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Hoermann G.,Medical University of Vienna | Cerny-Reiterer S.,Medical University of Vienna | Herrmann H.,Ludwig Boltzmann Cluster Oncology | Blatt K.,Medical University of Vienna | And 8 more authors.
FASEB Journal | Year: 2012

The JAK2 mutation V617F is detectable in a majority of patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). Enforced expression of JAK2 V617F in mice induces myeloproliferation and bone marrow (BM) fibrosis, suggesting a causal role for the JAK2 mutant in the pathogenesis of MPNs. However, little is known about mechanisms and effector molecules contributing to JAK2 V617F-induced myeloproliferation and fibrosis. We show that JAK2 V617F promotes expression of oncostatin M (OSM) in neoplastic myeloid cells. Correspondingly, OSM mRNA levels were increased in the BM of patients with MPNs (median 287% of ABL, range 22-1450%) compared to control patients (median 59% of ABL, range 12-264%; P < 0.0001). OSM secreted by JAK2 V617F+ cells stimulated growth of fibroblasts and microvascular endothelial cells and induced the production of angiogenic and profibrogenic cytokines (HGF, VEGF, and SDF-1) in BM fibroblasts. All effects of MPN cell-derived OSM were blocked by a neutralizing anti-OSM antibody, whereas the production of OSM in MPN cells was suppressed by a pharmacologic JAK2 inhibitor or RNAi-mediated knockdown of JAK2. In summary, JAK2 V617F-mediated up-regulation of OSM may contribute to fibrosis, neoangiogenesis, and the cytokine storm observed in MPNs, suggesting that OSM might serve as a novel therapeutic target molecule in these neoplasms. © FASEB.


Hoermann G.,Medical University of Vienna | Blatt K.,Medical University of Vienna | Greiner G.,Medical University of Vienna | Putz E.M.,University of Veterinary Medicine Vienna | And 12 more authors.
FASEB Journal | Year: 2014

Advanced systemic mastocytosis (SM) is an aggressive hematopoietic neoplasm with poor prognosis and short survival times. So far, no curative therapy is available for affected patients. We have identified the cell surface antigen CD52 (CAMPATH-1) as a molecular target expressed abundantly on the surface of primary neoplastic mast cells (MCs) in patients with advanced SM. In contrast, neoplastic MCs of patients with indolent SM and normal MCs expressed only low levels or did not express CD52. To study the mechanisms of CD52 expression and the value of this antigen as a potential therapeutic target, we generated a human MC cell line, designated MCPV-1, by lentiviral immortalization of cord blood-derived MC progenitor cells. Functional studies revealed that activated RAS profoundly promotes surface expression of CD52. The CD52-targeting antibody alemtuzumab induced cell death in CD52+ primary neoplastic MCs obtained from patients with SM as well as in MCPV-1 cells. NSG mice xenotransplanted with MCPV-1 cells survived significantly longer after treatment with alemtuzumab (median survival: 31 d untreated vs. 46 d treated; P=0.0012). We conclude that CD52 is a novel marker and potential therapeutic target in neoplastic MCs in patients with advanced SM. © FASEB.


Loeffler-Ragg J.,Innsbruck Medical University | Germing U.,Heinrich Heine University Düsseldorf | Sperr W.R.,Medical University of Vienna | Herrmann H.,Ludwig Boltzmann Cluster Oncology | And 4 more authors.
Critical Reviews in Oncology/Hematology | Year: 2011

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem cell disorders that are preferentially diagnosed in the elderly. Aberrant expression of the adhesion receptor CD44 correlates with poor prognosis in various neoplasms. To evaluate the prognostic impact of CD44 in MDS serum levels of soluble CD44 standard (solCD44s) were measured in 130 MDS patients (median age 68 years) using an enzyme-linked immunosorbent assay (ELISA). solCD44s levels were significantly elevated in MDS patients as compared to those of healthy donors (p<0.001) and were found to correlate with distinct FAB and WHO subtypes. The highest levels of solCD44s were found in patients with CMML, in RAEB and in patients with MDS transformed into secondary acute myeloid leukaemia (AML). In univariate analysis elevated levels of solCD44s (cut-off level > 688.5 ng/ml) correlated significantly with shorter overall survival in MDS patients (12 versus 39 months; p< 0.001). In multivariate analysis solCD44s displayed prognostic significance independent of the International Prognosis Scoring System (IPSS). To test for refined prognostication, IPSS risk groups were split into two separate categories based on the solCD44s levels. Using this approach, MDS patients with a shorter survival were identified both in the IPSS low-risk (p=0.037) and in the IPSS intermediate-1-risk group (p=0.015). The CD44s-adjusted IPSS defines a cohort of MDS patients with unfavorable prognosis, which might be helpful in risk stratification and in therapeutic algorithms. © 2010 Elsevier Ireland Ltd.


