Publications by authors named "Sabine Cerny-Reiterer"

49 Publications

Phenotyping and Target Expression Profiling of CD34/CD38 and CD34/CD38 Stem- and Progenitor cells in Acute Lymphoblastic Leukemia.

Neoplasia 2018 06 15;20(6):632-642. Epub 2018 May 15.

Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria; Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria. Electronic address:

Leukemic stem cells (LSCs) are an emerging target of curative anti-leukemia therapy. In acute lymphoblastic leukemia (ALL), LSCs frequently express CD34 and often lack CD38. However, little is known about markers and targets expressed in ALL LSCs. We have examined marker- and target expression profiles in CD34/CD38 LSCs in patients with Ph ALL (n = 22) and Ph ALL (n = 27) by multi-color flow cytometry and qPCR. ALL LSCs expressed CD19 (B4), CD44 (Pgp-1), CD123 (IL-3RA), and CD184 (CXCR4) in all patients tested. Moreover, in various subgroups of patients, LSCs also displayed CD20 (MS4A1) (10/41 = 24%), CD22 (12/20 = 60%), CD33 (Siglec-3) (20/48 = 42%), CD52 (CAMPATH-1) (17/40 = 43%), IL-1RAP (13/29 = 45%), and/or CD135 (FLT3) (4/20 = 20%). CD25 (IL-2RA) and CD26 (DPPIV) were expressed on LSCs in Ph ALL exhibiting BCR/ABL1, whereas in Ph ALL with BCR/ABL1, LSCs variably expressed CD25 but did not express CD26. In Ph ALL, CD34/CD38 LSCs expressed IL-1RAP in 6/18 patients (33%), but did not express CD25 or CD26. Normal stem cells stained negative for CD25, CD26 and IL-1RAP, and expressed only low amounts of CD52. In xenotransplantation experiments, CD34/CD38 and CD34/CD38 cells engrafted NSG mice after 12-20 weeks, and targeting with antibodies against CD33 and CD52 resulted in reduced engraftment. Together, LSCs in Ph and Ph ALL display unique marker- and target expression profiles. In Ph ALL with BCR/ABL1, the LSC-phenotype closely resembles the marker-profile of CD34/CD38 LSCs in chronic myeloid leukemia, confirming the close biologic relationship of these neoplasms. Targeting of LSCs with specific antibodies or related immunotherapies may facilitate LSC eradication in ALL.
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http://dx.doi.org/10.1016/j.neo.2018.04.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994777PMC
June 2018

The pan-BCL-2-blocker obatoclax (GX15-070) and the PI3-kinase/mTOR-inhibitor BEZ235 produce cooperative growth-inhibitory effects in ALL cells.

Oncotarget 2017 Sep 28;8(40):67709-67722. Epub 2017 Jun 28.

Department of Internal Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna, Vienna, Austria.

Acute lymphoblastic leukemia (ALL) is characterized by leukemic expansion of lymphoid blasts in hematopoietic tissues. Despite improved therapy only a subset of patients can be cured. Therefore, current research is focusing on new drug-targets. Members of the BCL-2 family and components of the PI3-kinase/mTOR pathway are critically involved in the regulation of growth and survival of ALL cells. We examined the effects of the pan-BCL-2 blocker obatoclax and the PI3-kinase/mTOR-inhibitor BEZ235 on growth and survival of ALL cells. In H-thymidine uptake experiments, both drugs suppressed the proliferation of leukemic cells in all patients with Philadelphia chromosome-positive (Ph) ALL and Ph ALL (obatoclax IC: 0.01-5 μM; BEZ235, IC: 0.01-1 μM). Both drugs were also found to produce growth-inhibitory effects in all Ph and all Ph cell lines tested. Moreover, obatoclax and BEZ235 induced apoptosis in ALL cells. In drug-combination experiments, obatoclax and BEZ235 exerted synergistic growth-inhibitory effects on ALL cells. Finally, we confirmed that ALL cells, including CD34/CD38 stem cells and all cell lines express transcripts for PI3-kinase, mTOR, BCL-2, MCL-1, and BCL-xL. Taken together, this data shows that combined targeting of the PI3-kinase/mTOR-pathway and BCL-2 family-members is a potent approach to counteract growth and survival of ALL cells.
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http://dx.doi.org/10.18632/oncotarget.18810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620205PMC
September 2017

Gene expression and mutation-guided synthetic lethality eradicates proliferating and quiescent leukemia cells.

J Clin Invest 2017 Jun 8;127(6):2392-2406. Epub 2017 May 8.

Princess Margaret Cancer Center, Ontario Cancer Institute, Toronto, Ontario, Canada.

Quiescent and proliferating leukemia cells accumulate highly lethal DNA double-strand breaks that are repaired by 2 major mechanisms: BRCA-dependent homologous recombination and DNA-dependent protein kinase-mediated (DNA-PK-mediated) nonhomologous end-joining, whereas DNA repair pathways mediated by poly(ADP)ribose polymerase 1 (PARP1) serve as backups. Here we have designed a personalized medicine approach called gene expression and mutation analysis (GEMA) to identify BRCA- and DNA-PK-deficient leukemias either directly, using reverse transcription-quantitative PCR, microarrays, and flow cytometry, or indirectly, by the presence of oncogenes such as BCR-ABL1. DNA-PK-deficient quiescent leukemia cells and BRCA/DNA-PK-deficient proliferating leukemia cells were sensitive to PARP1 inhibitors that were administered alone or in combination with current antileukemic drugs. In conclusion, GEMA-guided targeting of PARP1 resulted in dual cellular synthetic lethality in quiescent and proliferating immature leukemia cells, and is thus a potential approach to eradicate leukemia stem and progenitor cells that are responsible for initiation and manifestation of the disease. Further, an analysis of The Cancer Genome Atlas database indicated that this personalized medicine approach could also be applied to treat numerous solid tumors from individual patients.
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http://dx.doi.org/10.1172/JCI90825DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5451241PMC
June 2017

The JAK2/STAT5 signaling pathway as a potential therapeutic target in canine mastocytoma.

