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Bywater M.J.,University of Melbourne | Poortinga G.,University of Melbourne | Sanij E.,University of Melbourne | Wall M.,St Vincents Hospital | And 21 more authors.
Cancer Cell | Year: 2012

Increased transcription of ribosomal RNA genes (rDNA) by RNA Polymerase I is a common feature of human cancer, but whether it is required for the malignant phenotype remains unclear. We show that rDNA transcription can be therapeutically targeted with the small molecule CX-5461 to selectively kill B-lymphoma cells in vivo while maintaining a viable wild-type B cell population. The therapeutic effect is a consequence of nucleolar disruption and activation of p53-dependent apoptotic signaling. Human leukemia and lymphoma cell lines also show high sensitivity to inhibition of rDNA transcription that is dependent on p53 mutational status. These results identify selective inhibition of rDNA transcription as a therapeutic strategy for the cancer specific activation of p53 and treatment of hematologic malignancies. © 2012 Elsevier Inc..


Drygin D.,Cylene Pharmaceuticals | O'Brien S.E.,Senhwa Biosciences | Hannan R.D.,University of Melbourne | McArthur G.A.,University of Melbourne | Von Hoff D.D.,Translational Genomics Research Institute
Drug Discovery Today | Year: 2014

The tumor suppressor protein p53 plays a crucial part in the cellular defense against malignancies. DNA-damaging chemotherapeutics rely on the activation of p53 for their anticancer activity at the expense of genotoxicity. Nongenotoxic approaches for p53 activation have been extensively investigated validating p53 as a therapeutic target. However, their development has been hampered by low efficacy and a narrow therapeutic window. An alternate nongenotoxic approach for cancer-specific activation of wild-type p53 has been recently identified. It relies on the activation of a cellular checkpoint mechanism termed 'nucleolar stress', which can be triggered by acute inhibition of rRNA biogenesis. CX5461, the first selective inhibitor of rRNA biogenesis, and thus a potent activator of nucleolar stress, is poised to enter clinical development. © 2013 Elsevier Ltd.


Martins L.R.,University of Lisbon | Lucio P.,New University of Lisbon | Silva M.C.,University of Lisbon | Anderes K.L.,Cylene Pharmaceuticals | And 3 more authors.
Blood | Year: 2010

Expression of protein kinase CK2 is frequently deregulated in cancer and mounting evidence implicates CK2 in tumorigenesis. Here, we show that CK2 is overexpressed and hyperactivated in chronic lymphocytic leukemia (CLL). Inhibition of CK2 induces apoptosis of CLL cells without significantly affecting normal B and T lymphocytes. Importantly, this effect is not reversed by coculture with OP9 stromal cells, which are otherwise capable of rescuing CLL cells from in vitro spontaneous apoptosis. CLL cell death upon CK2 inhibition is mediated by inactivation of PKC, a PI3K downstream target, and correlates with increased PTEN activity, indicating that CK2 promotes CLL cell survival at least in part via PI3K-dependent signaling. Although CK2 antagonists induce significant apoptosis of CLL cells in all patient samples analyzed, sensitivity to CK2 blockade positively correlates with the percentage of CLL cells in the peripheral blood, β2 microglobulin serum levels and clinical stage. These data suggest that subsets of patients with aggressive and advanced stage disease may especially benefit from therapeutic strategies targeting CK2 function. Overall, our study indicates that CK2 plays a critical role in CLL cell survival, laying the groundwork for the inclusion of CK2 inhibitors into future therapeutic strategies. © 2010 by The American Society of Hematology.


Zheng Y.,University of Alabama at Birmingham | McFarland B.C.,University of Alabama at Birmingham | Drygin D.,Cylene Pharmaceuticals | Yu H.,University of Alabama at Birmingham | And 4 more authors.
Clinical Cancer Research | Year: 2013

Purpose: Gliomas are the most frequently occurring primary malignancies in the brain, and glioblastoma is the most aggressive of these tumors. Protein kinase CK2 is composed of two catalytic subunits (α and/or α') and two β regulatory subunits. CK2 suppresses apoptosis, promotes neoangiogenesis, and enhances activation of the JAK/STAT, NF-κB, PI3K/AKT, Hsp90, Wnt, and Hedgehog pathways. Aberrant activation of the NF-κB, PI3Kappa;/AKT, and JAK/STAT-3 pathways is implicated in glioblastoma progression. As CK2 is involved in their activation, the expression and function of CK2 in glioblastoma was evaluated. Experimental Design and Results: Analysis of 537 glioblastomas from The Cancer Genome Atlas Project demonstrates the CSNK2A1 gene, encoding CK2α, has gene dosage gains in glioblastoma (33.7%), and is significantly associated with the classical glioblastoma subtype. Inhibition of CK2 activity by CX-4945, a selective CK2 inhibitor, or CK2 knockdown by siRNA suppresses activation of the JAK/STAT, NF-κB, and AKT pathways and downstream gene expression in human glioblastoma xenografts. On a functional level, CX-4945 treatment decreases the adhesion and migration of glioblastoma cells, in part through inhibition of integrin β1 and α4 expression. In vivo, CX-4945 inhibits activation of STAT-3, NF-κB p65, and AKT, and promotes survival of mice with intracranial human glioblastoma xenografts. CK2 inhibitors may be considered for treatment of patients with glioblastoma. © 2013 American Association for Cancer Research.


