Phosphoinositide 3-kinase α (PI3Kα) is a critical regulator of cell growth and transformation, and its signaling pathway is the most commonly mutated pathway in human cancers. The mammalian target of ...rapamycin (mTOR), a class IV PI3K protein kinase, is also a central regulator of cell growth, and mTOR inhibitors are believed to augment the antiproliferative efficacy of PI3K/AKT pathway inhibition. 2,4-Difluoro-N-{2-(methyloxy)-5-4-(4-pyridazinyl)-6-quinolinyl-3-pyridinyl}benzenesulfonamide (GSK2126458, 1) has been identified as a highly potent, orally bioavailable inhibitor of PI3Kα and mTOR with in vivo activity in both pharmacodynamic and tumor growth efficacy models. Compound 1 is currently being evaluated in human clinical trials for the treatment of cancer.
KSP, also known as HsEg5, is a kinesin that plays an essential role in the formation of a bipolar mitotic spindle and is required for cell cycle progression through mitosis. Ispinesib is the first ...potent, highly specific small-molecule inhibitor of KSP tested for the treatment of human disease. This novel anticancer agent causes mitotic arrest and growth inhibition in several human tumor cell lines and is currently being tested in multiple phase II clinical trials. In this study we have used steady-state and pre-steady-state kinetic assays to define the mechanism of KSP inhibition by ispinesib. Our data show that ispinesib alters the ability of KSP to bind to microtubules and inhibits its movement by preventing the release of ADP without preventing the release of the KSP-ADP complex from the microtubule. This type of inhibition is consistent with the physiological effect of ispinesib on cells, which is to prevent KSP-driven mitotic spindle pole separation. A comparison of ispinesib to monastrol, another small-molecule inhibitor of KSP, reveals that both inhibitors share a common mode of inhibition.
Epigenetic dysregulation has emerged as an important mechanism in cancer. Alterations in epigenetic machinery have become a major focus for targeted therapies. The current report describes the ...discovery and biological activity of a cyclopropylamine containing inhibitor of Lysine Demethylase 1 (LSD1), GSK2879552. This small molecule is a potent, selective, orally bioavailable, mechanism-based irreversible inactivator of LSD1. A proliferation screen of cell lines representing a number of tumor types indicated that small cell lung carcinoma (SCLC) is sensitive to LSD1 inhibition. The subset of SCLC lines and primary samples that undergo growth inhibition in response to GSK2879552 exhibit DNA hypomethylation of a signature set of probes, suggesting this may be used as a predictive biomarker of activity.
•LSD1 is important in oncogenesis, suggesting it may serve as a therapeutic target•GSK2879552 is a potent, selective, oral, mechanism-based inactivator of LSD1•GSK2879552 has an antitumor effect in SCLC cells in vitro and in vivo•DNA hypomethylation of a signature probe set predicts sensitivity to GSK2879552
Mohammad et al. identify the orally available lysine demethylase 1 (LSD1)-selective inhibitor GSK2879552 and find unexpectedly that some small cell lung cancer cell lines are sensitive to LSD1 inhibition. Mohammad et al. further identify a potential biomarker predictive of response to GSK2879552.
We report herein the discovery of isoxazole amides as potent and selective SET and MYND Domain-Containing Protein 3 (SMYD3) inhibitors. Elucidation of the structure–activity relationship of the ...high-throughput screening (HTS) lead compound 1 provided potent and selective SMYD3 inhibitors. The SAR optimization, cocrystal structures of small molecules with SMYD3, and mode of inhibition (MOI) characterization of compounds are described. The synthesis and biological and pharmacokinetic profiles of compounds are also presented.
Kinesin spindle protein (KSP), an ATPase responsible for spindle pole separation during mitosis that is present only in proliferating cells, has become a novel and attractive anticancer target with ...potential for reduced side effects compared to currently available therapies. We report herein the discovery of the first known ATP-competitive inhibitors of KSP, which display a unique activity profile as compared to the known loop 5 (L5) allosteric KSP inhibitors that are currently under clinical evaluation. Optimization of this series led to the identification of biphenyl sulfamide 20, a potent KSP inhibitor with in vitro antiproliferative activity against human cells with either wild-type KSP (HCT116) or mutant KSP (HCT116 D130V). In a murine xenograft model with HCT116 D130V tumors, 20 showed significant antitumor activity following intraperitoneal dosing, providing in vivo proof-of-principle of the efficacy of an ATP-competitive KSP inhibitor versus tumors that are resistant to the other known KSP inhibitors.
Kinesin motor proteins utilize the energy from ATP hydrolysis to transport cellular cargo along microtubules. Kinesins that play essential roles in the mechanics of mitosis are attractive targets for ...novel antimitotic cancer therapies. Monastrol, a cell-permeable inhibitor that specifically inhibits the kinesin Eg5, the Xenopus laevis homologue of human KSP, can cause mitotic arrest and monopolar spindle formation. In this study, we show that the extent of monastrol inhibition of KSP microtubule-stimulated ATP hydrolysis is highly dependent upon ionic strength. Detailed kinetic analysis of KSP inhibition by monastrol in the presence and absence of microtubules suggests that monastrol binds to the KSP-ADP complex, forming a KSP-ADP-monastrol ternary complex, which cannot bind to microtubules productively and cannot undergo further ATP-driven conformational changes.
