Le problème Marivaux : le faux dans "Les fausses confidences"

Où est le faux dans les Fausses Confidences ? Chez le lecteur, le spectateur ou le metteur en scène - ou chez Marivaux. Il est chez l'amateur ou l'exégète lorsqu'ils veulent goûter ou expliquer allègrement la comédie sans mettre de côté aussi radicalement que ce projet l'exigerait le sérieux de la vie et leur volonté de connaissance. Il est chez l'auteur, si l'on ne refuse pas de reconnaître dans cette pièce le problème de l'existence de Marivaux, qui réside dans l'inadéquation entre son talent esthétique et sa raison analytique.Wherein lies "le faux" of les Fausses Confidences ? In the reader, the spectator or the director, or, alternatively, in Marivaux? It lies in the Marivaux lover or exegete, if he is unable to lay aside as he must his own high seriousness and will to knowledge in enjoying or interpreting les Fausses Confidences as pure unencumbered comedy. It lies in Marivaux, if one is prepared to recognize the problem of Marivaux's existence-le problème Marivaux-in the play. This problem consists in Marivaux's inability to raise his analytical powers to the level of his aesthetic gifts

Die Bedeutung des Wilms Tumor Gens (WT-1) für die Prognose und das Monitoring der Akuten Myeloischen Leukämie

Das Tumor­Suppressor­Gen wt­1 (Wilms Tumor Gen) kodiert ein Zink­Finger DNA­ bindendes Protein mit vorwiegend Transkriptions­hemmenden Eigenschaften. Da wt­1 Expression auch in leukämischen Blasten von Patienten mit akuten Leukämien nachgewiesen werden konnte, war das Ziel der Arbeit, das Expressionsmuster von wt­1 mRNA in Patienten mit akuter myeloischer Leukämie (AML) mittels der Polymerase­Kettenreaktion (PCR) zu untersuchen. Dabei war die Expressionsstärke visuell in negativ (­), schwach positiv ( ), mittelgradig positiv ( ) und stark positiv ( ) zu unterteilen. Die Ergebnisse, in ausgesuchten Fällen durch eine kompetitive PCR validiert, sollten mit FAB­Klassifikation, Karyotyp, Oberflächenmarker­Expression, Alter, Geschlecht und klinischem Verlauf verglichen werden, um eine Aussage über die Bedeutung der wt­1 Expression für Prognose, Verlaufskontrolle und das Erkennen von Minimal Residual Disease (MRD) zu treffen. Es wurden insgesamt mehr als 500 Proben von Patienten (mononukleäre Zellen (MC) aus Knochenmark (KM) und peripherem Blut (PB)) untersucht. Davon wurden insgesamt 129 Patienten bei Erstdiagnose und 32 Patienten bei 1. Rezidiv untersucht. Bei 77 Patienten konnte die wt­1 Expression im Verlauf untersucht werden. wt­1 mRNA fand sich bei 124 von 161 (77%) der Patienten bei Erstdiagnose und 1.Rezidiv. Die wt­1 Expression war unabhängig vom Alter, vorhergehendem myelodysplastischem Syndrom (MDS), Geschlecht und FAB­Subtyp mit Ausnahme einer signifikant niedrigeren wt­1 Expressionshäufigkeit in FAB M5 Leukämien von nur 40% (P=0,0025). Es fand sich keine Korrelation zwischen wt­1 mRNA Expressionsstärke und den durch den Karyotyp definierten prognostischen Gruppen. Die Ansprechrate auf Therapie war zwar umso höher, je niedriger die wt­1 Expression lag; es fand sich jedoch kein signifikanter Unterschied zwischen den Expressions­Gruppen. Patienten mit hoher wt­1 mRNA Expression ( , ) zeigten eine deutlich schlechtere Gesamt­ Überlebens­wahrscheinlichkeit (OS) als solche mit niedriger Expression (­, ). Das 3­Jahres­ OS für alle neu diagnostizierten AML­Patienten lag bei 13% bei starker und 38% bei schwacher wt­1 Expression (P=0,038); bei Patienten mit de novo AML bei 12% und 43% (P=0,014). Der Unterschied war bei der Patientengruppe unter 60 Jahren noch stärker ausgeprägt. Im Verlauf ließ sich bei allen Patienten, die eine komplette Remission (CR) erreichten, keine wt­1 Transkripte mehr nachweisen. Bei Rezidiv trat in den meisten Fällen erneut erhöhte wt­1 Expression auf. In einigen Fällen ging dies dem klinischen Befund eines Rezidivs voraus. Zusammenfassend konnte gezeigt werden, daß wt­1 von der Mehrzahl der AML­Patienten exprimiert wird und mittels PCR nachgewiesen werden kann, ein von Karyotyp und Alter unabhängiger prognostischer Faktor ist und sich mit Einschränkung zur Verlaufskontrolle und Detektion von MRD anbietet