Vet Comp Oncol 2018 Mar 11;16(1):55-68. Epub 2017 Apr 11.

Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria.

Background: Mastocytoma are frequently diagnosed cutaneous neoplasms in dogs. In non-resectable mastocytoma patients, novel targeted drugs are often applied. The transcription factor STAT5 has been implicated in the survival of human neoplastic mast cells (MC). Our study evaluated the JAK2/STAT5 pathway as a novel target in canine mastocytoma.

Materials And Methods: We employed inhibitors of JAK2 (R763, TG101348, AZD1480, ruxolitinib) and STAT5 (pimozide, piceatannol) and evaluated their effects on 2 mastocytoma cell lines, C2 and NI-1.

Results: Activated JAK2 and STAT5 were detected in both cell lines. The drugs applied were found to inhibit proliferation and survival in these cells with the following rank-order of potency: R763 > TG101348 > AZD1480 > pimozide > ruxolitinib > piceatannol. Moreover, synergistic anti-neoplastic effects were obtained by combining pimozide with KIT-targeting drugs (toceranib, masitinib, nilotinib, midostaurin) in NI-1 cells.

Conclusion: The JAK2/STAT5 pathway is a novel potential target of therapy in canine mastocytoma.
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http://dx.doi.org/10.1111/vco.12311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824979PMC
March 2018

Evaluation of efficacy of alemtuzumab in 5 patients with aplastic anemia and/or myelodysplastic neoplasm.

Wien Klin Wochenschr 2017 Jun 14;129(11-12):404-410. Epub 2016 Oct 14.

Department of Internal Medicine I, Division of Hematology & Hemostaseology, AKH, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.

Patients with aplastic anemia or hypoplastic myelodysplastic syndrome (MDS) may respond to immunosuppressive therapy, including the anti-CD52 antibody alemtuzumab. We analyzed treatment responses to alemtuzumab in 5 patients with MDS or aplastic anemia (AA) evolving to MDS. Two patients with hypoplastic MDS (hMDS) showed a partial response (PR) to alemtuzumab. In both responding patients, a concomitant paroxysmal nocturnal hemoglobinuria (PNH) clone was detected before therapy. One responder relapsed after 15 months and underwent successful allogeneic stem cell transplantation. Both patients are still alive and in remission after 40 and 20 months, respectively. The other patients showed no response to alemtuzumab. One patient died from pneumonia 4 months after treatment. In summary, our data confirm that alemtuzumab is an effective treatment option for a subset of patients with MDS, even in the presence of a PNH clone.
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http://dx.doi.org/10.1007/s00508-016-1091-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5486731PMC
June 2017

Maintenance therapy with histamine plus IL-2 induces a striking expansion of two CD56bright NK cell subpopulations in patients with acute myeloid leukemia and supports their activation.

Oncotarget 2016 Jul;7(29):46466-46481

Department of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria.

Histamine dihydrochloride (HDC) plus IL-2 has been proposed as a novel maintenance-immunotherapy in acute myeloid leukemia (AML). We analyzed the immunophenotype and function of natural killer (NK) cells in blood of AML patients treated after chemotherapy with HDC plus IL-2. The treatment caused a striking expansion of CD56brightCD16neg and CD56brightCD16low NK cell subpopulations. A reduced NK cell fraction recovered and high proportions of cells expressed the activating receptors NKG2D, NKp30, and NKp46. Concomitantly, KIR-expressing NK cells were reduced and NK cells with inhibitory NKG2A/CD94 receptors increased beyond normal levels. In addition, the immunotherapy-induced NK cells exhibited high capacity to produce IFN-γ and to degranulate. Furthermore, we provide evidence from subsequent in vitro studies that this is caused in part by direct effects of IL-2 on the CD56bright cells. IL-2 specifically induced proliferation of both CD56bright subpopulations, but not of CD56dim cells. It further preserved the expression of activating receptors and the capacity to produce IFN-γ and to degranulate. These data suggest that therapy with HDC plus IL-2 supports the reconstitution of a deficient NK cell fraction through the specific amplification of CD56bright NK cells giving rise to a functional NK cell compartment with high potential to combat leukemic disease.
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http://dx.doi.org/10.18632/oncotarget.10191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5216810PMC
July 2016

Normal ABL1 is a tumor suppressor and therapeutic target in human and mouse leukemias expressing oncogenic ABL1 kinases.

Blood 2016 04 10;127(17):2131-43. Epub 2016 Feb 10.

Department of Microbiology & Immunology, Temple University School of Medicine, Philadelphia, PA;

Leukemias expressing constitutively activated mutants of ABL1 tyrosine kinase (BCR-ABL1, TEL-ABL1, NUP214-ABL1) usually contain at least 1 normal ABL1 allele. Because oncogenic and normal ABL1 kinases may exert opposite effects on cell behavior, we examined the role of normal ABL1 in leukemias induced by oncogenic ABL1 kinases. BCR-ABL1-Abl1(-/-) cells generated highly aggressive chronic myeloid leukemia (CML)-blast phase-like disease in mice compared with less malignant CML-chronic phase-like disease from BCR-ABL1-Abl1(+/+) cells. Additionally, loss of ABL1 stimulated proliferation and expansion of BCR-ABL1 murine leukemia stem cells, arrested myeloid differentiation, inhibited genotoxic stress-induced apoptosis, and facilitated accumulation of chromosomal aberrations. Conversely, allosteric stimulation of ABL1 kinase activity enhanced the antileukemia effect of ABL1 tyrosine kinase inhibitors (imatinib and ponatinib) in human and murine leukemias expressing BCR-ABL1, TEL-ABL1, and NUP214-ABL1. Therefore, we postulate that normal ABL1 kinase behaves like a tumor suppressor and therapeutic target in leukemias expressing oncogenic forms of the kinase.
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http://dx.doi.org/10.1182/blood-2015-11-681171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4850868PMC
April 2016

Identification of CD25 as STAT5-Dependent Growth Regulator of Leukemic Stem Cells in Ph+ CML.

