Ser-727 phosphorylation of Stat3 affects the transcriptional activity of its downstream targets like SOCS3, bcl-xl and Cyclin D1. Stable cell lines constitutively expressing Stat3 S727A mutant showed increased survival, proliferation and invasion which are characteristics of a cancer cell. Rat tumor models generated with the Stat3 S727A mutant cell line formed more aggressive tumors when compared to the Stat3 WT expressing stable cell line. Thus, in glioma, reduced Stat3 Ser-727 phosphorylation enhances tumorigenicity which may be regulated in part by CK2-PP2A pathway.

Topics: Animals; bcl-X Protein; Brain Neoplasms; Casein Kinase II; Cell Line, Tumor; Cell Movement; Cell Transformation, Neoplastic; Cyclin D1; Glioma; HEK293 Cells; Humans; Okadaic Acid; Phosphorylation; Protein Phosphatase 2; Rats; Rats, Sprague-Dawley; Serine; STAT3 Transcription Factor; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Transplantation, Heterologous

Activation of the p21-activated kinase 1 (PAK1) is achieved through a conformational change that converts an inactive PAK1 dimer to an active monomer. In this paper, we show that this change is necessary but not sufficient to activate PAK1 and that it is, rather, required for CK2-dependent PAK1(S223) phosphorylation that converts a monomeric PAK1 into a catalytically active form. This phosphorylation appears to be essential for autophosphorylation at specific residues and overall activity of PAK1. A phosphomimetic mutation (S223E) bypasses the requirement for GTPases in PAK1 activation, whereas the constitutive activity of the PAK1 mutant (PAK1(H83,86L)), postulated to mimic GTPase-induced structural changes, is abolished by inhibition of S223 phosphorylation. Thus, S223 is likely accessible to CK2 upon conformational changes of PAK1 induced by GTPase-dependent and GTPase-independent stimuli, suggesting that S223 phosphorylation may play a key role in the final step of the PAK1 activation process. The physiological significance of this phosphorylation is reinforced by the observations that CK2 is responsible for epidermal growth factor-induced PAK1 activation and that inhibition of S223 phosphorylation abrogates PAK1-mediated malignant transformation of prostate epithelial cells. Taken together, these findings identify CK2 as an upstream activating kinase of PAK1, providing a novel mechanism for PAK1 activation.

Topics: Animals; Biocatalysis; Blotting, Western; Casein Kinase II; Cell Line, Tumor; Cell Transformation, Neoplastic; Enzyme Activation; Epidermal Growth Factor; Humans; Male; Mass Spectrometry; Mice; Models, Biological; Mutation; p21-Activated Kinases; Phosphorylation; Phosphoserine; Prostate; Reproducibility of Results

MicroRNAs (miRNAs) play important roles in diverse biological processes and are emerging as key regulators of tumorigenesis and tumor progression. To explore the dysregulation of miRNAs in breast cancer, a genome-wide expression profiling of 939 miRNAs was performed in 50 breast cancer patients. A total of 35 miRNAs were aberrantly expressed between breast cancer tissue and adjacent normal breast tissue and several novel miRNAs were identified as potential oncogenes or tumor suppressor miRNAs in breast tumorigenesis. miR-125b exhibited the largest decrease in expression. Enforced miR-125b expression in mammary cells decreased cell proliferation by inducing G2/M cell cycle arrest and reduced anchorage-independent cell growth of cells of mammary origin. miR-125b was found to perform its tumor suppressor function via the direct targeting of the 3'-UTRs of ENPEP, CK2-α, CCNJ, and MEGF9 mRNAs. Silencing these miR-125b targets mimicked the biological effects of miR-125b overexpression, confirming that they are modulated by miR-125b. Analysis of ENPEP, CK2-α, CCNJ, and MEGF9 protein expression in breast cancer patients revealed that they were overexpressed in 56%, 40-56%, 20%, and 32% of the tumors, respectively. The expression of ENPEP and CK2-α was inversely correlated with miR-125b expression in breast tumors, indicating the relevance of these potential oncogenic proteins in breast cancer patients. Our results support a prognostic role for CK2-α, whose expression may help clinicians predict breast tumor aggressiveness. In particular, our results show that restoration of miR-125b expression or knockdown of ENPEP, CK2-α, CCNJ, or MEGF9 may provide novel approaches for the treatment of breast cancer.

