Fragment-based discovery of JAK-2 inhibitors

Antonysamy, Stephen; Hirst, Gavin C.; Park, Frances; Sprengeler, Paul A.; Stappenbeck, Frank; Steensma, Ruo W.; Wilson, Mark R.; Wong, Melissa S.

doi:10.1016/j.bmcl.2008.08.064

Cited by 71 publications

(51 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…35 JAK2i IV dose-dependently reduced TPO-stimulated phosphorylation of JAK2 and downstream signaling events ( Figure 2E), whereas thrombin-stimulated total tyrosine phosphorylation events, which are mainly mediated by the Src kinase family, were unaffected ( Figure 2F). The inhibitor had no effect on thrombinstimulated phosphorylation of Akt, pleckstrin, ERK, JNK, and p38.…”

Section: Jak2 Is Essential For Tpo But Not Sfllrn-mediated Regulationmentioning

confidence: 99%

Dysfunction of the PI3 kinase/Rap1/integrin αIIbβ3 pathway underlies ex vivo platelet hypoactivity in essential thrombocythemia

Moore¹,

Hunter²,

Harper³

et al. 2013

Blood

View full text Add to dashboard Cite

Key Points• Platelets from essential thrombocythemia patients have an intrinsic impairment in the P13kinase/Rap1/integrin ␣IIb␤3 signaling pathway.• This explains the clinical observation that in vitro platelet aggregation is impaired in patients with essential thrombocythemia. IntroductionThe myeloproliferative disorders (MPDs) are a group of clonal hemopoietic disorders characterized by increased proliferation of one or more of the myeloid, erythroid, or megakaryocytic cell lineages. The MPDs include polycythemia vera (PV; excess production of red cells) and essential thrombocythemia (ET; excess production of platelets) and other disorders. 1 The clinical course of untreated MPDs is dominated by arterial and venous thrombosis, which are major causes of mortality and morbidity in patients with early stage disease. [2][3][4][5] Abnormal bleeding occurs in 5% to 10% of patients with ET during the disease course, particularly gastrointestinal, urogenital, and intracranial. 5,6 Several independent groups demonstrated in 2005 that the defect in the majority of patients with MPDs is a somatic V617F gain-of-function mutation in the gene encoding Janus kinase 2 (JAK2) in hematopoietic progenitor cells. 3 JAK2 V617F is present in peripheral blood cells, including platelets, 7,8 in virtually all patients with PV and approximately 60% of patients with ET. 8,9 In ET, JAK2 V617F increases the risk of thrombosis by approximately 2-fold 10,11 and the risk of thrombosis is even higher in ET patients with Ͼ 50% JAK2 V617F allele load. 12 The JAK2V617F mutation is also present in some patients presenting with thrombosis who do not meet the diagnostic criteria for MPDs. [13][14][15] Bleeding risk in ET appears not to be associated with the presence of JAK2 V617F. Flow cytometry studies demonstrated that JAK2V617F platelets express higher levels of platelet activation markers, such as P-selectin, compared with platelets from patients without the mutation, 16,17 suggesting that increased platelet activation may contribute to the thrombotic phenotype. A recent study also observed that platelet-mediated thrombin production is increased in ET patients. 18 In contrast, numerous studies performed over the past 35 years clearly showed that in vitro platelet function, in particular aggregation, is impaired in MPD patients, 19-22 a finding difficult to reconcile with the increased thrombotic risk. Although it is generally accepted that platelets contribute to the increased occurrence of thrombosis in patients with MPDs, very little is known how the JAK2V617F mutation changes intracellular platelet signaling pathways, subsequent platelet function and how this contributes to the MPD phenotype.In this study, we therefore aimed to identify the role of JAK2 in platelet function and how the JAK2V617F mutation affects platelet function in ET patients. We studied agonist-stimulated intracellular signaling pathways and related these findings to integrin ␣ IIb ␤ 3Submitted May 20, 2012; accepted November 26, 2012. Prepublished online as Blood First...

show abstract

Section: Jak2 Is Essential For Tpo But Not Sfllrn-mediated Regulationmentioning

confidence: 99%

Dysfunction of the PI3 kinase/Rap1/integrin αIIbβ3 pathway underlies ex vivo platelet hypoactivity in essential thrombocythemia

