Discovery of novel non-peptide thrombopoietin mimetic compounds that induce megakaryocytopoiesis

2008 ◽  
Vol 28 (5) ◽  
pp. 275-285 ◽  
Author(s):  
Noriko Yamane ◽  
Koji Takahashi ◽  
Yoshikazu Tanaka ◽  
Kazue Kato ◽  
Masami Takayama ◽  
...  
Keyword(s):  
Cell Line ◽  
Bone Marrow Cells ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Janus Kinase ◽  
Parent Cell ◽  
Tyrosine Kinase 2 ◽  
Thrombopoietin Receptor ◽  
Src Homology ◽  
Thrombopoietin Mimetic

We have identified a series of novel non-peptide compounds that activate the thrombopoietin-dependent cell line Ba/F3-huMPL. The compounds stimulated proliferation of Ba/F3-huMPL in the absence of other growth factors, but did not promote proliferation of the thrombopoietin-independent parent cell line Ba/F3. The thrombopoietin-mimetic compounds elicited signal-transduction responses comparable with recombinant human thrombopoietin, such as tyrosine phosphorylation of the thrombopoietin receptor, JAK (Janus kinase) 2, Tyk2 (tyrosine kinase 2), STAT (signal transducer and activator of transcription) 3, STAT5, MAPKs (mitogen-activated protein kinases), PLCγ (phospholipase Cγ), Grb2 (growth-factor-receptor-bound protein 2), Shc (Src homology and collagen homology), Vav, Cbl and SHP-2 (Src homology 2 domain-containing protein tyrosine phosphatase 2) and increased the number of CD41+ cells (megakaryocyte lineage) in cultures of human CD34+ bone-marrow cells (haematopoietic stem cells). These findings suggest that this series of compounds are novel agonists of the human thrombopoietin receptor and are possible lead compounds for the generation of anti-thrombocytopaenia drugs.

scholarly journals G-CSF receptor truncations found in SCN/AML relieve SOCS3-controlled inhibition of STAT5 but leave suppression of STAT3 intact

Blood ◽  
2004 ◽  
Vol 104 (3) ◽  
pp. 667-674 ◽  
Author(s):  
Gert-Jan M. van de Geijn ◽  
Judith Gits ◽  
Lambertus H. J. Aarts ◽  
Claudia Heijmans-Antonissen ◽  
Ivo P. Touw
Keyword(s):  
Bone Marrow Cells ◽  
Tyrosine Phosphatase ◽  
Receptor Internalization ◽  
Luciferase Reporter ◽  
Cytokine Signaling ◽  
Additional Contribution ◽  
Socs3 Expression ◽  
Reporter Assays ◽  
Src Homology ◽  
Activation Ratio

AbstractTruncated granulocyte colony-stimulating factor receptors (G-CSF-Rs) are implicated in severe congenital neutropenia (SCN) and the consecutive development of acute myeloid leukemia (AML). Mice expressing G-CSF-R truncation mutants (gcsfr-d715) show defective receptor internalization, an increased signal transducer and activator of transcription 5 (STAT5)/STAT3 activation ratio, and hyperproliferative responses to G-CSF treatment. We determined whether a lack of negative feedback by suppressor of cytokine signaling (SOCS) proteins contributes to the signaling abnormalities of G-CSF-R–d715. Expression of SOCS3 transcripts in bone marrow cells from G-CSF–treated gcsfr-d715 mice was approximately 60% lower than in wild-type (WT) littermates. SOCS3 efficiently suppressed STAT3 and STAT5 activation by WT G-CSF-R in luciferase reporter assays. In contrast, while SOCS3 still inhibited STAT3 activation by G-CSF-R–d715, STAT5 activation was no longer affected. This was due mainly to loss of the SOCS3 recruitment site Tyr729, with an additional contribution of the internalization defects of G-CSF-R–d715. Because Tyr729 is also a docking site for the Src homology 2–containing protein tyrosine phosphatase-2 (SHP-2), which binds to and inactivates STAT5, we suggest a model in which reduced SOCS3 expression, combined with the loss of recruitment of both SOCS3 and SHP-2 to the activated receptor complex, determine the increased STAT5/STAT3 activation ratio and the resulting signaling abnormalities projected by truncated G-CSF-R mutants.

scholarly journals Oncogenic TYK2P760L kinase is effectively targeted by combinatorial TYK2, mTOR and CDK4/6 kinase blockade

Haematologica ◽  
2022 ◽  
Author(s):  
Katharina Woess ◽  
Sabine Macho-Maschler ◽  
Dorette S. Van Ingen Schenau ◽  
Miriam Butler ◽  
Caroline Lassnig ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
De Novo ◽  
Bone Marrow Cells ◽  
Ex Vivo ◽  
Treatment Options ◽  
Specific Inhibitor ◽  
Janus Kinase ◽  
Cytokine Signaling ◽  
Tyrosine Kinase 2