Topics: 3' Untranslated Regions; Breast Neoplasms; Casein Kinase II; Cell Line; Cell Proliferation; Cell Transformation, Neoplastic; Cluster Analysis; Cyclins; Female; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Genes, Tumor Suppressor; Glutamyl Aminopeptidase; Humans; Membrane Proteins; MicroRNAs; Nerve Tissue Proteins; RNA Interference

It was previously reported that β-catenin contributes to the tumorigenesis of ALK-positive anaplastic large cell lymphoma (ALK(+)ALCL), and the oncogenic effects of β-catenin in these tumors are promoted by NPM-ALK, an abnormal fusion protein characteristic of ALK(+)ALCL. In this study, we hypothesized that NPM-ALK promotes the oncogenic activity of β-catenin via its functional interactions with the Wnt canonical pathway (WCP). To test this hypothesis, we examined if NPM-ALK modulates the gene expression of various members in the WCP. Using a Wnt pathway-specific oligonucleotide array and Western blots, we found that the expression of casein kinase 2α (CK2α) was substantially downregulated in ALK(+)ALCL cells in response to siRNA knockdown of NPM-ALK. CK2α is biologically important in ALK(+)ALCL, as its inhibition using 4,5,6,7-tetrabromobenzotriazole or siRNA resulted in a significant decrease in cell growth and a substantial decrease in the β-catenin protein level. Furthermore, CK2α co-immunoprecipitated with NPM-ALK and regulated its level of serine phosphorylation, a feature previously shown to correlate with the oncogenic potential of this fusion protein. To conclude, this study has revealed a novel crosstalk between NPM-ALK and CK2α, and our data supports the model that these two molecules work synergistically to promote the tumorigenicity of these lymphomas.

Topics: beta Catenin; Casein Kinase II; Cell Communication; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Down-Regulation; Enzyme Inhibitors; Humans; Lymphoma, Large-Cell, Anaplastic; Phosphorylation; Protein-Tyrosine Kinases; RNA Interference; RNA, Small Interfering; Signal Transduction; Triazoles; Wnt Proteins

Aberrant expression of casein kinase 2 (CK2) is associated with tumor progression; however, the molecular mechanism by which CK2 modulates tumorigenesis is incompletely understood. In this paper, we show that CK2α phosphorylates the C-terminal domain of the nuclear receptor corepressor (NCoR) at Ser-2436 to stabilize the NCoR against the ubiquitin-dependent proteasomal degradation pathway. Importantly, NCoR promoted the invasion of esophageal cancer cells in a CK2-dependent manner. By using cyclic DNA microarray analysis, we identified CXCL10/IP-10 as a novel CK2α-NCoR cascade-regulated gene. The depletion of both NCoR and HDAC3 commonly derepressed IP-10 transcription, demonstrating the functional engagement of the NCoR-HDAC3 axis in IP-10 transcriptional repression. Furthermore, chromatin immunoprecipitation assays showed that c-Jun recruits NCoR-HDAC3 corepressor complexes to the (AP1 site of IP-10, leading to histone hypoacetylation and IP-10 down-regulation. Collectively these data suggest that the CK2α-NCoR cascade selectively represses the transcription of IP-10 and promotes oncogenic signaling in human esophageal cancer cells.

Topics: Binding Sites; Casein Kinase II; Cell Line, Tumor; Cell Transformation, Neoplastic; Chemokine CXCL10; Co-Repressor Proteins; Esophageal Neoplasms; Gene Expression Regulation, Neoplastic; Histone Deacetylases; Humans; JNK Mitogen-Activated Protein Kinases; Neoplasm Invasiveness; Nuclear Receptor Co-Repressor 1; Promoter Regions, Genetic; Protein Binding; Proteolysis; Signal Transduction; Transcription, Genetic

CK2 is a serine threonine kinase that participates in a variety of cellular processes with more than 300 defined substrates. This critical enzyme is known to be upregulated in cancers, but the role of this upregulation in carcinogenesis is not yet fully understood but c-myc, one of the defined CK2 substrates, is a well-known proto- oncogene that is normally essential in developmental process but is also involved in tumor development. We evaluated the optimal enzyme and substrate concentrations for CK2 activity in both neoplastic and non-neoplastic human lung tissues using the c-myc 424-434 peptide (EQKLISEEDL) as a substrate. The activities measured for the neoplastic tissue were 600-750 U/mg protein while those for the control tissue was in the range of 650-800 U/ mg. Km value for c-myc peptide was determined as 0.33 μM in non-neoplastic tissue and 0.18 μM in neoplastic tissue. In this study, we did not observe an increased activity in the neoplastic tissue when compared with the non-neoplastic lung tissue, but we recorded two times higher affinity for c-myc 424-434 in cancer tissue. Considering the metabolic position of c-myc 424-434, our results suggest that phosphorylation by CK2 may be important in dimerization and thus it might affect the regulation of c-myc in cancer tissues.

