Intrinsic resistance to PIM kinase inhibition in AML through p38α-mediated feedback activation of mTOR signaling

Although conventional therapies for acute myeloid leukemia (AML) and diffuse large B-cell lymphoma (DLBCL) are effective in inducing remission, many patients relapse upon treatment. Hence, there is an urgent need for novel therapies. PIM kinases are often overexpressed in AML and DLBCL and are therefore an attractive therapeutic target. However, in vitro experiments have demonstrated that intrinsic resistance to PIM inhibition is common. It is therefore likely that only a minority of patients will benefit from single agent PIM inhibitor treatment. In this study, we performed an shRNA-based genetic screen to identify kinases whose suppression is synergistic with PIM inhibition. Here, we report that suppression of p38α (MAPK14) is synthetic lethal with the PIM kinase inhibitor AZD1208. PIM inhibition elevates reactive oxygen species (ROS) levels, which subsequently activates p38α and downstream AKT/mTOR signaling. We found that p38α inhibitors sensitize hematological tumor cell lines to AZD1208 treatment in vitro and in vivo. These results were validated in ex vivo patient-derived AML cells. Our findings provide mechanistic and translational evidence supporting the rationale to test a combination of p38α and PIM inhibitors in clinical trials for AML and DLBCL

Modulation of the <i>Neisseria gonorrhoeae </i>drug efflux conduit MtrE

We acknowledge funding through the Wellcome Trust Interdisciplinary Research Funds (grant WT097818MF), the Scottish Universities’ Physics Alliance (SUPA), Tenovus Tayside (grant T16/30) and the Tayside Charitable Trust. O.N.V. has been funded through a BBSRC CASE award (BB/J013072/1).Widespread antibiotic resistance, especially of Gram-negative bacteria, has become a severe concern for human health. Tripartite efflux pumps are one of the major contributors to resistance in Gram-negative pathogens, by efficiently expelling a broad spectrum of antibiotics from the organism. In Neisseria gonorrhoeae, one of the first bacteria for which pan-resistance has been reported, the most expressed efflux complex is MtrCDE. Here we present the electrophysiological characterisation of the outer membrane component MtrE and the membrane fusion protein MtrC, obtained by a combination of planar lipid bilayer recordings and in silico techniques. Our in vitro results show that MtrE can be regulated by periplasmic binding events and that the interaction between MtrE and MtrC is sufficient to stabilize this complex in an open state. In contrast to other efflux conduits, the open complex only displays a slight preference for cations. The maximum conductance we obtain in the in vitro recordings is comparable to that seen in our computational electrophysiology simulations conducted on the MtrE crystal structure, indicating that this state may reflect a physiologically relevant open conformation of MtrE. Our results suggest that the MtrC/E binding interface is an important modulator of MtrE function, which could potentially be targeted by new efflux inhibitors.Publisher PDFPeer reviewe

A83-01 inhibits TGF-β-induced upregulation of Wnt3 and epithelial to mesenchymal transition in HER2-overexpressing breast cancer cells

PurposeThe aim of this study is to investigate the mechanisms of interactions between TGF-β and Wnt/β-catenin pathways that induce and regulate EMT and promote breast cancer cells to become resistant to treatment.MethodsThe effect of TGF-β on Wnt/β-catenin signaling pathway was examined by using a human Wnt/β-catenin-regulated cDNA plate array and western blot analysis. The interaction of Twist at promoter of Wnt3 was examined by chromatin immunoprecipitation (ChIP) assay. Secreted Wnt3 level was determined by ELISA assay.ResultsHER2-overexpressing breast cancer cells treated with TGF-β have a reduced response to trastuzumab and exhibited EMT-like phenotype. The TGF-β-induced EMT in HER2-cells was concordant with upregulation of Wnt3 and β-catenin pathways. The TGF-β-induced induction of Wnt3 during EMT was found to be Smad3-dependent. ChIP analysis identified occupancy of Twist at promoter region of Wnt3. Knock-down of Twist by shRNA confirmed the significance of Twist in response to TGF-β regulating Wnt3 during EMT. Subsequently, TGF-β-induced matrix metalloproteinases, MMP1, MMP7, MMP9, MMP26, Vascular endothelial growth factors (VEGF), and activation of Wnt/β-catenin signaling were repressed by the shRNA treatment. TGF-βR1 ALK5 kinase inhibitor, A83-01 can effectively prevent the TGF-β-induced Twist and Wnt3. Co-treating A83-01 and trastuzumab inhibited TGF-β-induced cell invasion significantly in both trastuzumab responsive and resistant cells.ConclusionsOur data demonstrated an important interdependence between TGF-β and Wnt/β-catenin pathways inducing EMT in HER2-overexpressing breast cancer cells. Twist served as a linkage between the two pathways during TGF-β-induced EMT. A83-01 could inhibit the TGF-β-initiated pathway interactions and enhance HER2-cells response to trastuzumab treatment

Rapid Temporal Control of Foxp3 Protein Degradation by Sirtuin-1

Maintenance of Foxp3 protein expression in regulatory T cells (Treg) is crucial for a balanced immune response. We have previously demonstrated that Foxp3 protein stability can be regulated through acetylation, however the specific mechanisms underlying this observation remain unclear. Here we demonstrate that SIRT1 a member of the lysine deacetylase Sirtuin (SIRT) family, but not the related SIRTs 2–7, co-localize with Foxp3 in the nucleus. Ectopic expression of SIRT1, but not SIRTs 2–7 results in decreased Foxp3 acetylation, while conversely inhibition of endogenous SIRT activity increased Foxp3 acetylation. We show that SIRT1 inhibition decreases Foxp3 poly-ubiquitination, thereby increasing Foxp3 protein levels. Co-transfection of SIRT1 with Foxp3 results in increased Foxp3 proteasomal degradation, while SIRT inhibition increases FOXP3 transcriptional activity in human Treg. Taken together, these data support a central role for SIRT1 in the regulation of Foxp3 protein levels and thereby in regulation of Treg suppressive capacity. Pharmacological modulation of SIRT1 activity in Treg may therefore provide a novel therapeutic strategy for controlling immune responses