Cerny-Reiterer S.,Ludwig Boltzmann Cluster Oncology | Cerny-Reiterer S.,Medical University of Vienna | Ghanim V.,Medical University of Vienna | Hoermann G.,Medical University of Vienna | And 10 more authors.
Neoplasia (United States) | Year: 2012

Chronic myeloid leukemia (CML) is a hematopoietic neoplasm characterized by the Philadelphia chromosome and the related BCR-ABL1 oncoprotein. Acceleration of CML is usually accompanied by basophilia. Several proangiogenic molecules have been implicated in disease acceleration, including the hepatocyte growth factor (HGF). However, little is known so far about the cellular distribution and function of HGF in CML. We here report that HGF is expressed abundantly in purified CML basophils and in the basophil-committed CML line KU812, whereas all other cell types examined expressed only trace amounts of HGF or no HGF. Interleukin 3, a major regulator of human basophils, was found to promote HGF expression in CML basophils. By contrast, BCR-ABL1 failed to induce HGF synthesis in CML cells, and imatinib failed to inhibit expression of HGF in these cells. Recombinant HGF as well as basophil-derived HGF induced endothelial cell migration in a scratch wound assay, and these effects of HGF were reverted by an anti-HGF antibody as well as by pharmacologic c-Met inhibitors. In addition, anti-HGF and c-Met inhibitors were found to suppress the spontaneous growth of KU812 cells, suggesting autocrine growth regulation. Together, HGF is a BCR-ABL1-independent angiogenic and autocrine growth regulator in CML. Basophils are a unique source of HGF in these patients and may play a more active role in disease-associated angiogenesis and disease progression than has so far been assumed. Our data also suggest that HGF and c-Met are potential therapeutic targets in CML. © 2012 Neoplasia Press, Inc. All rights reserved.


Herrmann H.,Ludwig Boltzmann Cluster Oncology | Blatt K.,Medical University of Vienna | Shi J.,Cold Spring Harbor Laboratory | Gleixner K.V.,Medical University of Vienna | And 11 more authors.
Oncotarget | Year: 2012

Acute myeloid leukemia (AML) is a life-threatening stem cell disease characterized by uncontrolled proliferation and accumulation of myeloblasts. Using an advanced RNAi screen-approach in an AML mouse model we have recently identified the epigenetic 'reader' BRD4 as a promising target in AML. In the current study, we asked whether inhibition of BRD4 by a small-molecule inhibitor, JQ1, leads to growth-inhibition and apoptosis in primary human AML stem- and progenitor cells. Primary cell samples were obtained from 37 patients with freshly diagnosed AML (n=23) or refractory AML (n=14). BRD4 was found to be expressed at the mRNA and protein level in unfractionated AML cells as well as in highly enriched CD34+/CD38- and CD34+/CD38+ stem- and progenitor cells in all patients examined. In unfractionated leukemic cells, submicromolar concentrations of JQ1 induced major growth-inhibitory effects (IC50 0.05-0.5 μM) in most samples, including cells derived from relapsed or refractory patients. In addition, JQ1 was found to induce apoptosis in CD34+/CD38- and CD34+/CD38+ stem-and progenitor cells in all donors examined as evidenced by combined surface/Annexin-V staining. Moreover, we were able to show that JQ1 synergizes with ARA-C in inducing growth inhibition in AML cells. Together, the BRD4-targeting drug JQ1 exerts major anti-leukemic effects in a broad range of human AML subtypes, including relapsed and refractory patients and all relevant stem- and progenitor cell compartments, including CD34+/CD38- and CD34+/CD38+ AML cells. These results characterize BRD4-inhibition as a promising new therapeutic approach in AML which should be further investigated in clinical trials. © Herrmann et al.