Tyrosine kinase 2 (TYK2) is a member of the Janus kinase/signal transducer and activator of transcription pathway, which is central in cytokine signaling. Previously, germline TYK2 mutations have been described in two patients developing de novo T-cell acute lymphoblastic leukemias (T-ALLs) or precursor B-ALLs. The mutations (P760L and G761V) are located within the regulatory pseudokinase domain and lead to constitutive activation of TYK2. We demonstrate the transformation capacity of TYK2P760L in hematopoietic cell systems including primary bone marrow cells. In vivo engraftment of TYK2P760L-expressing cell lines led to development of leukemia. A kinase inhibitor screen uncovered that oncogenic TYK2 acts synergistically with the PI3K/AKT/mTOR and CDK4/6 pathways. Accordingly, the TYK2-specific inhibitor deucravacitinib (BMS986165) reduces cell viability of TYK2P760Ltransformed cell models and ex vivo cultured TYK2P760L-mutated patient-derived xenograft cells most efficiently when combined with mTOR or CDK4/6 inhibitors. Our study thereby pioneers novel treatment options for patients suffering from TYK2-driven acute leukemia.

scholarly journals Commentary: Regulation of autoimmune arthritis by the SHP-1 tyrosine phosphatase

2021 ◽  
Vol 2 (2) ◽  
pp. 1-3
Author(s):  
Adrienn Markovics ◽  
Daniel M. Toth ◽  
Tibor T. Glant ◽  
Katalin Mikecz
Keyword(s):  
Inflammatory Arthritis ◽  
Therapeutic Potential ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Janus Kinase ◽  
Systemic Autoimmune Disease ◽  
Autoimmune Arthritis ◽  
Jak Inhibitors ◽  
Src Homology ◽  
Patients Experience

Rheumatoid arthritis (RA) is a systemic autoimmune disease leading primarily to the inflammatory destruction of the synovial joints, ultimately resulting in loss of mobility and a decreased quality of life. Recent advances in RA-related research resulted in the introduction of Janus kinase (JAK) inhibitors to the therapeutic arsenal. JAK inhibitors are orally available and provide efficacy similar to that of disease-modifying anti-rheumatic drugs. However, due to the limited selectivity of these drugs, many RA patients experience adverse effects. The potential benefit of modulating protein tyrosine phosphatases, instead of inhibiting kinases, has not been explored. Using an animal model of RA, our group investigated the role of the Src homology region 2 domain-containing phosphatase 1 (SHP-1) in inflammatory arthritis. The purpose of the present article is to highlight important conclusions of our previous paper entitled “Regulation of autoimmune arthritis by the SHP-1 tyrosine phosphatase”. Herein we briefly present and discuss the observations of this study. We also outline future directions toward investigating the therapeutic potential of targeting SHP-1 in inflammatory arthritis in order to develop a new type of orally available drugs for the treatment of RA.

scholarly journals The molecular regulation of Janus kinase (JAK) activation

2014 ◽  
Vol 462 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Jeffrey J. Babon ◽  
Isabelle S. Lucet ◽  
James M. Murphy ◽  
Nicos A. Nicola ◽  
Leila N. Varghese
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Current Knowledge ◽  
Inflammatory Diseases ◽  
Sh2 Domain ◽  
Janus Kinase ◽  
Causative Role ◽  
Tyrosine Kinase 2 ◽  
Src Homology

The JAK (Janus kinase) family members serve essential roles as the intracellular signalling effectors of cytokine receptors. This family, comprising JAK1, JAK2, JAK3 and TYK2 (tyrosine kinase 2), was first described more than 20 years ago, but the complexities underlying their activation, regulation and pleiotropic signalling functions are still being explored. Here, we review the current knowledge of their physiological functions and the causative role of activating and inactivating JAK mutations in human diseases, including haemopoietic malignancies, immunodeficiency and inflammatory diseases. At the molecular level, recent studies have greatly advanced our knowledge of the structures and organization of the component FERM (4.1/ezrin/radixin/moesin)-SH2 (Src homology 2), pseudokinase and kinase domains within the JAKs, the mechanism of JAK activation and, in particular, the role of the pseudokinase domain as a suppressor of the adjacent tyrosine kinase domain's catalytic activity. We also review recent advances in our understanding of the mechanisms of negative regulation exerted by the SH2 domain-containing proteins, SOCS (suppressors of cytokine signalling) proteins and LNK. These recent studies highlight the diversity of regulatory mechanisms utilized by the JAK family to maintain signalling fidelity, and suggest alternative therapeutic strategies to complement existing ATP-competitive kinase inhibitors.