Clin Cancer Res 2016 Apr 25;22(8):2051-61. Epub 2015 Nov 25.

Division of Hematology and Hemostaseology, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria. Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Vienna, Austria.

Purpose: In chronic myelogenous leukemia (CML), leukemic stem cells (LSC) represent a critical target of therapy. However, little is known about markers and targets expressed by LSCs. The aim of this project was to identify novel relevant markers of CML LSCs.

Experimental Design: CML LSCs were examined by flow cytometry, qPCR, and various bioassays. In addition, we examined the multipotent CD25(+)CML cell line KU812.

Results: In contrast to normal hematopoietic stem cells, CD34(+)/CD38(-)CML LSCs expressed the IL-2 receptor alpha chain, IL-2RA (CD25). STAT5 was found to induce expression of CD25 in Lin(-)/Sca-1(+)/Kit(+)stem cells in C57Bl/6 mice. Correspondingly, shRNA-induced STAT5 depletion resulted in decreased CD25 expression in KU812 cells. Moreover, the BCR/ABL1 inhibitors nilotinib and ponatinib were found to decrease STAT5 activity and CD25 expression in KU812 cells and primary CML LSCs. A CD25-targeting shRNA was found to augment proliferation of KU812 cellsin vitroand their engraftmentin vivoin NOD/SCID-IL-2Rγ(-/-)mice. In drug-screening experiments, the PI3K/mTOR blocker BEZ235 promoted the expression of STAT5 and CD25 in CML cells. Finally, we found that BEZ235 produces synergistic antineoplastic effects on CML cells when applied in combination with nilotinib or ponatinib.

Conclusions: CD25 is a novel STAT5-dependent marker of CML LSCs and may be useful for LSC detection and LSC isolation in clinical practice and basic science. Moreover, CD25 serves as a growth regulator of CML LSCs, which may have biologic and clinical implications and may pave the way for the development of new more effective LSC-eradicating treatment strategies in CML.
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http://dx.doi.org/10.1158/1078-0432.CCR-15-0767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817228PMC
April 2016

Identification of the Ki-1 antigen (CD30) as a novel therapeutic target in systemic mastocytosis.

Blood 2015 Dec 20;126(26):2832-41. Epub 2015 Oct 20.

Department of Internal Medicine I, Division of Hematology and Hemostaseology and Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Vienna, Austria;

The Ki-1 antigen (CD30) is an established therapeutic target in patients with Hodgkin lymphoma and anaplastic large-cell lymphoma. We have recently shown that CD30 is expressed abundantly in the cytoplasm of neoplastic mast cells (MCs) in patients with advanced systemic mastocytosis (SM). In the current study, we asked whether CD30 is expressed on the surface of neoplastic MCs in advanced SM, and whether this surface structure may serve as therapeutic target in SM. As assessed by flow cytometry, CD30 was found to be expressed on the surface of neoplastic MCs in 3 of 25 patients (12%) with indolent SM, 4 of 7 patients (57%) with aggressive SM, and 4 of 7 patients (57%) with MC leukemia. The immature RAS-transformed human MC line MCPV-1.1 also expressed cell surface CD30, whereas the KIT-transformed MC line HMC-1.2 expressed no detectable CD30. The CD30-targeting antibody-conjugate brentuximab-vedotin inhibited proliferation in neoplastic MCs, with lower IC50 values obtained in CD30(+) MCPV-1.1 cells (10 µg/mL) compared with CD30(-) HMC-1.2 cells (>50 µg/mL). In addition, brentuximab-vedotin suppressed the engraftment of MCPV-1.1 cells in NSG mice. Moreover, brentuximab-vedotin produced apoptosis in all CD30(+) MC lines tested as well as in primary neoplastic MCs in patients with CD30(+) SM, but did not induce apoptosis in neoplastic MCs in patients with CD30(-) SM. Furthermore, brentuximab-vedotin was found to downregulate anti-IgE-induced histamine release in CD30(+) MCs. Finally, brentuximab-vedotin and the KIT D816V-targeting drug PKC412 produced synergistic growth-inhibitory effects in MCPV-1.1 cells. Together, CD30 is a promising new drug target for patients with CD30(+) advanced SM.
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http://dx.doi.org/10.1182/blood-2015-03-637728DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692143PMC
December 2015

Transcriptional plasticity promotes primary and acquired resistance to BET inhibition.

Nature 2015 Sep 14;525(7570):543-547. Epub 2015 Sep 14.

Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), 1030 Vienna, Austria.

Following the discovery of BRD4 as a non-oncogene addiction target in acute myeloid leukaemia (AML), bromodomain and extra terminal protein (BET) inhibitors are being explored as a promising therapeutic avenue in numerous cancers. While clinical trials have reported single-agent activity in advanced haematological malignancies, mechanisms determining the response to BET inhibition remain poorly understood. To identify factors involved in primary and acquired BET resistance in leukaemia, here we perform a chromatin-focused RNAi screen in a sensitive MLL-AF9;Nras(G12D)-driven AML mouse model, and investigate dynamic transcriptional profiles in sensitive and resistant mouse and human leukaemias. Our screen shows that suppression of the PRC2 complex, contrary to effects in other contexts, promotes BET inhibitor resistance in AML. PRC2 suppression does not directly affect the regulation of Brd4-dependent transcripts, but facilitates the remodelling of regulatory pathways that restore the transcription of key targets such as Myc. Similarly, while BET inhibition triggers acute MYC repression in human leukaemias regardless of their sensitivity, resistant leukaemias are uniformly characterized by their ability to rapidly restore MYC transcription. This process involves the activation and recruitment of WNT signalling components, which compensate for the loss of BRD4 and drive resistance in various cancer models. Dynamic chromatin immunoprecipitation sequencing and self-transcribing active regulatory region sequencing of enhancer profiles reveal that BET-resistant states are characterized by remodelled regulatory landscapes, involving the activation of a focal MYC enhancer that recruits WNT machinery in response to BET inhibition. Together, our results identify and validate WNT signalling as a driver and candidate biomarker of primary and acquired BET resistance in leukaemia, and implicate the rewiring of transcriptional programs as an important mechanism promoting resistance to BET inhibitors and, potentially, other chromatin-targeted therapies.
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http://dx.doi.org/10.1038/nature14898DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4921058PMC
September 2015

Cancer stem cells in basic science and in translational oncology: can we translate into clinical application?

