Palbociclib, a selective CDK4/6 kinase inhibitor, is approved in combination with endocrine therapies for the treatment of advanced estrogen receptor positive (ER+) breast cancer. In pre-clinical cancer models, CDK4/6 inhibitors act primarily as cytostatic agents. In two commonly studied ER+ breast cancer cell lines (MCF7 and T47D), CDK4/6 inhibition drives G1-phase arrest and the acquisition of a senescent-like phenotype, both of which are reversible upon palbociclib withdrawal (incomplete senescence).
View Article and Find Full Text PDFNucleic Acids Res
September 2020
CRISPR/Cas9 functional genomic screens have emerged as essential tools in drug target discovery. However, the sensitivity of available genome-wide CRISPR libraries is impaired by guides which inefficiently abrogate gene function. While Cas9 cleavage efficiency optimization and essential domain targeting have been developed as independent guide design rationales, no library has yet combined these into a single cohesive strategy to knock out gene function.
View Article and Find Full Text PDFPurpose: Endocrine therapy, using tamoxifen or an aromatase inhibitor, remains first-line therapy for the management of estrogen receptor (ESR1)-positive breast cancer. However, ESR1 mutations or other ligand-independent ESR1 activation mechanisms limit the duration of response. The clinical efficacy of fulvestrant, a selective estrogen receptor downregulator (SERD) that competitively inhibits agonist binding to ESR1 and triggers receptor downregulation, has confirmed that ESR1 frequently remains engaged in endocrine therapy-resistant cancers.
View Article and Find Full Text PDFCancer cells bypass normal controls over mitotic cell-cycle progression to achieve a deregulated state of proliferation. The retinoblastoma tumor suppressor protein (pRb) governs a key cell-cycle checkpoint that normally prevents G1-phase cells from entering S-phase in the absence of appropriate mitogenic signals. Cancer cells frequently overcome pRb-dependent growth suppression via constitutive phosphorylation and inactivation of pRb function by cyclin-dependent kinase (CDK) 4 or CDK6 partnered with D-type cyclins.
View Article and Find Full Text PDFIn addition to genetic alterations, cancer cells are characterized by myriad epigenetic changes. EZH2 is a histone methyltransferase that is over-expressed and mutated in cancer. The EZH2 gain-of-function (GOF) mutations first identified in lymphomas have recently been reported in melanoma (~2%) but remain uncharacterized.
View Article and Find Full Text PDFAntibody-drug conjugates (ADC) are emerging as clinically effective therapy. We hypothesized that cancers treated with ADCs would acquire resistance mechanisms unique to immunoconjugate therapy and that changing ADC components may overcome resistance. Breast cancer cell lines were exposed to multiple cycles of anti-Her2 trastuzumab-maytansinoid ADC (TM-ADC) at IC80 concentrations followed by recovery.
View Article and Find Full Text PDFPac Symp Biocomput
April 2016
The Cell Index Database, (CELLX) (http://cellx.sourceforge.net) provides a computational framework for integrating expression, copy number variation, mutation, compound activity, and meta data from cancer cells.
View Article and Find Full Text PDFCell Stress Chaperones
November 2010
Cancer cells are exposed to external and internal stresses by virtue of their unrestrained growth, hostile microenvironment, and increased mutation rate. These stresses impose a burden on protein folding and degradation pathways and suggest a route for therapeutic intervention in cancer. Proteasome and Hsp90 inhibitors are in clinical trials and a 20S proteasome inhibitor, Velcade, is an approved drug.
View Article and Find Full Text PDFA series of tricyclic anilinopyrimidines were synthesized and evaluated as IKKbeta inhibitors. Several analogues, including tricyclic phenyl (10, 18a, 18c, 18d, and 18j) and thienyl (26 and 28) derivatives were shown to have good in vitro enzyme potency and excellent cellular activity. Pharmaceutical profiling of a select group of tricyclic compounds compared to the non-tricyclic analogues suggested that in some cases, the improved cellular activity may be due to increased clog P and permeability.
View Article and Find Full Text PDFBosutinib (SKI-606) is an orally active Src and Abl kinase inhibitor presently in Phase III trials for treatment of chronic myelogenous leukaemia (CML), and in Phase II trials for treatment of breast cancer. Bosutinib is a potent antiproliferative and proapoptotic agent in CML cells and inhibits Bcr-Abl mediated signalling at nanomolar concentrations. Short-term administration of bosutinib causes regression of K562 and KU812 CML tumour xenografts.
View Article and Find Full Text PDFA series of 8,9-dimethoxy-5-(2-aminoalkoxy-pyridin-3-yl)-benzo[c][2,7]naphthyridin-4-ylamine-based inhibitors of 3-phosphoinositide-dependent kinase-1 (PDK-1) has been identified. Several examples appear to be potent and relatively selective inhibitors of PDK-1 over the related AGC kinases PKA, PKB/AKT, and p70S6K. The introduction of a stereochemical center beside the amino substituent on the aminoalkoxy-side chain had little effect upon the inhibitory activity against these enzymes, and X-ray crystallographic analyses of a representative pair of enantiomeric inhibitors bound to the active site of PDK-1 revealed comparable binding modes for each enantiomer.
