scholarly journals Dopaminergic Ric GTPase activity impacts amphetamine sensitivity and sleep quality in a dopamine transporter-dependent manner in Drosophila melanogaster

2021 ◽  
Author(s):  
Rita R. Fagan ◽  
Patrick J. Kearney ◽  
Dino Luethi ◽  
Nicholas C. Bolden ◽  
Harald H. Sitte ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Locomotor Activity ◽  
Sleep Quality ◽  
Cell Lines ◽  
Essential Role ◽  
Ex Vivo ◽  
Surface Expression ◽  
Dependent Manner ◽  
Gtpase Activity ◽  
And Function

AbstractDopamine (DA) is required for movement, sleep, and reward, and DA signaling is tightly controlled by the presynaptic DA transporter (DAT). Therapeutic and addictive psychostimulants, including methylphenidate (Ritalin; MPH), cocaine, and amphetamine (AMPH), markedly elevate extracellular DA via their actions as competitive DAT inhibitors (MPH, cocaine) and substrates (AMPH). DAT silencing in mice and invertebrates results in hyperactivity, reduced sleep, and blunted psychostimulant responses, highlighting DAT’s essential role in DA-dependent behaviors. DAT surface expression is not static; rather it is dynamically regulated by endocytic trafficking. PKC-stimulated DAT endocytosis requires the neuronal GTPase, Rit2, and Rit2 silencing in mouse DA neurons impacts psychostimulant sensitivity. However, it is unknown whether or not Rit2-mediated changes in psychostimulant sensitivity are DAT-dependent. Here, we leveraged Drosophila melanogaster to test whether the Drosophila Rit2 ortholog, Ric, impacts dDAT function, trafficking, and DA-dependent behaviors. Orthologous to hDAT and Rit2, dDAT and Ric directly interact, and the constitutively active Ric mutant Q117L increased dDAT surface levels and function in cell lines and ex vivo Drosophila brains. Moreover, DAergic RicQ117L expression caused sleep fragmentation in a DAT-dependent manner, but had no effect on total sleep and daily locomotor activity. Importantly, we found that Rit2 is required for AMPH-stimulated DAT internalization in mouse striatum, and that DAergic RicQ117L expression significantly increased Drosophila AMPH sensitivity in a DAT-dependent manner, suggesting a conserved impact of Ric-dependent DAT trafficking on AMPH sensitivity. These studies support that the DAT/Rit2 interaction impacts both baseline behaviors and AMPH sensitivity, potentially by regulating DAT trafficking.

scholarly journals FLAMs: A self-replicating ex vivo model of alveolar macrophages for functional genetic studies

2021 ◽  
Author(s):  
Sean Thomas ◽  
Kathryn Wierenga ◽  
James Pestka ◽  
Andrew Olive
Keyword(s):  
Alveolar Macrophages ◽  
Ex Vivo ◽  
Fetal Liver ◽  
Expression Profiles ◽  
Surface Expression ◽  
Specific Gene ◽  
Ex Vivo Model ◽  
A Genome ◽  
Underlying Mechanisms ◽  
And Function

Alveolar macrophages (AMs) are tissue resident cells in the lungs derived from the fetal liver that maintain lung homeostasis and respond to inhaled stimuli. While the importance of AMs is undisputed, they remain refractory to standard experimental approaches and high-throughput functional genetics as they are challenging to isolate and rapidly lose AM properties in standard culture. This limitation hinders our understanding of key regulatory mechanisms that control AM maintenance and function. Here, we describe the development of a new model, fetal liver-derived alveolar-like macrophages (FLAMs), which maintains cellular morphologies, expression profiles, and functional mechanisms similar to murine AMs. FLAMs combine treatment with two key cytokines for AM maintenance, GM-CSF and TGFβ. We leveraged the long-term stability of FLAMs to develop functional genetic tools using CRISPR-Cas9-mediated gene editing. Targeted editing confirmed the role of AM-specific gene Marco and the IL-1 receptor Il1r1 in modulating the AM response to crystalline silica. Furthermore, a genome-wide knockout library using FLAMs identified novel genes required for surface expression of the AM marker Siglec-F, most notably those related to the peroxisome. Taken together, our results suggest that FLAMs are a stable, self-replicating model of AM function that enables previously impossible global genetic approaches to define the underlying mechanisms of AM maintenance and function.