Pharmacological inhibition of c-Abl compromises genetic stability and DNA repair in Bcr-Abl-negative cells

Imatinib inhibits the kinase activity of Bcr-Abl and is currently the most effective drug for treatment of chronic myeloid leukemia (CML). Imatinib also blocks c-Abl, a physiological tyrosine kinase activated by a variety of stress signals including damaged DNA. We investigated the effect of pharmacological inhibition of c-Abl on the processing of irradiation-induced DNA damage in Bcr-Abl-negative cells. Cell lines and peripheral blood mononuclear cells (PBMCs) from healthy volunteers were treated with imatinib or dasatinib before gamma-irradiation. Inhibition of c-Abl caused an enhanced irradiation-induced mutation frequency and slowdown of DNA repair, whereas imatinib was ineffective in cells expressing a T315I variant of c-Abl. Mutation frequency and repair kinetics were also studied in c-Abl-/- murine embryonic fibroblasts (MEFs) retransfected with wild-type c-Abl (wt-Abl) or a kinase-defect variant of Abl (KD-Abl). Enhanced mutation frequency as well as delayed DNA repair was observed in cells expressing KD-Abl. These data indicate that pharmacological inhibition of c-Abl compromises DNA-damage response

An RNAi-based system for loss-of-function analysis identifies Raf1 as a crucial mediator of BCR-ABL - Driven leukemogenesis

Genetic loss-of-function studies in murine tumor models have been essential in the analysis of downstream mediators of oncogenic transformation. Unfortunately, these studies are frequently limited by the availability of genetically modified mouse strains. Here we describe a versatile method allowing the efficient expression of an oncogene and simultaneous knockdown of targets of interest (TOI) from a single retroviral vector. Both oncogene and TOI-specific miR30-based shRNA are under the control of the strong viral long terminal repeat promoter, resulting in a single shared RNA transcript. Using this vector in a murine syngeneic BM transplantation model for BCR-ABL - induced chronic myeloid leukemia, we find that oncogene expression andtargetknockdownin primary hematopoietic cells with this vector is efficient both in vitro and in vivo, and demonstrate that Raf1, but not BRAF, modulates BCR-ABL - dependent ERK activation and transformation of hematopoietic cells. This expression system could facilitate genetic loss-of-function studies and allow the rapid validation of potential drug targets in a broad range of oncogene-driven murine tumor models. © 2011 by The American Society of Hematology

Heat-Shock Protein 90 Controls the Expression of Cell-Cycle Genes by Stabilizing Metazoan-Specific Host-Cell Factor HCFC1

Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding. Their function in the cytosol has been well studied. Notably, chaperones are also present in the nucleus, a compartment where proteins enter after completing de novo folding in the cytosol, and this raises an important question about chaperone function in the nucleus. We performed a systematic analysis of the nuclear pool of heat-shock protein 90. Three orthogonal and independent analyses led us to the core functional interactome of HSP90. Computational and biochemical analyses identify host cell factor C1 (HCFC1) as a transcriptional regulator that depends on HSP90 for its stability. HSP90 was required to maintain the expression of HCFC1-targeted cell-cycle genes. The regulatory nexus between HSP90 and the HCFC1 module identified in this study sheds light on the relevance of chaperones in the transcription of cell-cycle genes. Our study also suggests a therapeutic avenue of combining chaperone and transcription inhibitors for cancer treatment

Cks1 Is Required for Tumor Cell Proliferation but Not Sufficient to Induce Hematopoietic Malignancies