J Hematol Oncol 2015 Feb 25;8:16. Epub 2015 Feb 25.

Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Spitalgasse 23, Vienna, 1090, Wien, Austria.

Since their description and identification in leukemias and solid tumors, cancer stem cells (CSC) have been the subject of intensive research in translational oncology. Indeed, recent advances have led to the identification of CSC markers, CSC targets, and the preclinical and clinical evaluation of the CSC-eradicating (curative) potential of various drugs. However, although diverse CSC markers and targets have been identified, several questions remain, such as the origin and evolution of CSC, mechanisms underlying resistance of CSC against various targeted drugs, and the biochemical basis and function of stroma cell-CSC interactions in the so-called 'stem cell niche.' Additional aspects that have to be taken into account when considering CSC elimination as primary treatment-goal are the genomic plasticity and extensive subclone formation of CSC. Notably, various cell fractions with different combinations of molecular aberrations and varying proliferative potential may display CSC function in a given neoplasm, and the related molecular complexity of the genome in CSC subsets is considered to contribute essentially to disease evolution and acquired drug resistance. In the current article, we discuss new developments in the field of CSC research and whether these new concepts can be exploited in clinical practice in the future.
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http://dx.doi.org/10.1186/s13045-015-0113-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4345016PMC
February 2015

Long-term treatment with imatinib results in profound mast cell deficiency in Ph+ chronic myeloid leukemia.

Oncotarget 2015 Feb;6(5):3071-84

Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Austria.

Although mast cells (MC) play an important role in allergic reactions, their physiologic role remains unknown. In mice, several models of MC-deficiency have been developed. However, no comparable human model is available. We examined the in vitro- and in vivo effects of the KIT-targeting drug imatinib on growth and development of human MC. Imatinib was found to inhibit stem cell factor (SCF)-induced differentiation of MC in long-term suspension cultures (IC50: 0.01 µM). Correspondingly, long-term treatment of chronic myeloid leukemia (CML) patients with imatinib (400 mg/day) resulted in a marked decrease in MC. In patients with continuous complete molecular response during therapy, bone marrow MC decreased to less than 5% of pre-treatment values, and also serum tryptase concentrations decreased significantly (pre-treatment: 32.0 ± 11.1 ng/ml; post-therapy: 3.4 ± 1.8, p<0.01). Other myeloid lineages, known to develop independently of KIT, were not affected by imatinib-therapy. Imatinib also produced a substantial decrease in MC-development in mice. However, no clinical syndrome attributable to drug-induced MC-deficiency was recorded in our CML patients. Together, imatinib suppresses MC production in vitro and in vivo. However, drug-induced MC depletion is not accompanied by adverse clinical events, suggesting that MC are less relevant to homeostasis in healthy tissues than we assumed so far.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4413638PMC
http://dx.doi.org/10.18632/oncotarget.3074DOI Listing
February 2015

DPPIV (CD26) as a novel stem cell marker in Ph+ chronic myeloid leukaemia.

Eur J Clin Invest 2014 Dec;44(12):1239-45

Division of Haematology & Hemostaseology, Department of Internal Medicine I, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Vienna, Austria.

The concept of leukaemic stem cells (LSCs) has been developed to explain the complex cellular hierarchy and biology of leukaemias and to screen for pivotal targets that can be employed to improve drug therapies through LSC eradication in these patients. Some of the newly discovered LSC markers seem to be expressed in a disease-specific manner and may thus serve as major research tools and diagnostic parameters. A useful LSC marker in chronic myeloid leukaemia (CML) appears to be CD26, also known as dipeptidylpeptidase IV. Expression of CD26 is largely restricted to CD34(+) /CD38(-) LSCs in BCR/ABL1(+) CML, but is not found on LSCs in other myeloid or lymphoid neoplasms, with the exception of lymphoid blast crisis of CML, BCR/ABL1p210 + acute lymphoblastic leukaemia, and a very few cases of acute myeloid leukaemia. Moreover, CD26 usually is not expressed on normal bone marrow (BM) stem cells. Functionally, CD26 is a cytokine-targeting surface enzyme that may facilitate the mobilization of LSCs from the BM niche. In this article, we review our current knowledge about the biology and function of CD26 on CML LSCs and discuss the diagnostic potential of this new LSC marker in clinical haematology.
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http://dx.doi.org/10.1111/eci.12368DOI Listing
December 2014

Chronic mast cell leukemia (MCL) with KIT S476I: a rare entity defined by leukemic expansion of mature mast cells and absence of organ damage.

Ann Hematol 2015 Feb 11;94(2):223-31. Epub 2014 Sep 11.