scholarly journals BHLHE40 Regulates IL-10 and IFN-γ Production in T Cells but Does Not Interfere With Human Type 1 Regulatory T Cell Differentiation

2021 ◽  
Vol 12 ◽  
Author(s):  
Molly Javier Uyeda ◽  
Robert A. Freeborn ◽  
Brandon Cieniewicz ◽  
Rosa Romano ◽  
Ping (Pauline) Chen ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
Ex Vivo ◽  
Surface Expression ◽  
Surface Molecules ◽  
Ifn Γ ◽  
And Function ◽  
Tr1 Cells

Type 1 regulatory T (Tr1) cells are subset of peripherally induced antigen-specific regulatory T cells. IL-10 signaling has been shown to be indispensable for polarization and function of Tr1 cells. However, the transcriptional machinery underlying human Tr1 cell differentiation and function is not yet elucidated. To this end, we performed RNA sequencing on ex vivo human CD49b+LAG3+ Tr1 cells. We identified the transcription factor, BHLHE40, to be highly expressed in Tr1 cells. Even though Tr1 cells characteristically produce high levels of IL-10, we found that BHLHE40 represses IL-10 and increases IFN-γ secretion in naïve CD4+ T cells. Through CRISPR/Cas9-mediated knockout, we determined that IL10 significantly increased in the sgBHLHE40-edited cells and BHLHE40 is dispensable for naïve CD4+ T cells to differentiate into Tr1 cells in vitro. Interestingly, BHLHE40 overexpression induces the surface expression of CD49b and LAG3, co-expressed surface molecules attributed to Tr1 cells, but promotes IFN-γ production. Our findings uncover a novel mechanism whereby BHLHE40 acts as a regulator of IL-10 and IFN-γ in human CD4+ T cells.

scholarly journals Silver Nanoparticles Induce Mitochondrial Protein Oxidation in Lung Cells Impacting Cell Cycle and Proliferation

Antioxidants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 552 ◽  
Author(s):  
Reetta J. Holmila ◽  
Stephen A. Vance ◽  
S. Bruce King ◽  
Allen W. Tsang ◽  
Ravi Singh ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Silver Nanoparticles ◽  
Ionizing Radiation ◽  
Cell Lines ◽  
Protein Oxidation ◽  
Mitochondrial Protein ◽  
Antibacterial Properties ◽  
Dependent Manner ◽  
Mitochondrial Redox State ◽  
And Function

Silver nanoparticles (AgNPs) are widely used nanomaterials in both commercial and clinical biomedical applications, due to their antibacterial properties. AgNPs are also being explored for the treatment of cancer in particular in combination with ionizing radiation. In this work, we studied the effects of AgNPs and ionizing radiation on mitochondrial redox state and function in a panel of lung cell lines (A549, BEAS-2B, Calu-1 and NCI-H358). The exposure to AgNPs caused cell cycle arrest and decreased cell proliferation in A549, BEAS-2B and Calu-1, but not in NCI-H358. The mitochondrial reactive oxygen species (ROS) and protein oxidation increased in a time- and dose-dependent manner in the more sensitive cell lines with the AgNP exposure, but not in NCI-H358. While ionizing radiation also induced changes in the mitochondrial redox profiles, in general, these were not synergistic with the effects of AgNPs with the exception of NCI-H358 and only at a higher dose of radiation.

scholarly journals HDAC11 plays an essential role in regulating OX40 ligand expression in Hodgkin lymphoma

Blood ◽  
2011 ◽  
Vol 117 (10) ◽  
pp. 2910-2917 ◽  
Author(s):  
Daniela Buglio ◽  
Noor M. Khaskhely ◽  
Kui Shin Voo ◽  
Hector Martinez-Valdez ◽  
Yong-Jun Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Hodgkin Lymphoma ◽  
Cell Lines ◽  
Essential Role ◽  
Histone Deacetylase Inhibitors ◽  
Interleukin 10 ◽  
Antitumor Immune Response ◽  
Dependent Manner ◽  
Small Interfering Rnas