Human kinesin spindle protein (KSP)/hsEg5, a member of the kinesin-5 family, is essential for mitotic spindle assembly in dividing human cells and is required for cell cycle progression through ...mitosis. Inhibition of the ATPase activity of KSP leads to cell cycle arrest during mitosis and subsequent cell death. Ispinesib (SB-715992), a potent and selective inhibitor of KSP, is currently in phase II clinical trials for the treatment of multiple tumor types. Mutations that attenuate Ispinesib binding to KSP in vitro have been identified, highlighting the need for inhibitors that target different binding sites and inhibit KSP activity by novel mechanisms. We report here a small-molecule modulator, KSPA-1, that activates KSP-catalyzed ATP hydrolysis in the absence of microtubules yet inhibits microtubule-stimulated ATP hydrolysis by KSP. KSPA-1 inhibits cell proliferation and induces monopolar-spindle formation in tumor cells. Results from kinetic analyses, microtubule (MT) binding competition assays, and hydrogen/deuterium-exchange studies show that KSPA-1 does not compete directly for microtubule binding. Rather, this compound acts by driving a conformational change in the KSP motor domain and disrupts productive ATP turnover stimulated by MT. These findings provide a novel mechanism for targeting KSP and perhaps other mitotic kinesins.
Tuberculosis remains a global health problem, and programs dedicated to discovery of novel compounds against
Mycobacterium tuberculosis require robust assays for high-throughput screening of chemical ...and natural product libraries. Enzymes involved in the biosynthesis of mycolic acids, vital components of the mycobacterial cell wall, have received much attention as potential drug targets. KasA and KasB, examples of the
β-ketoacyl-acyl carrier protein synthase I/II (KASI/II) class of condensing enzymes of the
M. tuberculosis fatty acid synthase II system have been the focus of several studies designed to biochemically characterize these enzymes. Whilst robust methods have been developed for FabH-like proteins, fast and sensitive assays for high-throughput screening of KASI/II enzymes have not been available. Here we report the development of a direct scintillation proximity assay (SPA) for the KASI/II enzymes, KasA and KasB. The SPA was more sensitive than existing assays, as shown by its ability to measure activity using less enzyme than other assay formats, and the SPA was validated using the known KAS inhibitor thiolactomycin. In addition, the KasA and KasB SPA was adapted for use with
Staphylococcus aureus FabF to show the versatility of this assay format to KAS enzymes from other pathogenic organisms.
Background Prior trials suggest it is safe to defer transfusion at hemoglobin levels above 7 to 8 g/dL in most patients. Patients with acute coronary syndrome may benefit from higher hemoglobin ...levels. Methods We performed a pilot trial in 110 patients with acute coronary syndrome or stable angina undergoing cardiac catheterization and a hemoglobin <10 g/dL. Patients in the liberal transfusion strategy received one or more units of blood to raise the hemoglobin level ≥10 g/dL. Patients in the restrictive transfusion strategy were permitted to receive blood for symptoms from anemia or for a hemoglobin <8 g/dL. The predefined primary outcome was the composite of death, myocardial infarction, or unscheduled revascularization 30 days post randomization. Results Baseline characteristics were similar between groups except age (liberal, 67.3; restrictive, 74.3). The mean number of units transfused was 1.6 in the liberal group and 0.6 in the restrictive group. The primary outcome occurred in 6 patients (10.9%) in the liberal group and 14 (25.5%) in the restrictive group (risk difference = 15.0%; 95% confidence interval of difference 0.7% to 29.3%; P = .054 and adjusted for age P = .076). Death at 30 days was less frequent in liberal group (n = 1, 1.8%) compared to restrictive group (n = 7, 13.0%; P = .032). Conclusions The liberal transfusion strategy was associated with a trend for fewer major cardiac events and deaths than a more restrictive strategy. These results support the feasibility of and the need for a definitive trial.
Red blood cell transfusion in clinical practice Klein, Harvey G, Dr; Spahn, Donat R, FRCA; Carson, Jeffrey L, MD
The Lancet (British edition),
08/2007, Letnik:
370, Številka:
9585
Journal Article
Recenzirano
Summary Every year, about 75 million units of blood are collected worldwide. Red blood cell (RBC) transfusion is one of the few treatments that adequately restore tissue oxygenation when oxygen ...demand exceeds supply. Although the respiratory function of blood has been studied intensively, the trigger for RBC transfusion remains controversial, and doctors rely primarily on clinical experience. Laboratory assays that indicate failing tissue oxygenation would be ideal to guide the need for transfusion, but none has proved easy, reproducible, and sensitive to regional tissue hypoxia. The clinical importance of the RBCs storage lesion (ie, the time-dependent metabolic, biochemical, and molecular changes that stored blood cells undergo) is poorly understood. RBCs can be filtered, washed, frozen, or irradiated for specific indications. Donor screening and testing have dramatically reduced infectious risks in the developed world, but infection remains a major hazard in developing countries, where 13 million units of blood are not tested for HIV or hepatitis viruses. Pathogen inactivation techniques are in clinical trials for RBCs, but none is available for use. Despite serious immunological and non-immunological complications, RBC transfusion holds a therapeutic index that exceeds that of many common medications.
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