Warsch W.,Medical University of Vienna | Kollmann K.,Medical University of Vienna | Eckelhart E.,Medical University of Vienna | Fajmann S.,Medical University of Vienna | And 13 more authors.
Blood | Year: 2011

In BCR-ABL1+ leukemia, drug resistance is often associated with up-regulation of BCR-ABL1 or multidrug transporters as well as BCR-ABL1 mutations. Here we show that the expression level of the transcription factor STAT5 is another parameter that determines the sensitivity of BCR-ABL1 + cells against tyrosine kinase inhibitors (TKIs), such as imatinib, nilotinib, or dasatinib. Abelson-transformed cells, expressing high levels of STAT5, were found to be significantly less sensitive to TKI-induced apoptosis in vitro and in vivo but not to other cytotoxic drugs, such as hydroxyurea, interferon-β, or Aca-dC. The STAT5-mediated protection requires tyrosine phosphorylation of STAT5 independent of JAK2 and transcriptional activity. In support of this concept, under imatinib treatment and with disease progression, STAT5 mRNA and protein levels increased in patients with Ph+ chronic myeloid leukemia. Based on our data, we propose a model in which disease progression in BCR-ABL1+ leukemia leads to up-regulated STAT5 expression. This may be in part the result of clonal selection of cells with high STAT5 levels. STAT5 then accounts for the resistance against TKIs, thereby explaining the dose escalation frequently required in patients reaching accelerated phase. It also suggests that STAT5 may serve as an attractive target to overcome imatinib resistance in BCR-ABL1+ leukemia. © 2011 by The American Society of Hematology.


Wicklein D.,University of Hamburg | Leal N.R.,University of Hamburg | Salamon J.,University of Hamburg | Thamer M.,University of Hamburg | And 5 more authors.
PLoS ONE | Year: 2012

We developed a xenograft model of human Chronic Eosinophilic Leukemia (CEL) to study disease progression and remission-induction under therapy with tyrosine kinase inhibitors using imatinib and nilotinib as examples. The FIP1L1/PDGFRA+ human CEL cell lineEOL-1 was injected intravenously into scid mice, and MR imaging and FACS analysis of mouse blood samples were performed to monitor disease development and the effects of imatinib and nilotinib. Organ infiltration was analyzed in detail by immunohistochemistry after sacrifice. All animals developed CEL and within one week of therapy, complete remissions were seen with both imatinib and nilotinib, resulting in reduced total tumor volumes by MR-imaging and almost complete disappearance of EOL-1 cells in the peripheral blood and in tissues. The new model system is feasible for the evaluation of new tyrosine kinase inhibitors and our data suggest that nilotinib may be a valuable additional targeted drug active in patients with FIP1L1/PDGFRA+ CEL. © 2012 Wicklein et al.


Wicklein D.,University of Hamburg | Schmidt A.,University of Hamburg | Labitzky V.,University of Hamburg | Ullrich S.,University of Hamburg | And 3 more authors.
PLoS ONE | Year: 2013

In chronic myelogenous (CML) and chronic eosinophilic leukemia (CEL), neoplastic cells spread via the circulation into various extramedullary organs. As E- and P-selectin constitute the starting point for the leucocyte adhesion/invasion cascade, and CEL and CML cells share many properties with normal granulocytes, we investigated the role of these selectins in CEL and CML cell expansion and organ invasion in a xenotransplantation model using scid mice. Using two human leukemic cell lines (EOL-1 and K562), we were able to show that E- and P-selectins mediate leukemia cell tethering and adherence in a laminar flow assay. While E-selectin binding depended on sialylated carbohydrate moieties, P-selectin binding was completely (K562) or partially (EOL-1) independent of these carbohydrates indicating the involvement of non-canonical selectin ligands. In a xenograft model in scid mice, both cell lines invaded the bone marrow and other organs, formed chloromas, and ultimately produced an overt leukemia. In contrast, in E- and P-selectin knockout scid mice, the cells failed to show engraftment in 8 out of 10 animals and even if they did engraft, they produced only little organ invasion and chloroma formation. Together, these data suggest that E- and P-selectins play an important role in leukemic dissemination in CML and CEL. © 2013 Wicklein et al.