Department of Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria,

Mast cell leukemia (MCL) is a rare, life-threatening malignancy defined by a substantial increase in neoplastic mast cells (MCs) in bone marrow (BM) smears, drug-resistance, and a poor prognosis. In most patients, the survival time is less than 1 year. However, exceptional cases may present with a less malignant course. We report on a 49-year-old female patient with MCL diagnosed in 2013. In February 2013, first symptoms, including flushing, headache, and diarrhea, were recorded. In addition, mild anemia was detected. The disease was characterized by a massive increase in well-granulated, mature, and often spindle-shaped MCs (80 %) in BM smears. The serum tryptase level amounted to 332 ng/mL. Like in most other MCL patients, no skin lesions were detected. However, unlike in other patients, tryptase levels remained stable, and no other signs or symptoms of MCL-induced organ damage were found. Sequencing studies revealed an isolated S476I point mutation in KIT but no mutation in codon 816. The patient received histamine receptor blockers but refused cytoreductive therapy. After 9 months, still no progression or organ damage was detected. However, progression with transformation to acute MCL occurred after 12 months. We propose that the chronic type of MCL with stable conditions, absence of organ damage, and a mature MC morphology is recognized as a distinct entity that should be distinguished from the acute variant of MCL.
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http://dx.doi.org/10.1007/s00277-014-2207-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4896380PMC
February 2015

Identification of campath-1 (CD52) as novel drug target in neoplastic stem cells in 5q-patients with MDS and AML.

Clin Cancer Res 2014 Jul 5;20(13):3589-602. Epub 2014 May 5.

Authors' Affiliations: Department of Internal Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna, Austria; Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Austria;

Purpose: The CD52-targeted antibody alemtuzumab induces major clinical responses in a group of patients with myelodysplastic syndromes (MDS). The mechanism underlying this drug effect remains unknown.

Experimental Design: We asked whether neoplastic stem cells (NSC) in patients with MDS (n = 29) or acute myelogenous leukemia (AML; n = 62) express CD52.

Results: As assessed by flow cytometry, CD52 was found to be expressed on NSC-enriched CD34(+)/CD38(-) cells in 8/11 patients with MDS and isolated del(5q). In most other patients with MDS, CD52 was weakly expressed or not detectable on NSC. In AML, CD34(+)/CD38(-) cells displayed CD52 in 23/62 patients, including four with complex karyotype and del(5q) and one with del(5q) and t(1;17;X). In quantitative PCR (qPCR) analyses, purified NSC obtained from del(5q) patients expressed CD52 mRNA. We were also able to show that CD52 mRNA levels correlate with EVI1 expression and that NRAS induces the expression of CD52 in AML cells. The CD52-targeting drug alemtuzumab, was found to induce complement-dependent lysis of CD34(+)/CD38(-)/CD52(+) NSC, but did not induce lysis in CD52(-) NSC. Alemtuzumab also suppressed engraftment of CD52(+) NSC in NSG mice. Finally, CD52 expression on NSC was found to correlate with a poor survival in patients with MDS and AML.

Conclusions: The cell surface target Campath-1 (CD52) is expressed on NSC in a group of patients with MDS and AML. CD52 is a novel prognostic NSC marker and a potential NSC target in a subset of patients with MDS and AML, which may have clinical implications and may explain clinical effects produced by alemtuzumab in these patients.
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http://dx.doi.org/10.1158/1078-0432.CCR-13-2811DOI Listing
July 2014

Dipeptidylpeptidase IV (CD26) defines leukemic stem cells (LSC) in chronic myeloid leukemia.

Blood 2014 Jun 28;123(25):3951-62. Epub 2014 Apr 28.

Ludwig Boltzmann Cluster Oncology, and Department of Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna, Vienna, Austria;

Chronic myeloid leukemia (CML) is a stem cell (SC) neoplasm characterized by the BCR/ABL1 oncogene. Although mechanisms of BCR/ABL1-induced transformation are well-defined, little is known about effector-molecules contributing to malignant expansion and the extramedullary spread of leukemic SC (LSC) in CML. We have identified the cytokine-targeting surface enzyme dipeptidylpeptidase-IV (DPPIV/CD26) as a novel, specific and pathogenetically relevant biomarker of CD34(+)/CD38(─) CML LSC. In functional assays, CD26 was identified as target enzyme disrupting the SDF-1-CXCR4-axis by cleaving SDF-1, a chemotaxin recruiting CXCR4(+) SC. CD26 was not detected on normal SC or LSC in other hematopoietic malignancies. Correspondingly, CD26(+) LSC decreased to low or undetectable levels during successful treatment with imatinib. CD26(+) CML LSC engrafted NOD-SCID-IL-2Rγ(-/-) (NSG) mice with BCR/ABL1(+) cells, whereas CD26(─) SC from the same patients produced multilineage BCR/ABL1(-) engraftment. Finally, targeting of CD26 by gliptins suppressed the expansion of BCR/ABL1(+) cells. Together, CD26 is a new biomarker and target of CML LSC. CD26 expression may explain the abnormal extramedullary spread of CML LSC, and inhibition of CD26 may revert abnormal LSC function and support curative treatment approaches in this malignancy.
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http://dx.doi.org/10.1182/blood-2013-10-536078DOI Listing
June 2014

CD52 is a molecular target in advanced systemic mastocytosis.

FASEB J 2014 Aug 23;28(8):3540-51. Epub 2014 Apr 23.

Ludwig Boltzmann Institute of Osteology, Hanusch Hospital, Vienna, Austria

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.
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http://dx.doi.org/10.1096/fj.14-250894DOI Listing
August 2014

Identification of heat shock protein 32 (Hsp32) as a novel target in acute lymphoblastic leukemia.

Oncotarget 2014 Mar;5(5):1198-211

Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Austria.

