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ABSTRACT: Arsenic trioxide (As2O3, arsenite) efficiently kills cells from various hematologic malignancies and has successfully been employed especially for the treatment of acute promyelocytic leukemia. There and in lymphoid cells, we demonstrated that As2O3 induces cell death in a caspase-2- and -9-independent fashion. Here, we address a potential role of death receptor signaling through the FADD/caspase-8 death-inducing signaling complex in As2O3-induced cell death. In detail, we demonstrate that As2O3 induces cell death independently of caspase-8 or FADD and cannot be blocked by disruption of CD95/Fas receptor ligand interaction. Unlike in death receptor ligation-induced apoptosis, As2O3-induced cell death was not blocked by the broad-spectrum caspase inhibitor z-VAD-fmk or the caspase-8-specific inhibitor z-IETD-fmk. Nevertheless, As2O3-induced cell death occurred in a regulated manner and was abrogated upon Bcl-2 overexpression. In contrast, As2O3-induced cell demise was neither blocked by the caspase-9 inhibitor z-LEHD-fmk nor substantially inhibited through the expression of a dominant negative caspase-9 mutant. Altogether our data demonstrate that As2O3-induced cell death occurs independently of the extrinsic death receptor pathway of apoptosis. Cell death proceeds entirely via an intrinsic, Bcl-2-controlled mitochondrial pathway that does, however, not rely on caspase-9.
Oncogene 11/2005; 24(47):7031-42. · 6.37 Impact Factor
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ABSTRACT: Tumor vaccination by the use of gene-modified cancer cells that provide costimulatory signals has been successfully applied in preclinical animal models and is currently evaluated in a variety of clinical settings. In previous work, we demonstrated the efficacy of B7.1/CD80 to promote tumor immunity in syngeneic murine models and to prevent deletion of activated T cells by activation-induced cell death (AICD). In clinical trials, tumor cell vaccines are generally inactivated to avoid transfer of live tumor cells, i.e., additional tumor burden. Previous data indicated, however, that inactivation of tumor cells by lethal ionizing irradiation abrogates tumor vaccination by CD80-expressing cells. Here, we compare living and irradiated allogeneic tumor cells regarding their capacity to induce T-cell effector functions and their propensity to interfere with T-cell deletion by apoptosis. Both lethally irradiated and nonirradiated tumor cells facilitated T-cell proliferation, tumor cell lysis, and interfered with T-cell AICD to a similar extent. In contrast, necrotic tumor cells failed to costimulate T-cell effector functions. Thus, irradiation does not seem to hamper tumor cell-mediated costimulation of T-cell effector functions. In contrast, necrosis of gene-modified tumor cells abrogates costimulation of T cells by CD80-expressing cells.
International Journal of Cancer 09/2005; 116(1):78-86. · 5.44 Impact Factor
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ABSTRACT: Costimulation is essential for induction of T lymphocyte proliferation and inhibition of activation-induced cell death. While signaling pathways activated following the ligation of the costimulatory molecule CD28 are well defined, less is known about the molecular events induced by alternative costimulators. CD137/4-1BB, a costimulatory member of the tumor necrosis factor receptor family, plays an important role during late primary T cell stimulation. Here, we demonstrate for the first time that inhibition of activation-induced cell death by exposure to the CD137/4-1BB ligand involves up-regulation of the anti-apoptotic protein c-FLIP(short). Inhibition of T cell death by 4-1BB ligation and up-regulation of c-FLIP(short) and Bcl-x(L) were abolished by blocking the phosphatidylinositol 3-kinase or the AKT/protein kinase B, which also mediate CD28-induced inhibition of activation-induced cell death. Our findings, therefore, demonstrate that costimulatory molecules, although belonging to different protein families and participating in distinct upstream signaling pathways, employ common downstream signaling pathways.
European Journal of Immunology 05/2005; 35(4):1257-66. · 5.10 Impact Factor
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ABSTRACT: Cell death is generally believed to occur either by accidental, lytic necrosis or by programmed cell death, that is, apoptosis. The initiation and execution of cell death, however, is far more complex and includes pathways like caspase-independent apoptosis or actively triggered necrosis. In this study, we investigated the mechanisms of cell death induced by arsenic trioxide (arsenite, As2O3), a clinically efficient agent in anticancer therapy. As2O3-induced cell death coincides with cytochrome c release, facilitates mitochondrial permeability transition and is sensitive to inhibition by Bcl-x(L), indicating that cell demise is regulated through the mitochondrial apoptosis pathway. Nevertheless, only little caspase-3 activation was observed and As2O3-induced cell death was only weakly obstructed by the broad spectrum caspase inhibitor z-VAD-fmk. Moreover, disruption of caspase-9 or -2 failed to decrease the amount of As2O3-mediated cell death. Interestingly, As2O3-induced cell death had a predominantly necrosis-like phenotype as assessed by Annexin-V/propidium iodide staining and LDH release. Finally, blocking glutathione synthetase by buthionine sulfoximine enhanced the As2O3-mediated necrosis-like cell death without increasing caspase-3 cleavage. As2O3 does, however, not directly inhibit caspases, but appears to interfere with caspase activation. Altogether, our data clearly delineate a mode of As2O3-triggered cell death that differs considerably from that induced by conventional anticancer drugs. These findings may explain the capability of As2O3 to efficiently kill even chemoresistant tumor cells with disturbed apoptosis signaling and caspase activation, a frequent finding in malignancy.
