Modulation of the Allosteric Communication between the Polo-Box Domain and the Catalytic Domain in Plk1 by Small Compounds

The Polo-like kinases (Plks) are an evolutionary conserved family of Ser/Thr protein kinases that possess, in addition to the classical kinase domain at the N-terminus, a C-terminal polo-box domain (PBD) that binds to phosphorylated proteins and modulates the kinase activity and its localization. Plk1, which regulates the formation of the mitotic spindle, has emerged as a validated drug target for the treatment of cancer, because it is required for numerous types of cancer cells but not for the cell division in noncancer cells. Here, we employed chemical biology methods to investigate the allosteric communication between the PBD and the catalytic domain of Plk1. We identified small compounds that bind to the catalytic domain and inhibit or enhance the interaction of Plk1 with the phosphorylated peptide PoloBoxtide in vitro. In cells, two new allosteric Plk1 inhibitors affected the proliferation of cancer cells in culture and the cell cycle but had distinct phenotypic effects on spindle formation. Both compounds inhibited Plk1 signaling, indicating that they specifically act on Plk1 in cultured cells.Fil: Raab, Monika. Goethe Universitat Frankfurt; AlemaniaFil: Sanhaji, Mourad. Goethe Universitat Frankfurt; AlemaniaFil: Pietsch, Larissa. German Cancer Research Center; Alemania. Goethe Universitat Frankfurt; AlemaniaFil: Béquignon, Isabelle. Goethe Universitat Frankfurt; AlemaniaFil: Herbrand, Amanda K.. Goethe Universitat Frankfurt; AlemaniaFil: Süß, Evelyn. Goethe Universitat Frankfurt; AlemaniaFil: Gande, Santosh L.. German Cancer Research Center; Alemania. Goethe Universitat Frankfurt; AlemaniaFil: Caspar, Birgit. Goethe Universitat Frankfurt; AlemaniaFil: Kudlinzki, Denis. Goethe Universitat Frankfurt; Alemania. German Cancer Research Center; AlemaniaFil: Saxena, Krishna. Goethe Universitat Frankfurt; AlemaniaFil: Sreeramulu, Sridhar. Goethe Universitat Frankfurt; AlemaniaFil: Schwalbe, Harald. Goethe Universitat Frankfurt; Alemania. German Cancer Research Center; AlemaniaFil: Strebhardt, Klaus. Goethe Universitat Frankfurt; Alemania. German Cancer Research Center; AlemaniaFil: Biondi, Ricardo Miguel. German Cancer Research Center; Alemania. Goethe Universitat Frankfurt; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; Argentin

Is It Safe to Switch From Intravenous Immunoglobulin to Subcutaneous Immunoglobulin in Patients With Common Variable Immunodeficiency and Autoimmune Thrombocytopenia?

BackgroundA significant amount of common variable immunodeficiency (CVID) patients manifest with autoimmunity. Particularly, autoimmune thrombocytopenia (AITP) is commonly seen. Intravenous immunoglobulins (IVIG) are an established treatment option for both, CVID and AITP. Nonetheless, due to fewer systemic side effects, immunoglobulins are increasingly applied subcutaneously (SCIG).ObjectiveTo compare the efficacy and safety of IVIG and SCIG treatment in patients with both CVID and clinical relevant thrombocytopenia in the prevention of AITP bouts.MethodsPatients with both CVID and AITP were enrolled at the Centre for Chronic Immunodeficiency in Freiburg, Germany and at the Royal Free Hospital, London, UK. Clinical and laboratory features of patients were collected and analyzed.ResultsThis retrospective study recruited 61 adult patients between 19 and 71 years of age who had a diagnosis of CVID and at least one bout of thrombocytopenia defined as a platelet count of <50,000/μl if bleeding episodes occurred, or a platelet count of <20,000/μl without bleeding. Thirty patients received immunoglobulin through IVIG, and 31 patients were on SCIG replacement. One patient of the IVIG-group was excluded, because of a diffuse large B-cell lymphoma. We did not find a higher occurrence of thrombocytopenic events in CVID patients who received SCIG, compared to CVID patients who had IVIG, but we identified a low IgG through level as a risk factor for AITP bouts.ConclusionSCIG is at least as safe as IVIG for patients with CVID and concomitant AITP. However, an IgG through level under 7 g/l is a key factor for the development of AITP

