43 research outputs found
Die Bedeutung des Wilms Tumor Gens (WT-1) für die Prognose und das Monitoring der Akuten Myeloischen Leukämie
Das TumorÂSuppressorÂGen wtÂ1 (Wilms Tumor Gen) kodiert ein ZinkÂFinger DNA bindendes Protein mit vorwiegend TranskriptionsÂhemmenden Eigenschaften. Da wtÂ1 Expression auch in leukämischen Blasten von Patienten mit akuten Leukämien nachgewiesen werden konnte, war das Ziel der Arbeit, das Expressionsmuster von wtÂ1 mRNA in Patienten mit akuter myeloischer Leukämie (AML) mittels der PolymeraseÂKettenreaktion (PCR) zu untersuchen. Dabei war die Expressionsstärke visuell in negativ (Â), schwach positiv ( ), mittelgradig positiv ( ) und stark positiv ( ) zu unterteilen. Die Ergebnisse, in ausgesuchten Fällen durch eine kompetitive PCR validiert, sollten mit FABÂKlassifikation, Karyotyp, OberflächenmarkerÂExpression, Alter, Geschlecht und klinischem Verlauf verglichen werden, um eine Aussage ĂĽber die Bedeutung der wtÂ1 Expression fĂĽr 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 wtÂ1 Expression im Verlauf untersucht werden. wtÂ1 mRNA fand sich bei 124 von 161 (77%) der Patienten bei Erstdiagnose und 1.Rezidiv. Die wtÂ1 Expression war unabhängig vom Alter, vorhergehendem myelodysplastischem Syndrom (MDS), Geschlecht und FABÂSubtyp mit Ausnahme einer signifikant niedrigeren wtÂ1 Expressionshäufigkeit in FAB M5 Leukämien von nur 40% (P=0,0025). Es fand sich keine Korrelation zwischen wtÂ1 mRNA Expressionsstärke und den durch den Karyotyp definierten prognostischen Gruppen. Die Ansprechrate auf Therapie war zwar umso höher, je niedriger die wtÂ1 Expression lag; es fand sich jedoch kein signifikanter Unterschied zwischen den ExpressionsÂGruppen. Patienten mit hoher wtÂ1 mRNA Expression ( , ) zeigten eine deutlich schlechtere Gesamt ÜberlebensÂwahrscheinlichkeit (OS) als solche mit niedriger Expression (Â, ). Das 3ÂJahres OS fĂĽr alle neu diagnostizierten AMLÂPatienten lag bei 13% bei starker und 38% bei schwacher wtÂ1 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 lieĂź sich bei allen Patienten, die eine komplette Remission (CR) erreichten, keine wtÂ1 Transkripte mehr nachweisen. Bei Rezidiv trat in den meisten Fällen erneut erhöhte wtÂ1 Expression auf. In einigen Fällen ging dies dem klinischen Befund eines Rezidivs voraus. Zusammenfassend konnte gezeigt werden, daĂź wtÂ1 von der Mehrzahl der AMLÂPatienten 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
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
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
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
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Existence of reprogrammed lymphoma stem cells in a murine ALCL-like model.
Funder: DJCLS (R14/22) MSCA-ITN-2015-ETN AlkatrasFunder: DFG (CRC850)Funder: DFG (CRC850) BMBF (DeCaRe, FKZ 01ZX1409B)Funder: DJCLS (R14/22) MSCA-ITN-2015-ETN Alkatras DFG (FOR 2033 B1)Funder: DJCLS (R14/22) MSCA-ITN-2015-ETN Alkatras Grant from the Government of Baden-Württemberg (BSL)While cancer stem cells are well established in certain hematologic and solid malignancies, their existence in T cell lymphoma is unclear and the origin of disease is not fully understood. To examine the existence of lymphoma stem cells, we utilized a mouse model of anaplastic large cell lymphoma. Established NPM-ALK+ lymphomas contained heterogeneous cell populations ranging from mature T cells to undifferentiated hematopoietic stem cells. Interestingly, CD4-/CD8- double negative (DN) lymphoma cells aberrantly expressed the T cell receptor α/β chain. Serial transplantation of sorted CD4/CD8 and DN lymphoma subpopulations identified lymphoma stem cells within the DN3/DN4 T cell population, whereas all other subpopulations failed to establish serial lymphomas. Moreover, transplanted lymphoma DN3/DN4 T cells were able to differentiate and gave rise to mature lymphoma T cells. Gene expression analyses unmasked stem-cell-like transcriptional regulation of the identified lymphoma stem cell population. Furthermore, these lymphoma stem cells are characterized by low CD30 expression levels, which might contribute to limited long-term therapeutic success in patients treated with anti-CD30-targeted therapies. In summary, our results highlight the existence of a lymphoma stem cell population in a NPM-ALK-driven CD30+ mouse model, thereby giving the opportunity to test innovative treatment strategies developed to eradicate the origin of disease
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
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A recurrent germline PAX5 mutation confers susceptibility to pre-B cell acute lymphoblastic leukemia
Somatic alterations of the lymphoid transcription factor gene PAX5 (also known as BSAP) are a hallmark of B cell precursor acute lymphoblastic leukemia (B-ALL)1–3, but inherited mutations of PAX5 have not previously been described. Here we report a new heterozygous germline variant, c.547G>A (p.Gly183Ser), affecting the octapeptide domain of PAX5 that was found to segregate with disease in two unrelated kindreds with autosomal dominant B-ALL. Leukemic cells from all affected individuals in both families exhibited 9p deletion, with loss of heterozygosity and retention of the mutant PAX5 allele at 9p13. Two additional sporadic ALL cases with 9p
loss harbored somatic PAX5 substitutions affecting Gly183. Functional and gene expression analysis of the PAX5 mutation demonstrated that it had significantly reduced transcriptional activity. These data extend the role of PAX5 alterations in the pathogenesis of pre-B cell ALL and implicate PAX5 in a new syndrome of susceptibility to pre-B cell neoplasia