-
Sabine Cerny-Reiterer,
Viviane Ghanim,
Gregor Hoermann, Karl J Aichberger,
Harald Herrmann,
Leonhard Muellauer,
Andreas Repa,
Christian Sillaber,
Andrew F Walls,
Matthias Mayerhofer,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: 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.
Neoplasia (New York, N.Y.) 07/2012; 14(7):572-84. · 5.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The second generation BCR/ABL kinase inhibitor nilotinib is increasingly used for the treatment of imatinib-resistant chronic myeloid leukemia (CML). So far, nilotinib is considered a well-tolerated drug with little if any side effects, although an increase in the fasting glucose level has been reported. We examined a series of 24 consecutive CML patients treated with nilotinib in our center for the development of non-hematologic adverse events. Three of these 24 CML patients developed a rapidly progressive peripheral arterial occlusive disease (PAOD) during treatment with nilotinib. In all three cases, PAOD required repeated angioplasty and/or multiple surgeries within a few months. No PAOD was known before nilotinib-therapy in these patients, although all three had received imatinib. In two patients, pre-existing risk factors predisposing for PAOD were known, and one of them had developed diabetes mellitus during nilotinib. In the other 21 patients treated with nilotinib in our center, one less severe PAOD, one myocardial infarction, one spinal infarction, one subdural hematoma, and one sudden death of unknown etiology were recorded. In summary, treatment with nilotinib may be associated with an increased risk of vascular adverse events, including PAOD development. In a subgroup of patients, these events are severe or even life-threatening. Although the exact mechanisms remain unknown, we recommend screening for pre-existing PAOD and for vascular risk factors such as diabetes mellitus in all patients before starting nilotinib and in the follow up during nilotinib-therapy.
American Journal of Hematology 07/2011; 86(7):533-9. · 4.67 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Aspergillus spp are ubiquitous spore-forming fungi. Construction work, renovation, demolition, or excavation activities within a hospital or in surrounding areas increase the risk for aspergillus infection in susceptible patients and are the main cause of nosocomial aspergillus outbreaks.
We investigated the efficacy of infection control measures on the frequency of fungal infection among hemato-oncologic patients undergoing stem cell transplantation during excavation and construction work of an adjacent hospital building. Clinical isolates from these patients obtained before and during the excavation and construction period were analyzed. Preventive measures consisted in the implementation of a multibarrier concept to protect these patients from fungal infection.
There was no record of any clinical isolate of Aspergillus spp in the observation period before the beginning of the groundwork. However, 3 clinically significant isolates of Aspergillus spp were detected in respiratory tract specimen of 2 patients after the beginning of excavation and demolition work, which were found to be community acquired.
Although our data cannot demonstrate the efficacy of infection control measures during construction work, it can be concluded that excavation work close to immunocompromised patients is safe if a bundle of preventive measures is implemented before groundwork.
American journal of infection control 06/2011; 39(9):746-51. · 3.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bacteremias caused by Staphylococcus aureus and Escherichia coli are among the most common bloodstream infections (BSIs) in adults. The aim of the study was to investigate risk factors for infection and clinical outcomes of bacteremias caused by S aureus or E coli.
We conducted a 1-year matched prospective cohort study including 150 patients with BSI caused by susceptible or resistant S aureus or E coli and 300 controls without BSI caused by these organisms.
Of the 150 episodes of bacteremia, 37% were caused by S aureus (including 5 cases of methicillin-resistant S aureus [MRSA]) and 63% were caused by E coli (including 9 cases of extended-spectrum beta lactamase [ESBL]-producing E coli). We identified 4 independent risk factors for acquisition of S aureus bacteremia (emergency, peripheral or central vascular catheter, renal disease) and 6 risk factors for E coli bacteremia (emergency, peripheral or central vascular catheter, malignancy, cytoreductive or immunosuppressive therapy). Both types of bacteremia were associated with an increased length of hospital stay compared with controls. We observed a 5-fold increase in the 30-day mortality rate for bacteremias due to S aureus, and a 2-fold increase in BSI caused by E coli. The in-hospital mortality rate was increased by 6-fold for S aureus and by 3-fold for E coli.