Ceritinib-induced regression of an insulin-like growth factor-driven neuroepithelial brain tumor

The insulin-like growth factor (IGF) pathway plays an important role in several brain tumor entities. However, the lack of inhibitors crossing the blood–brain barrier remains a significant obstacle for clinical translation. Here, we targeted the IGF pathway using ceritinib, an off-target inhibitor of the IGF1 receptor (IGF1R) and insulin receptor (INSR), in a pediatric patient with an unclassified brain tumor and a notch receptor 1 (NOTCH1) germline mutation. Pathway analysis of the tumor revealed activation of the sonic hedgehog (SHH), the wingless and integrated-1 (WNT), the IGF, and the Notch pathway. The proliferation of the patient tumor cells (225ZL) was inhibited by arsenic trioxide (ATO), which is an inhibitor of the SHH pathway, by linsitinib, which is an inhibitor of IGF1R and INSR, and by ceritinib. 225ZL expressed INSR but not IGF1R at the protein level, and ceritinib blocked the phosphorylation of INSR. Our first personalized treatment included ATO, but because of side effects, we switched to ceritinib. After 46 days, we achieved a concentration of 1.70 µM of ceritinib in the plasma, and after 58 days, MRI confirmed that there was a response to the treatment. Ceritinib accumulated in the tumor at a concentration of 2.72 µM. Our data suggest ceritinib as a promising drug for the treatment of IGF-driven brain tumors

Performanznahe und videobasierte Messung von DaZ-Kompetenz bei Lehrkräften: Skalierung und dimensionale Struktur des Testinstruments

Lemmrich S, Hecker S-L, Klein S, et al. Performanznahe und videobasierte Messung von DaZ-Kompetenz bei Lehrkräften: Skalierung und dimensionale Struktur des Testinstruments. In: Ehmke T, Kuhl P, Pietsch M, eds. Lehrer. Bildung. Gestalten. Beiträge zur empirischen Forschung in der Lehrerbildung . 1st ed. Weinheim / Basel: Beltz / Juventa; 2019: 190-204

N-cadherin is expressed on human hematopoietic progenitor cells and mediates interaction with human mesenchymal stromal cells

AbstractSpecific cell–cell junctions between hematopoietic stem cells (HSC) and their niche have been shown to regulate stem cell function. N-cadherin was suggested to play a central role in this process, whereas other studies indicated that it did not play an essential role in the murine model. We have analyzed the role of N-cadherin for interaction between hematopoietic progenitor cells (HPC) and supportive mesenchymal stromal cells (MSC) in a human–human setting. Expression of N-cadherin and of cadherin-11 (osteoblast cadherin) was analyzed in HPC by quantitative RT-PCR, Western blot, and flow cytometry. N-cadherin and cadherin-11 were expressed in HPC at a moderate level, whereas they were not detectable in differentiated cells. Confocal laser scanning microscopy revealed that N-cadherin and β-catenin are colocalized at the junction of HPC and MSC. siRNA knockdown of N-cadherin or cadherin-11 as well as treatment with the blocking function antibody decreased adhesive interaction of HPC to MSC. Furthermore, knockdown of N-cadherin or blocking function antibody impaired maintenance of long-term culture-initiating cells (LTC-IC) on coculture of HPC and MSC. These results indicate that N-cadherin is involved in the bidirectional interaction of human HPC with their cellular determinants in the niche

Crizotinib acts as ABL1 inhibitor combining ATP-binding with allosteric inhibition and is active against native BCR-ABL1 and its resistance and compound mutants BCR-ABL1 T315I and BCR-ABL1 T315I-E255K

