casein-kinase-ii and Pancreatic-Neoplasms

Casein kinase II (CK2) and cyclin-dependent kinases (CDKs) frequently interact within multiple pathways in pancreatic ductal adenocarcinoma (PDAC). Application of CK2- and CDK-inhibitors have been considered as a therapeutic option, but are currently not part of routine chemotherapy regimens. We investigated ten PDAC cell lines exposed to increasing concentrations of silmitasertib and dinaciclib. Cell proliferation, metabolic activity, biomass, and apoptosis/necrosis were evaluated, and bioinformatic clustering was used to classify cell lines into sensitive groups based on their response to inhibitors. Furthermore, whole exome sequencing (WES) and RNA sequencing (RNA-Seq) was conducted to assess recurrent mutations and the expression profile of inhibitor targets and genes frequently mutated in PDAC, respectively. Dinaciclib and silmitasertib demonstrated pronounced and limited cell line specific effects in cell death induction, respectively. WES revealed no genomic variants causing changes in the primary structure of the corresponding inhibitor target proteins. RNA-Seq demonstrated that the expression of all inhibitor target genes was higher in the PDAC cell lines compared to non-neoplastic pancreatic tissue. The observed differences in PDAC cell line sensitivity to silmitasertib or dinaciclib did not depend on target gene expression or the identified gene variants. For the PDAC hotspot genes kirsten rat sarcoma virus (

Topics: Carcinoma, Pancreatic Ductal; Casein Kinase II; Cell Line; Cell Line, Tumor; Cell Proliferation; Cyclic N-Oxides; Humans; Indolizines; Naphthyridines; Pancreatic Neoplasms; Phenazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins p21(ras); Pyridinium Compounds

Pancreatic cancer (PC) evades immune destruction by favoring the development of regulatory T cells (Tregs) that inhibit effector T cells. The transcription factor Ikaros is critical for lymphocyte development, especially T cells. We have previously shown that downregulation of Ikaros occurs as a result of its protein degradation by the ubiquitin-proteasome system in our Panc02 tumor-bearing (TB) mouse model. Mechanistically, we observed a deregulation in the balance between Casein Kinase II (CK2) and protein phosphatase 1 (PP1), which suggested that increased CK2 activity is responsible for regulating Ikaros' stability in our model. We also showed that this loss of Ikaros expression is associated with a significant decrease in CD4+ and CD8+ T cell percentages but increased CD4+CD25+ Tregs in TB mice. In this study, we evaluated the effects of the dietary flavonoid apigenin (API), on Ikaros expression and T cell immune responses. Treatment of splenocytes from naïve mice with (API) stabilized Ikaros expression and prevented Ikaros downregulation in the presence of murine Panc02 cells in vitro, similar to the proteasome inhibitor MG132. In vivo treatment of TB mice with apigenin (TB-API) improved survival, reduced tumor weights and prevented splenomegaly. API treatment also restored protein expression of some Ikaros isoforms, which may be attributed to its moderate inhibition of CK2 activity from splenocytes of TB-API mice. This partial restoration of Ikaros expression was accompanied by a significant increase in CD4+ and CD8+ T cell percentages and a reduction in Treg percentages in TB-API mice. In addition, CD8+ T cells from TB-API mice produced more IFN-γ and their splenocytes were better able to prime allogeneic CD8+ T cell responses compared to TB mice. These results provide further evidence that Ikaros is regulated by CK2 in our pancreatic cancer model. More importantly, our findings suggest that API may be a possible therapeutic agent for stabilizing Ikaros expression and function to maintain T cell homeostasis in murine PC.

Topics: Animals; Apigenin; Casein Kinase II; Cell Line, Tumor; Down-Regulation; Female; Homeostasis; Ikaros Transcription Factor; Leupeptins; Lymphocyte Culture Test, Mixed; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Pancreatic Neoplasms; Proteasome Inhibitors; Protein Phosphatase 1; T-Lymphocytes; Tumor Suppressor Proteins