The Cks1 component of the SCFSkp2 complex is necessary for p27Kip1 ubiquitylation and degradation. Cks1 expression is elevated in various B cell malignancies including Burkitt lymphoma and multiple myeloma. We have previously shown that loss of Cks1 results in elevated p27Kip1 levels and delayed tumor development in a mouse model of Myc-induced B cell lymphoma. Surprisingly, loss of Skp2 in the same mouse model also resulted in elevated p27Kip1 levels but exhibited no impact on tumor onset. This raises the possibility that Cks1 could have other oncogenic activities than suppressing p27Kip1. To challenge this notion we have targeted overexpression of Cks1 to B cells using a conditional retroviral bone marrow transduction-transplantation system. Despite potent ectopic overexpression, Cks1 was unable to promote B cell hyperproliferation or B cell malignancies, indicating that Cks1 is not oncogenic when overexpressed in B cells. Since Skp2 overexpression can drive T-cell tumorigenesis or other cancers we also widened the quest for oncogenic activity of Cks1 by ubiquitously expressing Cks1 in hematopoetic progenitors. At variance with c-Myc overexpression, which caused acute myeloid leukemia, Cks1 overexpression did not induce myeloproliferation or leukemia. Therefore, despite being associated with a poor prognosis in various malignancies, sole Cks1 expression is insufficient to induce lymphoma or a myeloproliferative disease in vivo

ROCK1/2 signaling contributes to corticosteroid-refractory acute graft-versus-host disease

Patients with corticosteroid-refractory acute graft-versus-host disease (aGVHD) have a low one-year survival rate. Identification and validation of novel targetable kinases in patients who experience corticosteroid-refractory-aGVHD may help improve outcomes. Kinase-specific proteomics of leukocytes from patients with corticosteroid-refractory-GVHD identified rho kinase type 1 (ROCK1) as the most significantly upregulated kinase. ROCK1/2 inhibition improved survival and histological GVHD severity in mice and was synergistic with JAK1/2 inhibition, without compromising graft-versus-leukemia-effects. ROCK1/2-inhibition in macrophages or dendritic cells prior to transfer reduced GVHD severity. Mechanistically, ROCK1/2 inhibition or ROCK1 knockdown interfered with CD80, CD86, MHC-II expression and IL-6, IL-1β, iNOS and TNF production in myeloid cells. This was accompanied by impaired T cell activation by dendritic cells and inhibition of cytoskeletal rearrangements, thereby reducing macrophage and DC migration. NF-κB signaling was reduced in myeloid cells following ROCK1/2 inhibition. In conclusion, ROCK1/2 inhibition interferes with immune activation at multiple levels and reduces acute GVHD while maintaining GVL-effects, including in corticosteroid-refractory settings

Senescence and tumour clearance is triggered by p53 restoration in murine liver carcinomas

Although cancer arises from a combination of mutations in oncogenes and tumour suppressor genes, the extent to which tumour suppressor gene loss is required for maintaining established tumours is poorly understood. p53 is an important tumour suppressor that acts to restrict proliferation in response to DNA damage or deregulation of mitogenic oncogenes, by leading to the induction of various cell cycle checkpoints, apoptosis or cellular senescence(1,2). Consequently, p53 mutations increase cell proliferation and survival, and in some settings promote genomic instability and resistance to certain chemotherapies(3). To determine the consequences of reactivating the p53 pathway in tumours, we used RNA interference (RNAi) to conditionally regulate endogenous p53 expression in a mosaic mouse model of liver carcinoma(4,5). We show that even brief reactivation of endogenous p53 in p53-deficient tumours can produce complete tumour regressions. The primary response to p53 was not apoptosis, but instead involved the induction of a cellular senescence program that was associated with differentiation and the upregulation of inflammatory cytokines. This program, although producing only cell cycle arrest in vitro, also triggered an innate immune response that targeted the tumour cells in vivo, thereby contributing to tumour clearance. Our study indicates that p53 loss can be required for the maintenance of aggressive carcinomas, and illustrates how the cellular senescence program can act together with the innate immune system to potently limit tumour growth

Functional Identification of Tumor Suppressor Genes Through an in vivo RNA Interference Screen in a Mouse Lymphoma Model

2010 April 6Short hairpin RNAs (shRNAs) capable of stably suppressing gene function by RNA interference (RNAi) can mimic tumor-suppressor-gene loss in mice. By selecting for shRNAs capable of accelerating lymphomagenesis in a well-characterized mouse lymphoma model, we identified over ten candidate tumor suppressors, including Sfrp1, Numb, Mek1, and Angiopoietin 2. Several components of the DNA damage response machinery were also identified, including Rad17, which acts as a haploinsufficient tumor suppressor that responds to oncogenic stress and whose loss is associated with poor prognosis in human patients. Our results emphasize the utility of in vivo RNAi screens, identify and validate a diverse set of tumor suppressors, and have therapeutic implications