AbstractIn Hodgkin lymphoma (HL), the malignant cells are surrounded by a large number of reactive infiltrating inflammatory cells, including OX40-expressing T cells and interleukin 10 (IL-10)–producing regulatory T (T-reg) cells. These T-reg cells can suppress the immune response and thus contribute to the maintenance of immune tolerance and to insufficient antitumor response. The engagement of OX40L with the OX40 receptor is essential for the generation of antigen-specific memory T cells and for the induction of host antitumor immunity. In the present study, we investigated whether histone deacetylase inhibitors (HDACis) may induce a favorable antitumor immune response by regulating the expression of OX40L in HL. We found that HDACis up-regulated OX40L surface expression in HL cell lines in a dose-dependent manner. Small interfering RNAs (siRNAs) that selectively inhibited HDAC11 expression, significantly up-regulated OX40L and induced apoptosis in HL cell lines, and silencing HDAC11 transcripts increased the production of tumor necrosis-α (TNF-α) and IL-17 in the supernatants of HL cells. Furthermore, HDACI-induced OX40L inhibited the generation of IL-10–producing type 1 T-reg cells. These results demonstrate for the first time that HDAC11 plays an essential role in regulating OX40L expression. Pharmacologic inhibition of HDAC11 may produce a favorable antitumor immune response in patients with HL.

Essential Role of the INK4/CDK4,6/Rb/E2F Signaling Pathway in AML with the Flt3 Internal Tandem Duplication.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2752-2752
Author(s):  
Lisheng Wang ◽  
Jie Wang ◽  
Blaser W. Bradley ◽  
Caligiuri A. Michael ◽  
Briesewitz Roger
Keyword(s):  
Cell Lines ◽  
Essential Role ◽  
Tandem Duplication ◽  
Dependent Manner ◽  
U937 Cells ◽  
Phase I Clinical Trials ◽  
Internal Tandem Duplication ◽  
Survival Signal ◽  
Apoptotic Protein

Abstract Mutationally activated tyrosine kinases provide a critical survival signal to cancer cells, thus, making such kinases and their downstream effectors attractive targets for cancer therapy. To study signaling of mutated kinases we have chosen the receptor tyrosine kinase Flt3 that harbors an activating internal tandem duplication (ITD) in about 25% of AML patients. The use of a Flt3 inhibitor (THRX-165724, Theravance, Inc.) in two Flt3 ITD AML cell lines (MOLM13 and MV4-11) led to the inhibition of the INK4/CDK4,6/Rb/E2F pathway within three hours as reflected by the downregulation of D-cyclin gene expression followed by a decrease in D-cyclin protein. As a result of reduced D-cyclin levels, CDK4,6 activity was downregulated as revealed by the hypophosphorylation of the main substrate of CDK4,6, the Rb protein. THRX-165724 had no effect on D-cyclin levels or Rb hyperphosphorylation in THP-1 and U937 cells, two AML cell lines that express wildtype Flt3. Furthermore, THRX-165724 did not affect the proliferation or survival of these two cell lines. To investigate the role of the INK4/CDK4,6/Rb/E2F pathway as part of the proliferation and survival signal provided by the Flt3 ITD, we used PD-0332991, a highly selective CDK4,6 kinase inhibitor from Pfizer currently in phase I clinical trials for solid tumors. A dose-response experiment revealed that in cells PD-0332991 inhibits CDK4,6 activity with an IC50 of 30–40 nM as assayed by following the dephosphorylation of Rb. The compound does not inhibit Flt3 kinase activity even at the highest concentrations tested (500 nM). In MV4-11 and MOLM13 cells, PD-0332991 induced G1 specific cell cycle arrest within 24 hours and apoptosis after 3 days. Hence, in MV4-11 and MOLM13, PD-0332991 is cytostatic and cytotoxic. In contrast, PD-0332991 was neither cytotoxic nor cytostatic in THP-1 and U937 cells. In a clonogenic assay PD-0332991 reduced in a dose dependent manner the colony formation of MV4-11 and MOLM13 cells as well as primary patient blasts with Flt3 ITD. In contrast, THP-1 and U937 cells as well as CD34+ primary hematopoietic progenitor cells were not affected in their ability to form colonies. In MV4-11 and MOLM13 cells PD-0332991 induced the downregulation of the anti-apoptotic protein Bcl-2 and in MOLM13 it also induced the upregulation of the pro-apoptotic protein Bak. The deregulation of Bcl-2 and Bak may represent the underlying mechanism for the observed cytotoxicity of PD-0332991 in MV4-11 and MOLM13. In a mouse model of AML, NOD/SCID mice were inoculated with MOLM13 cells which caused leukemia within eight days. Mice treated with PD-0332991 starting at day seven after inoculation had a significant survival advantage demonstrating that PD-0332991 has anti-leukemic activity in vivo (median survival time 15.0 days versus 11.5 days, P=.0003). Our data suggest that the activation of the INK4/CDK4,6/Rb/E2F pathway by Flt3 ITD has an essential role for proliferation and survival in AML cells. Targeting the INK4/CDK4,6/Rb/E2F pathway in Flt3 ITD AML using CDK4,6 inhibitors like PD-0332991 should be explored for clinical efficacy in FLT3 ITD AML.