View Article and Find Full Text PDFWe are introducing a novel series of 2,4-diaminoquinazolines as beta-catenin/Tcf4 inhibitors which were identified by ligand-based design. Here we elucidate the SAR of this series and explain how we were able to improve key molecular properties such as solubility and cLogP leading to compound 9. Analogue 9 exhibited better biological activity and improved physical and pharmacological properties relative to the HTS hit 49.
View Article and Find Full Text PDFThe synthesis and SAR of a series of 2,4-diamino-quinazoline derivatives as beta-catenin/Tcf-4 inhibitors are described. This series was developed by modifying the initial lead 1, which was identified by screening of our compound library and found to inhibit the beta-catenin/Tcf-4 pathway. Replacement of the biphenyl moiety in compound 1 with the N-phenylpiperidine-4-carboxamide chain as in 2, resulted in a number of new analogues, which are potent inhibitors of the beta-catenin/Tcf-4 pathway.
View Article and Find Full Text PDFA series of substituted benzo[c][2,7]-naphthyridines were prepared and showed good potency in inhibiting PDK-1. The synthesis and SAR of this series of compounds are presented as well as the X-ray crystal structure of one of these analogs in a complex with PDK-1.
View Article and Find Full Text PDFMany anticancer agents activate NF-kappaB, which plays an important role in the survival of cancer cells. Inhibition of NF-kappaB activity may therefore potentiate the efficacy of anticancer agents. We found that a previously used anticancer agent Streptonigrin (SN) was also a potent NF-kappaB inducer.
View Article and Find Full Text PDFTumor necrosis factor alpha (TNFalpha) has been used to treat patients with certain tumor types. However, its antitumor activity has been undermined by the activation of IkappaBalpha kinase (IKK), which in turn activates nuclear factor-kappaB (NF-kappaB) to help cancer cells survive. Therefore, inhibition of TNFalpha-induced IKK activity with specific IKK inhibitor represents an attractive strategy to treat cancer patients.
View Article and Find Full Text PDFHeat shock protein 90 (Hsp90) is a molecular chaperone that is responsible for activating many signaling proteins and is a promising target in tumor biology. We have identified small-molecule benzisoxazole derivatives as Hsp90 inhibitors. Crystallographic studies show that these compounds bind in the ATP binding pocket interacting with the Asp93.
View Article and Find Full Text PDFWith high-throughput screening, substituted dibenzo[c,f][2,7]naphthyridine 1 was identified as a novel potent and selective phosphoinositide-dependent kinase-1 (PDK-1) inhibitor. Various regions of the lead molecule were explored to understand the SAR requirement for this scaffold. The crystal structure of 1 with kinase domain of PDK-1 confirmed the binding in the active site.
View Article and Find Full Text PDFSrc up-regulation is a common event in human cancers. In colorectal cancer, increased Src levels are an indicator of poor prognosis, and progression to metastatic disease is associated with substantial increases in Src activity. Therefore, we examined the activity of SKI-606, a potent inhibitor of Src and Abl kinases, against colon tumor lines in vitro and in s.
View Article and Find Full Text PDFEukaryotic chaperonins, the Cct complexes, are assembled into two rings, each of which is composed of a stoichiometric array of eight different subunits, which are denoted Cct1p-Cct8p. Overexpression of a single CCT gene in Saccharomyces cerevisiae causes an increase of the corresponding Cct subunit, but not of the Cct complex. Nevertheless, overexpression of certain Cct subunits, especially CCT6, suppresses a wide range of abnormal phenotypes, including those caused by the diverse types of conditional mutations tor2-21, lst8-2 and rsp5-9 and those caused by the concomitant overexpression of Sit4p and Sap155p.
View Article and Find Full Text PDFCdc37 is a molecular chaperone that is important for the stability and activity of several protein kinases, including Cdk4 and Raf1. We first determined, using in vitro assays, that Cdc37 binds to the amino-terminal lobe of Cdk4. Subsequent mutagenesis revealed that Gly-15 (G15A) and Gly-18 (G18A) were critical for Cdc37-Cdk4 complex formation.
View Article and Find Full Text PDFConstitutive tyrosine kinase activity of Bcr-Abl promotes proliferation and survival of chronic myelogenous leukemia (CML) cells. Inhibition of Bcr-Abl tyrosine kinase activity or signaling proteins activated by Bcr-Abl in CML cells blocks proliferation and causes apoptotic cell death. The selective Abl kinase inhibitor, STI-571 (marketed as Gleevec), is toxic to CML cells in culture, causes regression of CML tumors in nude mice, and is currently used to treat CML patients.
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