Longer hospitalization periods and increased mortality of bacteremias caused by S aureus or E coli, irrespective of susceptibility, implicate controlling for risk factors at an early stage.
American journal of infection control 12/2010; 38(10):839-45. · 3.01 Impact Factor
-
Karl J Aichberger,
Karoline V Gleixner,
Irina Mirkina,
Sabine Cerny-Reiterer,
Barbara Peter,
Veronika Ferenc,
Michael Kneidinger,
Christian Baumgartner,
Matthias Mayerhofer,
Alexander Gruze,
Winfried F Pickl,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Systemic mastocytosis (SM) is a myeloid neoplasm involving mast cells (MCs) and their progenitors. In most cases, neoplastic cells display the D816V-mutated variant of KIT. KIT D816V exhibits constitutive tyrosine kinase (TK) activity and has been implicated in increased survival and growth of neoplastic MCs. Recent data suggest that the proapoptotic BH3-only death regulator Bim plays a role as a tumor suppressor in various myeloid neoplasms. We found that KIT D816V suppresses expression of Bim in Ba/F3 cells. The KIT D816-induced down-regulation of Bim was rescued by the KIT-targeting drug PKC412/midostaurin. Both PKC412 and the proteasome-inhibitor bortezomib were found to decrease growth and promote expression of Bim in MC leukemia cell lines HMC-1.1 (D816V negative) and HMC-1.2 (D816V positive). Both drugs were also found to counteract growth of primary neoplastic MCs. Furthermore, midostaurin was found to cooperate with bortezomib and with the BH3-mimetic obatoclax in producing growth inhibition in both HMC-1 subclones. Finally, a Bim-specific siRNA was found to rescue HMC-1 cells from PKC412-induced cell death. Our data show that KIT D816V suppresses expression of proapoptotic Bim in neoplastic MCs. Targeting of Bcl-2 family members by drugs promoting Bim (re)-expression, or by BH3-mimetics such as obatoclax, may be an attractive therapy concept in SM.
Blood 10/2009; 114(26):5342-51. · 9.90 Impact Factor
-
Irene Mittermann,
Renate Reininger,
Maya Zimmermann,
Katharina Gangl,
Jürgen Reisinger, Karl J Aichberger,
Elli K Greisenegger,
Verena Niederberger,
Joachim Seipelt,
Barbara Bohle,
Tamara Kopp,
Cezmi A Akdis,
Susanne Spitzauer,
Peter Valent,
Rudolf Valenta
[show abstract]
[hide abstract]
ABSTRACT: Hom s 2, the alpha-chain of the nascent polypeptide-associated complex, is an intracellular autoantigen that has been identified with IgE autoantibodies from atopic dermatitis patients. We investigated the humoral and cellular immune response to purified recombinant Hom s 2 (rHom s 2). rHom s 2 exhibited IgE reactivity comparable to exogenous allergens, but did not induce relevant basophil cell degranulation. The latter may be attributed to the fact that patients recognized single epitopes on Hom s 2 as revealed by IgE epitope mapping with rHom s 2 fragments. In contrast to exogenous allergens, rHom s 2 had the intrinsic ability to induce the release of IFN-gamma in cultured peripheral blood mononuclear cells from atopic as well as non-atopic individuals. IFN-gamma-containing culture supernatants from Hom s 2-stimulated peripheral blood mononuclear cells caused disintegration of respiratory epithelial cell layers and apoptosis of skin keratinocytes, which could be inhibited with a neutralizing anti-IFN-gamma antibody. Our data demonstrate that the Hom s 2 autoantigen can cause IFN-gamma-mediated cell damage.