Further Preclinical Studies with APR-246, a Novel Anticancer Compound Currently in Clinical Trials for Hematological Malignancies and Prostate Cancer.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3773-3773
Author(s):  
Nina Mohell ◽  
Charlotta Liljebris ◽  
Jessica Alfredsson ◽  
Ylva Lindman ◽  
Maria Uustalu ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Ex Vivo ◽  
Cancer Cell Lines ◽  
Solid Cancer ◽  
Dependent Manner

Abstract Abstract 3773 Poster Board III-709 Introduction The tumor suppressor protein p53 induces cell cycle arrest and/or apoptosis in response to various forms of cellular stress, through transcriptional regulation of a large number of down stream target genes. p53 is frequently mutated in cancer, and cancer cells carrying defects in the p53 protein are often more resistant to conventional chemotherapy. Thus, restoration of the wild type function to mutant p53 appears to be a new attractive strategy for cancer therapy. APR-246 is a novel small molecule quinuclidinone compound that has been shown to reactivate non-functional p53 and induce apoptosis. Although the exact molecular mechanism remains to be determined, recent results suggest that an active metabolite of APR-246 alkylates thiol groups in the core domain of p53, which promotes correct folding of p53 and induces apoptosis (Lambert et al., Cancer Cell 15, 2009). Currently, APR-246 is in Phase I/IIa clinical trials for hematological malignancies and prostate cancer. In the present abstract results from in vitro, ex vivo and in vivo preclinical studies with APR-246 are presented. Results The lead compound of APR-246, PRIMA-1 (p53 reactivation and induction of massive apoptosis), was originally identified by a cellular screening of the NCI library for low molecular weight compounds (Bykov et al., Nat. Med., 8, 2002). Further development and optimization of PRIMA-1 led to the discovery of the structural analog APR-246 (PRIMA-1MET), with improved drug like and preclinical characteristics. In in vitro experiments APR-246 reduced cell viability (WST-1 assay) in a large number of human cancer cell lines with various p53 status, including several leukemia (CCRF-CEM, CEM/VM-1, KBM3), lymphoma (U-937 GTP, U-937-vcr), and myeloma (RPMI 8226/S, 8226/dox40, 8226/LR5) cell lines, as well as many solid cancer cell lines, including osteosarcoma (SaOS-2, SaOS-2-His273,U-2OS), prostate (PC3, PC3-His175, 22Rv1), breast (BT474, MCF-7, MDA-MB-231), lung (H1299, H1299-His175) and colon cancer (HT-29). In human osteosarcoma cell lines APR-246 reduced cell viability and induced apoptosis (FLICA caspase assay) in a concentration dependent manner being more potent in the p53 mutant (SaOS-2-His273) than in the parental p53 null (SaOS-2) cells. The IC50 values (WST-1 assay) were 14 ± 3 and 27 ± 5 μM, respectively (n=35). In in vivo subcutaneous xenograft studies in SCID (severe combined immunodeficiency) mice APR-246 reduced growth of p53 mutant SaOS-2-His273 cells in a dose-dependent manner, when injected i.v. twice daily with 20 -100 mg/kg (64 – 76% inhibition). An in vivo anticancer effect of APR-246 was also observed in hollow-fiber test with NMRI mice using the acute myeloid leukemia (AML) cell line MV-4-11. An ex vivo cytotoxic effect of APR-246 and/or its lead compound PRIMA-1 has also been shown in primary cells from AML and CLL (chronic lymphocytic leukemia) patients, harbouring both hemizygously deleted p53 as well as normal karyotype (Nahi et al., Br. J. Haematol., 127, 2004; Nahi et al., Br. J. Haematol., 132, 2005; Jonsson-Videsater et al., abstract at this meeting). APR-246 was also tested in a FMCA (fluorometric