Heat shock proteins (Hsp) are increasingly employed as therapeutic targets in oncology. We have shown that Hsp32, also known as heme oxygenase-1 (HO-1), serves as survival factor and potential target in Ph+ chronic myeloid leukemia. We here report that primary cells and cell lines derived from patients with acute lymphoblastic leukemia (ALL) express Hsp32 mRNA and the Hsp32 protein in a constitutive manner. Highly enriched CD34+/CD38- ALL stem cells also expressed Hsp32. Two Hsp32-targeting drugs, pegylated zinc protoporphyrine (PEG-ZnPP) and styrene maleic acid-micelle-encapsulated ZnPP (SMA-ZnPP), induced apoptosis and growth arrest in the BCR/ABL1+ cell lines, in Ph- lymphoblastic cell lines and in primary Ph+ and Ph- ALL cells. The effects of PEG-ZnPP and SMA-ZnPP on growth of leukemic cells were dose-dependent. In Ph+ ALL, major growth-inhibitory effects of the Hsp32-targeting drugs were observed in imatinib-sensitive and imatinib-resistant cells. Hsp32-targeting drugs were found to synergize with imatinib, nilotinib, and bendamustine in producing growth inhibition and apoptosis in Ph+ ALL cells. A siRNA against Hsp32 was found to inhibit growth and survival of ALL cells and to synergize with imatinib in suppressing the growth of ALL cells. In conclusion, Hsp32 is an essential survival factor and potential new target in ALL.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012724PMC
http://dx.doi.org/10.18632/oncotarget.1805DOI Listing
March 2014

A new human mast cell line expressing a functional IgE receptor converts to tumorigenic growth by KIT D816V transfection.

Blood 2014 Jul 27;124(1):111-20. Epub 2014 Mar 27.

Laboratoire de Biologie et Pharmacologie Appliquée, Centre Nationale de la Recherche, Unité Mixte de Recherche 8113, Ecole Normale Supérieure de Cachan, Cachan, France; Laboratoire Central d'Hématologie, Groupe Hospitalier Pitié-Salpêtrière, Paris, France;

In systemic mastocytosis (SM), clinical problems arise from factor-independent proliferation of mast cells (MCs) and the increased release of mediators by MCs, but no human cell line model for studying MC activation in the context of SM is available. We have created a stable stem cell factor (SCF) -dependent human MC line, ROSA(KIT WT), expressing a fully functional immunoglobulin E (IgE) receptor. Transfection with KIT D816V converted ROSA(KIT WT) cells into an SCF-independent clone, ROSA(KIT D816V), which produced a mastocytosis-like disease in NSG mice. Although several signaling pathways were activated, ROSA(KIT D816V) did not exhibit an increased, but did exhibit a decreased responsiveness to IgE-dependent stimuli. Moreover, NSG mice bearing ROSA(KIT D816V)-derived tumors did not show mediator-related symptoms, and KIT D816V-positive MCs obtained from patients with SM did not show increased IgE-dependent histamine release or CD63 upregulation. Our data show that KIT D816V is a disease-propagating oncoprotein, but it does not activate MCs to release proinflammatory mediators, which may explain why mediator-related symptoms in SM occur preferentially in the context of a coexisting allergy. ROSA(KIT D816V) may provide a valuable tool for studying the pathogenesis of mastocytosis and should facilitate the development of novel drugs for treating SM patients.
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http://dx.doi.org/10.1182/blood-2013-10-534685DOI Listing
July 2014

Co-operating STAT5 and AKT signaling pathways in chronic myeloid leukemia and mastocytosis: possible new targets of therapy.

Haematologica 2014 Mar;99(3):417-29

Chronic myeloid leukemia and systemic mastocytosis are myeloid neoplasms sharing a number of pathogenetic and clinical features. In both conditions, an aberrantly activated oncoprotein with tyrosine kinase activity, namely BCR-ABL1 in chronic myeloid leukemia, and mutant KIT, mostly KIT D816V, in systemic mastocytosis, is key to disease evolution. The appreciation of the role of such tyrosine kinases in these diseases has led to the development of improved therapies with tyrosine kinase-targeted inhibitors. However, most drugs, including new KIT D816V-blocking agents, have failed to achieve long-lasting remissions in advanced systemic mastocytosis, and there is a similar problem in chronic myeloid leukemia, where imatinib-resistant patients sometimes fail to achieve remission, even with second- or third-line BCR-ABL1 specific tyrosine kinase inhibitors. During disease progression, additional signaling pathways become activated in neoplastic cells, but most converge into major downstream networks. Among these, the AKT and STAT5 pathways appear most critical and may result in drug-resistant chronic myeloid leukemia and systemic mastocytosis. Inhibition of phosphorylation of these targets has proven their crucial role in disease-evolution in both malignancies. Together, these observations suggest that STAT5 and AKT are key drivers of oncogenesis in drug-resistant forms of the diseases, and that targeting STAT5 and AKT might be an interesting approach in these malignancies. The present article provides an overview of our current knowledge about the critical role of AKT and STAT5 in the pathophysiology of chronic myeloid leukemia and systemic mastocytosis and on their potential value as therapeutic targets in these neoplasms.
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http://dx.doi.org/10.3324/haematol.2013.098442DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943304PMC
March 2014

FLAG-induced remission in a patient with acute mast cell leukemia (MCL) exhibiting t(7;10)(q22;q26) and KIT D816H.

Leuk Res Rep 2014 26;3(1):8-13. Epub 2013 Nov 26.

Institute of Pathology, Ludwig-Maximilians-University, Munich, Germany.

Mast cell leukemia (MCL) is a life-threatening disease associated with high mortality and drug-resistance. Only few patients survive more than 12 months. We report on a 55-year-old female patient with acute MCL diagnosed in May 2012. The disease was characterized by a rapid increase in white blood cells and mast cells (MC) in the peripheral blood, and a rapid increase of serum tryptase levels. The KIT D816H mutation was detected in the blood and bone marrow (BM). Induction chemotherapy with high-dose ARA-C and fludarabine (FLAG) was administered. Unexpectedly, the patient entered a hematologic remission with almost complete disappearance of neoplastic MC and a decrease of serum tryptase levels to normal range after 2 cycles of FLAG. Consecutively, the patient was prepared for allogeneic stem cell transplantation. However, shortly after the third cycle of FLAG, tryptase levels increased again, immature MC appeared in the blood, and the patient died from cerebral bleeding. Together, this case shows that intensive chemotherapy regimens, like FLAG, may induce remission in acute MCL. However, treatment responses are short-lived and the overall outcome remains dismal in these patients. We propose to separate this acute type of MCL from more subacute or chronic variants of MCL.
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http://dx.doi.org/10.1016/j.lrr.2013.11.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3939382PMC
March 2014

Long-lasting complete response to imatinib in a patient with systemic mastocytosis exhibiting wild type KIT.