Pancreatic cancer is the most lethal malignancy with only a few effective chemotherapeutic drugs. Because the inhibition of casein kinase 2 (CK2) has been reported as a novel therapeutic strategy for many cancers, we investigated the effects of CK2 inhibitors in pancreatic cancer cell lines.. The BxPC3, 8902, MIA PaCa-2 human pancreatic cancer cell lines, and CX-4945, a novel CK2 inhibitor, were used. Autophagy was analyzed by acridine orange staining, fluorescence microscope detection of punctuate patterns of GFP-tagged LC3 and immunoblotting for LC3. Cell survival, cell cycle, and apoptosis analysis was performed.. CX-4945 induced significant inhibition of proliferation and triggered autophagy in pancreatic cancer cells. This suppression of proliferation was caused by the direct inhibition of CK2α, which was required for autophagy and apoptosis in pancreatic cancer cells. CX-4945 suppressed cell cycle progression in G2/M and induced apoptosis. The inhibition of CX-4945-induced autophagy was rescued by 3-methyladenine or small interfering RNA against Atg7, which attenuated apoptosis in pancreatic cancer cells.. CX-4945, a potent and selective inhibitor of CK2, effectively induces autophagy and apoptosis in pancreatic cancer cells, indicating that the induction of autophagy by CX-4945 may have an important role in the treatment of pancreatic cancer.

Topics: Adenine; Apoptosis; Autophagy; Casein Kinase II; Cell Cycle; Cell Line, Tumor; Cell Survival; G2 Phase Cell Cycle Checkpoints; Humans; Naphthyridines; Pancreatic Neoplasms; Phenazines; RNA Interference

Maintenance of T cell immune homeostasis is critical for adequate anti-tumor immunity. The transcription factor Ikaros is essential for lymphocyte development including T cells. Alterations in Ikaros expression occur in blood malignancies in humans and mice. In this study, we investigated the role of Ikaros in regulating T cell immune balance in pancreatic cancer mouse models.. Using our Panc02 tumor-bearing (TB) mouse model, western blot analysis revealed a reduction in Ikaros proteins while qRT-PCR showed no differences in Ikaros mRNA levels in TB splenocytes compared to control. Treatment of naïve splenocytes with the proteasomal inhibitor, MG132, stabilized Ikaros expression and prevented Ikaros downregulation by Panc02 cells, in vitro. Western blot analyses showed a reduction in protein phosphatase 1 (PP1) and protein kinase CK2 expression in TB splenocytes while CK2 activity was increased. Immunofluorescence microscopy revealed altered punctate staining of Ikaros in TB splenocytes. Flow cytometry revealed a significant decrease in effector CD4+ and CD8+ T cell percentages but increased CD4+CD25+ regulatory T cells in TB splenocytes. Similar alterations in T cell percentages, as well as reduced Ikaros and CK2 but not PP1 expression, were observed in a transgenic, triple mutant (TrM) pancreatic cancer model. Ikaros expression was also reduced in enriched TB CD3+ T cells. MG132 treatment of naïve CD3+ T cells stabilized Ikaros expression in the presence of Panc02 cells. Western blots showed reduced PP1 and CK2 expression in TB CD3+ T cells.. The results of this study suggest that the pancreatic tumor microenvironment may cause proteasomal degradation of Ikaros, possibly via dysregulation of PP1 and CK2 expression and activity, respectively. This loss of Ikaros expression may contribute to an imbalance in T cell percentages. Ikaros may potentially be a therapeutic target to restore T cell homeostasis in pancreatic cancer hosts, which may be critical for effective anti-tumor immunity.

Topics: Adenocarcinoma; Animals; Casein Kinase II; CD3 Complex; Cell Line, Tumor; Disease Models, Animal; Female; Gene Expression Regulation, Neoplastic; Homeostasis; Ikaros Transcription Factor; Lymphocyte Count; Mice; Pancreatic Neoplasms; Proteasome Endopeptidase Complex; Proteolysis; Receptors, Neuropeptide Y; T-Lymphocytes; Ubiquitin