microculture assay) test using normal healthy lymphocytes (PBMC) and cancer lymphocytes (CLL). It was 4-8 fold more potent in killing cancer cells than normal cells, indicating a favorable therapeutic index. This is in contrast to conventional cytostatics that often show negative ratio in this test. Furthermore, when tested in a well-defined panel of 10 human cancer cell lines consisting of both hematological and solid cancer cell lines, the cytotoxicity profile/activity pattern of APR-246 differed from common chemotherapeutic drugs (correlation coefficient less than 0.4), suggesting a different mechanism of action. Conclusion In relevant in vitro, in vivo and ex vivo cancer models, APR-246 showed unique pharmacological properties in comparison with conventional cytostatics, by being effective also in cancer cells with p53 mutations and by demonstrating tumor specificity. Moreover, in experimental safety/toxicology models required to start clinical trials, APR-246 was non toxic at the predicted therapeutic plasma concentrations. Thus, APR-246 appears to be a promising novel anticancer compound that may specifically target cancer cells in patients with genetic abnormality associated with poor prognosis. Disclosures: Mohell: Aprea AB: Employment. Liljebris:Aprea AB: Employment. Alfredsson:Aprea AB: Employment. Lindman:Aprea AB: Employment. Uustalu:Aprea AB: Employment. Wiman:Aprea AB: Co-founder, shareholder, and member of the board. Uhlin:Aprea AB: Employment.

scholarly journals Citrullinated vimentin mediates development and progression of lung fibrosis

2021 ◽  
Vol 13 (585) ◽  
pp. eaba2927
Author(s):  
Fu Jun Li ◽  
Ranu Surolia ◽  
Huashi Li ◽  
Zheng Wang ◽  
Gang Liu ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Lung Fibrosis ◽  
Ex Vivo ◽  
Lavage Fluid ◽  
Surface Expression ◽  
Lung Fibroblasts ◽  
Dependent Manner ◽  
Ex Vivo Model ◽  
Molecular Pattern ◽  
Citrullinated Vimentin

The mechanisms by which environmental exposures contribute to the pathogenesis of lung fibrosis are unclear. Here, we demonstrate an increase in cadmium (Cd) and carbon black (CB), common components of cigarette smoke (CS) and environmental particulate matter (PM), in lung tissue from subjects with idiopathic pulmonary fibrosis (IPF). Cd concentrations were directly proportional to citrullinated vimentin (Cit-Vim) amounts in lung tissue of subjects with IPF. Cit-Vim amounts were higher in subjects with IPF, especially smokers, which correlated with lung function and were associated with disease manifestations. Cd/CB induced the secretion of Cit-Vim in an Akt1- and peptidylarginine deiminase 2 (PAD2)–dependent manner. Cit-Vim mediated fibroblast invasion in a 3D ex vivo model of human pulmospheres that resulted in higher expression of CD26, collagen, and α-SMA. Cit-Vim activated NF-κB in a TLR4-dependent fashion and induced the production of active TGF-β1, CTGF, and IL-8 along with higher surface expression of TLR4 in lung fibroblasts. To corroborate ex vivo findings, mice treated with Cit-Vim, but not Vim, independently developed a similar pattern of fibrotic tissue remodeling, which was TLR4 dependent. Moreover, wild-type mice, but not PAD2−/− and TLR4 mutant (MUT) mice, exposed to Cd/CB generated high amounts of Cit-Vim, in both plasma and bronchoalveolar lavage fluid, and developed lung fibrosis in a stereotypic manner. Together, these studies support a role for Cit-Vim as a damage-associated molecular pattern molecule (DAMP) that is generated by lung macrophages in response to environmental Cd/CB exposure. Furthermore, PAD2 might represent a promising target to attenuate Cd/CB-induced fibrosis.