Am J Blood Res 2014 15;4(2):93-100. Epub 2014 Dec 15.

Ludwig Boltzmann Cluster Oncology, Medical University of Vienna Austria ; Department of Dermatology, Medical University of Vienna Austria.

Systemic mastocytosis (SM) is a hematopoietic disorder characterized by abnormal expansion of mast cells (MCs) in visceral organs. The skin is involved in most cases. In adult patients the transforming KIT mutation D816V is usually present and confers resistance against imatinib. Therefore, imatinib is not recommended for patients with KIT D816V+ SM. Nonetheless, imatinib may work in patients with SM lacking KIT D816V. However, little is known about long-term efficacy and safety of this drug in SM. We report on a 62-year-old female patient with indolent SM (ISM) who suffered from severe debilitating skin involvement despite therapy with anti-mediator-type drugs, psoralen and ultraviolet-A-radiation. Although multifocal MC infiltrates were detected in the bone marrow by immunohistochemistry, no KIT mutation was found by sequencing analysis. In 2003, treatment with imatinib (induction, 400 mg/day; maintenance, 200 mg/day) was initiated. During therapy, skin lesions and tryptase levels decreased. Treatment was well tolerated without any side effects. After 10 years, skin lesions have disappeared and the tryptase level is within normal range. This case-study confirms the long-term efficacy and safety of imatinib in patients with SM lacking activating KIT mutations. Imatinib should be considered in select cases of SM in whom MCs exhibit wild-type KIT.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351647PMC
March 2015

A target-disease network model of second-generation BCR-ABL inhibitor action in Ph+ ALL.

PLoS One 2013 10;8(10):e77155. Epub 2013 Oct 10.

CeMM - Research Center, Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is in part driven by the tyrosine kinase bcr-abl, but imatinib does not produce long-term remission. Therefore, second-generation ABL inhibitors are currently in clinical investigation. Considering different target specificities and the pronounced genetic heterogeneity of Ph+ ALL, which contributes to the aggressiveness of the disease, drug candidates should be evaluated with regard to their effects on the entire Ph+ ALL-specific signaling network. Here, we applied an integrated experimental and computational approach that allowed us to estimate the differential impact of the bcr-abl inhibitors nilotinib, dasatinib, Bosutinib and Bafetinib. First, we determined drug-protein interactions in Ph+ ALL cell lines by chemical proteomics. We then mapped those interactions along with known genetic lesions onto public protein-protein interactions. Computation of global scores through correlation of target affinity, network topology, and distance to disease-relevant nodes assigned the highest impact to dasatinib, which was subsequently confirmed by proliferation assays. In future, combination of patient-specific genomic information with detailed drug target knowledge and network-based computational analysis should allow for an accurate and individualized prediction of therapy.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077155PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3795025PMC
June 2014

The pan-Bcl-2 blocker obatoclax promotes the expression of Puma, Noxa, and Bim mRNA and induces apoptosis in neoplastic mast cells.

J Leukoc Biol 2014 Jan 19;95(1):95-104. Epub 2013 Sep 19.

1.Division of Hematology and Hemostaseology and Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, A-1090 Vienna, Austria.

Advanced SM is an incurable neoplasm with short survival time. So far, no effective therapy is available for these patients. We and others have shown recently that neoplastic MC in ASM and MCL express antiapoptotic Mcl-1, Bcl-2, and Bcl-xL. In this study, we examined the effects of the pan-Bcl-2 family blocker obatoclax (GX015-070) on primary neoplastic MC, the human MC leukemia cell line HMC-1, and the canine mastocytoma cell line C2. Obatoclax was found to inhibit proliferation in primary human neoplastic MC (IC₅₀: 0.057 μM), in HMC-1.2 cells expressing KIT D816V (IC₅₀: 0.72 μM), and in HMC-1.1 cells lacking KIT D816V (IC₅₀: 0.09 μM), as well as in C2 cells (IC₅₀: 0.74 μM). The growth-inhibitory effects of obatoclax in HMC-1 cells were accompanied by an increase in expression of Puma, Noxa, and Bim mRNA, as well as by apoptosis, as evidenced by microscopy, TUNEL assay, and caspase cleavage. Viral-mediated overexpression of Mcl-1, Bcl-xL, or Bcl-2 in HMC-1 cells was found to introduce partial resistance against apoptosis-inducing effects of obatoclax. We were also able to show that obatoclax synergizes with several other antineoplastic drugs, including dasatinib, midostaurin, and bortezomib, in producing apoptosis and/or growth arrest in neoplastic MC. Together, obatoclax exerts major growth-inhibitory effects on neoplastic MC and potentiates the antineoplastic activity of other targeted drugs. Whether these drug effects can be translated to application in patients with advanced SM remains to be determined.
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http://dx.doi.org/10.1189/jlb.1112609DOI Listing
January 2014

Overexpression of primary microRNA 221/222 in acute myeloid leukemia.

BMC Cancer 2013 Jul 29;13:364. Epub 2013 Jul 29.

Department of Medicine I, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria.

Background: Acute myeloid leukemia (AML) is a hematopoietic malignancy with a dismal outcome in the majority of cases. A detailed understanding of the genetic alterations and gene expression changes that contribute to its pathogenesis is important to improve prognostication, disease monitoring, and therapy. In this context, leukemia-associated misexpression of microRNAs (miRNAs) has been studied, but no coherent picture has emerged yet, thus warranting further investigations.