Preformed Pd(II) Catalysts based on Monoanionic [N,O] Ligands for Suzuki-Miyaura Cross-Coupling at Low Temperature

This paper describes the synthesis and catalytic testing of a palladium complex with a 5-membered chelating [N,O] ligand, derived from the condensation of 2,6-diisopropylphenyl aniline and maple lactone. This catalyst was active towards the Suzuki-Miyaura cross-coupling reaction, and its activity was optimised through the selection of base, solvent, catalytic loading and temperature. The optimised conditions are mild, occurring at room temperature and over a short timescale (1 h) using solvents considered to be ‘green’. A substrate scope was then carried out in which the catalyst showed good activity towards aryl bromides with electron-withdrawing groups. The catalyst was active across a broad scope of electron-donating and high-withdrawing aryl bromides with the highest activity shown for weak electron-withdrawing groups. The catalyst also showed good activity across a range of boronic acids and pinacol esters with even boronic acids featuring strong electron-withdrawing groups showing some activity. The catalyst was also a capable catalyst for the cross-coupling of aryl chlorides and phenylboronic acid. This more challenging reaction requires slightly elevated temperatures over a longer timescale but is still considered mild compared to similar examples in the literature

TGF-β: an emerging player in drug resistance.

The transforming growth factor β (TGF-β) pathway acts as a double-edged sword in tumorigenesis. By constraining epithelial cell growth, TGF-β is a potent tumor suppressor. However, TGF-β also acts as a key player in the induction of epithelial-to-mesenchymal transition (EMT), thereby enhancing invasiveness and metastasis. Furthermore, TGF-β signaling has recently been correlated with resistance against both targeted and conventional anticancer agents. Here, we present data demonstrating a role for TGF-β in chemotherapy resistance in colorectal cancer (CRC). We discuss these results in the context of recent findings indicating TGF-β signaling as an emerging player in cancer drug resistance

Liga : ein Programm zur Berechnung der lokalen individuellen Gammasubmersionsdosis durch Abluftfahnen aus kerntechnischen Anlagen

Zur Berechnung der $\gamma$-Submersionsdosis, der Personen unter radioaktiv kontaminierten Abluftfahnen exponiert werden, wurde ein verbessertes Modell entwickelt, das über die Dosisbeiträge der Volurnenelemente des Halbraurns integriert und Absorption und Streuung der $\gamma$-Strahlung in Luft (Aufbaufaktor) berücksichtigt. Für die Auswertung wurde das. Rechenprograrnrn LIGA aufgestellt, das das aus den Ausbreitungsuntersuchungen in der Umgebung der Kernforschungsanlage Jülich ermittelte System von Ausbreitungsparametern verwendet. Die Ausbreitungsparameter wurden für alle Wetterlagen (Diffusionskategorien) in 50 und 100 m Ernissionshöhe gemessen und gelten für mittlere bis größere Bodenrauhigkeit, die in der BRO für die Standorte kerntechnischer Anlagen relativ häufig vorkommt. Aus den Kurzzeitausbreitungsfaktoren, die die Dosisverteilung unter einer kurzzeitig, d. h. bei konstanten meteorologischen Bedingungen, freigesetzten Abluftfahnen angeben, wurden durch Oberlagerung von Einzelemissionen unter Verwendung ausbreitungsmeteorologischer Statistiken Langzeitausbreitungsfaktoren berechnet, die die Umgebungsbelastung kontinuierlich emittierender Quellen in den einzelnen Sektoren einer 12-teiligen Windrose beschreiben. Hierbei werden die Beiträge der Nebensektoren erstmalig ohne unzulässige Vernachlässigungen erfaßt.In Sensitivitätsanalysen wird der Einfluß wichtiger Parameter, wie der $\gamma$-Energie der Radionuklide in der Abluftfahne, untersucht. Ferner wird die Frage behandelt, welcher Fehler in Kauf zu nehmen ist, wenn man anstelle einer genauen Rechnung unter Verwendung der dreidimensionalen Ausbreitungsstatistik(Windrichtung, Windgeschwindigkeit, Diffusionskategorie) des jeweiligen Standortes von dem $\gamma$-Submersionsfaktor einer für die Bundesrepublik einheitlichen Basisstandortklasse ausgeht, der nur noch mit der lokalen Windrichtungshäufigkeitsverteilung des Standortes in den 12 Windrichtungs sektoren zu multiplizierenist

TGF-β: an emerging player in drug resistance.

The transforming growth factor β (TGF-β) pathway acts as a double-edged sword in tumorigenesis. By constraining epithelial cell growth, TGF-β is a potent tumor suppressor. However, TGF-β also acts as a key player in the induction of epithelial-to-mesenchymal transition (EMT), thereby enhancing invasiveness and metastasis. Furthermore, TGF-β signaling has recently been correlated with resistance against both targeted and conventional anticancer agents. Here, we present data demonstrating a role for TGF-β in chemotherapy resistance in colorectal cancer (CRC). We discuss these results in the context of recent findings indicating TGF-β signaling as an emerging player in cancer drug resistance