Numerous studies have shown that platinum compounds stimulate the expression of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase resulting in anti-proliferative activity and apoptosis. As many cancer cell types including pancreatic cancer cells express high levels of polyamines, the possibility to develop anti-tumor strategies to deplete polyamine pools has drawn considerable attention in recent years. This has been effectively accomplished by treating cells with platinum drugs in combination with polyamine analogs such as N(1),N(11)-diethylnorspermine (DENSPM). The present study, examined the cytotoxic effects of oxaliplatin in combination with stimulators of polyamine catabolism in human pancreatic cancer cells, that are notoriously resistant to chemotherapeutic treatment, and colorectal cancer cells. Additionally, as protein kinase CK2 has been shown to be an anti-apoptotic and pro-survival enzyme regulated by the intracellular polyamine pools, we aimed to investigate the effect of combined DENSPM and oxaliplatin treatment on CK2-mRNA and -protein levels. Results reported here show that treatment with oxaliplatin and DENSPM in combination impairs cell viability particularly in the case of colorectal cancer cells. The analysis of CK2 expression and activity indicates that the response to a specific treatment may depend on the impact that individual compounds exert on pro-survival and pro-death proteins at the transcription and translation levels that should be carefully evaluated in view of subsequent clinical studies.

Topics: Acetyltransferases; Antineoplastic Agents; Casein Kinase II; Cell Death; Cell Line, Tumor; Cell Proliferation; Cell Survival; Colorectal Neoplasms; Drug Synergism; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Organoplatinum Compounds; Oxaliplatin; Pancreatic Neoplasms; Polyamines; RNA, Messenger; Spermine

Pancreatic cancer is a complex genetic disorder that is characterized by rapid progression, invasiveness, resistance to treatment and high molecular heterogeneity. Various agents have been used in clinical trials showing only modest improvements with respect to gemcitabine-based chemotherapy, which continues to be the standard first-line treatment for this disease. However, owing to the overwhelming molecular alterations that have been reported in pancreatic cancer, there is increasing focus on targeting molecular pathways and networks, rather than individual genes or gene-products with a combination of novel chemotherapeutic agents.. Cells were transfected with small interfering RNAs (siRNAs) targeting the individual CK2 subunits. The CK2 protein expression levels were determined and the effect of its down-regulation on chemosensitization of pancreatic cancer cells was investigated.. The present study examined the impact on cell death following depletion of the individual protein kinase CK2 catalytic subunits alone or in combination with gemcitabine and the molecular mechanisms by which this effect is achieved. Depletion of the CK2alpha or -alpha' subunits in combination with gemcitabine resulted in marked apoptotic and necrotic cell death in PANC-1 cells. We show that the mechanism of cell death is associated with deregulation of distinct survival signaling pathways. Cellular depletion of CK2alpha leads to phosphorylation and activation of MKK4/JNK while down-regulation of CK2alpha' exerts major effects on the PI3K/AKT pathway.. Results reported here show that the two catalytic subunits of CK2 contribute differently to enhance gemcitabine-induced cell death, the reduced level of CK2alpha' being the most effective and that simultaneous reduction in the expression of CK2 and other survival factors might be an effective therapeutic strategy for enhancing the sensitivity of human pancreatic cancer towards chemotherapeutic agents.

Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Pancreatic Ductal; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Deoxycytidine; Gemcitabine; Humans; Pancreatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; Signal Transduction

Malignant transformation and maintenance of the malignant phenotype depends on oncogenic and non-oncogenic proteins that are essential to mediate oncogene signaling and to support the altered physiologic demands induced by transformation. Protein kinase CK2 supports key prosurvival signaling pathways and represents a prototypical non-oncogene. In this study, we describe CX-4945, a potent and selective orally bioavailable small molecule inhibitor of CK2. The antiproliferative activity of CX-4945 against cancer cells correlated with expression levels of the CK2α catalytic subunit. Attenuation of PI3K/Akt signaling by CX-4945 was evidenced by dephosphorylation of Akt on the CK2-specific S129 site and the canonical S473 and T308 regulatory sites. CX-4945 caused cell-cycle arrest and selectively induced apoptosis in cancer cells relative to normal cells. In models of angiogenesis, CX-4945 inhibited human umbilical vein endothelial cell migration, tube formation, and blocked CK2-dependent hypoxia-induced factor 1 alpha (HIF-1α) transcription in cancer cells. When administered orally in murine xenograft models, CX-4945 was well tolerated and demonstrated robust antitumor activity with concomitant reductions of the mechanism-based biomarker phospho-p21 (T145). The observed antiproliferative and anti-angiogenic responses to CX-4945 in tumor cells and endothelial cells collectively illustrate that this compound exerts its antitumor effects through inhibition of CK2-dependent signaling in multiple pathways. Finally, CX-4945 is the first orally bioavailable small molecule inhibitor of CK2 to advance into human clinical trials, thereby paving the way for an entirely new class of targeted treatment for cancer.