Induction of megakaryocytopoiesis and thrombocytopoiesis by JTZ-132, a novel small molecule with thrombopoietin mimetic activities

Blood ◽  
2004 ◽  
Vol 104 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Koji Inagaki ◽  
Tomohiro Oda ◽  
Yuichi Naka ◽  
Hisashi Shinkai ◽  
Norio Komatsu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Line ◽  
Small Molecule ◽  
Bone Marrow Cells ◽  
Janus Kinase ◽  
Specific Marker ◽  
Human Carcinoma ◽  
Platelet Recovery ◽  
Marrow Cells

Abstract We report in this paper that a novel small molecule, JTZ-132, induced growth and differentiation of megakaryocytic progenitor cells and improved thrombocytopenia in myelosuppressed mice. JTZ-132 stimulated proliferation of UT-7/TPO cells, a cell line highly sensitive to thrombopoietin (TPO), and exhibited full efficacy comparable to TPO with an approximate EC50 (median effective concentration) value of 0.43 μM, whereas little proliferation was observed in a TPO-insensitive cell line, UT-7/EPO, and human carcinoma cell line, HCT116. Signal transduction studies revealed that JTZ-132 induced tyrosine phosphorylation of c-Mpl, Janus kinase-2 (JAK2), and signal transducers and activators of transcription 5 (STAT5) in UT-7/TPO cells as well as TPO. JTZ-132 increased the number of megakaryocyte-specific marker, CD61+ and CD41+, cells in cultures of mouse and human bone marrow cells, respectively, and the colonyforming unit megakaryocytes in mouse bone marrow cells. In vivo experiments in x-ray irradiation– or busulfan injection–induced myelosuppressed mice demonstrated that subcutaneously injected JTZ-132 at 30 mg/kg showed significantly higher platelet number at nadir and accelerated platelet recovery without affecting white blood cell number. These data suggest that JTZ-132 is a novel stimulator of megakaryocytopoiesis and thrombocytopoiesis in vitro and in vivo with TPO mimetic activities and that it is useful for the treatment of thrombocytopenia.

scholarly journals Vitamin C functions as double-edge sword on cancer progression depending on ERK activation or inhibition mediated by its receptor SVCT2

2022 ◽  
Author(s):  
Yian Guan ◽  
Bingxue Chen ◽  
Yongyan Wu ◽  
Zhuo Han ◽  
Hongyu Xu ◽  
...  
Keyword(s):  
Vitamin C ◽  
Cancer Progression ◽  
Feedback Inhibition ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Janus Kinase ◽  
High Dose ◽  
Erk Activation ◽  
Double Edge Sword ◽  
Cancer Phenotypes

The effect of Vitamin C (Vc) in oncotherapy was controversial for decades. And hyperactivation of extracellular signal-regulated kinase (ERK) drove tumorigenesis. Herein, we demonstrated that Vc activated ERK through sodium-dependent Vc transporter 2 (SVCT2), while high-dose Vc resulted in persistent ERK feedback inhibition following activation. Extracellular Vc binding to SVCT2 initiated ERK activation, then transmembrane transport of Vc induced dimerization of SVCT2. Activated ERK phosphorylated protein tyrosine phosphatase non-receptor type 12 (PTPN12) at Ser434 and inhibited PTPN12 activity, thus enhancing phosphorylation of Janus kinase 2 (JAK2), which phosphorylated growth factor receptor bound protein 2 (GRB2) at Tyr160 to promote GRB2 dimers dissociation and recruitment of GRB2 to SVCT2, leading to further ERK activation. Different cancers have different sensitivities to Vc, the dose effects of Vc on cancer phenotypes depended on that ERK was activated or inhibited. These findings suggest SVCT2 is a Vc receptor mediating the ERK-PTPN12-JAK2-GRB2-ERK positive feedback loop and a potential target for oncotherapy.

scholarly journals Early signaling dynamics of the epidermal growth factor receptor

2016 ◽  
Vol 113 (11) ◽  
pp. 3114-3119 ◽  
Author(s):  
Raven J. Reddy ◽  
Aaron S. Gajadhar ◽  
Eric J. Swenson ◽  
Daniel A. Rothenberg ◽  
Timothy G. Curran ◽  
...  
Keyword(s):  
Growth Factor ◽  
Egf Receptor ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Extensive Study ◽  
Signaling Network ◽  
Egfr Signaling ◽  
Activation Patterns ◽  
Src Homology ◽  
Src Homology 2 Domain

Despite extensive study of the EGF receptor (EGFR) signaling network, the immediate posttranslational changes that occur in response to growth factor stimulation remain poorly characterized; as a result, the biological mechanisms underlying signaling initiation remain obscured. To address this deficiency, we have used a mass spectrometry-based approach to measure system-wide phosphorylation changes throughout the network with 10-s resolution in the 80 s after stimulation in response to a range of eight growth factor concentrations. Significant changes were observed on proteins far downstream in the network as early as 10 s after stimulation, indicating a system capable of transmitting information quickly. Meanwhile, canonical members of the EGFR signaling network fall into clusters with distinct activation patterns. Src homology 2 domain containing transforming protein (Shc) and phosphoinositol 3-kinase (PI3K) phosphorylation levels increase rapidly, but equilibrate within 20 s, whereas proteins such as Grb2-associated binder-1 (Gab1) and SH2-containing tyrosine phosphatase (SHP2) show slower, sustained increases. Proximity ligation assays reveal that Shc and Gab1 phosphorylation patterns are representative of separate timescales for physical association with the receptor. Inhibition of phosphatases with vanadate reveals site-specific regulatory mechanisms and also uncovers primed activating components in the network, including Src family kinases, whose inhibition affects only a subset of proteins within the network. The results presented highlight the complexity of signaling initiation and provide a window into exploring mechanistic hypotheses about receptor tyrosine kinase (RTK) biology.

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