Methods: The expression of 636 human miRNAs was compared between samples from 52 patients with AML and 13 healthy individuals by highly specific locked nucleic acid (LNA) based microarray technology. The levels of individual mature miRNAs and of primary miRNAs (pri-miRs) were determined by quantitative reverse transcriptase (qRT) PCR. Transfections and infections of human cell lines were performed using standard procedures.

Results: 64 miRNAs were significantly differentially expressed between AML and controls. Further studies on the clustered miRNAs 221 and 222, already known to act as oncogenes in other tumor types, revealed a deficiency of human myeloid cell lines to process vector derived precursor transcripts. Moreover, endogenous pri-miR-221/222 was overexpressed to a substantially higher extent than its mature products in most primary AML samples, indicating that its transcription was enhanced, but processing was rate limiting, in these cells. Comparison of samples from the times of diagnosis, remission, and relapse of AML demonstrated that pri-miR-221/222 levels faithfully reflected the stage of disease.

Conclusions: Expression of some miRNAs is strongly regulated at the posttranscriptional level in AML. Pri-miR-221/222 represents a novel molecular marker and putative oncogene in this disease.
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http://dx.doi.org/10.1186/1471-2407-13-364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733744PMC
July 2013

STAT5 triggers BCR-ABL1 mutation by mediating ROS production in chronic myeloid leukaemia.

Oncotarget 2012 Dec;3(12):1669-87

Institute of Pharmacology and Toxicology, Veterinary University Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.

We recently reported that chronic myeloid leukaemia (CML) patients harbour high levels of STAT5 when they progress to advanced phases of disease. Advanced disease is characterized by an increased incidence of BCR-ABL1 mutations. We now describe a highly significant correlation between STAT5 expression and the incidence of BCR-ABL1 mutations in primary CML. Forced expression of STAT5 in murine BCR-ABL1 transformed cells sufficed to enhance the production of reactive oxygen species (ROS) and to trigger DNA damage. STAT5-mediated ROS production is independent of JAK2 but requires concomitant BCR-ABL1 signalling as forced STAT5 expression in untransformed BCR-ABL1 negative cells has no impact on ROS levels. Only within the context of a BCR-ABL1 positive cell does STAT5 transcriptionally regulate a target gene or set of genes that causes the enhanced ROS production. Our study suggests the existence of a feed-forward loop accelerating disease progression, in which BCR-ABL1 enhances its own mutation rate in a STAT5-ROS dependent manner. This model explains the increased occurrence of inhibitor-resistant BCR-ABL1 mutations in advanced disease stages driven and characterized by high STAT5 expression.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681503PMC
http://dx.doi.org/10.18632/oncotarget.806DOI Listing
December 2012

Small-molecule inhibition of BRD4 as a new potent approach to eliminate leukemic stem- and progenitor cells in acute myeloid leukemia AML.

Oncotarget 2012 Dec;3(12):1588-99

Ludwig Boltzmann Cluster Oncology, Vienna, Austria.

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.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3681497PMC
http://dx.doi.org/10.18632/oncotarget.733DOI Listing
December 2012

Cancer stem cell definitions and terminology: the devil is in the details.

Nat Rev Cancer 2012 11 11;12(11):767-75. Epub 2012 Oct 11.

The Department of Internal Medicine I, Division of Hematology & Hemostaseology, Medical University of Vienna & Ludwig-Boltzmann Cluster Oncology, Waehringer Guertel 18-20, A-1090 Vienna, Austria.

The cancer stem cell (CSC) concept has important therapeutic implications, but its investigation has been hampered both by a lack of consistency in the terms used for these cells and by how they are defined. Evidence of their heterogeneous origins, frequencies and their genomic, as well as their phenotypic and functional, properties has added to the confusion and has fuelled new ideas and controversies. Participants in The Year 2011 Working Conference on CSCs met to review these issues and to propose a conceptual and practical framework for CSC terminology. More precise reporting of the parameters that are used to identify CSCs and to attribute responses to them is also recommended as key to accelerating an understanding of their biology and developing more effective methods for their eradication in patients.
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http://dx.doi.org/10.1038/nrc3368DOI Listing
November 2012

Anti-Fas/CD95 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) differentially regulate apoptosis in normal and neoplastic human basophils.

Leuk Lymphoma 2013 Apr 9;54(4):835-42. Epub 2012 Oct 9.

Department of Dermatology, University of Cologne, Cologne, Germany.

Basophilia is associated with allergic and parasitic diseases and advanced chronic myeloid leukemia. In the present study, we characterized the expression and function of the death receptors Fas/CD95 and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors in basophils from healthy donors compared to neoplastic basophils. Peripheral blood basophils obtained from healthy donors (HD-PBB) and from patients with chronic myeloid leukemia (CML-PBB) were found to express high levels of Fas/CD95 and low levels of TRAIL-R2, whereas the basophil-like chronic myeloid leukemia cell line KU-812 expressed significant levels of TRAIL-R1 and TRAIL-R2. HD-PBB underwent apoptosis in response to anti-Fas/CD95, but showed resistance to TRAIL, unless they were co-treated with actinomycin D. Interestingly, CML-PBB and KU-812 cells exhibited the opposite response pattern with resistance to anti-Fas/CD95, but significant susceptibility to TRAIL-induced apoptosis. Our data show that anti-Fas/CD95 and TRAIL differentially regulate apoptosis of normal and neoplastic human basophils, which may direct the development of novel therapeutic strategies.
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http://dx.doi.org/10.3109/10428194.2012.731600DOI Listing
April 2013

Identification of basophils as a major source of hepatocyte growth factor in chronic myeloid leukemia: a novel mechanism of BCR-ABL1-independent disease progression.

Neoplasia 2012 Jul;14(7):572-84

Ludwig Boltzmann Cluster Oncology, Vienna, Austria.

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.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3421954PMC
http://dx.doi.org/10.1593/neo.12724DOI Listing
July 2012