Topics: Amino Acid Sequence; Casein Kinase II; Cell Transformation, Neoplastic; Gene Expression Regulation, Neoplastic; Humans; Lung; Lung Neoplasms; Molecular Sequence Data; Peptide Fragments; Prognosis; Proto-Oncogene Mas; Proto-Oncogene Proteins c-myc

To investigate the expression of casein kinase 2β (ck2β) in colorectal cancer in relation to the metastatic ability of the cancer cells.. The expression of ck2β in 46 normal colorectal mucosa, 20 colorectal adenomas and 66 colorectal cancers were detected immunohistochemically. In colorectal cancer cells, Ck2β protein expression was knockdown by RNA interference using ck2β-specific small interfering RNA (siRNA) and the interference efficiency was assessed by Western blotting. The effect of ck2β gene knockdown on the proliferation of the colorectal cancer cells was tested with colony formation assay, and the changes in the invasive ability of the cells were observed using Transwell chamber assay.. Negative or weak ck2β expression was detected in normal colorectal mucosa, with nuclear positivity in 8.7% and cytoplasmic positivity in 13.0% of the cases. Colorectal adenomas showed moderate ck2β expression, with 60% cases showing positivity in the cell nuclei and 40% in the cytoplasm. In colorectal cancers, significantly stronger expression of ck2β was found than that in colorectal adenomas and normal colorectal mucosa (P<0.05), and 75.8% cases showed positivity in the cell nuclei and 62.1% showed cytoplasmic positivity; the expression of ck2β protein in colorectal cancers with lymph node metastasis was even higher (P<0.05). Ck2β knockdown obviously inhibited the proliferation and invasiveness of colorectal cancer cells in vitro.. The high expression of ck2β in colorectal cancer is closely correlated to the carcinogenesis and metastasis of the tumor.

Topics: Adult; Aged; Casein Kinase II; Cell Proliferation; Cell Transformation, Neoplastic; Colorectal Neoplasms; Female; Humans; Intestinal Mucosa; Male; Middle Aged; Tumor Cells, Cultured; Young Adult

Arsenic is a well-known human skin carcinogen but the underlying mechanisms of carcinogenesis are unclear. Transcription factor Nrf2-mediated antioxidant response represents a critical cellular defense mechanism, and emerging data suggest that constitutive activation of Nrf2 contributes to malignant phenotype. In the present study when an immortalized, nontumorigenic human keratinocyte cell line (HaCaT) was continuously exposed to an environmentally relevant level of inorganic arsenite (100 nM) for 28 weeks, malignant transformation occurred as evidenced by the formation of highly aggressive squamous cell carcinoma after inoculation into nude mice. To investigate the mechanisms involved, a broad array of biomarkers for transformation were assessed in these arsenic-transformed cells (termed As-TM). In addition to increased secretion of matrix metalloproteinase-9 (MMP-9), a set of markers for squamous differentiation and skin keratinization, including keratin-1, keratin-10, involucrin, and loricrin, were significantly elevated in As-TM cells. Furthermore, As-TM cells showed increased intracellular glutathione and elevated expression of Nrf2 and its target genes, as well as generalized apoptotic resistance. In contrast to increased basal Nrf2 activity in As-TM cells, a diminished Nrf2-mediated antioxidant response induced by acute exposure to high doses of arsenite or tert-butyl hydroxyquinone occurred. The findings that multiple biomarkers for malignant transformation observed in As-TM cells, including MMP-9 and cytokeratins, are potentially regulated by Nrf2 suggest that constitutive Nrf2 activation may be involved in arsenic carcinogenesis of skin. The weakened Nrf2 activation in response to oxidative stressors observed in As-TM cells, coupled with acquired apoptotic resistance, would potentially have increased the likelihood of transmittable oxidative DNA damage and fixation of mutational/DNA damage events.