The EGFR-Inhibitor Erlotinib Induces Apoptosis in Neoplastic Cells of Myelodysplastic Syndrome (MDS) and Acute Myeloid Leukemia (AML), an Effect Determined by the Expression Level of Nucleophosmin (NPM).

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 856-856
Author(s):  
Simone Boehrer ◽  
Lionel Ades ◽  
Claire Fabre ◽  
Pierre Fenaux ◽  
Guido Kroemer
Keyword(s):  
Cell Lines ◽  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Ex Vivo ◽  
Myeloid Cell ◽  
Expression Level ◽  
Apoptotic Cells ◽  
Dependent Manner ◽  
Egfr Inhibitor ◽  
Down Regulation

Abstract Background: the epidermal-growth-factor-receptor (EGFR)-inhibitor erlotinib was rationally designed to antagonize the deregulated EGFR-activity in solid tumors. Abundant studies in these entities not only demonstrated clinical efficacy, but also a favorable toxicity profile. In particular the absence of hematopoietic toxicity prompted us to investigate the therapeutic potential of erlotinib in MDS and AML cells. Methods: We incubated ex vivo cells from patients with MDS (n=4, 2 lower risk and 2 higher risk) and AML (n=6, de novo: 3; post MDS: 3), as well as a broad spectrum of myeloid cell lines (P39, KG-1, HL-60, MV4-11, MOLM-13) with increasing dosages of erlotinib (1μM to 10μM). As controls (n=4) we used non-malignant CD34 + bone marrow cells. Before incubation, all ex vivo cells underwent CD34 + selection. Serial FACS-analyses of parameters determining apoptosis (DIOC/PI and AnnexinV/PI) were carried out over a maximum of 6 days. Results: We found that erlotinib was able to induce a considerable degree of apoptosis in MDS and AML cells. Although there was a high interindividual difference in sensitivity towards erlotinib, “responders” treated with 10μM erlotinib showed an increase of apoptotic cells between 20–30% after 72h, which reached a maximum of 60% on day 6. This apoptosis-inducing effect was achieved in a dose-dependent manner and not restricted to a specific entity. Noteworthy, erlotinib exhibited no toxicity towards non-neoplastic progenitor cells. Evaluating the molecular mechanisms determining sensitivity we showed that the apoptosis-inducing effect of erlotinib critically depended on the expression level of NPM. Thus erlotinib-resistant myeloid cell lines (i.e. P39) exhibited a higher epression of NPM than sensitive cell lines (i.e. KG-1). In addition, down-regulation of NPM by small-interfering RNA not only increased the apoptosis-inducing effect of erlotinib in sensitive cells, but moreover established sensitivity in otherwise erlotinib-resistant cells. Accordingly, siRNA-induced down-regulation of NPM in P39 cells elevated the percentage of apoptotic cells upon treatment with 10μM erlotinib by about 30% as compared to mock-transfected controls. Conclusion, we showed an off-target effect of erlotinib, as evidenced by its ability to induce apoptosis in EGFR-negative cells. Of particular interest is the observation that erlotinib induced apoptosis exclusively in neoplastic myeloid cells while sparing non-malignant progenitors. To the best of our knowledge, this is the first report providing evidence for the therapeutic potential of erlotinib in MDS and AML.