Journal of Investigative Dermatology 07/2008; 128(6):1451-9. · 6.31 Impact Factor
-
Matthias Mayerhofer,
Karoline V Gleixner,
Andrea Hoelbl,
Stefan Florian,
Gregor Hoermann, Karl J Aichberger,
Martin Bilban,
Harald Esterbauer,
Maria-Theresa Krauth,
Wolfgang R Sperr,
Jack B Longley,
Robert Kralovics,
Richard Moriggl,
Jacques Zappulla,
Roland S Liblau,
Ilse Schwarzinger,
Veronika Sexl,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Oncogenic tyrosine kinases (TK) usually convert growth factor-dependent cells to factor independence with autonomous proliferation. However, TK-driven neoplasms often are indolent and characterized by cell differentiation rather than proliferation. A prototype of an indolent TK-driven neoplasm is indolent systemic mastocytosis. We found that the D816V-mutated variant of KIT, a TK detectable in most patients with systemic mastocytosis, induces cluster formation and expression of several mast cell differentiation and adhesion Ags, including microphthalmia transcription factor, IL-4 receptor, histamine, CD63, and ICAM-1 in IL-3-dependent BaF3 cells. By contrast, wild-type KIT did not induce cluster formation or mast cell differentiation Ags. Additionally, KIT D816V, but not wild-type KIT, induced STAT5 activation in BaF3 cells. However, despite these intriguing effects, KIT D816V did not convert BaF3 cells to factor-independent proliferation. Correspondingly, BaF3 cells with conditional expression of KIT D816V did not form tumors in nude mice. Together, the biologic effects of KIT D816V in BaF3 cells match strikingly with the clinical course of indolent systemic mastocytosis and with our recently established transgenic mouse model, in which KIT D816V induces indolent mast cell accumulations but usually does not induce a malignant mast cell disease. Based on all these results, it is hypothesized that KIT D816V as a single hit may be sufficient to cause indolent systemic mastocytosis, whereas additional defects may be required to induce aggressive mast cell disorders.
The Journal of Immunology 05/2008; 180(8):5466-76. · 5.79 Impact Factor
-
Matthias Mayerhofer,
Karoline V Gleixner,
Julia Mayerhofer,
Gregor Hoermann,
Eva Jaeger, Karl J Aichberger,
Rene G Ott,
Khaled Greish,
Hideaki Nakamura,
Sophia Derdak,
Puchit Samorapoompichit,
Winfried F Pickl,
Veronika Sexl,
Harald Esterbauer,
Ilse Schwarzinger,
Christian Sillaber,
Hiroshi Maeda,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Resistance toward imatinib and other BCR/ABL tyrosine kinase inhibitors remains an increasing clinical problem in the treatment of advanced stages of chronic myeloid leukemia (CML). We recently have identified the heat shock protein 32 (Hsp32)/heme oxygenase-1 (HO-1) as a BCR/ABL-dependent survival molecule in CML cells. We here show that silencing Hsp32/HO-1 in CML cells by an siRNA approach results in induction of apoptosis. Moreover, targeting Hsp32/HO-1 by either pegylated zinc protoporphyrine (PEG-ZnPP) or styrene maleic acid-micelle-encapsulated ZnPP (SMA-ZnPP) resulted in growth inhibition of BCR/ABL-transformed cells. The effects of PEG-ZnPP and SMA-ZnPP were demonstrable in Ba/F3 cells carrying various imatinib-resistant mutants of BCR/ABL, including the T315I mutant, which exhibits resistance against all clinically available BCR/ABL tyrosine kinase inhibitors. Growth-inhibitory effects of PEG-ZnPP and SMA-ZnPP also were observed in the CML-derived human cell lines K562 and KU812 as well as in primary leukemic cells obtained from patients with freshly diagnosed CML or imatinib-resistant CML. Finally, Hsp32/HO-1-targeting compounds were found to synergize with either imatinib or nilotinib in producing growth inhibition in imatinib-resistant K562 cells and in Ba/F3 cells harboring the T315I mutant of BCR/ABL. In summary, these data show that HO-1 is a promising novel target in imatinib-resistant CML.
Blood 03/2008; 111(4):2200-10. · 9.90 Impact Factor
-
Karoline V Gleixner,
Matthias Mayerhofer,
Karoline Sonneck,
Alexander Gruze,
Puchit Samorapoompichit,
Christian Baumgartner,
Francis Y Lee, Karl J Aichberger,
Paul W Manley,
Doriano Fabbro,
Winfried F Pickl,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: In a majority of all patients with systemic mastocytosis (SM) including those with mast cell leukemia (MCL), neoplastic mast cells (MC) display the D816V-mutated variant of KIT. The respective oncoprotein, KIT D816V, exhibits constitutive tyrosine kinase (TK) activity and has been implicated in malignant cell growth. Therefore, several attempts have been made to identify KIT D816V-targeting drugs.