Valent P.,Ludwig Boltzmann Cluster Oncology | Valent P.,Medical University of Vienna | Cerny-Reiterer S.,Ludwig Boltzmann Cluster Oncology | Herrmann H.,Ludwig Boltzmann Cluster Oncology | And 6 more authors.
Best Practice and Research: Clinical Haematology | Year: 2010

Mast cells (MC) are specialized immune cells that play a key role in anaphylactic reactions. Growth, differentiation, and function of these cells are regulated by a complex network of cytokines, surface receptors, signaling molecules, the microenvironment, and the genetic background. A number of previous and more recent data suggest that MC are heterogeneous in terms of cytokine-regulation, expression of cytoplasmic and cell surface antigens, and response to ligands. MC heterogeneity is often organ-specific and is considered to be related to MC plasticity, disease-associated factors, and the maturation stage of the cells. The stem cell factor (SCF) receptor KIT (CD117) is expressed on all types of MC independent of maturation and activation-status. In systemic mastocytosis (SM), KIT is often expressed in MC in a mutated and constitutively activated form. In these patients, MC aberrantly display CD2 and CD25, diagnostic markers of neoplastic MC in all SM variants. In advanced SM, MC co-express substantial amounts of CD30, whereas CD2 expression on MC may be decreased compared to indolent SM. Other surface molecules, such as CD63 or CD203c, are overexpressed on neoplastic MC in SM, and are further upregulated upon cross-linking of the IgE receptor. Some of the cell surface antigens expressed on MC or their progenitors may serve as therapeutic targets in the future. These targets include CD25, CD30, CD33, CD44, and CD117/KIT. The current article provides an overview on cell surface antigens and target receptors expressed by MC in physiologic and reactive tissues, and in patients with SM, with special reference to phenotypic heterogeneity and clinical implications. © 2010 Elsevier Ltd. All rights reserved.


Herrmann H.,Ludwig Boltzmann Cluster Oncology | Cerny-Reiterer S.,Medical University of Vienna | Gleixner K.V.,Medical University of Vienna | Blatt K.,Medical University of Vienna | And 10 more authors.
Haematologica | Year: 2012

Background: CD33 is a well-known stem cell target in acute myeloid leukemia. So far, however, little is known about expression of CD33 on leukemic stem cells in chronic leukemias. Design and Methods: We analyzed expression of CD33 in leukemic progenitors in chronic myeloid leukemia by multi-color flow cytometry and quantitative polymerase chain reaction. In addition, the effects of a CD33-targeting drug, gemtuzumab/ozogamicin, were examined. Results: As assessed by flow cytometry, stem cell-enriched CD34+/CD38-/CD123+ leukemic cells expressed significantly higher levels of CD33 compared to normal CD34+/CD38- stem cells. Moreover, highly enriched leukemic CD34+/CD38- cells (>98% purity) displayed higher levels of CD33 mRNA. In chronic phase patients, CD33 was found to be expressed invariably on most or all stem cells, whereas in accelerated or blast phase of the disease, the levels of CD33 on stem cells varied from donor to donor. The MDR1 antigen, supposedly involved in resistance against ozogamicin, was not detectable on leukemic CD34+/CD38- cells. Correspondingly, gemtuzumab/ozogamicin produced growth inhibition in leukemic progenitor cells in all patients tested. The effects of gemtuzumab/ozogamicin were dose-dependent, occurred at low concentrations, and were accompanied by apoptosis in suspension culture. Moreover, the drug was found to inhibit growth of leukemic cells in a colony assay and long-term culture-initiating cell assay. Finally, gemtuzumab/ozogamicin was found to synergize with nilotinib and bosu-tinib in inducing growth inhibition in leukemic cells. Conclusions: CD33 is expressed abundantly on immature CD34+/CD38- stem cells and may serve as a stem cell target in chronic myeloid leukemia. © 2012 Ferrata Storti Foundation.

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