Topics: Administration, Oral; Animals; Biological Availability; Casein Kinase II; Cell Line, Tumor; Endothelial Cells; Female; HeLa Cells; Humans; Inflammatory Breast Neoplasms; Mice; Naphthyridines; Neovascularization, Pathologic; Pancreatic Neoplasms; Phenazines; Protein Kinase Inhibitors; Random Allocation; Xenograft Model Antitumor Assays

A panel of kinases whose inhibition increased apoptosis of pancreatic adenocarcinoma cells in vitro was recently established. The aim of this work was to observe in a mouse xenograft model whether inhibition of these kinases would alter pancreatic tumor growth. Rate of apoptosis, caspase-3 activity and cell viability were assessed in two pancreatic cancer cell lines, MiaPaCa2 and BxPC3, after inhibiting selected kinases by transfection of specific siRNAs. For in vivo experiments, MiaPaCa2 cells were injected into the pancreas of nude mice, where they formed tumors. Inhibition of kinases was obtained by repeated intraperitoneal (i.p.) injections of modified O-Methyl (OMe) siRNAs specific for the selected kinases. Tumor volumes were assessed after 21 days. Among selected kinases, PAK7, MAP3K7 and CK2alpha were those whose inhibition increased apoptosis the most in vitro. Simultaneous inhibition of two of them increased apoptosis up to five times. Moreover, inhibiting these kinases had little effect on 10 non-pancreatic cell lines, suggesting pancreatic specificity. In vivo, OMe-siRNAs induced significant but incomplete inhibition of kinase expression (45-75%). Nevertheless, such inhibition resulted in a twofold increase in caspase-3 activity in tumors and a strong reduction in tumor volume (about 75%). In vivo inhibition by OMe-siRNAs of three survival kinases apparently specific for pancreatic cancer cells, PAK7, MAP3K7 and CK2alpha, decreases significantly the growth of xenografted MiaPaCa2 cells. This strategy is therefore of potential clinical interest.

Topics: Animals; Apoptosis; Casein Kinase II; Cell Line, Tumor; Disease Progression; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Genetic Therapy; Male; MAP Kinase Kinase Kinases; Mice; Mice, Nude; p21-Activated Kinases; Pancreatic Neoplasms; RNA, Messenger; RNA, Small Interfering; Xenograft Model Antitumor Assays

Pancreatic cancer is one of the most common causes of cancer death in western civilization. The five-year survival rate is below 1% and of the 10% of patients with resectable disease only around one-fifth survives 5 years. Survival rates have not changed much during the last 20 years, demonstrating the inefficacy of current available therapies. To improve the prognosis of pancreatic cancer, there is the need to develop effective non-surgical treatment for this disease. The protein kinase casein kinase II (CK2) is a ubiquitously expressed serine-threonine kinase and its activity is enhanced in all human tumors examined so far. The contribution of CK2 to the tumor maintenance of pancreatic cancer has not been investigated. To investigate the function of CK2 in pancreatic cancer cells we used the CK2 specific inhibitors 5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole and Apigenin. Furthermore, we interfered with CK2 expression using CK2 specific siRNAs. Interfering with CK2 function led to a reduction of pancreatic cancer cell viability, which was due to caspase-dependent apoptosis. The induction of apoptosis correlated with a reduced NF-kappaB-dependent transcriptional activity. This study validates CK2 as a molecular drug target in a preclinical in vitro model of pancreatic cancer.

Topics: Apoptosis; Casein Kinase II; Cell Survival; Humans; Oligodeoxyribonucleotides; Pancreatic Neoplasms; Protein Kinase Inhibitors; RNA, Small Interfering; Transfection; Tumor Cells, Cultured

The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.

Topics: Adenosine Triphosphate; Animals; Calcium; Casein Kinase II; Cell Line; Cytoplasmic Granules; Egtazic Acid; Exocytosis; Insulin; Insulin Secretion; Insulinoma; Islets of Langerhans; Kinesins; Kinetics; Pancreatic Neoplasms; Phosphates; Phosphoprotein Phosphatases; Phosphorylation; Protein Kinases; Protein Serine-Threonine Kinases; Protein Subunits; Protein Transport; Rats; Tumor Cells, Cultured