We examined the effects of the novel TK-inhibitor dasatinib alone and in combination with other targeted drugs on growth of neoplastic MC.
Confirming previous studies, dasatinib was found to inhibit the TK activity of wild type (wt) KIT and KIT-D816V as well as growth and survival of neoplastic MC and of the MCL cell line, HMC-1. The growth-inhibitory effects of dasatinib in HMC-1 cells were found to be associated with a decrease in expression of CD2 and CD63. In addition, we found that dasatinib blocks KIT D816V-induced cluster-formation and viability in Ba/F3 cells. In drug combination experiments, dasatinib was found to co-operate with PKC412, AMN107, imatinib, and 2CdA in producing growth-inhibition and apoptosis in neoplastic MC. In HMC-1.1 cells lacking KIT D816V, all drug interactions were found to be synergistic in nature. By contrast, in HMC-1.2 cells exhibiting KIT D816V, only the combinations dasatinib+PKC412 and dasatinib+2CdA were found to produce synergistic effects.
Combinations of targeted drugs may represent an interesting pharmacologic approach for the treatment of aggressive SM or MCL.
Haematologica 12/2007; 92(11):1451-9. · 6.42 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Vascular endothelial growth factor (VEGF) is produced in neoplastic cells in various myeloid neoplasms and may act as an autocrine growth-regulator. We have examined the expression of five VEGF receptors (VEGR1/Flt-1, VEGFR2/KDR, Flt-4, neuropilin-1 = NRP-1, NRP-2) in leukemic cells obtained from patients with acute myeloid leukemia (n = 28), chronic myeloid leukemia (n = 14), chronic eosinophilic leukemia (n = 3), chronic myelomonocytic leukemia (n = 9), or mast cell leukemia/systemic mastocytosis (n = 3) as well as in respective cell lines. Expression of VEGFR mRNA was analyzed by RT-PCR, and expression of VEGFR protein by immunocytochemistry. In most patients, leukemic cells expressed NRP-1 mRNA and NRP-2 mRNA independent of the type of disease. By contrast, transcripts for Flt-1, KDR, and Flt-4 were expressed variably without a clear correlation to the type of leukemia. Expression of VEGF receptors was also demonstrable at the protein level in all cases tested. In conclusion, neoplastic cells in myeloid leukemias frequently express VEGFR including NRP-1 and NRP-2.
Leukemia and Lymphoma 11/2007; 48(10):1997-2007. · 2.58 Impact Factor
-
Rudin Kondo,
Karoline V Gleixner,
Matthias Mayerhofer,
Anja Vales,
Alexander Gruze,
Puchit Samorapoompichit,
Khaled Greish,
Maria-Theresa Krauth, Karl J Aichberger,
Winfried F Pickl,
Harald Esterbauer,
Christian Sillaber,
Hiroshi Maeda,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Systemic mastocytosis (SM) is a myeloid neoplasm characterized by increased survival and accumulation of neoplastic mast cells (MCs). In most patients, the D816V-mutated variant of KIT is detectable. We report here that heat shock protein 32 (Hsp32), also known as heme oxygenase-1 (HO-1), is a novel KIT-inducible survival factor in neoplastic MCs. As assessed by reverse transcription-polymerase chain reaction (RT-PCR), immunocytochemistry, and Western blotting, the KIT D816V(+) MC line HMC-1.2 as well as highly enriched primary neoplastic MCs were found to express Hsp32 mRNA and the Hsp32 protein. Moreover, KIT D816V and stem cell factor (SCF)-activated wild-type KIT were found to induce Hsp32 promoter activity, expression of Hsp32 mRNA, and expression of the Hsp32 protein in Ba/F3 cells. Correspondingly, the KIT D816V-targeting drug PKC412 decreased the expression of Hsp32 as well as proliferation/survival in neoplastic MCs. The inhibitory effects of PKC412 on the survival of HMC-1.2 cells were counteracted by the HO-1 inductor hemin or lentiviral-transduced HO-1. Moreover, 2 Hsp32-targeting drugs, pegylated zinc protoporphyrin (PEG-ZnPP) and styrene maleic acid copolymer micelle-encapsulated ZnPP (SMA-ZnPP), were found to inhibit proliferation and to induce apoptosis in neoplastic MCs. Furthermore, both drugs were found to cooperate with PKC412 in producing growth inhibition. Together, these data show that Hsp32 is an important survival factor and interesting new therapeutic target in neoplastic MCs.
