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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. Source

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. Source

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. Source

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. Source

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. Source

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