Topics: Apoptosis; Arsenites; Casein Kinase II; Cell Line; Cell Nucleus; Cell Transformation, Neoplastic; Humans; Keratinocytes; NF-E2-Related Factor 2

A number of cancers are characterized by elevated expression of CK2 (formerly casein kinase II), which has been implicated as a key component in cell proliferation and transformation. Two lines of evidence, (a) deregulated expression of CK2 and (b) CK2beta ubiquitination and degradation of these in a proteasome-dependent manner prompted further investigation of the regulation of CK2beta protein stability. We demonstrate that mutating six surface-exposed lysine residues to arginine (6KR) to interfere with ubiquitin attachment can stabilize CK2beta. Examination of 6KR expression in cells revealed increased stability over time and increased its steady-state expression level compared with CK2beta. In cells, 6KR was no longer sensitive to proteasome inhibition but maintained an elevated expression level. In our studies, 6KR functioned as a normal CK2 regulatory subunit, because it participated in CK2beta dimerization, associated with catalytic subunits, was autophosphorylated, and formed active, stable CK2 tetramers. The physiological role of CK2beta stabilization was investigated in cell proliferation assays, which showed a significant decrease in proliferation in cells expressing 6KR compared with CK2beta. Overall, our results indicate that a stabilized form of CK2beta can be used to inhibit cell proliferation.

Topics: Amino Acid Sequence; Animals; Casein Kinase II; Cell Proliferation; Cell Transformation, Neoplastic; Chlorocebus aethiops; COS Cells; Gene Expression Regulation; HeLa Cells; Humans; Lysine; Molecular Sequence Data; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Sequence Homology, Amino Acid; Ubiquitin

We have previously shown that the Ste20-like kinase SLK is a microtubule-associated protein inducing actin stress fiber disassembly. Here, we show that v-Src expression can down-regulate SLK activity. This down-regulation is independent of focal adhesion kinase but requires v-Src kinase activity and membrane translocation. SLK down-regulation by v-Src is indirect and is accompanied by SLK hyperphosphorylation on serine residues. Deletion analysis revealed that casein kinase II (CK2) sites at position 347/348 are critical for v-Src-dependent modulation of SLK activity. Further studies show that CK2 can directly phosphorylate SLK at these positions and that inhibition of CK2 in v-Src-transformed cells results in normal kinase activity. Finally, CK2 and SLK can be co-localized in fibroblasts spreading on fibronectin-coated substrates, suggesting a mechanism whereby SLK may be regulated at sites of actin remodeling, such as membrane lamellipodia and ruffles, through CK2.

Topics: Animals; Casein Kinase II; Cell Line; Cell Transformation, Neoplastic; Cytoskeleton; Down-Regulation; Focal Adhesion Protein-Tyrosine Kinases; Humans; Oncogene Protein pp60(v-src); Phosphorylation; Protein Serine-Threonine Kinases; Protein Transport

The PML protein induces senescence, and, upon oncogenic stress, its absence promotes cellular transformation. In this issue of Cell, Scaglioni et al. (2006) show that phosphorylation of PML by CK2, a kinase frequently activated in human cancers, promotes PML degradation. Therefore, pharmacological inhibition of CK2-induced PML loss could be used to offset tumor establishment.

Topics: Carcinoma, Non-Small-Cell Lung; Casein Kinase II; Cell Transformation, Neoplastic; Enzyme Activation; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; Lung Neoplasms; Neoplasm Proteins; Nuclear Proteins; Phosphorylation; Promyelocytic Leukemia Protein; Proteasome Endopeptidase Complex; Transcription Factors; Tumor Suppressor Proteins

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

Theileria annulata and T. parva are protozoa that infect bovine leukocytes which leads to subsequent transformation and uncontrolled proliferation of these cells. It has been proposed that the CKIIalpha subunit of T. parva induces mitogenic pathways of host leukocytes by being exported into the host cell. The evidence for this is the existence of a predicted N-terminal secretion signal-like peptide. We tested this hypothesis by analyzing gene structure, translation, and protein localization of the T. annulata CKIIalpha (TaCKIIalpha). The determined TaCKIIalpha-ORF potentially codes for a 50 kDa protein with an N-terminal extension including a possible signal sequence not present in CKIIalpha proteins of non-Theileria species. However, antisera raised against TaCKIIalpha recognized a protein of a molecular weight of about 40 kDa and, therefore, inconsistent with this predicted molecular weight. We demonstrate by in vitro transcription/translation that this discrepancy is due to translation from a downstream initiation site omitting the putative N-terminal signal sequence and thus excluding the notion that the protein product is secreted via the classical secretory pathway. In corroboration immunofluorescence investigations suggest that the TaCKIIalpha subunit is confined to the parasite schizonts within the host cell. On the basis of the above findings it seems highly unlikely that export via the classical pathway of the parasite CKIIalpha is the way in which this protein possibly contributes to host cell transformation.