Blood 08/2007; 110(2):661-9. · 9.90 Impact Factor
-
Karl J Aichberger,
Matthias Mayerhofer,
Karoline V Gleixner,
Maria-Theresa Krauth,
Alexander Gruze,
Winfried F Pickl,
Volker Wacheck,
Edgar Selzer,
Leonhard Müllauer,
Hermine Agis,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: MCL-1 is a Bcl-2 family member that has been described as antiapoptotic in various myeloid neoplasms. Therefore, MCL-1 has been suggested as a potential new therapeutic target. Systemic mastocytosis (SM) is a myeloid neoplasm involving mast cells (MCs) and their progenitors. In the present study, we examined the expression and functional role of MCL-1 in neoplastic MCs and sought to determine whether MCL-1 could serve as a target in SM. As assessed by RT-PCR and immunohistochemical examination, primary neoplastic MCs expressed MCL-1 mRNA and the MCL-1 protein in all SM patients examined. Moreover, MCL-1 was detectable in both subclones of the MC line HMC-1--HMC-1.1 cells, which lack the SM-related KIT mutation D816V, and HMC-1.2 cells, which carry KIT D816V. Exposure of HMC-1.1 cells or HMC-1.2 cells to MCL-1-specific antisense oligonucleotides (ASOs) or MCL-1-specific siRNA resulted in reduced survival and increased apoptosis compared with untreated cells. Moreover, MCL-1 ASOs were found to cooperate with various tyrosine kinase inhibitors in producing growth inhibition in neoplastic MCs, with synergistic effects observed with PKC412, AMN107, and imatinib in HMC-1.1 cells and with PKC412 in HMC-1.2 cells. Together, these data show that MCL-1 is a novel survival factor and an attractive target in neoplastic MCs.
Blood 05/2007; 109(7):3031-41. · 9.90 Impact Factor
-
Karl J Aichberger,
Matthias Mayerhofer,
Anja Vales,
Maria-Theresa Krauth,
Karoline V Gleixner,
Martin Bilban,
Harald Esterbauer,
Karoline Sonneck,
Stefan Florian,
Sophia Derdak,
Winfried F Pickl,
Hermine Agis,
Andras Falus,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Basophil numbers are typically elevated in chronic myeloid leukemia (CML) and increase during disease progression. Histamine is an essential mediator and marker of basophils and is highly up-regulated in CML. We examined the biochemical basis of histamine synthesis in CML cells. The CML-specific oncoprotein BCR/ABL was found to promote expression of histidine decarboxylase (HDC) and synthesis of histamine in Ba/F3 cells. Moreover, the BCR/ABL tyrosine kinase inhibitors imatinib (STI571) and nilotinib (AMN107) decreased histamine levels and HDC mRNA expression in BCR/ABL-transformed Ba/F3 cells, in the CML-derived basophil cell line KU812, and in primary CML cells. Synthesis of histamine was found to be restricted to the basophil compartment of the CML clone and to depend on signaling through the PI3-kinase pathway. CML cells also expressed histamine receptors (HRs), including HR-1, HR-2, HR-4, and histamine-binding CYP450 isoenzymes which also serve as targets of HR antagonists. The HR-1 antagonists loratadine and terfenadine, which bind to CYP450, were found to counteract proliferation of CML cells, whereas no growth inhibition was observed with the HR-1 antagonist fexofenadine which is not targeted or metabolized by CYP450. Moreover, DPPE, an inhibitor of histamine-binding CYP450 isoenzymes, produced growth inhibition in CML cells. Together, these data show that BCR/ABL promotes histamine production in CML cells and that certain HR-targeting drugs exert antileukemic effects on CML cells.