Regan C.F.,Cylene Pharmaceuticals | Pierre F.,Cylene Pharmaceuticals | Schwaebe M.K.,Cylene Pharmaceuticals | Haddach M.,Cylene Pharmaceuticals | And 2 more authors.
Synlett | Year: 2012

This paper reports the synthesis of various 5-halopyrimidine-4-carboxylic acid esters via the Minisci homolytic alkoxycarbonylation of 5-halopyrimidines. The reaction was found to be highly regioselective, allowing the one-step synthesis of useful amounts (>10 g) of ethyl 5-bromopyrimidine-4-carboxylate where other methods proved difficult. Ethyl 5-bromopyrimidine-4-carboxylate was used for the preparation of potent CK2 inhibitors including CX-5011. This work represents an interesting application of radical chemistry for the preparation of pharmacologically active molecules. © Georg Thieme Verlag Stuttgart · New York.


Zanin S.,University of Padua | Borgo C.,University of Padua | Girardi C.,University of Padua | O'Brien S.E.,Cylene Pharmaceuticals | And 6 more authors.
PLoS ONE | Year: 2012

CK2 is a pleiotropic protein kinase, which regulates many survival pathways and plays a global anti-apoptotic function. It is highly expressed in tumor cells, and is presently considered a promising therapeutic target. Among the many inhibitors available for this kinase, the recently developed CX-4945 and CX-5011 have proved to be very potent, selective and effective in inducing cell death in tumor cells; CX-4945 has recently entered clinical trials. However, no data are available on the efficacy of these compounds to overcome drug resistance, a major reasons of cancer therapy failure. Here we address this point, by studying their effects in several tumor cell lines, each available as variant R resistant to drug-induced apoptosis, and normal-sensitive variant S. We found that the inhibition of endogenous CK2 was very similar in S and R treated cells, with more than 50% CK2 activity reduction at sub-micromolar concentrations of CX-4945 and CX-5011. A consequent apoptotic response was induced both in S and R variants of each pairs. Moreover, the combined treatment of CX-4945 plus vinblastine was able to sensitize to vinblastine R cells that are otherwise almost insensitive to this conventional antitumor drug. Consistently, doxorubicin accumulation in multidrug resistant (MDR) cells was greatly increased by CX-4945. In summary, we demonstrated that all the R variants are sensitive to CX-4945 and CX-5011; since some of the treated R lines express the extrusion pump Pgp, often responsible of the MDR phenotype, we can also conclude that the two inhibitors can successfully overcome the MDR phenomenon. © 2012 Zanin et al.


Siddiqui-Jain A.,Cylene Pharmaceuticals | Drygin D.,Cylene Pharmaceuticals | Streiner N.,Cylene Pharmaceuticals | Chua P.,Cylene Pharmaceuticals | And 11 more authors.
Cancer Research | Year: 2010

Malignant transformation and maintenance of the malignant phenotype depends on oncogenic and nononcogenic proteins that are essential tomediate 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. Inmodels 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 inmurine xenograft models,CX-4945waswell 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. ©2010 AACR.


Siddiqui-Jain A.,Cylene Pharmaceuticals | Bliesath J.,Cylene Pharmaceuticals | Macalino D.,Cylene Pharmaceuticals | Omori M.,Cylene Pharmaceuticals | And 11 more authors.
Molecular Cancer Therapeutics | Year: 2012

Drug combination therapies are commonly used for the treatment of cancers to increase therapeutic efficacy, reduce toxicity, and decrease the incidence of drug resistance.Althoughdrug combination therapies were originally devised primarily by empirical methods, the increased understanding of drug mechanisms and the pathways they modulate provides a unique opportunity to design combinations that are based on mechanistic rationale.We have identified protein kinase CK2 as a promising therapeutic target for combination therapy, because CK2 regulates not just one butmany oncogenic pathways and processes that play important roles in drug resistance, includingDNArepair, epidermal growth factor receptor signaling,PI3K/AKT/mTORsignaling, Hsp90machinery activity, hypoxia, and interleukin-6 expression. In this article, we show that CX-4945, a clinical stage selective small molecule inhibitor of CK2, blocks the DNA repair response induced by gemcitabine and cisplatin and synergizes with these agents inmodels of ovarian cancer.Mechanistic studies show that the enhanced activity is a result of inactivation of XRCC1 andMDC1, two mediator/adaptor proteins that are essential for DNA repair and that require phosphorylation by CK2 for their function. These data position CK2 as a valid pharmacologic target for intelligent drug combinations and support the evaluation of CX-4945 in combination with gemcitabine and platinum-based chemotherapeutics in the clinical setting. ©2012 AACR.


Bliesath J.,Cylene Pharmaceuticals | Huser N.,Cylene Pharmaceuticals | Omori M.,Cylene Pharmaceuticals | Bunag D.,Cylene Pharmaceuticals | And 10 more authors.
Cancer Letters | Year: 2012

Ser/Thr protein kinase CK2 regulates multiple processes that play important roles in the sensitivity of cancer to epidermal growth factor receptor targeting therapeutics, including PI3K-Akt-mTOR signaling, Hsp90 activity, and inhibition of apoptosis. We hypothesized that top-down inhibition of EGFR, combined with lateral suppression of multiple oncogenic pathways by targeting CK2, would create a pharmacologic synthetic lethal event and result in an improved cancer therapy compared to EGFR inhibition alone. This hypothesis was tested by combining CX-4945, a first-in-class clinical stage inhibitor of CK2, with the EGFR tyrosine kinase inhibitor, erlotinib, in vitro and in vivo in models of non-small cell lung carcinoma, NCI-H2170, and squamous cell carcinoma, A431. Our results demonstrate that combination of CX-4945 with erlotinib results in enhanced attenuation of the PI3K-Akt-mTOR pathway. We also observed an increase in apoptosis, synergistic killing of cancer cells in vitro, as well as improved antitumor efficacy in vivo. Taken together, these data position CK2 as a valid pharmacologic target for drug combinations and support further evaluation of CX-4945 in combination with EGFR targeting agents. © 2012 Elsevier Ireland Ltd.

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