Topics: Amino Acid Sequence; Animals; Casein Kinase II; Cell Division; Cell Line; Cell Transformation, Neoplastic; Gene Expression Regulation, Enzymologic; Host-Parasite Interactions; Introns; Molecular Sequence Data; Molecular Weight; Open Reading Frames; Protein Biosynthesis; Protein Serine-Threonine Kinases; Protein Sorting Signals; Protein Transport; Sequence Alignment; Species Specificity; Theileria annulata; Transcription, Genetic

The Her-2/neu oncogene, the second member of the epidermal growth factor (EGF) receptor family, encodes a transmembrane tyrosine kinase receptor. Overexpression of Her-2/neu in approximately 30% of breast cancers is associated with poor overall survival. Recently, we have found that Her-2/neu activates nuclear factor (NF)-kappaB via a phosphatidylinositol 3 kinase (PI3-K)-Akt kinase signaling pathway in mouse mammary tumor virus (MMTV)-Her-2/neu NF639 mouse breast cancer cells. Surprisingly, the IkappaB kinase (IKK) kinase complex, implicated in proteasome-mediated degradation of IkappaB-alpha and activation of NF-kappaB via the canonical pathway, was not activated in these cells. Degradation of IkappaB-alpha was mediated via calpain, which in B cells is facilitated by phosphorylation of IkappaB-alpha by the protein kinase CK2. Here, we report that the inhibition of CK2 blocks Her-2/neu-mediated activation of NF-kappaB. NF639 breast cancer cells, stably expressing CK2alpha or CK2alpha' kinase-inactive mutants, displayed decreased NF-kappaB binding and reduced ability to grow in soft agar, as well as increased sensitivity to tumor necrosis factor (TNF)-alpha killing. Similarly, CK2 kinase-inactive subunits inhibited NF-kappaB activity in Hs578T human breast cancer cells, which also display elevated CK2 activity. In NIH 3T3 fibroblasts, which express low basal NF-kappaB and CK2 activities, overexpression of CK2 by retroviral gene delivery led to increased IkappaB-alpha turnover and the induction of classical NF-kappaB (p50/RelA). Thus, CK2 plays an important role in Her-2/neu signaling, promoting IkappaB-alpha degradation and, thereby, NF-kappaB activation. Furthermore, because ectopic CK2 activity appears sufficient to induce NF-kappaB, the elevated CK2 activity observed in many primary human breast cancers likely plays a role in aberrant activation of NF-kappaB and, therefore, represents a potential therapeutic target.

Topics: 3T3 Cells; Animals; Apoptosis; Breast Neoplasms; Casein Kinase II; Cell Survival; Cell Transformation, Neoplastic; Gene Amplification; Genes, erbB-2; Humans; I-kappa B Proteins; Kidney; Mammary Neoplasms, Experimental; Mice; NF-kappa B; NF-KappaB Inhibitor alpha; Protein Serine-Threonine Kinases; Transcriptional Activation; Transfection; Tumor Cells, Cultured