Blood 12/2006; 108(10):3538-47. · 9.90 Impact Factor
-
Karoline Sonneck,
Stefan Florian,
Alexandra Böhm,
Maria-Theresa Krauth,
Rudin Kondo,
Alexander W Hauswirth,
Karoline V Gleixner, Karl J Aichberger,
Sophia Derdak,
Winfried F Pickl,
Wolfgang R Sperr,
Lawrence B Schwartz,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: A number of autocrine and paracrine growth regulators are considered to be involved in the survival and proliferation of blast cells in acute myeloid leukemia (AML). We have recently shown that blast cells in a group of patients with AML produce and secrete the mitogenic enzyme tryptase. In the present study, we examined functional effects of tryptase in the context of AML. As assessed by 3H-thymidine uptake experiments, tryptase-containing serum from patients with AML as well as heparin-complexed recombinant tryptase were found to promote the proliferation of cultured bone marrow- and lung fibroblasts in a dose-dependent manner. A neutralizing antibody against human beta-tryptase was found to diminish these growth-stimulatory effects of serum-tryptase in all patients examined. Tryptase also induced the expression of mRNA for GM-CSF and SCF, two cytokines known to promote growth of AML cells, in cultured bone marrow fibroblasts. Neither recombinant tryptase nor tryptase-rich serum of AML patients, showed an effect on the growth of leukemic blast cells irrespective of the FAB category or expression of protease-activated receptor (PAR)-2, a putative molecular target of tryptase. Together, tryptase is secreted from AML blasts as a biologically active molecule that may exhibit paracrine rather than autocrine effects in AML.
Leukemia and Lymphoma 06/2006; 47(5):897-906. · 2.58 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Synthesis of histamine in hematopoietic progenitor cells may be one of the earliest events in mastopoiesis. We therefore asked whether the key enzyme involved in histamine production, histidine decarboxylase (HDC), can be used as an immunohistochemical marker for the detection of immature neoplastic mast cells (MC) in patients with MC-proliferative disorders. To address this question, we examined bone marrow biopsy specimens in a cohort of 102 patients with mastocytosis using an antibody against HDC. Independent of the maturation stage of MC, the anti-HDC antibody produced clear diagnostic staining results in all patients with systemic MC disease examined including those with MC leukemia and MC sarcoma, in which MCs are particularly immature. In these patients, expression of HDC was reconfirmed at the messenger RNA level by reverse transcriptase polymerase chain reaction analyses performed with RNA of highly enriched CD117(+) MC. In summary, HDC is expressed in neoplastic MC in patients with systemic mastocytosis independent of the maturation stage of cells or the variant of disease. Histidine decarboxylase should therefore be considered as a new MC marker in the screen panel of antigens used to diagnose high-grade MC malignancies.
Human Pathlogy 05/2006; 37(4):439-47. · 2.88 Impact Factor
-
Friedrich Wimazal,
Maria-Theresa Krauth,
Anja Vales,
Alexandra Böhm,
Hermine Agis,
Karoline Sonneck, Karl J Aichberger,
Matthias Mayerhofer,
Ingrid Simonitsch-Klupp,
Leonhard Müllauer,
Wolfgang R Sperr,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Recent data suggest that vascular endothelial growth factor (VEGF) is produced in neoplastic cells in various myeloid neoplasms and plays a key role as an autocrine regulator and mediator of angiogenesis. We examined the expression of VEGF in paraffin-embedded bone marrow sections obtained from normal donors (n = 5) and 46 patients with myelodysplastic syndromes [MDS, French-American-British (FAB)-type refractory anemia (RA), n = 10; refractory anemia with ringed sideroblasts (RARS), n = 10; refractory anemia with excess blasts (RAEB), n = 10; RAEB in transformation (RAEB-T), n = 8; chronic myelomonocytic leukemia (CMML), n = 8] by immunohistochemistry using an anti-VEGF antibody. In normal bone marrow, the anti-VEGF antibody was found to react with myeloid progenitor cells, immature monocytic cells, plasma cells and megakaryocytes, but not with erythroid cells or mature granulocytic cells. Higher levels of VEGF were found in patients with MDS, subtypes RAEB, RAEB-T and CMML, compared to patients with RA or RARS, or the normal bone marrow. These differences were found to result from expression of VEGF in immature myeloid cells in RAEB, RAEB-T and CMML. The microvessel density was also higher in patients with RAEB-T and CMML compared to RA and RARS or the normal bone marrow. Expression of VEGF mRNA was demonstrable in isolated neoplastic cells by reverse transcriptase-polymerase chain reaction in all patients examined. In aggregate, these data show that VEGF is expressed in bone marrow cells in patients with MDS. The amount of expressed VEGF is related to the percentage of immature myeloid cells (blasts and monocytic progenitors) and correlates with the FAB category.