Moore¹,

Hunter²,

Harper³

et al. 2013

Blood

View full text Add to dashboard Cite

show abstract

“…The fi nal molecule, for example, featured a cyclopropyl urea group that provided the right conformation and lipophilicity for cell potency and solubility. Another indazole fragment found for JAK2 kinase through X-ray crystallographic screening was recently reported [ 73 ]. Using the SGX X-ray crystallographic screening protocol, a fragment library designed to have good physical chemical and drug-like properties, yielded several hits.…”

Section: Vbsmentioning

confidence: 99%

Fragment-Based Design of Kinase Inhibitors: A Practical Guide

Erickson

2015

Methods in Molecular Biology

View full text Add to dashboard Cite

Fragment-based drug design has become an important strategy for drug design and development over the last decade. It has been used with particular success in the development of kinase inhibitors, which are one of the most widely explored classes of drug targets today. The application of fragment-based methods to discovering and optimizing kinase inhibitors can be a complicated and daunting task; however, a general process has emerged that has been highly fruitful. Here a practical outline of the fragment process used in kinase inhibitor design and development is laid out with specific examples. A guide to the overall process from initial discovery through fragment screening, including the difficulties in detection, to the computational methods available for use in optimization of the discovered fragments is reported.

show abstract

“…The template used was the crystal struc-ture of Jak2 kinase domain in complex with the Jak2 inhibitor 5B3 (Protein Data Bank code 3E64) (21). The coordinates for ATP, ACP, and each of the small molecules were generated and energy-minimized using PRODRG (22).…”

Section: Methodsmentioning

confidence: 99%

“…Computational Docking of G6 and Its Derivatives into the ATP-binding Pocket of the Jak2 Kinase Domain-Using the known structure of the Jak2 kinase domain (21), ATP, the ATP analog ACP, G6, and each of its five structurally related derivatives were docked into the ATP-binding pocket. The goal was to analyze the potential interactions of these compounds with amino acids in this binding region.…”

Section: Stilbenoid Core-bearing Derivatives Of G6 Suppress Pathologimentioning

confidence: 99%

Structure-Function Correlation of G6, a Novel Small Molecule Inhibitor of Jak2

Majumder

Govindasamy

Magis

et al. 2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

Somatic mutations in the Jak2 protein, such as V617F, cause aberrant Jak/STAT signaling and can lead to the development of myeloproliferative neoplasms. This discovery has led to the search for small molecule inhibitors that target Jak2. Using structure-based virtual screening, our group recently identified a novel small molecule inhibitor of Jak2 named G6. Here, we identified a structure-function correlation of this compound. Specifically, five derivative compounds of G6 having structural similarity to the original lead compound were obtained and analyzed for their ability to (i) inhibit Jak2-V617F-mediated cell growth, (ii) inhibit the levels of phospho-Jak2, phospho-STAT3, and phospho-STAT5; (iii) induce apoptosis in human erythroleukemia cells; and (iv) suppress pathologic cell growth of Jak2-V617F-expressing human bone marrow cells ex vivo. Additionally, we computationally examined the interactions of these compounds with the ATP-binding pocket of the Jak2 kinase domain. We found that the stilbenoid core-containing derivatives of G6 significantly inhibited Jak2-V617F-mediated cell proliferation in a time-and dose-dependent manner. They also inhibited phosphorylation of Jak2, STAT3, and STAT5 proteins within cells, resulting in higher levels of apoptosis via the intrinsic apoptotic pathway. Finally, the stilbenoid derivatives inhibited the pathologic growth of Jak2-V617F-expressing human bone marrow cells ex vivo. Collectively, our data demonstrate that G6 has a stilbenoid core that is indispensable for maintaining its Jak2 inhibitory potential.

show abstract

Fragment-based discovery of JAK-2 inhibitors

Cited by 71 publications

References 9 publications

Dysfunction of the PI3 kinase/Rap1/integrin αIIbβ3 pathway underlies ex vivo platelet hypoactivity in essential thrombocythemia

Dysfunction of the PI3 kinase/Rap1/integrin αIIbβ3 pathway underlies ex vivo platelet hypoactivity in essential thrombocythemia

Fragment-Based Design of Kinase Inhibitors: A Practical Guide

Structure-Function Correlation of G6, a Novel Small Molecule Inhibitor of Jak2

Contact Info

Product

Resources

About