Oncogene 04/2005; 24(11):1904-13. · 6.37 Impact Factor
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ABSTRACT: Patterns of DNA methylation are substantially altered in malignancies compared to normal tissue, with both genome-wide hypomethylation and regional increase of cytosine methylation at dinucleotides of cytosine and guanine, i.e., CpG dinucleotides. While genome-wide hypomethylation renders chromosomes instable, hypermethylation of CpGs in promoter regions is generally associated with transcriptional silencing, e.g., of tumor suppressor genes. To investigate whether disease-specific methylation profiles exist for different entities of acute leukemia, a microarray-based DNA methylation analysis simultaneously assessing 249 CpG dinucleotides originating from 57 genes was employed. Hereby, samples from precursor B-cell acute lymphoblastic leukemia (ALL) could be distinguished from cases of acute myeloid leukemia by virtue of N33, EGR4, CDC2, CCND2, or MOS hypermethylation in ALL.
Annals of Hematology 04/2005; 84(4):236-44. · 2.62 Impact Factor
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ABSTRACT: A combination of docetaxel and fluorouracil (DF) was evaluated in an outpatient setting and compared with epirubicin, cisplatin, and fluorouracil (ECF), which served as an internal control arm to avoid selection bias.
Patients with metastatic or locally advanced gastric adenocarcinoma without prior chemotherapy were randomly assigned to receive either ECF (epirubicin 50 mg/m(2) day 1, cisplatin 60 mg/m(2) day 1, and fluorouracil 200 mg/m(2) days 1 through 21, every 3 weeks) or DF (docetaxel 75 mg/m(2) day 1, and fluorouracil 200 mg/m(2) days 1 through 21, every 3 weeks).
Ninety patients were randomly assigned. Toxicity was rarely severe. Major toxic effects included diarrhea, stomatitis, and leukopenia in the DF arm and nausea, vomiting, and leukopenia in the ECF arm. Forty-three of 45 patients in each arm were assessable. In the DF arm, two patients (4.4%, intent to treat) experienced a confirmed complete tumor remission as best response, and 15 patients (33.3%) experienced a confirmed partial remission (overall response rate [ORR], 37.8%; 95% CI, 25.9% to 51.9%). Two patients (4.4%) in the ECF arm showed confirmed complete remission, and 14 (31.1%) showed confirmed partial remission (ORR, 35.6%; 95% CI, 24.8% to 48.7%). For the DF and ECF arms, the median survival was 9.5 and 9.7 months, and the median time to tumor progression 5.5 and 5.3 months, respectively.
DF can be safely given in an ambulant setting. Compared with ECF, the dual combination of DF shows promising efficacy and may be an alternative treatment option that avoids cisplatin.
Journal of Clinical Oncology 02/2005; 23(3):494-501. · 18.37 Impact Factor
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Péter Adorján,
Jürgen Distler,
Evelyne Lipscher,
Fabian Model,
Jürgen Müller,
Cécile Pelet,
Aron Braun,
Andrea R Florl,
David Gütig,
Gabi Grabs, [......],
Volker Müller,
Thomas Otto, Christian Scholz,
Wolfgang A Schulz,
Hans-Helge Seifert,
Ina Schwope,
Heike Ziebarth,
Kurt Berlin,
Christian Piepenbrock,
Alexander Olek
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ABSTRACT: Aberrant DNA methylation of CpG sites is among the earliest and most frequent alterations in cancer. Several studies suggest that aberrant methylation occurs in a tumour type-specific manner. However, large-scale analysis of candidate genes has so far been hampered by the lack of high throughput assays for methylation detection. We have developed the first microarray-based technique which allows genome-wide assessment of selected CpG dinucleotides as well as quantification of methylation at each site. Several hundred CpG sites were screened in 76 samples from four different human tumour types and corresponding healthy controls. Discriminative CpG dinucleotides were identified for different tissue type distinctions and used to predict the tumour class of as yet unknown samples with high accuracy using machine learning techniques. Some CpG dinucleotides correlate with progression to malignancy, whereas others are methylated in a tissue-specific manner independent of malignancy. Our results demonstrate that genome-wide analysis of methylation patterns combined with supervised and unsupervised machine learning techniques constitute a powerful novel tool to classify human cancers.
Nucleic Acids Research 04/2002; 30(5):e21. · 8.03 Impact Factor
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Peter Adorjan,
Jurgen Distler,
Evelyne Lipscher,
Fabian Model,
Jurgen Muller,
Cecile Pelet,
Aron Braun,
Andrea R Florl,
David Gutig,
Gabi Grabs, [......],
Volker Muller,
Thomas Otto, Christian Scholz,
Wolfgang A Schulz,
Hans H. Seifert,
Ina Schwope,
Heike Ziebarth,
Kurt Berlin,
Christian Piepenbrock,
Alexander Olek
Nucleic Acids Research, v.30, e21-e21 (2002).