Nuclear factor-kappaB (NF-kappaB)/Rel transcription factors regulate genes that control cell proliferation, survival, and transformation. In normal breast epithelial cells, NF-kappaB/Rel proteins are mainly sequestered in the cytoplasm bound to one of the specific inhibitory IkappaB proteins, whereas in breast cancers they are activated aberrantly. Human breast tumor cell lines, carcinogen-transformed mammary epithelial cells, and the majority of primary human or rodent breast tumor tissue samples express constitutively high levels of nuclear NF-kappaB/REL: To begin to understand the mechanism of this aberrant NF-kappaB/Rel expression, in this study we measured the activity of the major kinases implicated in regulation of IkappaB stability, namely IKKalpha, IKKbeta, and protein kinase, CK2 (formerly casein kinase II). Hs578T, D3-1, and BP-1 breast cancer cell lines displayed higher levels of IKKalpha, IKKbeta, and CK2 activity than untransformed MCF-10F mammary epithelial cells. Inhibition of IKK activity upon expression of dominant negative kinases or of CK2 activity by treatment with selective inhibitors decreased NF-kappaB/Rel activity in breast cancer cells. Inactivation of the IkappaB kinase complex in Hs578T cells via expression of a dominant negative IKKgamma/NF-kappaB essential modulator/IKK-associated protein 1 reduced soft agar colony growth. Thus, the aberrant expression of CK2 or IKK kinases promotes increased nuclear levels of NF-kappaB/Rel and transformation of breast cancer cells. Furthermore, primary human breast cancer specimens that displayed aberrant constitutive expression of NF-kappaB/Rel were found to exhibit increased CK2 and/or IKK kinase activity. These observations suggest these kinases play a similar role in an intracellular signaling pathway that leads to the elevated NF-kappaB/Rel levels seen in primary human mammary tumors and, therefore, represent potential therapeutic targets in the treatment of patients with breast cancer.

Topics: Breast Neoplasms; Casein Kinase II; Cell Adhesion; Cell Division; Cell Survival; Cell Transformation, Neoplastic; Enzyme Activation; Humans; I-kappa B Kinase; NF-kappa B; Protein Serine-Threonine Kinases; Tumor Cells, Cultured

Protein kinase CK2 is a ubiquitous and evolutionarily conserved serine/threonine kinase that is upregulated in many human cancers and can serve as an oncogene in lymphocytes. Recently, we have demonstrated that CK2 potentiates Wnt/beta-catenin signaling in mammary epithelial cells. To determine whether CK2 overexpression contributes to mammary tumorigenesis, we have performed comparative studies of human and rat breast cancer specimens and we have engineered transgenic mice with dysregulated expression of CK2alpha in the mammary gland. We find that CK2 is highly expressed in human breast tumor specimens and in carcinogen-induced rat mammary tumors. Overexpression of CK2alpha in the mammary gland of transgenic mice, under control of the MMTV-LTR, causes hyperplasia and dysplasia of the female mammary gland. Thirty per cent of the female MMTV-CK2alpha transgenic mice develop mammary adenocarcinomas at a median of 23 months of age, often associated with Wnt pathway activation, as evidenced by upregulation of beta-catenin protein. NF-kappaB activation and upregulation of c-Myc also occur frequently. Thus, in mice, rats, and humans, dysregulated expression of CK2 is associated with and is capable of contributing to mammary tumorigenesis. Targeted inhibition of CK2 could be useful in the treatment of breast cancer.

Topics: Adenocarcinoma; Age of Onset; Animals; beta Catenin; Breast Neoplasms; Casein Kinase II; Cell Transformation, Neoplastic; Cytoskeletal Proteins; Female; Fibrocystic Breast Disease; Humans; Hyperplasia; Lactation; Mammary Glands, Animal; Mammary Neoplasms, Animal; Mammary Tumor Virus, Mouse; Mice; Mice, Transgenic; NF-kappa B; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-myc; Signal Transduction; Trans-Activators; Wnt Proteins; Zebrafish Proteins

Protein kinase CK2 (formerly casein kinase II) is a serine/threonine kinase overexpressed in many human tumors, transformed cell lines, and rapidly proliferating tissues. Recent data have shown that many cancers involve inappropriate reactivation of Wnt signaling through ectopic expression of Wnts themselves, as has been seen in a number of human breast cancers, or through mutation of intermediates in the Wnt pathway, such as adenomatous polyposis coli or beta-catenin, as described in colon and other cancers. Wnts are secreted factors that are important in embryonic development, but overexpression of certain Wnts, such as Wnt-1, leads to proliferation and transformation of cells. We report that upon stable transfection of Wnt-1 into the mouse mammary epithelial cell line C57MG, morphological changes and increased proliferation are accompanied by increased levels of CK2, as well as of beta-catenin. CK2 and beta-catenin co-precipitate with the Dvl proteins, which are Wnt signaling intermediates. A major phosphoprotein of the size of beta-catenin appears in in vitro kinase reactions performed on the Dvl immunoprecipitates. In vitro translated beta-catenin, Dvl-2, and Dvl-3 are phosphorylated by CK2. The selective CK2 inhibitor apigenin blocks proliferation of Wnt-1-transfected cells, abrogates phosphorylation of beta-catenin, and reduces beta-catenin and Dvl protein levels. These results demonstrate that endogenous CK2 is a positive regulator of Wnt signaling and growth of mammary epithelial cells.