Leukemia and Lymphoma 04/2006; 47(3):451-60. · 2.58 Impact Factor
-
Karoline V Gleixner,
Matthias Mayerhofer, Karl J Aichberger,
Sophia Derdak,
Karoline Sonneck,
Alexandra Böhm,
Alexander Gruze,
Puchit Samorapoompichit,
Paul W Manley,
Doriano Fabbro,
Winfried F Pickl,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: In most patients with systemic mastocytosis (SM), including aggressive SM and mast cell leukemia (MCL), neoplastic cells express the oncogenic KIT mutation D816V. KIT D816V is associated with constitutive tyrosine kinase (TK) activity and thus represents an attractive drug target. However, imatinib and most other TK inhibitors fail to block the TK activity of KIT D816V. We show that the novel TK-targeting drugs PKC412 and AMN107 counteract TK activity of D816V KIT and inhibit the growth of Ba/F3 cells with doxycycline-inducible expression of KIT D816V as well as the growth of primary neoplastic mast cells and HMC-1 cells harboring this KIT mutation. PKC412 was a superior agent with median inhibitory concentration (IC(50)) values of 50 to 250 nM without differences seen between HMC-1 cells exhibiting or lacking KIT D816V. By contrast, AMN107 exhibited more potent effects in KIT D816V(-) HMC-1 cells. Corresponding results were obtained with Ba/F3 cells exhibiting wild-type or D816V-mutated KIT. The growth-inhibitory effects of PKC412 and AMN107 on HMC-1 cells were associated with induction of apoptosis and down-regulation of CD2 and CD63. PKC412 was found to cooperate with AMN107, imatinib, and cladribine (2CdA) in producing growth inhibition in HMC-1, but synergistic drug interactions were observed only in cells lacking KIT D816V. Together, PKC412 and AMN107 represent promising novel agents for targeted therapy of SM.
Blood 02/2006; 107(2):752-9. · 9.90 Impact Factor
-
Karl J Aichberger,
Matthias Mayerhofer,
Maria-Theresa Krauth,
Anja Vales,
Rudin Kondo,
Sophia Derdak,
Winfried F Pickl,
Edgar Selzer,
Michael Deininger,
Brian J Druker,
Christian Sillaber,
Harald Esterbauer,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: Chronic myeloid leukemia (CML) is a myeloproliferative disease in which BCR/ABL enhances survival of leukemic cells through modulation of proapoptotic and antiapoptotic molecules. Recent data suggest that proapoptotic Bcl-2-interacting mediator (Bim) plays a role as a tumor suppressor in myeloid cells, and that leukemic cells express only low amounts of this cell death activator. We here show that primary CML cells express significantly lower amounts of bim mRNA and Bim protein compared with normal cells. The BCR/ABL inhibitors imatinib and AMN107 were found to promote expression of Bim in CML cells. To provide direct evidence for the role of BCR/ABL in Bim modulation, we employed Ba/F3 cells with doxycycline-inducible expression of BCR/ABL and found that BCR/ABL decreases expression of bim mRNA and Bim protein in these cells. The BCR/ABL-induced decrease in expression of Bim was found to be a posttranscriptional event that depended on signaling through the mitogen-activated protein kinase pathway and was abrogated by the proteasome inhibitor MG132. Interestingly, MG132 up-regulated the expression of bim mRNA and Bim protein and suppressed the growth of Ba/F3 cells containing wild-type BCR/ABL or imatinib-resistant mutants of BCR/ABL. To show functional significance of "Bim reexpression," a Bim-specific small interfering RNA was applied and found to rescue BCR/ABL-transformed leukemic cells from imatinib-induced cell death. In summary, our data identify BCR/ABL as a Bim suppressor in CML cells and suggest that reexpression of Bim by novel tyrosine kinase inhibitors, proteasome inhibition, or by targeting signaling pathways downstream of BCR/ABL may be an attractive therapeutic approach in imatinib-resistant CML.