Preclinical Characterization of the JAK-2 Inhibitor, SGI-1252

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2629-2629 ◽  
Author(s):  
Kausar Begam Riaz Ahmed ◽  
Roberto H Nussenzveig ◽  
Andrew T. Chen ◽  
Josef T. Prchal ◽  
Charles J. Parker ◽  
...  
Keyword(s):  
Cell Lines ◽  
Potent Inhibitor ◽  
Ex Vivo ◽  
Philadelphia Chromosome ◽  
Hematological Toxicity ◽  
Significant Activity ◽  
Dependent Manner ◽  
Erythroid Progenitor ◽  
Luminex Technology ◽  
Ic50 Values

Abstract Discovery of somatic mutation of JAK-2 (G1849T that produces JAK-2V617F) in the hematopoietic cells of patients with Philadelphia chromosome negative myeloproliferative disorders (Ph−MPDs) was a watershed event that not only provided new insights into the pathobiology of polycythemia vera, essential thrombocytosis and primary myelofibrosis but also identified a potential target for therapy. Herein we report the results of preclinical studies designed to characterize the activity of a novel inhibitor of JAK-2. The compound, SGI-1252, developed by SuperGen (Dublin, CA) incorporates with high affinity into the ATP-binding site of JAK-2. SGI-1252 was tested against a panel of 75 kinases and was found to have significant activity against only FLT-3, TYK-2 and the SRC family members, ABL, LCK, YES, in addition to JAK-2 and JAK-1. SGI-1252 has an IC50 for JAK-2 of 5.4 nM with an IC50 for JAK-2V617F of 19.7 nM. The inhibitor also effectively blocks the activity of JAK-1 (IC50 14.8 nM) but has little JAK-3 inhibitory activity (IC50 1,700 nM). SGI-1252 is a potent inhibitor of STAT-5 phosphorylation (EC50 76.2 nM) and was also found to block the JAK-2 dependent expression of the anti-apoptotic protein, BCL-XL (EC50 778 nM). Drug treatment of a murine cell line (FDCP) transfected with either human wild-type JAK-2 or JAK-2G1849Tgenerated IC50 values of 83 nM and 108 nM, respectively, and SGI-1252 treatment of human cell lines, HEL, UKE-1 and SET-2, that express mutant JAK2 in different copy numbers, gave IC50 values of 472 nM, 83 nM and 63 nM, repectively. When tested in ex-vivo expanded native human erythroid progenitor cells from 17 patients with Ph−MPDs (10 PV and 7 MF), SGI-1252 showed an IC50 of ~100 nM, regardless of the JAK-2V617F allele burden. Using a flow cytometric assay, SGI-1252 was shown to induce apoptotic cell death in a concentration dependent manner. Luminex technology allows for concurrent quantitative analysis of multiple proteins from the same tissue source, and this technology was used to investigate simultaneously the effects of SGI-1252 on total and phospho ERK1/2, total and phospho STAT3, phospho STAT5, caspase 3, cleaved PARP and GAPDH (control) in untreated and drug treated cells at IC50 and IC80 concentrations. Significant in vivo efficacy of SGI-1252 was also observed using HEL and MV-4-11 xenograft models when compared to treatment with vehicle or daunorubicin. Using a murine model, we found that SGI-1252 has high oral bioavailability and is well tolerated with a five-day repeat maximum dose of at least 900 mg/kg. Together, these studies demonstrate that SGI-1252 is a potent inhibitor of JAK-2 dependent proliferation in both JAK-2V617F positive cell lines and in ex vivo expanded erythroid progenitors derived from patients with JAK-2V617F positive Ph−MPDs. Moreover, our studies show that the effects of SGI-1252 are mediated by blocking both JAK-2 dependent anti-apoptoic pathways and JAK-2 dependent proliferative pathways. Using the orally available form of the compound, pharmacokinetic, pharmacodynamic and toxicity studies in mice suggest that serum concentration of the drug well above the predicted therapeutic range can be achieved without significant hematological toxicity. Based on these preclinical experiments, SGI-1252 appears to be an excellent candidate for phase I/II studies in patients with Ph−MPDs.

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