Topics: Adaptor Proteins, Signal Transducing; Animals; Apigenin; beta Catenin; Casein Kinase II; Cell Line; Cell Transformation, Neoplastic; Cytoskeletal Proteins; Dishevelled Proteins; Epithelial Cells; Flavonoids; Mammary Glands, Animal; Mice; Mitogens; Models, Genetic; Phosphoproteins; Phosphorylation; Protein Binding; Protein Serine-Threonine Kinases; Proteins; Proto-Oncogene Proteins; Signal Transduction; Trans-Activators; Transfection; Up-Regulation; Wnt Proteins; Wnt1 Protein; Zebrafish Proteins

Timely deactivation of kinase cascades is crucial to the normal control of cell signaling and is partly accomplished by protein phosphatase 2A (PP2A). The catalytic (alpha) subunit of the serine-threonine kinase casein kinase 2 (CK2) bound to PP2A in vitro and in mitogen-starved cells; binding required the integrity of a sequence motif common to CK2alpha and SV40 small t antigen. Overexpression of CK2alpha resulted in deactivation of mitogen-activated protein kinase kinase (MEK) and suppression of cell growth. Moreover, CK2alpha inhibited the transforming activity of oncogenic Ras, but not that of constitutively activated MEK. Thus, CK2alpha may regulate the deactivation of the mitogen-activated protein kinase pathway.

Topics: 3T3 Cells; Amino Acid Sequence; Animals; Antigens, Polyomavirus Transforming; Binding Sites; Casein Kinase II; Cell Division; Cell Transformation, Neoplastic; MAP Kinase Kinase 1; Mice; Mitogen-Activated Protein Kinase Kinases; Mutation; Okadaic Acid; Phosphoprotein Phosphatases; Phosphorylation; Platelet-Derived Growth Factor; Protein Phosphatase 2; Protein Serine-Threonine Kinases; Protein-Tyrosine Kinases; ras Proteins; Recombinant Fusion Proteins; Transfection

We hypothesized that malignant transformation of normal mucosa of the upper aerodigestive tract to squamous cell carcinoma of the head and neck (SCCHN) might be associated with altered CK2 activity in the chromatin compartment of these tumors. We measured CK2 activity in the cytosol and chromatin of 7 surgical specimens of SCCHN, and 5 specimens of normal oropharyngeal mucosa from non-smokers/non-drinkers. CK2 activity in SCCHN tumors was significantly elevated in both the nuclear chromatin (P < 0.0005) and cytosolic (P <0.04) compartments relative to normal mucosa. These data suggest that activation of dysregulation of the chromatin-associated CK2 signal may play a role in the pathobiology od SCCHN.

Topics: Amino Acid Sequence; Base Sequence; Biomarkers, Tumor; Carcinoma, Squamous Cell; Casein Kinase II; Cell Nucleus; Cell Transformation, Neoplastic; Chromatin; Cytosol; Head and Neck Neoplasms; Humans; Molecular Sequence Data; Mouth Mucosa; Oligopeptides; Protein Serine-Threonine Kinases; Reference Values

Infection of cattle with the protozoan parasite Theileria parva results in a fatal lymphoproliferative syndrome that is associated with the overexpression of casein kinase II. The role of this enzyme in the pathogenesis of lymphoproliferative disorders was investigated by expressing the catalytic subunit in lymphocytes of transgenic mice. Adult transgenic mice displayed a stochastic propensity to develop lymphoma; co-expression of a c-myc transgene in addition to casein kinase II resulted in neonatal leukemia. Thus, the casein kinase II gene can serve as an oncogene, and its dysregulated expression is capable of transforming lymphocytes in a two-step pathway with c-myc.