Cancer Research 11/2005; 65(20):9436-44. · 7.86 Impact Factor
-
Karl J Aichberger,
Irene Mittermann,
Renate Reininger,
Susanne Seiberler,
Ines Swoboda,
Susanne Spitzauer,
Tamara Kopp,
Georg Stingl,
Wolfgang R Sperr,
Peter Valent,
Andreas Repa,
Barbara Bohle,
Dietrich Kraft,
Rudolf Valenta
[show abstract]
[hide abstract]
ABSTRACT: Skin inflammation in atopic dermatitis starts with Th2 and IgE-mediated responses against exogenous allergens and, for unknown reasons, resembles features of a Th1-driven reaction in the chronic stages. We report the characterization of a human protein, Hom s 4, recognized by IgE autoantibodies from atopic dermatitis patients. The complete Hom s 4 cDNA codes for a 54-kDa basic protein containing two typical calcium-binding domains separated by an unusually long alpha-helical domain. Therefore, Hom s 4 and homologous proteins found by sequence comparison in mice, fruit flies, and nematodes constitute a novel subfamily of calcium-binding proteins. Using Hom s 4-specific Abs, it is demonstrated that the protein is strongly expressed within epidermal keratinocytes and dermal endothelial cells. Purified Hom s 4 showed IgE cross-reactivity with exogenous calcium-binding allergens from plants and fish but, in contrast to the exogenous allergens, induced only weak histamine release from patient basophils. However, the analysis of Hom s 4-specific cytokine and humoral immune responses indicated that Hom s 4 strongly induces Th1 responses which are accompanied by the release of IFN-gamma, a cytokine implicated in epithelial cell damage. Hom s 4-induced IFN-gamma production was found in normal individuals, in patients with chronic inflammatory skin diseases and in Th2-prone atopic persons, suggesting that Hom s 4 represents a protein with an intrinsic property to induce Th1-mediated autoreactivity. It may thus contribute to chronic skin inflammation in atopic as well as in nonatopic persons.
The Journal of Immunology 08/2005; 175(2):1286-94. · 5.79 Impact Factor
-
Matthias Mayerhofer, Karl J Aichberger,
Stefan Florian,
Maria-Theresa Krauth,
Alexander W Hauswirth,
Sophia Derdak,
Wolfgang R Sperr,
Harald Esterbauer,
Oswald Wagner,
Christine Marosi,
Winfried F Pickl,
Michael Deininger,
Ellen Weisberg,
Brian J Druker,
James D Griffin,
Christian Sillaber,
Peter Valent
[show abstract]
[hide abstract]
ABSTRACT: The mammalian target of rapamycin (mTOR) has recently been described to be constitutively activated in Bcr-Abl-transformed cells and to mediate rapamycin-induced inhibition of growth in respective cell lines. We have recently shown that rapamycin down-regulates expression of vascular endothelial growth factor (VEGF), a mediator of leukemia-associated angiogenesis, in primary CML cells. In the present study, we analyzed growth-inhibitory in vitro and in vivo effects of rapamycin on primary CML cells and asked whether rapamycin-induced suppression of VEGF in leukemic cells is related to growth inhibition. Rapamycin dose dependently inhibited growth of primary CML cells obtained from patients with imatinib-responsive or imatinib-resistant disease as well as growth of Bcr-Abl-transformed imatinib-resistant cell lines. Moreover, we observed potent cytoreductive effects of rapamycin in a patient with imatinib-resistant Bcr-Abl+ leukemia. The growth-inhibitory effects of rapamycin on CML cells were found to be associated with G1 cell cycle arrest and with induction of apoptosis. In all cell types tested, rapamycin was found to down-regulate expression of VEGF. However, exogenously added VEGF did not counteract the rapamycin-induced decrease in proliferation. In conclusion, rapamycin inhibits growth of CML cells in vitro and in vivo and, in addition, down-regulates expression of VEGF. Both effects may contribute to the antileukemic activity of the drug in CML.
The FASEB Journal 07/2005; 19(8):960-2. · 5.71 Impact Factor