Resistance remains the major clinical challenge for the therapy of Philadelphia chromosome-positive (Ph+) leukemia. With the exception of ponatinib, all approved tyrosine kinase inhibitors (TKIs) are unable to inhibit the common gatekeeper mutation T315I. Here we investigated the therapeutic potential of crizotinib, a TKI approved for targeting ALK and ROS1 in non-small cell lung cancer patients, which inhibited also the ABL1 kinase in cell-free systems, for the treatment of advanced and therapy-resistant Ph+ leukemia. By inhibiting the BCR-ABL1 kinase, crizotinib efficiently suppressed growth of Ph+ cells without affecting growth of Ph- cells. It was also active in Ph+ patient-derived long-term cultures (PD-LTCs) independently of the responsiveness/resistance to other TKIs. The efficacy of crizotinib was confirmed in vivo in syngeneic mouse models of BCR-ABL1- or BCR-ABL1T315I-driven chronic myeloid leukemia-like disease and in BCR-ABL1-driven acute lymphoblastic leukemia (ALL). Although crizotinib binds to the ATP-binding site, it also allosterically affected the myristol binding pocket, the binding site of GNF2 and asciminib (former ABL001). Therefore, crizotinib has a seemingly unique double mechanism of action, on the ATP-binding site and on the myristoylation binding pocket. These findings strongly suggest the clinical evaluation of crizotinib for the treatment of advanced and therapy-resistant Ph+ leukemia

Ceritinib-induced regression of an insulin-like growth factor-driven neuroepithelial brain tumor

The insulin-like growth factor (IGF) pathway plays an important role in several brain tumor entities. However, the lack of inhibitors crossing the blood–brain barrier remains a significant obstacle for clinical translation. Here, we targeted the IGF pathway using ceritinib, an off-target inhibitor of the IGF1 receptor (IGF1R) and insulin receptor (INSR), in a pediatric patient with an unclassified brain tumor and a notch receptor 1 (NOTCH1) germline mutation. Pathway analysis of the tumor revealed activation of the sonic hedgehog (SHH), the wingless and integrated-1 (WNT), the IGF, and the Notch pathway. The proliferation of the patient tumor cells (225ZL) was inhibited by arsenic trioxide (ATO), which is an inhibitor of the SHH pathway, by linsitinib, which is an inhibitor of IGF1R and INSR, and by ceritinib. 225ZL expressed INSR but not IGF1R at the protein level, and ceritinib blocked the phosphorylation of INSR. Our first personalized treatment included ATO, but because of side effects, we switched to ceritinib. After 46 days, we achieved a concentration of 1.70 µM of ceritinib in the plasma, and after 58 days, MRI confirmed that there was a response to the treatment. Ceritinib accumulated in the tumor at a concentration of 2.72 µM. Our data suggest ceritinib as a promising drug for the treatment of IGF-driven brain tumors

Gradient-Doped Colloidal Quantum Dot Solids Enable Thermophotovoltaic Harvesting of Waste Heat

Electromagnetic radiation emitted from hot objects represents a sizable source of energy, one that in most applications is not harvested efficiently. Even for a blackbody at 800 °C, the radiation intensity peaks near 2.7 μm wavelength, and this requires a semiconductor absorber having a band gap in the short-wavelength infrared and beyond to enable thermophotovoltaic (TPV) heat recovery. Here we report the first solution-processed TPV device to harvest efficiently 800 °C heat. The active layer consists of colloidal quantum dots (CQDs), infrared-absorbing nanoparticles synthesized using a scalable solution-based method, having 0.75 eV band gap. We construct rectifying junction devices based on controllably p- and n-doped CQD solids that benefit from a gradient in electron affinity that extends over the devices’ thickness. The gradient-doped architecture relies on engineered charge carrier drift and overcomes the existing limitations of small band gap CQD solids. The devices provide 2.7% efficiency in the conversion of optical power from above-band gap photons from a blackbody source at 800 ± 20 °C into electrical power. The cells were thermally stable up to 140 °C, increasing the promise of CQD solids for TPV applications