Topics: Amino Acid Sequence; Animals; Base Sequence; Casein Kinase II; Cattle; Cell Transformation, Neoplastic; Cloning, Molecular; Gene Expression Regulation, Enzymologic; Gene Rearrangement, T-Lymphocyte; Genes, myc; Leukemia; Lymphocytes; Lymphoma; Mice; Mice, Transgenic; Molecular Sequence Data; Protein Serine-Threonine Kinases; Theileriasis; Up-Regulation

Protein kinase CK2 (also known as casein kinase 2) is a messenger-independent protein serine/threonine kinase ubiquitously distributed in eukaryotes. CK2 has been found to phosphorylate a wide variety of cytosolic and nuclear substrates which are intimately involved in regulation of DNA, RNA, and protein synthesis, and differentiation. We therefore addressed the hypothesis that malignant transformation of upper aerodigestive tract mucosa to squamous cell carcinoma of the head and neck (SCCHN) might be associated with altered CK2 activity.. To this end, we subjected surgical specimens of SCCHN tumors and of normal oropharyngeal mucosa to subcellular fractionation. We then quantitated CK2 activity in cytosol and nuclei of these specimens using a CK2-specific peptide substrate (Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu).. We found that CK2 activity was significantly elevated in both nuclear (p < 0.0005) and cytosolic (p < 0.0034) compartments of SCCHN tumors, relative to normal oropharyngeal mucosa. Moreover, CK2 activity in the cellular cytosolic fraction of SCCHN tumors was associated with less differentiated histologic grade (p < 0.037), positive nodal metastatic status (p < 0.056), and a poor clinical outcome (p < 0.028). Kaplan-Meier cumulative survival analysis revealed greatly reduced survival in the high-CK2 activity patient group, with high statistical significance (p < 0.023).. These preliminary data reveal that malignant transformation of the upper aerodigestive tract mucosa is associated with altered CK2 activity. The results further suggest that dysregulation of this protein kinase may play a significant role in the pathobiology of SCCHN, and that CK2 activity may be a prognostic indicator in this malignancy.

Topics: Adult; Aged; Amino Acid Sequence; Biomarkers, Tumor; Carcinoma, Squamous Cell; Casein Kinase II; Cell Nucleus; Cell Transformation, Neoplastic; Cytosol; Female; Head and Neck Neoplasms; Humans; Lymphatic Metastasis; Male; Middle Aged; Molecular Sequence Data; Mucous Membrane; Oligopeptides; Oropharynx; Prognosis; Protein Serine-Threonine Kinases; Reference Values; Substrate Specificity; Survival Rate

Caveolae are flask-shaped micro-invaginations associated with the plasma membrane of a wide variety of cell types. Caveolin, an integral membrane component of caveolae, was first identified as the major phosphoprotein whose phosphorylation was elevated in v-Src transformed cells. As both v-Src transformation and elevated caveolin phosphorylation were dependent on membrane attachment of v-Src, it has been suggested that caveolin is a critical target in v-Src transformation. Although an increase in tyrosine phosphorylation of caveolin was evident, the increase in caveolin phosphorylation was predominantly on serine residues. In accordance with these in vivo observations, isolated caveolin-rich membrane domains undergo phosphorylation in vitro predominantly on serine and contain an unidentified serine kinase activity. Here, we have identified this serine kinase activity as a casein kinase II-like enzyme, since the phosphorylation of caveolin-rich membrane domains is stimulated and inhibited by known effectors of casein kinase II (poly-L-lysine, endogenous polyamines, and a casein kinase II inhibitor peptide), but is unaffected by modulators of other known kinases. In support of these observations, caveolin contains a consensus sequence for casein kinase II phosphorylation in its cytoplasmic N-terminal domain (Ser-88). A peptide containing this sequence inhibits the in vitro phosphorylation of caveolin-rich membrane domains, while many other peptides derived from the N-terminal domain of caveolin do not affect phosphorylation. Caveolin-rich membrane domains were also a substrate for exogenously added purified casein kinase II, but not casein kinase I. Finally, immunoblotting of these domains with an antibody directed against the alpha and alpha' subunits of casein kinase II reveals two bands with apparent molecular weights consistent with the known molecular weights of the alpha and alpha' subunits of casein kinase II. As casein kinase II appears to play a role in mitogenic signalling events and casein kinase II activators (endogenous polyamines) are required for v-Src transformation, our results may have implications for understanding the mechanism of v-Src oncogenesis.

Topics: Amino Acid Sequence; Animals; Casein Kinase II; Caveolin 1; Caveolins; Cell Transformation, Neoplastic; Cells, Cultured; Genes, src; Membrane Proteins; Molecular Sequence Data; Phosphorylation; Protein Serine-Threonine Kinases